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APOE ε4 associated with preserved executive function performance and maintenance of temporal and cingulate brain volumes in younger adults. Brain Imaging Behav 2018; 11:194-204. [PMID: 26843007 DOI: 10.1007/s11682-016-9522-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
The APOE ε4 allele is associated with cognitive deficits and brain atrophy in older adults, but studies in younger adults are mixed. We examined APOE genotype effects on cognition and brain structure in younger adults and whether genotype effects differed by age and with presence of depression. 157 adults (32 % ε4 carriers, 46 % depressed) between 20 and 50 years of age completed neuropsychological testing, 131 of which also completed 3 T cranial MRI. We did not observe a direct effect of APOE genotype on cognitive performance or structural MRI measures. A significant genotype by age interaction was observed for executive function, where age had less of an effect on executive function in ε4 carriers. Similar interactions were observed for the entorhinal cortex, rostral and caudal anterior cingulate cortex and parahippocampal gyrus, where the effect of age on regional volumes was reduced in ε4 carriers. There were no significant interactions between APOE genotype and depression diagnosis. The ε4 allele benefits younger adults by allowing them to maintain executive function performance and volumes of cingulate and temporal cortex regions with aging, at least through age fifty years.
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Abstract
BACKGROUND Childhood early life stress (ELS) increases risk of adulthood major depressive disorder (MDD) and is associated with altered brain structure and function. It is unclear whether specific ELSs affect depression risk, cognitive function and brain structure. METHOD This cross-sectional study included 64 antidepressant-free depressed and 65 never-depressed individuals. Both groups reported a range of ELSs on the Early Life Stress Questionnaire, completed neuropsychological testing and 3T magnetic resonance imaging (MRI). Neuropsychological testing assessed domains of episodic memory, working memory, processing speed and executive function. MRI measures included cortical thickness and regional gray matter volumes, with a priori focus on the cingulate cortex, orbitofrontal cortex (OFC), amygdala, caudate and hippocampus. RESULTS Of 19 ELSs, only emotional abuse, sexual abuse and severe family conflict independently predicted adulthood MDD diagnosis. The effect of total ELS score differed between groups. Greater ELS exposure was associated with slower processing speed and smaller OFC volumes in depressed subjects, but faster speed and larger volumes in non-depressed subjects. In contrast, exposure to ELSs predictive of depression had similar effects in both diagnostic groups. Individuals reporting predictive ELSs exhibited poorer processing speed and working memory performance, smaller volumes of the lateral OFC and caudate, and decreased cortical thickness in multiple areas including the insula bilaterally. Predictive ELS exposure was also associated with smaller left hippocampal volume in depressed subjects. CONCLUSIONS Findings suggest an association between childhood trauma exposure and adulthood cognitive function and brain structure. These relationships appear to differ between individuals who do and do not develop depression.
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Widespread white matter but focal gray matter alterations in depressed individuals with thoughts of death. Prog Neuropsychopharmacol Biol Psychiatry 2015; 62:22-8. [PMID: 25963377 PMCID: PMC4458419 DOI: 10.1016/j.pnpbp.2015.05.001] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Revised: 04/23/2015] [Accepted: 05/03/2015] [Indexed: 01/11/2023]
Abstract
BACKGROUND Past work demonstrates that depressed individuals with suicidal thoughts or behaviors exhibit specific neuroanatomical alterations. This may represent a distinct phenotype characterized by specific findings on neuroimaging, but it is unclear if these findings extend to individuals with milder thoughts of death. We examined this question in outpatients with recurrent Major Depressive Disorder not receiving antidepressant treatment. METHODS We examined 165 subjects: 53 depressed without thoughts of death, 21 depressed with thoughts of death, and 91 healthy comparison subjects. Participants completed 3T cranial MRI, including anatomical and diffusion tensor imaging acquisitions. Automated methods measured regional gray matter volumes in addition to cortical thickness. White matter analyses examined diffusion measures within specific fiber tracts and included voxelwise comparisons. RESULTS After adjustment for multiple comparisons, the depressed group with thoughts of death did not exhibit differences in regional gray matter volume, but did exhibit reduced cortical thickness in frontoparietal regions and the insula. This depressed group with thoughts of death also exhibited widespread white matter differences in fractional anisotropy and radial diffusivity. These differences were observed primarily in posterior parietal white matter regions and central white matter tracts adjacent to the basal ganglia and thalamus. CONCLUSIONS Mild thoughts of death are associated with structural alterations in regions of the salience network, default mode network, and thalamocortical circuits. Further work is needed to understand the pathological basis of these findings.
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Hippocampus atrophy and the longitudinal course of late-life depression. Am J Geriatr Psychiatry 2014; 22:1504-12. [PMID: 24378256 PMCID: PMC4031313 DOI: 10.1016/j.jagp.2013.11.004] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Revised: 11/06/2013] [Accepted: 11/18/2013] [Indexed: 01/26/2023]
Abstract
OBJECTIVES Smaller hippocampal volumes are observed in depression but it remains unclear how antidepressant response and persistent depression relate to changes in hippocampal volume. We examined the longitudinal relationship between hippocampal atrophy and course of late-life depression. SETTING Academic medical center. PARTICIPANTS Depressed and never-depressed cognitively intact subjects age 60 years or older. MEASUREMENTS Depression severity was measured every three months with the Montgomery-Asberg Depression Rating Scale (MADRS). Participants also completed cranial 1.5-T magnetic resonance imaging every 2 years. We compared 2-year change in hippocampal volume based on remission status, then in expanded analyses examined how hippocampal volumes predicted MADRS score. RESULTS In analyses of 92 depressed and 70 never-depressed subjects, over 2 years the cohort whose depression never remitted exhibited greater hippocampal atrophy than the never-depressed cohort. In expanded analyses of a broader sample of 152 depressed elders, depression severity was significantly predicted by a hippocampus × time interaction where smaller hippocampus volumes over time were associated with greater depression severity. CONCLUSIONS Hippocampal atrophy is associated with greater and persistent depression severity. Neuropathological studies are needed to determine if this atrophy is related to the toxic effects of persistent depression or related to underlying Alzheimer disease.
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Association of gene variants of the renin-angiotensin system with accelerated hippocampal volume loss and cognitive decline in old age. Am J Psychiatry 2014; 171:1214-21. [PMID: 25124854 PMCID: PMC4329281 DOI: 10.1176/appi.ajp.2014.13111543] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE Genetic factors confer risk for neuropsychiatric phenotypes, but the polygenic etiology of these phenotypes makes identification of genetic culprits challenging. An approach to this challenge is to examine the effects of genetic variation on relevant endophenotypes, such as hippocampal volume loss. A smaller hippocampus is associated with gene variants of the renin-angiotensin system (RAS), a system implicated in vascular disease. However, no studies to date have investigated longitudinally the effects of genetic variation of RAS on the hippocampus. METHOD The authors examined the effects of polymorphisms of AGTR1, the gene encoding angiotensin-II type 1 receptor of RAS, on longitudinal hippocampal volumes of older adults. In all, 138 older adults (age ≥60 years) were followed for an average of about 4 years. The participants underwent repeated structural MRI and comprehensive neurocognitive testing, and they were genotyped for four AGTR1 single-nucleotide polymorphisms (SNPs) with low pairwise linkage disequilibrium values and apolipoprotein E (APOE) genotype. RESULTS Genetic variants at three AGTR1 SNPs (rs2638363, rs1492103, and rs2675511) were independently associated with accelerated hippocampal volume loss over the 4-year follow-up period in the right but not left hemisphere. Intriguingly, these AGTR1 risk alleles also predicted worse episodic memory performance but were not related to other cognitive measures. Two risk variants (rs2638363 and rs12721331) interacted with the APOE4 allele to accelerate right hippocampal volume loss. CONCLUSIONS Risk genetic variants of the RAS may accelerate memory decline in older adults, an effect that may be conferred by accelerated hippocampal volume loss. Molecules involved in this system may hold promise as early therapeutic targets for late-life neuropsychiatric disorders.
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Comprehensive population-averaged arterial input function for dynamic contrast-enhanced vmagnetic resonance imaging of head and neck cancer. Int J Radiat Oncol Biol Phys 2014; 89:658-65. [PMID: 24929169 DOI: 10.1016/j.ijrobp.2014.03.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2013] [Revised: 02/13/2014] [Accepted: 03/06/2014] [Indexed: 11/19/2022]
Abstract
PURPOSE To generate a population-averaged arterial input function (PA-AIF) for quantitative analysis of dynamic contrast-enhanced MRI data in head and neck cancer patients. METHODS AND MATERIALS Twenty patients underwent dynamic contrast-enhanced MRI during concurrent chemoradiation therapy. Imaging consisted of 2 baseline scans 1 week apart (B1/B2) and 1 scan after 1 week of chemoradiation therapy (Wk1). Regions of interest (ROIs) in the right and left carotid arteries were drawn on coronal images. Plasma concentration curves of all ROIs were averaged and fit to a biexponential decay function to obtain the final PA-AIF (AvgAll). Right-sided and left-sided ROI plasma concentration curves were averaged separately to obtain side-specific AIFs (AvgRight/AvgLeft). Regions of interest were divided by time point to obtain time-point-specific AIFs (AvgB1/AvgB2/AvgWk1). The vascular transfer constant (Ktrans) and the fractional extravascular, extracellular space volume (Ve) for primaries and nodes were calculated using the AvgAll AIF, the appropriate side-specific AIF, and the appropriate time-point-specific AIF. Median Ktrans and Ve values derived from AvgAll were compared with those obtained from the side-specific and time-point-specific AIFs. The effect of using individual AIFs was also investigated. RESULTS The plasma parameters for AvgAll were a1,2 = 27.11/17.65 kg/L, m1,2 = 11.75/0.21 min(-1). The coefficients of repeatability (CRs) for AvgAll versus AvgLeft were 0.04 min(-1) for Ktrans and 0.02 for Ve. For AvgAll versus AvgRight, the CRs were 0.08 min(-1) for Ktrans and 0.02 for Ve. When AvgAll was compared with AvgB1/AvgB2/AvgWk1, the CRs were slightly higher: 0.32/0.19/0.78 min(-1), respectively, for Ktrans; and 0.07/0.08/0.09 for Ve. Use of a PA-AIF was not significantly different from use of individual AIFs. CONCLUSION A PA-AIF for head and neck cancer was generated that accounts for differences in right carotid artery versus left carotid artery, day-to-day fluctuations, and early treatment-induced changes. The small CRs obtained for Ktrans and Ve indicate that side-specific AIFs are not necessary. However, a time-point-specific AIF may improve pharmacokinetic accuracy.
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Perfluoropropane gas as a magnetic resonance lung imaging contrast agent in humans. Chest 2014; 144:1300-1310. [PMID: 23722696 DOI: 10.1378/chest.12-2597] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
BACKGROUND Fluorine-enhanced MRI is a relatively inexpensive and straightforward technique that facilitates regional assessments of pulmonary ventilation. In this report, we assess its suitability through the use of perfluoropropane (PFP) in a cohort of human subjects with normal lungs and subjects with lung disease. METHODS Twenty-eight subjects between the ages of 18 and 71 years were recruited for imaging and were classified based on spirometry findings and medical history. Imaging was carried out on a Siemens TIM Trio 3T MRI scanner using two-dimensional, gradient echo, fast low-angle shot and three-dimensional gradient echo, volumetric, interpolated, breath-hold examination sequences for proton localizers and PFP functional scans, respectively. Respiratory waveforms and physiologic signals of interest were monitored throughout the imaging sessions. A region-growing algorithm was applied to the proton localizers to define the lung field of view for analysis of the PFP scans. RESULTS All subjects tolerated the gas mixture well with no adverse side effects. Images of healthy lungs demonstrated a homogeneous distribution of the gas with sufficient signal-to-noise ratios, while lung images from asthmatic and emphysematous lungs demonstrated increased heterogeneity and ventilation defects. CONCLUSIONS Fluorine-enhanced MRI using a normoxic PFP gas mixture is a well-tolerated, radiation-free technique for regionally assessing pulmonary ventilation. The inherent physical characteristics and applicability of the gaseous agent within a magnetic resonance setting facilitated a clear differentiation between normal and diseased lungs.
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A comparison of radial keyhole strategies for high spatial and temporal resolution 4D contrast-enhanced MRI in small animal tumor models. Med Phys 2013; 40:022304. [PMID: 23387766 DOI: 10.1118/1.4774050] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Dynamic contrast-enhanced (DCE) MRI has been widely used as a quantitative imaging method for monitoring tumor response to therapy. The simultaneous challenges of increasing temporal and spatial resolution in a setting where the signal from the much smaller voxel is weaker have made this MR technique difficult to implement in small-animal imaging. Existing protocols employed in preclinical DCE-MRI acquire a limited number of slices resulting in potentially lost information in the third dimension. This study describes and compares a family of four-dimensional (3D spatial + time), projection acquisition, radial keyhole-sampling strategies that support high spatial and temporal resolution. METHODS The 4D method is based on a RF-spoiled, steady-state, gradient-recalled sequence with minimal echo time. An interleaved 3D radial trajectory with a quasi-uniform distribution of points in k-space was used for sampling temporally resolved datasets. These volumes were reconstructed with three different k-space filters encompassing a range of possible radial keyhole strategies. The effect of k-space filtering on spatial and temporal resolution was studied in a 5 mM CuSO(4) phantom consisting of a meshgrid with 350-μm spacing and in 12 tumors from three cell lines (HT-29, LoVo, MX-1) and a primary mouse sarcoma model (three tumors∕group). The time-to-peak signal intensity was used to assess the effect of the reconstruction filters on temporal resolution. As a measure of heterogeneity in the third dimension, the authors analyzed the spatial distribution of the rate of transport (K(trans)) of the contrast agent across the endothelium barrier for several different types of tumors. RESULTS Four-dimensional radial keyhole imaging does not degrade the system spatial resolution. Phantom studies indicate there is a maximum 40% decrease in signal-to-noise ratio as compared to a fully sampled dataset. T1 measurements obtained with the interleaved radial technique do not differ significantly from those made with a conventional Cartesian spin-echo sequence. A bin-by-bin comparison of the distribution of the time-to-peak parameter shows that 4D radial keyhole reconstruction does not cause significant temporal blurring when a temporal resolution of 9.9 s is used for the subsamples of the keyhole data. In vivo studies reveal substantial tumor heterogeneity in the third spatial dimension that may be missed with lower resolution imaging protocols. CONCLUSIONS Volumetric keyhole imaging with projection acquisition provides a means to increase spatiotemporal resolution and coverage over that provided by existing 2D Cartesian protocols. Furthermore, there is no difference in temporal resolution between the higher spatial resolution keyhole reconstruction and the undersampled projection data. The technique allows one to measure complex heterogeneity of kinetic parameters with isotropic, microscopic spatial resolution.
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Negative life stress and longitudinal hippocampal volume changes in older adults with and without depression. J Psychiatr Res 2013; 47:829-34. [PMID: 23478048 PMCID: PMC3622849 DOI: 10.1016/j.jpsychires.2013.02.008] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Revised: 02/08/2013] [Accepted: 02/14/2013] [Indexed: 10/27/2022]
Abstract
Major depressive disorder is associated with smaller hippocampal volumes but the mechanisms underlying this relationship are unclear. To examine the effect of environmental influences, we examined the relationship between self-reported stressors and two-year change in hippocampal volume. Seventy elderly nondepressed subjects and eighty-nine elderly depressed subjects were followed for two years. The number of negative stressful life events (nSLE), perceived stress levels, and cranial MRI were obtained at baseline and at the two-year assessment. For secondary analyses, subjects provided blood for 5-HTTLPR polymorphism genotyping. After controlling for covariates including presence or absence of depression, greater numbers of baseline nSLEs were significantly associated with greater baseline hippocampal volumes bilaterally. Greater numbers of baseline nSLEs were also associated with reduction in hippocampal volume over two years in the right but not the left hemisphere. Neither perceived stress levels nor changes in stress measures were significantly associated with hippocampal volume measures. However, in secondary analyses, we found that increases in perceived stress over time was associated with volume reduction of the left hippocampus, but only in 5-HTTLPR L/L homozygotes. Our findings suggest different short- and long-term effects of negative life stressors on hippocampal volumes in older adults. These effects appear independent on the presence or absence of depression. Furthermore, these effects may be moderated by genetic polymorphisms in key neurotransmitter systems. These novel findings have important implications for understanding environmental influences on brain aging.
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Abstract
OBJECTIVE In order to assess the effect of gray matter volumes and cortical thickness on antidepressant treatment response in late-life depression, the authors examined the relationship between brain regions identified a priori and Montgomery-Åsberg Depression Rating Scale (MADRS) scores over the course of an antidepressant treatment trial. METHOD In a nonrandomized prospective trial, 168 patients who were at least 60 years of age and met DSM-IV criteria for major depression underwent MRI and were enrolled in a 12-week treatment study. Exclusion criteria included cognitive impairment or severe medical disorders. The volumes or cortical thicknesses of regions of interest that differed between the depressed group and a comparison group (N=50) were determined. These regions of interest were used in analyses of the depressed group to predict antidepressant treatment outcome. Mixed-model analyses adjusting for age, education, age at depression onset, race, baseline MADRS score, scanner, and interaction with time examined predictors of MADRS scores over time. RESULTS Smaller hippocampal volumes predicted a slower response to treatment. With the inclusion of white matter hyper-intensity severity and neuropsychological factor scores, the best model included hippocampal volume and cognitive processing speed to predict rate of response over time. A secondary analysis showed that hippocampal volume and frontal pole thickness differed between patients who achieved remission and those who did not. CONCLUSIONS These data expand our understanding of the prediction of treatment course in late-life depression. The authors propose that the primary variables of hippocampal volume and cognitive processing speed, subsuming other contributing variables (episodic memory, executive function, language processing) predict antidepressant response.
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AGTR1 gene variation: association with depression and frontotemporal morphology. Psychiatry Res 2012; 202:104-9. [PMID: 22703619 PMCID: PMC3398195 DOI: 10.1016/j.pscychresns.2012.03.007] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2011] [Revised: 02/29/2012] [Accepted: 03/26/2012] [Indexed: 11/27/2022]
Abstract
The renin-angiotensin system (RAS) is implicated in the response to physiological and psychosocial stressors, but its role in stress-related psychiatric disorders is poorly understood. We examined if variation in AGTR1, the gene coding for the type 1 angiotensin II receptor (AT(1)R), is associated with a diagnosis of depression and differences in white matter hyperintensities and frontotemporal brain volumes. Participants comprised 257 depressed and 116 nondepressed elderly Caucasian subjects who completed clinical assessments and provided blood samples for genotyping. We used a haplotype-tagging single nucleotide polymorphism (htSNP) analysis to test for variation in AGTR1. For measurement of hyperintense lesions, 1.5 Tesla magnetic resonance imaging (MRI) data were available on 33 subjects. For measurements of the hippocampus and dorsolateral prefrontal cortex (dlPFC), 3 Tesla MRI data were available on 70 subjects. Two htSNPs exhibited statistically significant frequency differences between diagnostic cohorts: rs10935724 and rs12721331. Although hyperintense lesion volume did not significantly differ by any htSNP, dlPFC and hippocampus volume differed significantly for several htSNPs. Intriguingly, for those htSNPs differing significantly for both dlPFC and hippocampus volume, the variant associated with smaller dlPFC volume was associated with larger hippocampal volume. This supports the idea that genetic variation in AGTR1 is associated with depression and differences in frontotemporal morphology.
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Dynamic Contrast-Enhanced MRI in Head-and-Neck Cancer: The Impact of Region of Interest Selection on the Intra- and Interpatient Variability of Pharmacokinetic Parameters. Int J Radiat Oncol Biol Phys 2012; 82:e345-50. [DOI: 10.1016/j.ijrobp.2011.05.059] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2011] [Revised: 05/27/2011] [Accepted: 05/31/2011] [Indexed: 01/21/2023]
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Prospective trial of synchronous bevacizumab, erlotinib, and concurrent chemoradiation in locally advanced head and neck cancer. Clin Cancer Res 2012; 18:1404-14. [PMID: 22253412 DOI: 10.1158/1078-0432.ccr-11-1982] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE We assessed the safety and efficacy of synchronous VEGF and epidermal growth factor receptor (EGFR) blockade with concurrent chemoradiation (CRT) in locally advanced head and neck cancer (HNC). EXPERIMENTAL DESIGN Newly diagnosed patients with stage III/IV HNC received a 2-week lead-in of bevacizumab and/or erlotinib, followed by both agents with concurrent cisplatin and twice daily radiotherapy. Safety was assessed using Common Toxicity Criteria version 3.0. The primary efficacy endpoint was clinical complete response (CR) rate after CRT. RESULTS Twenty-nine patients enrolled on study, with 27 completing therapy. Common grade III toxicities were mucositis (n = 14), dysphagia (n = 8), dehydration (n = 7), osteoradionecrosis (n = 3), and soft tissue necrosis (n = 2). Feeding tube placement was required in 79% but no patient remained dependent at 12-month posttreatment. Clinical CR after CRT was 96% [95% confidence interval (CI), 82%-100%]. Median follow-up was 46 months in survivors, with 3-year locoregional control and distant metastasis-free survival rates of 85% and 93%. Three-year estimated progression-free survival, disease-specific survival, and overall survival rates were 82%, 89%, and 86%, respectively. Dynamic contrast enhanced MRI (DCE-MRI) analysis showed that patients who had failed had lower baseline pretreatment median K(trans) values, with subsequent increases after lead-in therapy and 1 week of CRT. Patients who did not fail had higher median K(trans) values that decreased during therapy. CONCLUSIONS Dual VEGF/EGFR inhibition can be integrated with CRT in locally advanced HNC, with efficacy that compares favorably with historical controls albeit with an increased risk of osteoradionecrosis. Pretreatment and early DCE-MRI may prospectively identify patients at high risk of failure.
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Fiber tract-specific white matter lesion severity Findings in late-life depression and by AGTR1 A1166C genotype. Hum Brain Mapp 2011; 34:295-303. [PMID: 22021115 DOI: 10.1002/hbm.21445] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2011] [Revised: 06/23/2011] [Accepted: 07/25/2011] [Indexed: 11/07/2022] Open
Abstract
Past work demonstrated that late-life depression is associated with greater severity of ischemic cerebral hyperintense white matter lesions, particularly frontal lesions. However, these lesions are also associated with other neuropsychiatric deficits, so these clinical relationships may depend on which fiber tracts are damaged. We examined the ratio of lesion to nonlesioned white matter tissue within multiple fiber tracts between depressed and nondepressed elders. We also sought to determine if the AGTR1 A1166C and BDNF Val66Met polymorphisms contributed to vulnerability to lesion development in discrete tracts. The 3T structural MR images and blood samples for genetic analyses were acquired on 54 depressed and 37 nondepressed elders. Lesion maps were created through an automated tissue segmentation process and applied to a probabilistic white matter fiber tract atlas allowing for identification of the fraction of the tract occupied by lesion. The depressed cohort exhibited a significantly greater lesion ratio only in the left upper cingulum near the cingulate gyrus (F((1,86)) = 4.62, P = 0.0344), supporting past work implicating cingulate dysfunction in the pathogenesis of depression. In the 62 Caucasian subjects with genetic data, AGTR1 C1166 carriers exhibited greater lesion ratios across multiple tracts including the anterior thalamic radiation and inferior fronto-occipital fasciculus. In contrast, BDNF Met allele carriers exhibited greater lesion ratios only in the frontal corpus callosum. Although these findings did not survive correction for multiple comparisons, this study supports our hypothesis and provides preliminary evidence that genetic differences related to vascular disease may increase lesion vulnerability differentially across fiber tracts.
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Reduction of dorsolateral prefrontal cortex gray matter in late-life depression. Psychiatry Res 2011; 193:1-6. [PMID: 21596532 PMCID: PMC3105213 DOI: 10.1016/j.pscychresns.2011.01.003] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2010] [Revised: 01/07/2011] [Accepted: 01/07/2011] [Indexed: 11/30/2022]
Abstract
Postmortem studies have documented abnormalities in the dorsolateral prefrontal cortex (dlPFC) in depressed subjects. In this study we used magnetic resonance imaging to test for dlPFC volume differences between older depressed and non-depressed individuals. Eighty-eight subjects meeting DSM IV criteria for major depressive disorder and thirty-five control subjects completed clinical evaluations and cranial 3T magnetic resonance imaging. After tissue types were identified using an automated segmentation process, the dlPFC was measured in both hemispheres using manual delineation based on anatomical landmarks. Depressed subjects had significantly lower gray matter in the left and right dorsolateral prefrontal cortex (standardized to cerebral parenchyma) after controlling for age and sex. Our study confirmed the reduction of dorsolateral prefrontal cortex in elderly depressed subjects, especially in the gray matter. These regional abnormalities may be associated with psychopathological changes in late-life depression.
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Correction of breathing-induced errors in magnetic resonance thermometry of hyperthermia using multiecho field fitting techniques. Med Phys 2011; 37:6300-9. [PMID: 21302786 DOI: 10.1118/1.3515462] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
PURPOSE Breathing motion can create large errors when performing magnetic resonance (MR) thermometry of the breast. Breath holds can be used to minimize these errors, but not eliminate them. Between breath holds, the referenceless method can be used to further reduce errors by relying on regions of nonheated fatty tissue surrounding the heated region. When the surrounding tissue is heated (i.e., for a hyperthermia treatment), errors can result due to phase changes of the small amounts of water in the tissue. Therefore, an extension of the referenceless method is proposed which fits for the field in fatty tissue independent of temperature change and extrapolates it to the water-rich regions. METHODS Nonheating experiments were performed with male volunteers performing breath holds on top of a phantom mimicking a breast with a tumor. Heating experiments were also conducted with the same phantom while mechanically simulated breath holds were performed. A nonheating experiment was also performed with a healthy female breast. For each experiment, a nonlinear fitting algorithm was used to fit for temperature change and B0 field inside of the fatty tissue. The field changes were then extrapolated into water-rich (tumor) portions of the image using a least-squares fit to a fifth-order equation, to correct for field changes due to breath hold changes. Similar results were calculated using the image phase, to mimic the use of the referenceless method. RESULTS Phantom results showed large reduction of mean error and standard deviation. In the non-heating experiments, the traditional referenceless method and our extended method both corrected by similar amounts. However, in the heating experiments, the average deviation of the temperature calculated with the extended method from a fiber optic probe temperature was approximately 50% less than the deviation with the referenceless method. The in vivo breast results demonstrated reduced standard deviation and mean. CONCLUSIONS In this paper, we have developed an extension of the referenceless method to correct for breathing errors using multiecho fitting methods to fit for the B0 field in the fatty tissue and using measured field changes as references to extrapolate field corrections into a water-only (tumor) region. This technique has been validated in a number of situations, and in all cases, the correction method has been shown to greatly reduce temperature error in water-rich regions. The method has also been shown to be an improvement over similar methods that use image phase changes instead of field changes, particularly when temperature changes are induced.
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Comparison of genomics and functional imaging from canine sarcomas treated with thermoradiotherapy predicts therapeutic response and identifies combination therapeutics. Clin Cancer Res 2011; 17:2549-60. [PMID: 21292819 DOI: 10.1158/1078-0432.ccr-10-2583] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE While hyperthermia is an effective adjuvant treatment to radiotherapy, we do not completely understand the nature of the response heterogeneity. EXPERIMENTAL DESIGN We performed gene expression analysis of 22 spontaneous canine sarcomas before and after the first hyperthermia treatment administered as an adjuvant to radiotherapy. In parallel, diffusion-weighted MRI (DWI) was done prior to the treatment course and at the end of therapy. RESULTS From the integrative analysis of gene expression and DWI, we identified significant correlation between tumor responses with genes involved in VEGF signaling, telomerase, DNA repair, and inflammation. The treatment-induced changes in gene expression identified 2 distinct tumor subtypes with significant differences in their gene expression and treatment response, as defined by changes in DWI. The 2 tumor subtypes could also be readily identified by pretreatment gene expression. The tumor subtypes, with stronger expression response and DWI increase, had higher levels of HSP70, POT1, and centrosomal proteins, and lower levels of CD31, vWF, and transferrin. Such differential gene expression between the 2 subtypes was used to interrogate connectivity map and identify linkages to an HSP90 inhibitor, geldanamycin. We further validated the ability of geldanamycin to enhance cell killing of human tumor cells with hyperthermia and radiotherapy in clonogenic assays. CONCLUSIONS To our knowledge, this is one of the first successful attempts to link changes in gene expression and functional imaging to understand the response heterogeneity and identify compounds enhancing thermoradiotherapy. This study also demonstrates the value of canine tumors to provide information generalizable to human tumors.
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Noninvasive temperature mapping with MRI using chemical shift water-fat separation. Magn Reson Med 2010; 63:1238-46. [PMID: 20432295 DOI: 10.1002/mrm.22310] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Tissues containing both water and lipids, e.g., breast, confound standard MR proton reference frequency-shift methods for mapping temperatures due to the lack of temperature-induced frequency shift in lipid protons. Generalized Dixon chemical shift-based water-fat separation methods, such as GE's iterative decomposition of water and fat with echo asymmetry and least-squares estimation method, can result in complex water and fat images. Once separated, the phase change over time of the water signal can be used to map temperature. Phase change of the lipid signal can be used to correct for non-temperature-dependent phase changes, such as amplitude of static field drift. In this work, an image acquisition and postprocessing method, called water and fat thermal MRI, is demonstrated in phantoms containing 30:70, 50:50, and 70:30 water-to-fat by volume. Noninvasive heating was applied in an Off1-On-Off2 pattern over 50 min, using a miniannular phased radiofrequency array. Temperature changes were referenced to the first image acquisition. Four fiber optic temperature probes were placed inside the phantoms for temperature comparison. Region of interest (ROI) temperature values colocated with the probes showed excellent agreement (global mean +/- standard deviation: -0.09 +/- 0.34 degrees C) despite significant amplitude of static field drift during the experiments.
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Abstract
This longitudinal study examined the relationship between 2-year change in white matter hyperintense lesion (WML) volume and polymorphisms in genes coding for the angiotensin-II type 1 and type 2 receptors, AGTR1 A1166C and AGTR2 C3123A, respectively. 137 depressed and 94 non-depressed participants aged >or=60 years were enrolled. Standard clinical evaluations were performed on all participants and blood samples obtained for genotyping. 1.5-T MRI (magnetic resonance imaging) data were obtained at baseline and approximately 2 years later. These scans were processed using a semi-automated segmentation process, which allowed for the calculation of WML volume at each time point. Statistical models were tested for the relationship between change in WML volume and genotype, while also controlling for age, sex, diagnostic strata, baseline WML volume and comorbid cerebrovascular risk factors. In men, AGTR1 1166A allele homozygotes exhibited significantly less change in WML volume than 1166C carriers. We also found that men reporting hypertension (HTN) with the AGTR2 3123C allele exhibit less change in WML volume than hypertensive men with the 3123A allele, or men without HTN. There were no significant relationships between these polymorphisms and change in WML volume in women. No significant gene-gene or gene-depression interactions were observed. Our results parallel earlier observed gender differences of the relationship between other renin-angiotensin system polymorphisms and HTN. Further work is needed to determine whether these observed relationships are secondary to polymorphisms affecting response to antihypertensive medication, and whether antihypertensive medications can slow WML progression and lower the risk of morbidity associated with WMLs.
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Support for the vascular depression hypothesis in late-life depression: results of a 2-site, prospective, antidepressant treatment trial. ACTA ACUST UNITED AC 2010; 67:277-85. [PMID: 20194828 DOI: 10.1001/archgenpsychiatry.2009.204] [Citation(s) in RCA: 195] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
CONTEXT Research on vascular depression has used 2 approaches to subtype late-life depression, based on executive dysfunction or white matter hyperintensity severity. OBJECTIVE To evaluate the relationship of neuropsychological performance and white matter hyperintensity with clinical response in late-life depression. DESIGN Two-site, prospective, nonrandomized controlled trial. SETTING Outpatient clinics at Washington University and Duke University. PARTICIPANTS A total of 217 subjects aged 60 years or older met DSM-IV criteria for major depression, scored 20 or more on the Montgomery-Asberg Depression Rating Scale (MADRS), and received vascular risk factor scores, neuropsychological testing, and magnetic resonance imaging; they were excluded for cognitive impairment or severe medical disorders. Fazekas rating was conducted to grade white matter hyperintensity lesions. Intervention Twelve weeks of sertraline treatment, titrated by clinical response. Main Outcome Measure Participants' MADRS scores over time. RESULTS Baseline neuropsychological factor scores correlated negatively with baseline Fazekas scores. A mixed model examined effects of predictor variables on MADRS scores over time. Baseline episodic memory (P = .002), language (P = .007), working memory (P = .01), processing speed (P < .001), executive function factor scores (P = .002), and categorical Fazekas ratings (P = .05) predicted MADRS scores, controlling for age, education, age of onset, and race. Controlling for baseline MADRS scores, these factors remained significant predictors of decrease in MADRS scores, except for working memory and Fazekas ratings. Thirty-three percent of subjects achieved remission (MADRS < or =7). Remitters differed from nonremitters in baseline cognitive processing speed, executive function, language, episodic memory, and vascular risk factor scores. CONCLUSIONS Comprehensive neuropsychological function and white matter hyperintensity severity predicted MADRS scores prospectively over a 12-week treatment course with selective serotonin reuptake inhibitors in late-life depression. Baseline neuropsychological function differentiated remitters from nonremitters and predicted time to remission in a proportional hazards model. Predictor variables correlated highly with vascular risk factor severity. These data support the vascular depression hypothesis and highlight the importance of linking subtypes based on neuropsychological function and white matter integrity. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT00045773.
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Accuracy of real time noninvasive temperature measurements using magnetic resonance thermal imaging in patients treated for high grade extremity soft tissue sarcomas. Med Phys 2010; 36:4848-58. [PMID: 19994492 DOI: 10.1118/1.3227506] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE To establish accuracy of real time noninvasive temperature measurements using magnetic resonance thermal imaging in patients treated for high grade extremity soft tissue sarcomas. METHODS Protocol patients with advanced extremity sarcomas were treated with external beam radiation therapy and hyperthermia. Invasive temperature measures were compared to noninvasive magnetic resonance thermal imaging (MRTI) at 1.5 T performed during hyperthermia. Volumetric temperature rise images were obtained using the proton resonance frequency shift (PRFS) technique during heating in a 140 MHz miniannular phased array applicator. MRTI temperature changes were compared to invasive measurements of temperature with a multisensor fiber optic probe inside a #15 g catheter in the tumor. Since the PRFS technique is sensitive to drifts in the primary imaging magnetic field, temperature change distributions were corrected automatically during treatment using temperature-stable reference materials to characterize field changes in 3D. The authors analyzed MRT images and compared, in evaluable treatments, MR-derived temperatures to invasive temperatures measured in extremity sarcomas. Small regions of interest (ROIs) were specified near each invasive sensor identified on MR images. Temperature changes in the interstitial sensors were compared to the corresponding ROI PRFS-based temperature changes over the entire treatment and over the steady-state period. Nonevaluable treatments (motion/imaging artifacts, noncorrectable drifts) were not included in the analysis. RESULTS The mean difference between MRTI and interstitial probe measurements was 0.91 degrees C for the entire heating time and 0.85 degrees C for the time at steady state. These values were obtained from both tumor and normal tissue ROIs. When the analysis is done on just the tumor ROIs, the mean difference for the whole power on time was 0.74 degrees C and during the period of steady state was 0.62 degrees C. CONCLUSIONS The data show that for evaluable treatments, excellent correlation (deltaT < 1 degrees C) of MRTI-ROI and invasive measurements can be achieved, but that motion and other artifacts are still serious challenges that must be overcome in future work.
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Temporal lobe volume in bipolar disorder: relationship with diagnosis and antipsychotic medication use. J Affect Disord 2009; 114:50-7. [PMID: 18691766 PMCID: PMC2643314 DOI: 10.1016/j.jad.2008.07.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2008] [Revised: 06/30/2008] [Accepted: 07/01/2008] [Indexed: 11/26/2022]
Abstract
BACKGROUND We tested for differences in temporal lobe volume in bipolar disorder and the relationship between these volumes and psychotropic medication use. METHODS 125 subjects with bipolar disorder and 87 comparison subjects with no psychiatric illness completed clinical interviews and 1.5T MRI brain scans. Temporal lobe volumes were manually traced and segmented into gray matter and white matter volumes using an automated process. General linear models examined the relationship between these volumes and diagnosis as the primary predictor with age, sex, education, and race as copredictors. Secondary analyses incorporated the use of psychotropic medication into the linear models, and parsimonious models developed through backwards regression. RESULTS In initial models, subjects with bipolar disorder exhibited larger temporal lobe white matter bilaterally (left: F(1,211)=2.86, p=0.0047; right: F(1,211)=3.25, p=0.0014). Current antipsychotic use was significantly associated with larger bilateral temporal lobe white matter volumes (left: F(2,211)=9.45, p=0.0001; right: F(2,211)=10.79, p<0.0001), wherein bipolar subjects taking antipsychotics had larger volumes than bipolar subjects not taking antipsychotics or healthy comparison subjects. Temporal lobe gray matter volume was not significantly associated with diagnosis or medication use. LIMITATIONS Excluding subjects with substance use disorders may limit the study's generalizability. CONCLUSIONS These findings indicate that differences in temporal lobe white matter are associated with bipolar disorder and use of antipsychotic medications.
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Teasing apart the heterogeneity of autism: Same behavior, different brains in toddlers with fragile X syndrome and autism. J Neurodev Disord 2009; 1:81-90. [PMID: 20700390 PMCID: PMC2917990 DOI: 10.1007/s11689-009-9009-8] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2008] [Accepted: 02/15/2009] [Indexed: 11/22/2022] Open
Abstract
To examine brain volumes in substructures associated with the behavioral features of children with FXS compared to children with idiopathic autism and controls. A cross-sectional study of brain substructures was conducted at the first time-point as part of an ongoing longitudinal MRI study of brain development in FXS. The study included 52 boys between 18-42 months of age with FXS and 118 comparison children (boys with autism-non FXS, developmental-delay, and typical development). Children with FXS and autistic disorder had substantially enlarged caudate volume and smaller amygdala volume; whereas those children with autistic disorder without FXS (i.e., idiopathic autism) had only modest enlargement in their caudate nucleus volumes but more robust enlargement of their amygdala volumes. Although we observed this double dissociation among selected brain volumes, no significant differences in severity of autistic behavior between these groups were observed. This study offers a unique examination of early brain development in two disorders, FXS and idiopathic autism, with overlapping behavioral features, but two distinct patterns of brain morphology. We observed that despite almost a third of our FXS sample meeting criteria for autism, the profile of brain volume differences for children with FXS and autism differed from those with idiopathic autism. These findings underscore the importance of addressing heterogeneity in studies of autistic behavior.
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APOE related hippocampal shape alteration in geriatric depression. Neuroimage 2008; 44:620-6. [PMID: 19010425 DOI: 10.1016/j.neuroimage.2008.10.010] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2008] [Revised: 10/02/2008] [Accepted: 10/15/2008] [Indexed: 10/21/2022] Open
Abstract
Late-onset depression often precedes the onset of dementia associated with the hippocampal degeneration. Using large deformation diffeomorphic metric mapping (LDDMM), we evaluated apolipoprotein E epsilon-4 allele (apoE E4) effects on hippocampal volume and shape in 38 depressed patients without the apoE E4, 14 depressed patients with one apoE E4, and 31 healthy comparison subjects without the apoE E4. The hippocampal volumes were manually assessed. We applied a diffeomorphic template generation procedure for creating the hippocampal templates based on a subset of the population. The LDDMM mappings were used to generate the hippocampal shape of each subject and characterize the surface deformation of each hippocampus relative to the template. Such deformation was modeled as random field characterized by the Laplace-Beltrami basis functions in the template coordinates. Linear regression was used to examine group differences in the hippocampal volume and shape. We found that there were significant hippocampal shape alternations in both depressed groups while the groups of depressed patients and the group of healthy subjects did not differ in the hippocampal volume. The depressed patients with one apoE E4 show more pronounced shape inward-compression in the anterior CA1 than the depressed patients without the apoE E4 when compared with the healthy controls without the apoE E4. Thus, hippocampal shape abnormalities in late-onset depressed patients with one apoE E4 may indicate future conversion of this group to AD at higher risk than depressed patients without the apoE E4.
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Comparison of three physiologically-based pharmacokinetic models for the prediction of contrast agent distribution measured by dynamic MR imaging. J Magn Reson Imaging 2008; 27:1388-98. [PMID: 18504759 DOI: 10.1002/jmri.21344] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
PURPOSE To compare the performance of three physiologically-based pharmacokinetic (PBPK) models for predicting gadolinium contrast agent concentration-time curves (Gd-CTCs) obtained in superior sagittal sinus (SSS), cerebral cortex, and psoas muscle. MATERIALS AND METHODS Three published whole-body PBPK models were modified to predict Gd-CTCs in normal-appearing tissue. The models differed in the number of organs modeled and total number of compartments, and were designated as the "well-mixed," "delay," and "dispersion" models. The suitability of the three models to predict Gd-CTC was studied using data from dynamic contrast-enhanced MR perfusion imaging obtained at 1.5T from 10 patients with glioblastoma multiforme and at 3.0T from five patients with liver metastases. RESULTS The dispersion model produced better fits than the delay model in the SSS (P < 0.0001) and cerebral cortex (P < 0.0001), and better fits than the well-mixed model in psoas muscle (P < 0.005). No model produced better fits than the dispersion model at any of the three locations. CONCLUSION In this evaluation, the dispersion model was most robust for prediction of Gd-CTCs derived from dynamic contrast-enhanced (DCE)-MRI. This represents a preliminary step in the development of a PBPK model useful for predicting Gd-CTCs at a time resolution appropriate for dynamic MRI applications.
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Classification of white matter lesions on magnetic resonance imaging in elderly persons. Biol Psychiatry 2008; 64:273-80. [PMID: 18471801 PMCID: PMC2593803 DOI: 10.1016/j.biopsych.2008.03.024] [Citation(s) in RCA: 331] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2007] [Revised: 03/06/2008] [Accepted: 03/20/2008] [Indexed: 10/22/2022]
Abstract
White matter lesions, commonly seen on MRIs of elderly people, are related to various geriatric disorders, including cerebrovascular diseases, cardiovascular diseases, dementia, and psychiatric disorders. Currently, white matter lesions are divided into periventricular white matter lesions and deep white matter lesions. Although the meaning of these terms varies by study and this dichotomization itself is still in debate, a possible dissimilarity in pathogenic mechanisms between periventricular white matter lesions and deep white matter lesions are providing some clues for understanding pathophysiology of many geriatric syndromes associated with white matter lesions. We have reviewed the distinctions between periventricular white matter lesions and deep white matter lesions in terms of etiology, histopathology, functional correlates, and imaging methodologies. We suggest a new subclassification of white matter lesions that might have better etiological and functional relevance than the current simple dichotomization. The new categories are juxtaventricular, periventricular, deep white, and juxtacortical. This new classification scheme might contribute to reducing the heterogeneity of white matter lesion findings in future research.
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Abstract
Studies of depression and hippocampal volume have yielded inconsistent results. This inconsistency could stem from the heterogeneity of depressive disorders. We conducted cross-sectional and longitudinal analyses of hippocampal volumes in atypical depressive, melancholic depressive, and control subjects. We found no effect of depression subtype on hippocampal volume or memory performance.
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The brain-derived neurotrophic factor VAL66MET polymorphism and cerebral white matter hyperintensities in late-life depression. Am J Geriatr Psychiatry 2008; 16:263-71. [PMID: 18263664 DOI: 10.1097/jgp.0b013e3181591c30] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE In animal models, brain-derived neurotrophic factor (BDNF) appears to protect against cerebral ischemia. The authors examined whether the BDNF Val66Met polymorphism, which affects BDNF distribution, was associated with greater volumes of hyperintense lesions as detected on magnetic resonance imaging in a cohort of depressed and nondepressed elders. DESIGN Subjects completed cross-sectional assessments, including clinical evaluation and a brain magnetic resonance imaging scan, and provided blood samples for Val66Met genotyping. SETTING The study was conducted at a university-based academic hospital. PARTICIPANTS Participants included 199 depressed and 113 nondepressed subjects aged 60 years or older. MEASUREMENT Hyperintensity lesion volumes were measured using a semiautomated segmentation procedure. Statistical models examined the relationship between genotype and lesion volume while controlling for depression, presence of hypertension, age, and sex. RESULTS After controlling for covariates, Met66 allele carriers exhibited significantly greater white matter hyperintensity volumes (F(1,311) = 4.09, p = 0.0442). This effect was independent of a diagnosis of depression or report of hypertension. Genotype was not significantly related to gray matter hyperintensity volume (F(1,311) = 1.14, p = 0.2871). CONCLUSIONS The BDNF Met66 allele is associated with greater white matter hyperintensity volumes in older individuals. Further work is needed to determine how this may be associated with other clinically relevant findings in late-life depression.
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Abstract
Major depression in the elderly is associated with brain structural changes and vascular lesions. Changes in the subcortical regions of the limbic system have also been noted. Studies examining hippocampus volumetric differences in depression have shown variable results, possibly due to any volume differences being secondary to local shape changes rather than differences in the overall volume. Shape analysis offers the potential to detect such changes. The present study applied spherical harmonic (SPHARM) shape analysis to the left and right hippocampi of 61 elderly subjects with major depression and 43 non-depressed elderly subjects. Statistical models controlling for age, sex, and total cerebral volume showed a significant reduction in depressed compared with control subjects in the left hippocampus (F1,103 = 5.26; p = 0.0240) but not right hippocampus volume (F1,103 = 0.41; p = 0.5213). Shape analysis showed significant differences in the mid-body of the left (but not the right) hippocampus between depressed and controls. When the depressed group was dichotomized into those whose depression was remitted at time of imaging and those who were unremitted, the shape comparison showed remitted subjects to be indistinguishable from controls (both sides) while the unremitted subjects differed in the midbody and the lateral side near the head. Hippocampal volume showed no difference between controls and remitted subjects but nonremitted subjects had significantly smaller left hippocampal volumes with no significant group differences in the right hippocampus. These findings may provide support to other reports of neurogenic effects of antidepressants and their relation to successful treatment for depressive symptoms.
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Abstract
There is growing clinical evidence that the combination of radiation therapy and hyperthermia, when delivered at moderate temperatures (40 degrees-45 degrees C) for sustained times (30-90 minutes), is of benefit with regard to palliative relief of cancer, tumor response, local control, and survival. Adequate measurement of the temperature distribution achieved with the hyperthermia is a key element in successful therapy. Thermal dosimetry, even invasive dosimetry, is a complex topic when applied to the heterogeneous tissue of a tumor and associated organ systems. Imaging in hyperthermia therapy is performed primarily for estimation and control of temperature. Magnetic resonance (MR) imaging has unique parameter dependences that make it possible to monitor hyperthermia therapy by detection of proton resonant frequency changes or diffusion coefficient changes. In addition, MR imaging can be used to assess vascular parameters that not only allow selection of suitable patients for therapy but may also allow demonstration of response to therapy. Finally, as the use of thermally sensitive liposomes for delivery of chemotherapeutic agents is developed, MR imaging may allow determination of local drug dose.
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Predicting memory decline in normal elderly: Genetics, MRI, and cognitive reserve. Neurobiol Aging 2007; 28:1644-56. [PMID: 16916565 DOI: 10.1016/j.neurobiolaging.2006.07.001] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2006] [Revised: 06/23/2006] [Accepted: 07/06/2006] [Indexed: 11/16/2022]
Abstract
Major predictors of Alzheimer's disease (AD) include apolipoprotein E (APOE)-epsilon4, hippocampal atrophy on magnetic resonance imaging (MRI), and memory dysfunction prior to diagnosis. We examined 159 normal elderly subjects with MRI and the California Verbal Learning Test (CVLT); 84 returned for longitudinal follow-up 5 years later. Analyses at baseline revealed significant variance in hippocampal volume accounted for by cerebral volume and age but not by APOE isoform. However, interactions involving APOE isoform and laterality were observed. As hypothesized, an APOE x time interaction was revealed for CVLT long-delay free recall: APOE-epsilon3/4 subjects had significantly poorer performance than APOE-epsilon3/3 subjects at follow-up. Forward stepwise multiple regression analysis predicting follow-up long-delay free recall selected baseline recall, followed by number of APOE-epsilon4 alleles, followed by left-hippocampal volume. Age and sex did not enter into the model. We conclude that APOE-epsilon4 predicts longitudinal memory decline in healthy controls and that MRI morphometry of hippocampus adds slightly to predictive value.
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Longitudinal magnetic resonance imaging vascular changes, apolipoprotein E genotype, and development of dementia in the neurocognitive outcomes of depression in the elderly study. Am J Geriatr Psychiatry 2007; 15:839-49. [PMID: 17623814 DOI: 10.1097/jgp.0b013e318048a1a0] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Several studies suggest that depression is a risk factor for development of dementia in the elderly. In a study of older depressed individuals, the authors examined both neuroimaging and genetic factors in development of dementia. The authors hypothesized that change in subcortical gray matter and white matter hyperintensity volumes would be associated with development of dementia, as would presence of an apolipoprotein E (APOE) epsilon 4 allele. METHODS The sample consisted of 161 older depressed subjects without dementia who had magnetic resonance imaging scans at baseline and at two years. Blood samples were also taken to determine APOE genotype. All participants were treated with antidepressants using a guideline-based treatment algorithm. Their cognitive status was evaluated annually. A consensus panel of experts evaluated each case to determine cognitive status and assign a diagnosis. RESULTS Twenty subjects became demented over the follow-up period (5.4 years on average). Change in white matter hyperintensity volume was significantly associated with development of dementia, especially among non-Alzheimer dementias. There was a trend for change in subcortical gray matter hyperintensity volume to be associated with incident dementia. APOE genotype was not associated with onset of dementia. CONCLUSION Worsening cerebrovascular disease in older depressed adults is associated with cognitive decline and dementia, particularly of the non-Alzheimer disease type. The association of change in white matter lesion volume and incident dementia among depressed elders extends the vascular depression hypothesis of geriatric depression to include cognitive outcomes of depression in the elderly.
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The COMT Val158Met polymorphism and temporal lobe morphometry in healthy adults. Psychiatry Res 2007; 155:173-7. [PMID: 17521892 PMCID: PMC1950247 DOI: 10.1016/j.pscychresns.2007.01.005] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2006] [Revised: 01/05/2007] [Accepted: 01/20/2007] [Indexed: 11/17/2022]
Abstract
We examined the relationship between COMT Val158Met genotype and temporal lobe volumes, including the caudate as a control region. Thirty-one healthy subjects completed 1.5T brain MRI and genotyping. After controlling for demographics, Val158 allele homozygotes exhibited significantly smaller temporal lobe and hippocampal volumes, with a trend for smaller amygdala volumes.
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Abstract
OBJECTIVE Hyperintense lesions are a common finding on neuroimaging and are associated not only with aging, medical illness, and some invasive medical procedures, but also with neurologic and psychiatric morbidity. We hypothesized that hyperintense lesions are associated with alterations in white matter structure beyond the visible lesion boundaries as assessed with diffusion tensor imaging (DTI). SUBJECTS AND METHODS Eighty-two neurologically intact older individuals completed brain MRI with DTI. DTI scans were analyzed using regions of interest placed in normal-appearing white matter to measure fractional anisotropy and diffusivity in the white matter of the frontal lobe, the genu of the corpus callosum, and the internal capsule. Hyperintense lesions volumes were measured separately in subcortical gray matter and anterior white matter through a semiautomated segmentation program. The relationship between lesion volumes and DTI measures was examined while controlling for patient age, patient sex, and total cerebral volume. RESULTS Greater anterior white matter lesion volumes were associated with higher diffusivity and lower anisotropy in the white matter of the dorsolateral prefrontal cortex and with higher diffusivity of the internal capsule and white matter lateral to the anterior cingulate cortex. Gray matter lesion volumes were associated with higher diffusivity in the genu of the corpus callosum and the internal capsule. CONCLUSION Ischemic hyperintense lesions are associated with widespread effects on the structure of the frontal lobe white matter and central white matter structures. This may reflect effects of lesions on neural circuits or identification of white matter changes that have not yet become visible on conventional MRI.
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Structural integrity of the uncinate fasciculus in geriatric depression: Relationship with age of onset. Neuropsychiatr Dis Treat 2007; 3:669-74. [PMID: 19300596 PMCID: PMC2656303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND The uncinate fasciculus connects limbic structures, such as the hippocampus and amygdala, with frontal regions. This study utilized diffusion tensor imaging to examine the structural integrity of the uncinate fasciculus in late-life depression. METHOD 18 elderly depressed and 19 elderly nondepressed subjects were matched for age and sex; 8 subjects had mid- to late-onset of depression while 10 subjects had early-onset depression. 3T diffusion tensor imaging-based fiber tract mapping delineated the uncinate fasciculus in each hemisphere, which guided measurement of the fractional anisotropy of the uncinate fasciculus in the temporal stem. After controlling for age and sex, differences between diagnostic groups were assessed. RESULTS After controlling for age and sex, individuals with early onset depression exhibited lower anisotropy of the left uncinate fasciculus than did mid- and late-onset or nondepressed subjects (F(2,36) = 4.50, p = 0.02). Analyses of the right uncinate fasciculus were not statistically significant. CONCLUSIONS This provides preliminary evidence that there is a structural connectivity deficit between left frontal and limbic structures in early-onset depression. Further work is needed to determine if this is seen in younger depressed subjects, and if it influences treatment outcomes.
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Dorsolateral prefrontal cortex and anterior cingulate cortex white matter alterations in late-life depression. Biol Psychiatry 2006; 60:1356-63. [PMID: 16876144 DOI: 10.1016/j.biopsych.2006.03.052] [Citation(s) in RCA: 213] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2005] [Revised: 03/12/2006] [Accepted: 03/14/2006] [Indexed: 10/24/2022]
Abstract
BACKGROUND The dorsolateral prefrontal cortex (DLPFC) and anterior cingulate cortex (ACC) are critical for mood regulation. Alterations in the white matter connections of these regions may impair their role in mood regulation and increase the risk of developing depression. This study used diffusion tensor imaging to examine for white matter microstructural abnormalities of these regions and of central white matter structures in late-life depression. METHODS One hundred six elderly depressed subjects and eighty-four elderly nondepressed subjects underwent clinical assessment and diffusion tensor imaging. The apparent diffusion coefficient (ADC) and fractional anisotropy (FA) were measured in regions of interest placed in the white matter of the DLPFC, ACC, corpus callosum, and internal capsule. Differences between groups were assessed, controlling for age, sex, and total cerebral volume. RESULTS After controlling for covariates, depressed subjects had significantly lower FA values in white matter of the right ACC, bilateral superior frontal gyri, and left middle frontal gyrus. There were no significant differences in ADC values. CONCLUSIONS Lower FA, representing lower tissue organization, is observed in depressed elders in the DLPFC and right ACC. These findings support the hypothesis that altered connectivity between brain regions contributes to the risk of depression.
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Abstract
Effective cancer chemotherapy depends on the delivery of therapeutic drugs to cancer cells at cytotoxic concentrations. However, physiologic barriers, such as variable vessel permeability, high interstitial fluid pressure, and heterogeneous perfusion, make it difficult to achieve that goal. Efforts to improve drug delivery have been limited by the lack of noninvasive tools to evaluate intratumoral drug concentration and distribution. Here we demonstrate that tumor drug concentration can be measured in vivo using T(1)-weighted MRI, following systemic administration of liposomes containing both drug (doxorubicin (DOX)) and contrast agent (manganese (Mn)). Mn and DOX concentrations were calculated using T(1) relaxation times and Mn:DOX loading ratios, as previously described. Two independent validations by high-performance liquid chromatography (HPLC) and histologic fluorescence in a rat fibrosarcoma (FSA) model indicate a concordant linear relationship between DOX concentrations determined using T(1) and those measured invasively. This method of imaging exhibits potential for real-time evaluation of chemotherapeutic protocols and prediction of tumor response on an individual patient basis.
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Differences in brain volumes among males and female hormone-therapy users and nonusers. Psychiatry Res 2006; 147:127-34. [PMID: 16935478 DOI: 10.1016/j.pscychresns.2006.01.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2005] [Revised: 09/03/2005] [Accepted: 01/08/2006] [Indexed: 11/23/2022]
Abstract
Numerous studies have shown gender differences in the brain volumes of elderly adults. Some evidence shows that higher estrogen levels may be neuroprotective, suggesting that hormone therapy (HT) may in part be responsible for these gender differences; however, few studies have examined the relation between HT and brain volumes. Brain volumes of caudate, putamen, hippocampus, gray matter, white matter, white-matter lesions, and cerebrospinal fluid were measured on magnetic resonance imaging scans. A comprehensive neuropsychological battery was administered. Women were separated into two groups based on HT use, and we used multiple regression analyses to compare these groups with one another and with men. Results of brain-volume measurements showed that HT users had significantly less gray matter and more cerebrospinal fluid than nonusers. Results of the neuropsychological testing showed that HT users performed better on the Shipley Vocabulary Test than males did.
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Lobar distribution of lesion volumes in late-life depression: the Biomedical Informatics Research Network (BIRN). Neuropsychopharmacology 2006; 31:1500-7. [PMID: 16341022 DOI: 10.1038/sj.npp.1300986] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
White matter hyperintense lesions on T2-weighted images are associated with late-life depression. Little work has been carried out examining differences in lesion location between elderly individuals with and without depression. In contrast to previous studies examining total brain white matter lesion volume, this study examined lobar differences in white matter lesion volumes derived from brain magnetic resonance imaging. This study examined 49 subjects with a DSM-IV diagnosis of major depression and 50 comparison subjects without depression. All participants were age 60 years or older. White matter lesion volumes were measured in each hemisphere using a semiautomated segmentation process and localized to lobar regions using a lobar atlas created for this sample using the imaging tools provided by the Biomedical Informatics Research Network (BIRN). The lobar lesion volumes were compared against depression status. After controlling for age and hypertension, subjects with depression exhibited significantly greater total white matter lesion volume in both hemispheres and in both frontal lobes than did control subjects. Although a similar trend was observed in the parietal lobes, the difference did not reach a level of statistical significance. Models of the temporal and occipital lobes were not statistically significant. Older individuals with depression have greater white matter disease than healthy controls, predominantly in the frontal lobes. These changes are thought to disrupt neural circuits involved in mood regulation, thus increasing the risk of developing depression.
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Abstract
This article reports on preliminary findings describing microstructural abnormalities in the white matter of cortical areas thought to be associated with bipolar disorder. In all, 14 patients with bipolar disorder and 21 nonpsychiatrically ill control subjects underwent MR imaging including a diffusion tensor imaging (DTI) pulse sequence (six directions, b=1000 mm(2)/s). DTI data were analyzed on a workstation using a program that allowed calculation of apparent diffusion coefficient (ADC) and fractional anisotropy (FA) within the following three white matter fiber tracts bilaterally: the orbital frontal cortex, and the superior and middle frontal gyri. These values were compared across patient groups. The left and right orbital frontal white matter exhibited significantly higher ADC values in bipolar subjects than control subjects on both the left (p=0.028) and right (p=0.011). Microstructural changes in the white matter of the orbital frontal areas as reflected by increased ADC values appear to be associated with bipolar disorder. Further research is needed to better understand the interaction of microstructural changes and bipolar symptoms and whether these changes are specific to bipolar disorder.
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Brain Morphometry, T2-Weighted Hyperintensities, and IQ in Children With Neurofibromatosis Type 1. ACTA ACUST UNITED AC 2005; 62:1904-8. [PMID: 16344348 DOI: 10.1001/archneur.62.12.1904] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
BACKGROUND Larger gray matter (GM) volume in healthy children is correlated with higher IQ. Children with neurofibromatosis type 1 (NF1) have larger brains, their magnetic resonance images frequently show T2-weighted hyperintensities, and their IQs are lower. OBJECTIVES To confirm the hypotheses that (1) children with NF1 have larger GM and white matter volumes, (2) the greatest volume differences are in the frontal and parietal regions and in children with NF1 with hyperintensities, and (3) GM volume is inversely related to IQ in children with NF1. DESIGN Wechsler Intelligence Scale for Children-Third Edition IQ testing and measurement of cerebral volumes and hyperintensities in brain magnetic resonance images were performed on 36 children with NF1 and on 36 matched relatives who served as control subjects. RESULTS Gray matter and white matter volumes were significantly larger in children with NF1. The greatest difference was observed in cerebral white matter volume, predominantly in the frontal lobes, whereas the greatest difference in GM volume was in the temporal, parietal, and occipital regions. In controls, IQ was significantly related to GM volume, but in children with NF1, IQ was not inversely associated with GM volume, although IQs of children with NF1 were significantly lower. CONCLUSIONS Children with NF1 do not have the normal relationship between GM volume and IQ. Larger GM volume in the posterior brain regions and larger white matter volumes in the frontal brain regions contribute to the larger brain volume in children with NF1.
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Greater MRI lesion volumes in elderly depressed subjects than in control subjects. Psychiatry Res 2005; 139:1-7. [PMID: 15927454 DOI: 10.1016/j.pscychresns.2004.08.004] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/09/2004] [Revised: 07/09/2004] [Accepted: 08/03/2004] [Indexed: 02/07/2023]
Abstract
Hyperintense lesions in both white matter and gray matter on T2-weighted magnetic resonance imaging (MRI) are associated with late-life depression. This large study examined differences in gray and white matter lesion volumes on brain MRI between 253 elderly depressed and 146 control subjects. White matter and gray matter lesion volumes were measured in each hemisphere using a semi-automated segmentation process and compared against depression status. Depressed subjects exhibited significantly greater total white matter (mean 7.22 ml) and gray matter (mean 0.30 ml) lesion volumes in both hemispheres than did control subjects (mean 4.87 ml in white matter and 0.18 ml in gray matter). This difference remained statistically significant even after controlling for confounders such as age, sex, race and reports of hypertension, diabetes and heart disease. Patients with late-life depression have larger white matter lesion and gray matter lesion volumes than do control subjects. Future research should combine similar volumetric techniques with methods of identifying the location of lesions specific to late-life depression.
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Influence of Serotonin Transporter Promoter Region Polymorphisms on Hippocampal Volumes in Late-Life Depression. ACTA ACUST UNITED AC 2005; 62:537-44. [PMID: 15867107 DOI: 10.1001/archpsyc.62.5.537] [Citation(s) in RCA: 144] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
CONTEXT Polymorphisms in the promoter region of the serotonin transporter gene (5-HTTLPR) influence transcription and may play a role in the pathogenesis and course of depression. Recent research demonstrates that specific polymorphisms may be associated with differences in hippocampal volumes in subjects with depression. OBJECTIVE To examine associations between 5-HTTLPR genotype and hippocampal volumes in elderly control subjects and elderly subjects classified as having early or late onset of depression. DESIGN Cohort study examining baseline characteristics. PARTICIPANTS Subjects were community dwelling and 60 years or older. Using a definition of early-onset depression as depression first occurring at 50 years or younger, we examined 72 subjects with early-onset depression, 63 subjects with late-onset depression, and 83 healthy control subjects. MAIN OUTCOME MEASURES All subjects underwent genotyping for the 5-HTTLPR and underwent brain magnetic resonance imaging. Analyses of hippocampal volumes were controlled for total cerebral volume, age, and sex. RESULTS The interaction between diagnosis and 5-HTTLPR genotype was statistically significant for the right hippocampus (P = .04). Subjects with late-onset depression who were homozygous for the long (L) allele (L /L genotype) had significantly smaller right hippocampal volumes than did L /L subjects with early-onset depression (P = .046) or L /L control subjects (P = .01). Post hoc analyses showed that later age of depression onset was associated with smaller hippocampal volumes in subjects with the L /L genotype, but earlier age of onset was associated with smaller hippocampal volumes in subjects who were homozygous for the short (S) allele (S/S genotype). CONCLUSIONS Subjects with late-onset depression who were homozygous for the L allele exhibited smaller hippocampal volumes than other groups. Genotype also mediated the effect of age of onset on hippocampal volumes. Our findings differ from previous work; however, we examined an older and larger cohort of subjects than previous studies. Possible explanations for these findings include interactions between the serotonergic system and neurotrophic factors or cortisol response to stresses, each of which may affect hippocampal volumes.
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Abstract
OBJECTIVE In this study, we examined 204 older depressed individuals for up to 64 months to determine factors related to depression outcome. We hypothesized that both presence of vascular brain lesions seen on baseline magnetic resonance imaging (MRI) scans and lower baseline social support measures would be related to worse depression outcome. METHOD At study entry, all subjects were at least 59 years old, had a diagnosis of major depression, and were free of other major psychiatric illness and primary neurological illness, including dementia and stroke. Depression was diagnosed via structured interview and clinical assessment by a geriatric psychiatrist who completed a Montgomery Asberg Depression Rating Scale (MADRS) to determine severity of depression. Subjects provided self-report data on social support variables and ability to perform basic and instrumental activities of daily living (ADL, IADL). All subjects agreed to have a baseline standardized MRI brain scan. Ratings of severity of hyperintensities were determined for the periventricular white matter, deep white matter, and subcortical gray matter by two readers who decided by consensus. Treatment was provided by geropsychiatrists following clinical guidelines. Using mixed models to analyze the data, we determined the effect of a variety of demographic, social and imaging variables on the trajectory of MADRS score, the outcome variable of interest. RESULTS MADRS scores decreased steadily over time. In a final HLM model, in which time since entry, a baseline time indicator, age, gender, education and Mini-mental State Examination score were controlled, subjective social support, instrumental ADL impairment, subcortical gray matter severity, and the interactions of time with social network and with subcortical gray matter lesions remained significantly associated with MADRS score. CONCLUSIONS Both social and biological factors at baseline are associated with longitudinal depression severity in geriatric depression.
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In vivo monitoring of tissue pharmacokinetics of liposome/drug using MRI: illustration of targeted delivery. Magn Reson Med 2004; 51:1153-62. [PMID: 15170835 DOI: 10.1002/mrm.20074] [Citation(s) in RCA: 148] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The purpose of this study was to determine if MnSO(4)/doxorubicin (DOX) loaded liposomes could be used for in vivo monitoring of liposome concentration distribution and drug release using MRI. In vitro results show that T(1) shortening correlates with MnSO(4) concentration. Using a temperature-sensitive liposome formulation, it was found that MnSO(4) release significantly shortened T(1). This feature, therefore, suggests that content release can also be measured with these MnSO(4)-loaded liposomes. The feasibility of monitoring this drug delivery and release-imaging agent was shown in a murine tumor model. Upon tumor heating, nonthermally sensitive liposomes selectively but heterogeneously accumulated in the tumor region. The thermally sensitive liposomes showed a clear pattern of accumulation at the periphery of the tumor, concordant with the release temperature of this formulation (39-40 degrees C). This liposome contrast agent has potential for use with hyperthermia by providing individualized monitoring of tissue drug concentration distribution during or after treatment. This would allow for: 1) modification of treatment variables to improve the uniformity of drug delivery, and 2) provide a means to select patients most likely to benefit from this liposomal drug treatment. Additionally, the drug-loading method used for this liposome is applicable to a wide range of drugs, thereby broadening its applicability. The method is also applicable to other liposomal formulations with triggered release mechanisms.
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Abstract
OBJECTIVE The purpose of this study was to determine whether microstructural abnormalities in the white matter of the dorsolateral prefrontal cortex are associated with late-life depression. METHOD Seventeen elderly depressed subjects were compared with 16 elderly subjects who were not depressed. Diffusion tensor imaging was used to measure the fractional anisotropy of the white matter in the dorsolateral prefrontal cortex's superior and middle frontal gyri bilaterally and in the left occipital lobe as a control region. The authors compared results between groups while controlling for age, sex, and comorbid medical disorders. RESULTS Even after controlling for age, sex, hypertension, and heart disease, the authors found significantly lower fractional anisotropy values in the right superior frontal gyrus white matter of depressed patients than comparison subjects. CONCLUSIONS Microstructural changes in the white matter of the right superior frontal gyrus are associated with late-life depression. Further work is needed to determine how these changes contribute to depression outcomes.
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Diffusion tensor imaging of adult age differences in cerebral white matter: relation to response time. Neuroimage 2004; 21:1174-81. [PMID: 15006684 DOI: 10.1016/j.neuroimage.2003.11.004] [Citation(s) in RCA: 301] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2003] [Revised: 11/08/2003] [Accepted: 11/13/2003] [Indexed: 11/28/2022] Open
Abstract
Diffusion tensor imaging (DTI) measures the displacement of water molecules across tissue components, thus providing information regarding the microstructure of cerebral white matter. Fractional anisotropy (FA), the degree to which diffusion is directionally dependent, is typically higher for compact, homogeneous fiber bundles such as the corpus callosum. Previous DTI studies in adults have demonstrated an age-related decline in white matter FA, but whether the relation between FA and behavioral performance varies as a function of age has not been determined. We investigated adult age differences in FA, and age-related changes in the relation between FA and response time (RT), in a visual target-detection task. The results confirmed that, independently of age, FA is higher in the corpus callosum than in other brain regions. We also observed an age-related decline in FA that did not vary significantly across the brain regions. For both age groups, a lower level of integrity of the cerebral white matter (as indexed by FA), in specific brain regions, was associated with slower responses in the visual task. An age-related change in this relation was evident, however, in that the best predictor of RT for younger adults was FA in the splenium of the corpus callosum, whereas for older adults the best predictor was FA in the anterior limb of the internal capsule. This pattern is consistent with measures of the task-related cortical activation obtained from these same individuals and suggests an age-related increase in the attentional control of responses mediated by corticostriatal or corticothalamic circuits.
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Abstract
CONTEXT White matter hyperintensities (WMHs) are bright foci seen in the parenchyma of the brain on T2-weighted cranial magnetic resonance imaging (MRI) scans and are associated with geriatric depression. Because they are associated with age, they should increase in number and size over time. To our knowledge, this is the first longitudinal, volumetric MRI study of WMHs in depression. OBJECTIVE To determine if WMH progression over 2 years influences depression outcomes. DESIGN Over 2 years, depressed subjects received antidepressant treatment according to a naturalistic somatic treatment algorithm designed to offer the best possible treatment to the individual. After the treatment period, depressed subjects were dichotomized based on whether they had reached and sustained remission during this period. PARTICIPANTS One hundred thirty-three subjects aged 60 years or older meeting DSM-IV criteria for major depressive disorder. MEASURES Cranial MRI was obtained at baseline and approximately 2 years later. White matter hyperintensity volume was measured in each hemisphere using a semiautomated segmentation process. OUTCOMES Subjects were dichotomized based on achieving or not achieving remission of depressive symptoms, defined as a Montgomery-Asberg Depression Rating Scale score of 8 or less. RESULTS The depressed subgroup that achieved and sustained remission had significantly less increases in WMH volume (11.5%) than did the group that did not achieve or sustain remission (31.6%) (P =.01). In a regression model, greater change in WMH volume was significantly associated with failure to sustain remission (P =.004) even when controlling for baseline depression severity, medical illness severity, age, sex, and race. Education was associated with achieving and sustaining remission (P =.02). CONCLUSIONS Greater progression of WMH volume is associated with poor outcomes in geriatric depression. Future work is needed to develop means of slowing the rate of WMH progression and to determine whether this will lead to improved depression outcomes in elderly persons.
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Clinical characteristics of magnetic resonance imaging-defined subcortical ischemic depression. Biol Psychiatry 2004; 55:390-7. [PMID: 14960292 DOI: 10.1016/j.biopsych.2003.08.014] [Citation(s) in RCA: 151] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/29/2003] [Revised: 08/19/2003] [Accepted: 08/21/2003] [Indexed: 02/07/2023]
Abstract
BACKGROUND There is a substantial body of research supporting the vascular depression hypothesis of late-life depression. To update this hypothesis so it incorporates recent research, we propose that the term subcortical ischemic vascular depression may be a more accurate representation of the disease process. We sought to investigate this diagnosis as a construct by examining differences between depressed subjects with and without magnetic resonance imaging defined subcortical ischemic vascular depression. METHODS This case-control study examined 139 depressed elderly subjects. Demographic data, psychiatric, medical, and family history, depressive symptomatology, and functional impairment were compared between groups dichotomized based on neuroimaging findings. RESULTS Seventy-five (54%) of the subjects met neuroimaging criteria for subcortical ischemic vascular depression. Age was most strongly associated with increased prevalence of subcortical ischemic vascular depression. Lassitude and a history of hypertension were also positively associated with the diagnosis; a family history of mental illness and loss of libido were negatively associated with the diagnosis. CONCLUSIONS These data support that subcortical ischemic vascular depression may be a specific syndrome from other types of late-life depression. Further research is needed to further characterize this disorder, particularly in regards to cognitive function and treatment implications.
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Abstract
Diffusion tensor imaging is a variation of magnetic resonance imaging that measures the diffusion of water in tissues. This can help measure and quantify a tissue's orientation and structure, making it an ideal tool for examining cerebral white matter and neural fiber tracts. It is only beginning to be utilized in psychiatric research. This article reviews the theory behind diffusion tensor imaging, its potential to map fiber tracts in the brain, and its recent use in psychiatric research.
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