451
|
Čeponienė R, Westerfield M, Torki M, Townsend J. Modality-specificity of sensory aging in vision and audition: Evidence from event-related potentials. Brain Res 2008; 1215:53-68. [DOI: 10.1016/j.brainres.2008.02.010] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2007] [Revised: 01/13/2008] [Accepted: 02/04/2008] [Indexed: 10/22/2022]
|
452
|
Ikram MA, Vrooman HA, Vernooij MW, den Heijer T, Hofman A, Niessen WJ, van der Lugt A, Koudstaal PJ, Breteler MMB. Brain tissue volumes in relation to cognitive function and risk of dementia. Neurobiol Aging 2008; 31:378-86. [PMID: 18501994 DOI: 10.1016/j.neurobiolaging.2008.04.008] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2008] [Revised: 03/25/2008] [Accepted: 04/09/2008] [Indexed: 12/14/2022]
Abstract
We investigated in a population-based cohort study the association of global and lobar brain tissue volumes with specific cognitive domains and risk of dementia. Participants (n=490; 60-90 years) were non-demented at baseline (1995-1996). From baseline brain MRI-scans we obtained global and lobar volumes of CSF, GM, normal WM, white matter lesions and hippocampus. We performed neuropsychological testing at baseline to assess information processing speed, executive function, memory function and global cognitive function. Participants were followed for incident dementia until January 1, 2005. Larger volumes of CSF and WML were associated with worse performance on all neuropsychological tests, and an increased risk of dementia. Smaller WM volume was related to poorer information processing speed and executive function. In contrast, smaller GM volume was associated with worse memory function and increased risk of dementia. When investigating lobar GM volumes, we found that hippocampal volume and temporal GM volume were most strongly associated with risk of dementia, even in persons without objective and subjective cognitive deficits at baseline, followed by frontal and parietal GM volumes.
Collapse
Affiliation(s)
- M Arfan Ikram
- Department of Epidemiology, Erasmus MC University Medical Center, P.O. Box 2040, 3000 CA, Rotterdam, The Netherlands
| | | | | | | | | | | | | | | | | |
Collapse
|
453
|
Sullivan EV, Pfefferbaum A. Neuroradiological characterization of normal adult ageing. Br J Radiol 2008; 80 Spec No 2:S99-108. [PMID: 18445750 DOI: 10.1259/bjr/22893432] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
This paper provides a review of MRI and diffusion tensor imaging (DTI) findings in normal ageing as an essential context for evaluating imaging in dementia, and adding to the ever-growing number of such overviews. An additional extensive literature details the physics, MR acquisition, image reconstruction and mathematical computation approaches to both imaging modalities. The aim of this review is to illustrate how MR imaging modalities, spanning structural and diffusion tensor imaging, are suitable for visualizing and quantifying the macrostructural and microstructural disruptions sustained by the brain in normal ageing and to recognize the importance of normative data for identifying abnormalities characterizing neurodegenerative diseases and other conditions affecting brain tissue integrity.
Collapse
Affiliation(s)
- E V Sullivan
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, CA, USA
| | | |
Collapse
|
454
|
Jack CR, Weigand SD, Shiung MM, Przybelski SA, O'Brien PC, Gunter JL, Knopman DS, Boeve BF, Smith GE, Petersen RC. Atrophy rates accelerate in amnestic mild cognitive impairment. Neurology 2008; 70:1740-52. [PMID: 18032747 PMCID: PMC2734477 DOI: 10.1212/01.wnl.0000281688.77598.35] [Citation(s) in RCA: 133] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND We tested if rates of brain atrophy accelerate in individuals with amnestic mild cognitive impairment (aMCI) as they progress to typical late onset Alzheimer disease (AD). We included comparisons to subjects with aMCI who did not progress (labeled aMCI-S) and also to cognitively normal elderly subjects (CN). METHODS We studied 46 subjects with aMCI who progressed to AD (labeled aMCI-P), 46 CN, and 23 aMCI-S. All subjects must have had three or more serial MRI scans. Rates of brain shrinkage and ventricular expansion were measured across all available serial MRI scans in each subject. Change in volumes relative to the point at which subjects progressed to a clinical diagnosis of AD (the index date) was modeled in aMCI-P. Change in volumes relative to age was modeled in all three clinical groups. RESULTS In aMCI-P the change in pre to post index rate (i.e., acceleration) of ventricular expansion was 1.7 cm(3)/year, and acceleration in brain shrinkage was 5.3 cm(3)/year. Brain volume declined and ventricular volume increased in all three groups with age. Volume changes decelerated with increasing age in aMCI-P, and to a lesser extent in aMCI-S, but were linear in the matched CN. Among all subjects with aMCI, rates of atrophy were greater in apolipoprotein E epsilon 4 carriers than noncarriers. CONCLUSIONS Rates of atrophy accelerate as individuals progress from amnestic mild cognitive impairment (aMCI) to typical late onset Alzheimer disease (AD). Rates of atrophy are greater in younger than older subjects with aMCI who progressed to AD and subjects with aMCI who did not progress. We did not find that atrophy rates varied with age in 70- to 90-year-old cognitively normal subjects.
Collapse
Affiliation(s)
- C R Jack
- Department of Radiology, Mayo Clinic and Foundation, Rochester, MN 55905, USA.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
455
|
Fornage M, Chiang YA, O'Meara ES, Psaty BM, Reiner AP, Siscovick DS, Tracy RP, Longstreth WT. Biomarkers of Inflammation and MRI-Defined Small Vessel Disease of the Brain: The Cardiovascular Health Study. Stroke 2008; 39:1952-9. [PMID: 18436879 DOI: 10.1161/strokeaha.107.508135] [Citation(s) in RCA: 130] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
BACKGROUND AND PURPOSE To clarify the role of inflammation in the pathogenesis of small vessel disease of the brain, we investigated the association between common variation in the C-reactive protein (CRP) and interleukin (IL)-6 genes, plasma CRP and IL6 levels, and presence of MRI-defined white matter lesions (WML) and brain infarcts (BI) in elderly participants of the Cardiovascular Health Study. METHODS Tag single nucleotide polymorphisms (SNPs) in the CRP and IL6 genes were selected from the SeattleSNPs database. In cross-sectional analyses, logistic regression models adjusting for known cardiovascular disease risk factors were constructed to assess the associations of plasma CRP and IL6 levels and common CRP and IL6 gene haplotypes with presence of WML or BI in Blacks (n=532) and Whites (n=2905). RESULTS Plasma IL6 and CRP levels were associated with presence of WML and BI in both races. In Whites, common haplotypes of the IL6 gene were significantly associated with WML and BI. The common haplotype tagged by the -174G/C promoter polymorphism was associated with an increased risk of WML (OR=1.14; 95% CI: [1.02; 1.28]). The common haplotype tagged by the -572G/C promoter polymorphism was associated with an increased risk of BI (OR=1.57; 95% CI: [1.15; 2.14]). Significant associations were lacking for WML or BI with IL6 gene variation in Blacks, or with CRP gene variation in either race. CONCLUSIONS This study provides evidence of a genetic basis underlying the relationship between plasma biomarkers of inflammation and small vessel disease of the brain. Further studies to elucidate the specific role of IL6 in disease pathogenesis are warranted.
Collapse
Affiliation(s)
- Myriam Fornage
- Brown Foundation Institute of Molecular Medicine, University of Texas Health Science Center at Houston, Houston, TX 77030, USA.
| | | | | | | | | | | | | | | |
Collapse
|
456
|
Silvay G, Castillo JG, Chikwe J, Flynn B, Filsoufi F. Cardiac anesthesia and surgery in geriatric patients. Semin Cardiothorac Vasc Anesth 2008; 12:18-28. [PMID: 18397906 DOI: 10.1177/1089253208316446] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The average age of US population is steadily increasing, with more than 15 million people aged 80 and older. Coronary artery disease and degenerative cardiovascular diseases are particularly prevalent in this population. Consequently, an increasing number of elderly patients are referred for surgical intervention. Advanced age is associated with decreased physiologic reserve and significant comorbidity. Thorough preoperative assessment, identification of the risk factors for perioperative morbidity and mortality, and optimal preparation are critical in these patients. Age-related changes in comorbidities and altered pharmacokinetics and pharmacodynamics impacts anesthetic management, perioperative monitoring, postoperative care, and outcome. This article updates the age-related changes in organ subsystems relevant to cardiac anesthesia, perioperative issues, and intraoperative management. Early and late operative outcome in octogenarians undergoing cardiac surgery are reviewed. The data clearly indicate that no patient group is "too old" for cardiac surgery and that excellent outcomes can be achieved in selected group of elderly patients.
Collapse
Affiliation(s)
- George Silvay
- Department of Anesthesiology, Mount Sinai Medical Center, New York, NY 10029-6574, USA.
| | | | | | | | | |
Collapse
|
457
|
Sheline YI, Price JL, Vaishnavi SN, Mintun MA, Barch DM, Epstein AA, Wilkins CH, Snyder AZ, Couture L, Schechtman K, McKinstry RC. Regional white matter hyperintensity burden in automated segmentation distinguishes late-life depressed subjects from comparison subjects matched for vascular risk factors. Am J Psychiatry 2008; 165:524-32. [PMID: 18281408 PMCID: PMC4118770 DOI: 10.1176/appi.ajp.2007.07010175] [Citation(s) in RCA: 148] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
OBJECTIVE Segmented brain white matter hyperintensities were compared between subjects with late-life depression and age-matched subjects with similar vascular risk factor scores. Correlations between neuropsychological performance and whole brain-segmented white matter hyperintensities and white and gray matter volumes were also examined. METHOD Eighty-three subjects with late-life depression and 32 comparison subjects underwent physical examination, psychiatric evaluation, neuropsychological testing, vascular risk factor assessment, and brain magnetic resonance imaging (MRI). Automated segmentation methods were used to compare the total brain and regional white matter hyperintensity burden between depressed patients and comparison subjects. RESULTS Depressed patients and comparison subjects did not differ in demographic variables, including vascular risk factor, or whole brain-segmented volumes. However, depressed subjects had seven regions of greater white matter hyperintensities located in the following white matter tracts: the superior longitudinal fasciculus, fronto-occipital fasciculus, uncinate fasciculus, extreme capsule, and inferior longitudinal fasciculus. These white matter tracts underlie brain regions associated with cognitive and emotional function. In depressed patients but not comparison subjects, volumes of three of these regions correlated with executive function; whole brain white matter hyperintensities correlated with executive function; whole brain white matter correlated with episodic memory, processing speed, and executive function; and whole brain gray matter correlated with processing speed. CONCLUSIONS These findings support the hypothesis that the strategic location of white matter hyperintensities may be critical in late-life depression. Further, the correlation of neuropsychological deficits with the volumes of whole brain white matter hyperintensities and gray and white matter in depressed subjects but not comparison subjects supports the hypothesis of an interaction between these structural brain components and depressed status.
Collapse
|
458
|
Levy-Cooperman N, Ramirez J, Lobaugh NJ, Black SE. Misclassified Tissue Volumes in Alzheimer Disease Patients With White Matter Hyperintensities. Stroke 2008; 39:1134-41. [DOI: 10.1161/strokeaha.107.498196] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background and Purpose—
MRI-based quantification of gray and white matter volume is common in studies involving elderly patient populations. The aim of the present study was to describe the effects of not accounting for subcortical white matter hyperintensities (WMH) on tissue volumes in Alzheimer Disease patients with varying degrees of WMH (mild: n=19, moderate: n=22, severe: n=18).
Methods—
An automated tissue segmentation protocol that was optimized for an elderly population, a brain regional parcellation procedure, and a lesion segmentation protocol were applied to measure tissue volumes (whole brain and regional lobar volumes) with and without lesion segmentation to quantify the volume of misclassified tissue.
Results—
After application of the tissue segmentation protocol and lesion analysis, mean total percentage misclassified volume across all subjects was 2% (17.9 cm
3
) of whole brain volume (corrected for total intracranial capacity). Mean percentage of misclassified tissue volumes for the severe group was 4.8% of whole brain, which translates to a mean volume 42.2 cm
3
. Gray matter volume was most overestimated in the severe group, where 6.4% of the total gray matter volume was derived from misclassified WMH. The regional analysis showed that frontal (41%, 7.4 cm
3
) and inferior parietal (18%, 3.25 cm
3
) lobes were most affected by tissue misclassification.
Conclusion—
MRI-based volumetric studies of Alzheimer Disease that do not account for WMH can expect an erroneous inflation of gray or white matter volumes, especially in the frontal and inferior parietal regions. To avoid this source of error, MRI-based volumetric studies in patient populations susceptible to hyperintensities should include a WMH segmentation protocol.
Collapse
Affiliation(s)
- Naama Levy-Cooperman
- From the L.C. Campbell Cognitive Neurology Research Unit (N.L.-C., J.R., N.J.L., S.E.B.), Heart and Stroke Foundation Centre for Stroke Recovery (N.J.L., S.E.B.), Sunnybrook Health Sciences Centre, Division of Neurology (N.J.L., S.E.B.), Department of Medicine, and the Institute of Medical Science (N.L.-C., J.R., N.J.L., S.E.B.), University of Toronto, Ontario, Canada
| | - Joel Ramirez
- From the L.C. Campbell Cognitive Neurology Research Unit (N.L.-C., J.R., N.J.L., S.E.B.), Heart and Stroke Foundation Centre for Stroke Recovery (N.J.L., S.E.B.), Sunnybrook Health Sciences Centre, Division of Neurology (N.J.L., S.E.B.), Department of Medicine, and the Institute of Medical Science (N.L.-C., J.R., N.J.L., S.E.B.), University of Toronto, Ontario, Canada
| | - Nancy J. Lobaugh
- From the L.C. Campbell Cognitive Neurology Research Unit (N.L.-C., J.R., N.J.L., S.E.B.), Heart and Stroke Foundation Centre for Stroke Recovery (N.J.L., S.E.B.), Sunnybrook Health Sciences Centre, Division of Neurology (N.J.L., S.E.B.), Department of Medicine, and the Institute of Medical Science (N.L.-C., J.R., N.J.L., S.E.B.), University of Toronto, Ontario, Canada
| | - Sandra E. Black
- From the L.C. Campbell Cognitive Neurology Research Unit (N.L.-C., J.R., N.J.L., S.E.B.), Heart and Stroke Foundation Centre for Stroke Recovery (N.J.L., S.E.B.), Sunnybrook Health Sciences Centre, Division of Neurology (N.J.L., S.E.B.), Department of Medicine, and the Institute of Medical Science (N.L.-C., J.R., N.J.L., S.E.B.), University of Toronto, Ontario, Canada
| |
Collapse
|
459
|
Piguet O, Double KL, Kril JJ, Harasty J, Macdonald V, McRitchie DA, Halliday GM. White matter loss in healthy ageing: a postmortem analysis. Neurobiol Aging 2008; 30:1288-95. [PMID: 18077060 DOI: 10.1016/j.neurobiolaging.2007.10.015] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2007] [Revised: 10/23/2007] [Accepted: 10/27/2007] [Indexed: 10/22/2022]
Abstract
Age-related brain changes are widely documented. Because of differences in measurement methods and case selection, the reported effects of age on regional grey and white matter brain volumes, however, are much more pronounced and widespread in neuroimaging than in postmortem studies. Consequently, the magnitude of the effect that is specific to chronological age remains unresolved. We present postmortem volume measurements for 26 cortical, subcortical and white matter regions, in 24 human brains aged 46-92 years, free of neuropathological abnormalities. Significant age-related loss was observed in anterior and posterior white matter but not in total grey matter volumes. Further analyses on five cortical subregions previously reported to exhibit large age-related loss on MRI yielded negative results. These analyses demonstrate smaller changes with age than those reported in imaging studies. Although this discrepancy between postmortem and imaging studies may partly be explained by the increase in noise of the neuroimaging data with age, our results suggest that healthy brain ageing is a process affecting predominantly white matter not grey matter.
Collapse
Affiliation(s)
- O Piguet
- Prince of Wales Medical Research Institute and the University of New South Wales, NSW, Australia.
| | | | | | | | | | | | | |
Collapse
|
460
|
Deformation field morphometry reveals age-related structural differences between the brains of adults up to 51 years. J Neurosci 2008; 28:828-42. [PMID: 18216191 DOI: 10.1523/jneurosci.3732-07.2008] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Age-related differences in the anatomical structure of the brains from 51 healthy male subjects (age: 18-51 years) were analyzed by deformation field morphometry in a cross-sectional study. The magnetic resonance images of the brains were nonlinearly registered onto the image of a reference brain: the registration algorithm simulated an elastic deformation of each brain (source brain) so that the voxelwise intensity differences with the reference brain were minimized. A three-dimensional deformation field was calculated for each source brain that encoded the anatomical differences between the source brain and the reference brain. Maps of voxelwise volume differences between each subject's brain and the reference brain were analyzed. They showed age-related differences in anatomically defined regions of interest. Major volume decreases were found in the white matter and nuclei of the cerebellum, as well as in the ventral thalamic nuclei and the somatosensory and motor cortices, including the underlying white matter. These findings suggest that aging between the second and sixth decade predominantly affects subcortical nuclei and cortical areas of the sensorimotor system, forming the cortico-rubro-cerebello-thalamo-cortical pathway. Additionally, a pronounced age-related decline in volume was observed in the rostral anterior cingulate, orbitofrontal, and lateral prefrontal cortices. Almost no differences were observed in the occipital and temporal lobes. The ventricles showed a pronounced widening. Remarkably, these volume differences occur at a relatively early period of the human life span. It may be speculated that these structural differences accompany or precede differences in sensorimotor functions and behavior.
Collapse
|
461
|
Bangen KJ, Restom K, Liu TT, Jak AJ, Wierenga CE, Salmon DP, Bondi MW. Differential age effects on cerebral blood flow and BOLD response to encoding: associations with cognition and stroke risk. Neurobiol Aging 2007; 30:1276-87. [PMID: 18160181 DOI: 10.1016/j.neurobiolaging.2007.11.012] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2007] [Revised: 10/12/2007] [Accepted: 11/02/2007] [Indexed: 01/06/2023]
Abstract
Changes in the cerebrovascular system due to age or disease can significantly alter the blood-oxygenation-level-dependent (BOLD) signal and complicate its interpretation. The simultaneous acquisition of arterial spin labeling (ASL) and BOLD data represents a useful technique to more fully characterize the neurovascular underpinnings of functional brain response to cognition. We conducted a functional magnetic resonance imaging (FMRI) study of episodic memory encoding to investigate whether age is related to cerebral blood flow (CBF) and BOLD response in the medial temporal lobe (MTL). Results demonstrated a significant reduction in resting-state CBF in older compared to young adults. Conversely, older adults showed significantly increased CBF but not BOLD response in the MTL during picture encoding relative to young adults. Correlations between CBF response and cognition were demonstrated whereas associations with BOLD were not observed. Stroke risk was associated with both CBF and BOLD response. Results suggest that aging effects on CBF and BOLD responses to encoding are dissociable and that cerebrovascular alterations contribute to findings of age-related differences.
Collapse
Affiliation(s)
- Katherine J Bangen
- San Diego State University/University of California San Diego, Joint Doctoral Program in Clinical Psychology, San Diego, CA 92120-4913, USA
| | | | | | | | | | | | | |
Collapse
|
462
|
Marcus DS, Wang TH, Parker J, Csernansky JG, Morris JC, Buckner RL. Open Access Series of Imaging Studies (OASIS): cross-sectional MRI data in young, middle aged, nondemented, and demented older adults. J Cogn Neurosci 2007; 19:1498-507. [PMID: 17714011 DOI: 10.1162/jocn.2007.19.9.1498] [Citation(s) in RCA: 757] [Impact Index Per Article: 44.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
The Open Access Series of Imaging Studies is a series of magnetic resonance imaging data sets that is publicly available for study and analysis. The initial data set consists of a cross-sectional collection of 416 subjects aged 18 to 96 years. One hundred of the included subjects older than 60 years have been clinically diagnosed with very mild to moderate Alzheimer's disease. The subjects are all right-handed and include both men and women. For each subject, three or four individual T1-weighted magnetic resonance imaging scans obtained in single imaging sessions are included. Multiple within-session acquisitions provide extremely high contrast-to-noise ratio, making the data amenable to a wide range of analytic approaches including automated computational analysis. Additionally, a reliability data set is included containing 20 subjects without dementia imaged on a subsequent visit within 90 days of their initial session. Automated calculation of whole-brain volume and estimated total intracranial volume are presented to demonstrate use of the data for measuring differences associated with normal aging and Alzheimer's disease.
Collapse
|
463
|
Vernooij MW, Ikram MA, Tanghe HL, Vincent AJPE, Hofman A, Krestin GP, Niessen WJ, Breteler MMB, van der Lugt A. Incidental findings on brain MRI in the general population. N Engl J Med 2007; 357:1821-8. [PMID: 17978290 DOI: 10.1056/nejmoa070972] [Citation(s) in RCA: 1046] [Impact Index Per Article: 61.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
BACKGROUND Magnetic resonance imaging (MRI) of the brain is increasingly used both in research and in clinical medicine, and scanner hardware and MRI sequences are continually being improved. These advances are likely to result in the detection of unexpected, asymptomatic brain abnormalities, such as brain tumors, aneurysms, and subclinical vascular pathologic changes. We conducted a study to determine the prevalence of such incidental brain findings in the general population. METHODS The subjects were 2000 persons (mean age, 63.3 years; range, 45.7 to 96.7) from the population-based Rotterdam Study in whom high-resolution, structural brain MRI (1.5 T) was performed according to a standardized protocol. Two trained reviewers recorded all brain abnormalities, including asymptomatic brain infarcts. The volume of white-matter lesions was quantified in milliliters with the use of automated postprocessing techniques. Two experienced neuroradiologists reviewed all incidental findings. All diagnoses were based on MRI findings, and additional histologic confirmation was not obtained. RESULTS Asymptomatic brain infarcts were present in 145 persons (7.2%). Among findings other than infarcts, cerebral aneurysms (1.8%) and benign primary tumors (1.6%), mainly meningiomas, were the most frequent. The prevalence of asymptomatic brain infarcts and meningiomas increased with age, as did the volume of white-matter lesions, whereas aneurysms showed no age-related increase in prevalence. CONCLUSIONS Incidental brain findings on MRI, including subclinical vascular pathologic changes, are common in the general population. The most frequent are brain infarcts, followed by cerebral aneurysms and benign primary tumors. Information on the natural course of these lesions is needed to inform clinical management.
Collapse
Affiliation(s)
- Meike W Vernooij
- Department of Epidemiology and Biostatistics, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | | | | | | | | | | | | | | | | |
Collapse
|
464
|
Asllani I, Borogovac A, Wright C, Sacco R, Brown TR, Zarahn E. An investigation of statistical power for continuous arterial spin labeling imaging at 1.5 T. Neuroimage 2007; 39:1246-56. [PMID: 18036834 DOI: 10.1016/j.neuroimage.2007.10.015] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2007] [Revised: 10/15/2007] [Accepted: 10/16/2007] [Indexed: 11/16/2022] Open
Abstract
Variance estimates can be used in conjunction with scientifically meaningful effect sizes to design experiments with type II error control. Here we present estimates of intra- and inter-subject variances for region of interest (ROI) from resting cerebral blood flow (CBF) maps obtained using whole brain, spin echo echoplanar (SE-EPI) continuous arterial spin labeling (CASL) imaging on 52 elderly subjects (age=70.5+/-7.9 years, 29 males). There was substantial intrasubject systematic variability in CBF of gray matter ROIs corresponding to a range of standard deviations=[39-168] (ml/(100 g min)). This variability was mainly due to two factors: (1) an expected inverse relationship between ROI volume and intrasubject variance and (2) an increased effective post-labeling delay for more superior slices acquired later in the sequence. For example, intrasubject variance in Brodmann area 4 (BA 4) was approximately 8 times larger than in hippocampus, despite their similar gray matter volumes. Estimated ROI-wise power was computed for various numbers of acquired CBF images, numbers of subjects, and CBF effect sizes for two experimental designs: independent sample t-test and paired t-test. The theoretical effects of pulse sequence and field strength on general applicability of these results are discussed.
Collapse
Affiliation(s)
- Iris Asllani
- The Department of Radiology, Columbia University College of Physicians and Surgeons, 630 West 168th Street, Columbia University, New York, New York 10032, USA.
| | | | | | | | | | | |
Collapse
|
465
|
Lunetta KL, Erlich PM, Cuenco KT, Cupples LA, Green RC, Farrer LA, Decarli C. Heritability of magnetic resonance imaging (MRI) traits in Alzheimer disease cases and their siblings in the MIRAGE study. Alzheimer Dis Assoc Disord 2007; 21:85-91. [PMID: 17545732 DOI: 10.1097/wad.0b013e3180653bf7] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Magnetic resonance imaging (MRI) traits can serve as more specific measures of degenerative or cerebrovascular brain injury than can be ascertained through personal history, risk factors, clinical signs, or symptoms. They are potentially useful intermediate phenotypes for genetic studies of Alzheimer disease (AD). Recent studies have estimated heritability of white matter hyperintensity (WMH) among cognitively normal family members to be between 0.55 and 0.73. Persons discordant for AD are expected to have substantially different MRI phenotype distributions; our goal was to determine whether MRI traits in siblings discordant for AD are heritable. We measured cerebral atrophy, medial temporal atrophy (MTA), WMH, and a rating of cerebrovascular disease (CVR) via MRI in 815 participants from 424 families of the Multi-Institutional Research in Alzheimer's Genetic Epidemiology Study. Residual heritability after adjustment for covariates ranged from 0.17 (P=0.009) for MTA to 0.57 (P=10(-7)) for CVR. The number of APOE-epsilon4 alleles was significantly associated with WMH (P=0.01) and CVR (P=0.005) but not cerebral atrophy (P=0.25) or MTA (P=0.83). Heritability remained significant and high after adjusting for APOE genotype, suggesting that a substantial proportion of the additive genetic variation in these MRI traits is explained by other genes. In the Multi-Institutional Research in Alzheimer's Genetic Epidemiology Study of AD-discordant siblings, MRI traits are heritable and are potential endophenotypes for genetic association studies.
Collapse
Affiliation(s)
- Kathryn L Lunetta
- Department of Biostatistics, Boston University School of Public Health, Boston, MA 02118, USA.
| | | | | | | | | | | | | |
Collapse
|
466
|
Prabhakaran S, Wright CB, Yoshita M, Delapaz R, Brown T, DeCarli C, Sacco RL. Prevalence and determinants of subclinical brain infarction: the Northern Manhattan Study. Neurology 2007; 70:425-30. [PMID: 17898325 PMCID: PMC2714050 DOI: 10.1212/01.wnl.0000277521.66947.e5] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVE Risk factors for subclinical brain infarcts (SBI) have not been well studied, especially in Hispanic and black populations who may be at higher risk for vascular disease. We examined the prevalence and determinants of SBI in a multiethnic community cohort. METHODS The Northern Manhattan Study (NOMAS) includes 892 stroke-free participants who underwent brain MRI. Baseline demographic and vascular risk factor data were collected. The presence of SBI was determined from the size, location, and imaging characteristics of the lesion based on fluid attenuated inversion recovery (FLAIR) T1 and T2, and proton density MRI sequences. We calculated the prevalence of SBI and cross-sectional associations with sociodemographic and vascular risk factors, using logistic regression to adjust for relevant covariates. RESULTS Among 892 subjects (mean age 71.3 years), 158 (17.7%) had SBI (13.5% had 1 lesion, 4.3% had >1 lesion). Of the total 216 infarcts, most were small (<1 cm, 82.4%) and subcortical (82.9%). SBI prevalence increased with age (<65: 9.7%; 65 to 75: 16.4%; >75: 26.1%), was increased among men (21.3% vs 15.2% in women), and was increased among blacks (24.0% vs 18.1% in whites and 15.8% in Hispanics). The presence of SBI was independently associated with older age (per year: OR 1.06, 95% CI 1.04 to 1.09), male sex (OR 1.79, 95% CI 1.22 to 2.61), and hypertension (OR 2.08, 95% CI 1.35 to 3.22) adjusting for age, sex, race-ethnicity, and vascular risk factors. A significant interaction (p = 0.002) between race and age was observed such that younger black subjects had greater odds of having SBI. CONCLUSIONS SBI were detected in nearly 18% of subjects in a multiethnic community-based cohort. Age, male sex, and hypertension were independently associated with SBI. Subclinical cerebral infarcts are more prevalent than symptomatic infarcts and may increase the true public health burden of stroke.
Collapse
Affiliation(s)
- Shyam Prabhakaran
- Rush University Medical Center, 1725 W. Harrison St, Chicago, IL 60612
| | | | | | | | - Truman Brown
- Columbia University, 710 W. 168 St., New York, NY 10032
| | - Charles DeCarli
- University of California-Davis, 4860 Y Street, Sacramento, CA 95817
| | - Ralph L. Sacco
- Columbia University, 710 W. 168 St., New York, NY 10032
- University of Miami, 1120 NW 14 Street, Miami, FL 33136
| |
Collapse
|
467
|
Seshadri S, DeStefano AL, Au R, Massaro JM, Beiser AS, Kelly-Hayes M, Kase CS, D'Agostino RB, DeCarli C, Atwood LD, Wolf PA. Genetic correlates of brain aging on MRI and cognitive test measures: a genome-wide association and linkage analysis in the Framingham Study. BMC MEDICAL GENETICS 2007; 8 Suppl 1:S15. [PMID: 17903297 PMCID: PMC1995608 DOI: 10.1186/1471-2350-8-s1-s15] [Citation(s) in RCA: 156] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
BACKGROUND Brain magnetic resonance imaging (MRI) and cognitive tests can identify heritable endophenotypes associated with an increased risk of developing stroke, dementia and Alzheimer's disease (AD). We conducted a genome-wide association (GWA) and linkage analysis exploring the genetic basis of these endophenotypes in a community-based sample. METHODS A total of 705 stroke- and dementia-free Framingham participants (age 62 +9 yrs, 50% male) who underwent volumetric brain MRI and cognitive testing (1999-2002) were genotyped. We used linear models adjusting for first degree relationships via generalized estimating equations (GEE) and family based association tests (FBAT) in additive models to relate qualifying single nucleotide polymorphisms (SNPs, 70,987 autosomal on Affymetrix 100K Human Gene Chip with minor allele frequency > or = 0.10, genotypic call rate > or = 0.80, and Hardy-Weinberg equilibrium p-value > or = 0.001) to multivariable-adjusted residuals of 9 MRI measures including total cerebral brain (TCBV), lobar, ventricular and white matter hyperintensity (WMH) volumes, and 6 cognitive factors/tests assessing verbal and visuospatial memory, visual scanning and motor speed, reading, abstract reasoning and naming. We determined multipoint identity-by-descent utilizing 10,592 informative SNPs and 613 short tandem repeats and used variance component analyses to compute LOD scores. RESULTS The strongest gene-phenotype association in FBAT analyses was between SORL1 (rs1131497; p = 3.2 x 10(-6)) and abstract reasoning, and in GEE analyses between CDH4 (rs1970546; p = 3.7 x 10(-8)) and TCBV. SORL1 plays a role in amyloid precursor protein processing and has been associated with the risk of AD. Among the 50 strongest associations (25 each by GEE and FBAT) were other biologically interesting genes. Polymorphisms within 28 of 163 candidate genes for stroke, AD and memory impairment were associated with the endophenotypes studied at p < 0.001. We confirmed our previously reported linkage of WMH on chromosome 4 and describe linkage of reading performance to a marker on chromosome 18 (GATA11A06), previously linked to dyslexia (LOD scores = 2.2 and 5.1). CONCLUSION Our results suggest that genes associated with clinical neurological disease also have detectable effects on subclinical phenotypes. These hypothesis generating data illustrate the use of an unbiased approach to discover novel pathways that may be involved in brain aging, and could be used to replicate observations made in other studies.
Collapse
Affiliation(s)
- Sudha Seshadri
- The National Heart Lung and Blood Institute's Framingham Heart Study, Framingham, MA, USA
- Department of Neurology, Boston University School of Medicine, Boston, MA, USA
| | - Anita L DeStefano
- The National Heart Lung and Blood Institute's Framingham Heart Study, Framingham, MA, USA
- Department of Biostatistics, Boston University School of Public Health, Boston, MA, USA
| | - Rhoda Au
- The National Heart Lung and Blood Institute's Framingham Heart Study, Framingham, MA, USA
- Department of Neurology, Boston University School of Medicine, Boston, MA, USA
| | - Joseph M Massaro
- The National Heart Lung and Blood Institute's Framingham Heart Study, Framingham, MA, USA
- Department of Biostatistics, Boston University School of Public Health, Boston, MA, USA
- Statistics and Consulting Unit, Department of Mathematics, Boston University, Boston, MA, USA
| | - Alexa S Beiser
- The National Heart Lung and Blood Institute's Framingham Heart Study, Framingham, MA, USA
- Department of Neurology, Boston University School of Medicine, Boston, MA, USA
- Department of Biostatistics, Boston University School of Public Health, Boston, MA, USA
| | - Margaret Kelly-Hayes
- The National Heart Lung and Blood Institute's Framingham Heart Study, Framingham, MA, USA
- Department of Neurology, Boston University School of Medicine, Boston, MA, USA
| | - Carlos S Kase
- The National Heart Lung and Blood Institute's Framingham Heart Study, Framingham, MA, USA
- Department of Neurology, Boston University School of Medicine, Boston, MA, USA
| | - Ralph B D'Agostino
- The National Heart Lung and Blood Institute's Framingham Heart Study, Framingham, MA, USA
- Statistics and Consulting Unit, Department of Mathematics, Boston University, Boston, MA, USA
| | - Charles DeCarli
- The Department of Neurology, University of California – Davis, Sacramento, CA, USA
| | - Larry D Atwood
- The National Heart Lung and Blood Institute's Framingham Heart Study, Framingham, MA, USA
- Department of Neurology, Boston University School of Medicine, Boston, MA, USA
| | - Philip A Wolf
- The National Heart Lung and Blood Institute's Framingham Heart Study, Framingham, MA, USA
- Department of Neurology, Boston University School of Medicine, Boston, MA, USA
| |
Collapse
|
468
|
Ikram MA, Vernooij MW, Vrooman HA, Hofman A, Breteler MMB. Brain tissue volumes and small vessel disease in relation to the risk of mortality. Neurobiol Aging 2007; 30:450-6. [PMID: 17766013 DOI: 10.1016/j.neurobiolaging.2007.07.009] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2007] [Revised: 07/09/2007] [Accepted: 07/18/2007] [Indexed: 10/22/2022]
Abstract
Brain atrophy and small vessel disease increase the risk of dementia and stroke. In a population-based cohort study (n=490; 60-90 years) we investigated how volumetric measures of atrophy and small vessel disease were related to mortality and whether this was independent of incident dementia or stroke. Brain volume and hippocampal volume were considered as measures of atrophy, whereas white matter lesions (WML) and lacunar infarcts reflected small vessel disease. We first investigated all-cause mortality in the whole cohort. In subsequent analyses we censored persons at incident dementia or incident stroke. Finally, we separately investigated cardiovascular mortality. The average follow-up was 8.4 years, during which 191 persons died. Brain atrophy and hippocampal atrophy, as well as WML increased the risk of death. The risks associated with hippocampal atrophy attenuated when censoring persons at incident dementia, but not at incident stroke. Censoring at either incident dementia or stroke did not change the risk associated with brain atrophy and WML. Moreover, WML were particularly associated with cardiovascular mortality.
Collapse
Affiliation(s)
- M Arfan Ikram
- Department of Epidemiology & Biostatistics, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | | | | | | | | |
Collapse
|
469
|
Kramer JH, Mungas D, Reed BR, Wetzel ME, Burnett MM, Miller BL, Weiner MW, Chui HC. Longitudinal MRI and cognitive change in healthy elderly. Neuropsychology 2007; 21:412-8. [PMID: 17605574 PMCID: PMC2780018 DOI: 10.1037/0894-4105.21.4.412] [Citation(s) in RCA: 185] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Cross-sectional studies of normal aging indicate an association between memory and hippocampal volume, and between executive functioning and subcortical-frontal circuits. Much less is known, however, about the relationship between longitudinal MRI changes and cognitive decline. The authors hypothesized that longitudinal change in memory would be best predicted by change in hippocampal volumes, whereas change in executive functioning would be best predicted by cortical atrophy and progression of MRI markers of cerebrovascular disease. For this study, 50 healthy elderly subjects underwent structural MRI and cognitive testing at baseline and again at follow-up, with a mean follow-up interval of 45 months. Volumetric MRI measures were hippocampus, cortical gray matter, white matter signal hyperintensity (WMSH), and lacunae. Neuropsychological measures were psychometrically robust composite scores of episodic memory (MEM) and executive functioning (EXEC). Hierarchical multiple regression indicated that a decrease in hippocampus was associated with a decline in MEM, whereas decreased cortical gray matter and increased WMSH were independently associated with a decline in EXEC. Results suggest that in normal aging, cognitive functioning declines as cortical gray matter and hippocampus decrease, and WMSH increases. The association between WMSH and EXEC further highlights the cognitive sequealae associated with cerebrovascular disease in normal elderly.
Collapse
Affiliation(s)
- Joel H Kramer
- Department of Neurology, San Francisco Medical Center, University of California, San Francisco, CA 94143, USA.
| | | | | | | | | | | | | | | |
Collapse
|
470
|
Abstract
As the availability and quality of imaging techniques improve, doctors are identifying more patients with no history of transient ischaemic attack or stroke in whom imaging shows brain infarcts. Until recently, little was known about the relevance of these lesions. In this systematic review, we give an overview of the frequency, causes, and consequences of MRI-defined silent brain infarcts, which are detected in 20% of healthy elderly people and up to 50% of patients in selected series. Most infarcts are lacunes, of which hypertensive small-vessel disease is thought to be the main cause. Although silent infarcts, by definition, lack clinically overt stroke-like symptoms, they are associated with subtle deficits in physical and cognitive function that commonly go unnoticed. Moreover, the presence of silent infarcts more than doubles the risk of subsequent stroke and dementia. Future studies will have to show whether screening and treating high-risk patients can effectively reduce the risk of further infarcts, stroke, and dementia.
Collapse
Affiliation(s)
- Sarah E Vermeer
- Department of Neurology, Erasmus Medical Center, Rotterdam, The Netherlands.
| | | | | |
Collapse
|
471
|
Hugenschmidt CE, Peiffer AM, Kraft RA, Casanova R, Deibler AR, Burdette JH, Maldjian JA, Laurienti PJ. Relating imaging indices of white matter integrity and volume in healthy older adults. Cereb Cortex 2007; 18:433-42. [PMID: 17575289 DOI: 10.1093/cercor/bhm080] [Citation(s) in RCA: 125] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Age-related alterations in white matter have the potential to profoundly affect cognitive functioning. In fact, magnetic resonance imaging (MRI) studies using fractional anisotropy (FA) to measure white matter integrity reveal a positive correlation between FA and behavioral performance in older adults. Confounding these results are imaging studies demonstrating age-related white matter atrophy in some areas displaying altered FA, suggesting changes in diffusion may be simply an epiphenomenon of tissue loss. In the current study, structural MRI techniques were used to identify the relationship between white matter integrity and decreased volume in healthy aging adults. The data demonstrated that white matter atrophy did in fact account for differences in some areas, but significant FA decreases remained across much of the white matter after adjusting for atrophy. Results suggest a complex relationship between changes in white matter integrity and volume. FA appears to be more sensitive than volume loss to changes in normal appearing tissue, and these FA changes may actually precede white matter atrophy in some brain areas. As such, the ability to detect early white matter alterations may facilitate development of targeted treatments that prevent or slow age-related white matter degradation and associated cognitive sequelae.
Collapse
|
472
|
Jaramillo SA, Felton D, Andrews L, Desiderio L, Hallarn RK, Jackson SD, Coker LH, Robinson JG, Ockene JK, Espeland MA. Enrollment in a brain magnetic resonance study: results from the Women's Health Initiative Memory Study Magnetic Resonance Imaging Study (WHIMS-MRI). Acad Radiol 2007; 14:603-12. [PMID: 17434074 PMCID: PMC1934046 DOI: 10.1016/j.acra.2007.02.001] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2006] [Revised: 02/01/2007] [Accepted: 02/01/2007] [Indexed: 11/25/2022]
Abstract
RATIONALE AND OBJECTIVES The rates of enrollment of volunteers for brain magnetic resonance imaging (MRI) studies vary by demographic and clinical characteristics. We use data from a large MRI study to identify factors associated with differential enrollment and to examine potential biases this may produce in study results. MATERIALS AND METHODS Results from recruitment of 1,431 women into the MRI substudy of the Women's Health Initiative Memory Study (WHIMS-MRI) are described. A sensitivity analysis was conducted to estimate the degree of bias associated with missing data on estimates of risk factor relationships. RESULTS Of 2,345 women contacted from an established cohort of women older than 70 years of age, 72% consented to undergo screening for WHIMS-MRI. Scanning was ultimately completed on 61%. Completion rates varied according to a range of sociodemographic, lifestyle, and clinical characteristics that may be related to study outcomes. Plausible levels of selective enrollment in magnetic resonance imaging studies may produce moderate biases (< +/-20%) in characterizations of risk factor relationships. Adverse events, such as claustrophobia, occurred during 1.7% of the attempted scans and, in 0.8% of instances, led to lost data. CONCLUSIONS Enrollment of older women into brain imaging studies is feasible, although selection biases may limit how well study cohorts reflect more general populations.
Collapse
Affiliation(s)
- Sarah A Jaramillo
- Division of Public Health Sciences, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, NC 27157, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
473
|
Aurlien H, Aarseth JH, Gjerde IO, Karlsen B, Skeidsvoll H, Gilhus NE. Focal epileptiform activity described by a large computerised EEG database. Clin Neurophysiol 2007; 118:1369-76. [PMID: 17452009 DOI: 10.1016/j.clinph.2007.02.027] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2006] [Revised: 01/25/2007] [Accepted: 02/21/2007] [Indexed: 11/17/2022]
Abstract
OBJECTIVE To study the age-related topographical tendency of expressing epileptiform activity, and the effect of focal epileptiform activity (FEA) on the general cortical brain activity. METHODS 1647 consecutive routine EEGs containing FEA were visually assessed for FEA location and asymmetry. Background activity was compared with that in normal EEGs from 3268 drug-free outpatient controls. RESULTS FEA localisation was age-related (p<0.0005) except for the temporal region (p=0.22) where FEA was found equally often in the young and the old. The left hemisphere was more prone to FEA (p=0.018). The left-right asymmetry varied by age (p=0.013). FEA asymmetry occurred most frequently in EEGs from patients older than 80 years, and least frequent in the age-group 20-39 years. FEA was associated with lower alpha rhythm (AR) frequencies (p=0.0041) and higher AR amplitudes (p=0.0023), as well as higher general background activity (GBA) amplitude (p<0.0005), while GBA frequencies were the same (p=0.96). CONCLUSIONS Topographical localisation of FEA was age-dependent. There was an overall left dominance, but the side asymmetry was modest and varied by age. FEA was associated with changes in AR and GBA. SIGNIFICANCE The results demonstrate that FEA is associated with cerebral cortical dysfunction also distant from the epileptic focus.
Collapse
Affiliation(s)
- H Aurlien
- Section of Clinical Neurophysiology, Department of Neurology, Haukeland University Hospital, Bergen, Norway.
| | | | | | | | | | | |
Collapse
|
474
|
Chen X, Sachdev PS, Wen W, Anstey KJ. Sex differences in regional gray matter in healthy individuals aged 44-48 years: a voxel-based morphometric study. Neuroimage 2007; 36:691-9. [PMID: 17499524 DOI: 10.1016/j.neuroimage.2007.03.063] [Citation(s) in RCA: 132] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2007] [Revised: 03/28/2007] [Accepted: 03/29/2007] [Indexed: 12/28/2022] Open
Abstract
The study examined sex-related differences in regional gray matter (GM) in 44-48 year old healthy individuals. T1-weighted MRI scans were acquired in 411 subjects aged 44-48 from a random community sample and optimized voxel-based morphometry was applied to detect regional GM difference between men and women, correcting for effects of age, years of education, handedness, and total intracranial volume (TIV). Men had larger brain volumes and higher white matter (WM) to TIV ratios compared with women. Women had higher GM to TIV ratios than men. After controlling for age, years of education, handedness, and TIV, there were no significant differences between men and women in the total GM volumes. Regional sex dimorphism was present, with men having more GM volume in midbrain, left inferior temporal gyrus, right occipital lingual gyrus, right middle temporal gyrus, and both cerebellar hemispheres. Women showed more GM in dorsal anterior, posterior and ventral cingulate cortices, and right inferior parietal lobule. Our results suggest sex dimorphism in GM in middle aged healthy individuals, which is not likely to be explained by brain pathology. These differences may provide the structural brain basis for sex differences in certain cognitive functions.
Collapse
Affiliation(s)
- Xiaohua Chen
- School of Psychiatry, University of New South Wales, Australia.
| | | | | | | |
Collapse
|
475
|
Jefferson AL, Massaro JM, Wolf PA, Seshadri S, Au R, Vasan RS, Larson MG, Meigs JB, Keaney JF, Lipinska I, Kathiresan S, Benjamin EJ, DeCarli C. Inflammatory biomarkers are associated with total brain volume: the Framingham Heart Study. Neurology 2007; 68:1032-8. [PMID: 17389308 PMCID: PMC2758770 DOI: 10.1212/01.wnl.0000257815.20548.df] [Citation(s) in RCA: 207] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Systemic inflammation is associated with ischemia and Alzheimer disease (AD). We hypothesized that inflammatory biomarkers would be associated with neuroimaging markers of ischemia (i.e., white matter hyperintensities [WMH]) and AD (i.e., total brain volume [TCB]). METHODS MRI WMH and TCB were quantified on 1,926 Framingham Offspring participants free from clinical stroke, TIA, or dementia (mean age 60 +/- 9 years; range 35 to 85 years; 54% women) who underwent measurement of a circulating inflammatory marker panel, including CD40 ligand, C-reactive protein, interleukin-6 (IL-6), soluble intracellular adhesion molecule-1, monocyte chemoattractant protein-1, myeloperoxidase, osteoprotegerin (OPG), P-selectin, tumor necrosis factor-alpha (TNFalpha), and tumor necrosis factor receptor II. To account for head size, both TCB (TCBV) and WMH (WMH/TCV) were divided by total cranial volume. We used multivariable linear regression to relate 10 log-transformed inflammatory biomarkers to brain MRI measures. RESULTS In multivariable models, inflammatory markers as a group were associated with TCBV (p < 0.0001) but not WMH/TCV (p = 0.28). In stepwise models adjusted for clinical covariates with backwards elimination of markers, IL-6 and OPG were inversely associated with TCBV; TNFalpha was inversely related to TCBV in a subset of 1,430 participants. Findings were similar in analyses excluding individuals with prevalent cardiovascular disease. The relations between TCBV and inflammatory markers were modified by both sex and age, and generally were more pronounced in men and in older individuals. CONCLUSIONS Although our observational cross-sectional data cannot establish causality, they are consistent with the hypothesis that higher inflammatory markers are associated with greater atrophy than expected for age.
Collapse
Affiliation(s)
- A L Jefferson
- Department of Neurology, Boston University School of Medicine, Boston, MA 02118, USA.
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
476
|
Heaton KJ, Palumbo CL, Proctor SP, Killiany RJ, Yurgelun-Todd DA, White RF. Quantitative magnetic resonance brain imaging in US army veterans of the 1991 Gulf War potentially exposed to sarin and cyclosarin. Neurotoxicology 2007; 28:761-9. [PMID: 17485118 DOI: 10.1016/j.neuro.2007.03.006] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2006] [Revised: 01/29/2007] [Accepted: 03/09/2007] [Indexed: 11/29/2022]
Abstract
BACKGROUND In March 1991, a munitions storage complex at Khamisiyah, Iraq was destroyed, potentially exposing more than 100,000 US troops to low levels of the organophosphate nerve agents sarin and cyclosarin. Little is known about the neurophysiological effects of low-dose exposure to sarin/cyclosarin in humans, although some research has indicated subtle but persistent neurobehavioral and neurochemical changes in individuals exposed to sarin/cyclosarin at levels insufficient to produce obvious clinical symptoms. However, the neuroanatomical correlates of these changes are unclear. The current study examined the association between modeled estimates of sarin/cyclosarin exposure levels and volumetric measurements of gross neuroanatomical structures in 1991 Gulf War veterans with varying degrees of possible low-level sarin/cyclosarin exposure. METHODS Twenty-six GW-deployed veterans recruited from the Devens Cohort Study participated. Magnetic resonance images of the brain were acquired and analyzed using morphometric techniques, producing volumetric measurements of white matter, gray matter, right and left lateral ventricles, and cerebrospinal fluid. Volumetric data were analyzed using exposure estimates obtained from refined models of the 1991 Khamisiyah presumed exposure hazard area. RESULTS Binary comparisons of sarin/cyclosarin 'exposed' (N=13) and 'unexposed' (N=13) veterans revealed no differences in volumetric measurements of discrete brain tissues. However, linear trend analyses showed a significant association between higher levels of estimated sarin/cyclosarin exposure and both reduced white matter (adjusted parameter estimate=-4.64, p<0.0001) and increased right lateral ventricle (adjusted parameter estimate=.11, p=0.0288) and left lateral ventricle (adjusted parameter estimate=.13, p<0.0001) volumes. CONCLUSIONS These findings suggest subtle but persistent central nervous system pathology in Gulf War veterans potentially exposed to low levels of sarin/cyclosarin and argue for further investigation of the long-term effects of low-dose sarin/cyclosarin exposures in humans.
Collapse
Affiliation(s)
- Kristin J Heaton
- Boston Environmental Hazards Research Center, VA Boston Healthcare System, Boston, MA, USA.
| | | | | | | | | | | |
Collapse
|
477
|
Kuller LH. Dementia epidemiology research: it is time to modify the focus of research. J Gerontol A Biol Sci Med Sci 2007; 61:1314-8. [PMID: 17234827 DOI: 10.1093/gerona/61.12.1314] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The incidence and prevalence of dementia are increasing. There is an urgent need to develop a preventive strategy. The identification of modifiable risk factors must therefore be a high priority. Newer imaging techniques provide an opportunity to identify subclinical manifestations of "dementias" that can be limited to the risk factors and subsequent clinical disease. The contribution of vascular disease to dementia and Alzheimer's disease (AD) should be a high priority as it offers a potential preventive strategy. Study designs need to be modified, including a greater emphasis on geographic variations in AD and dementia based on imaging studies, longitudinal studies of successful aging without cardiovascular disease (CVD) or AD, gene-environment interactions, and studies of unique populations that may be at lower risk because of specific lifestyles. Primary prevention trials for vascular disease should include a dementia component. Most, if not all, studies should include newer imaging studies.
Collapse
Affiliation(s)
- Lewis H Kuller
- Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, Pennsylvania 15213, USA.
| |
Collapse
|
478
|
Yoshita M, Fletcher E, Harvey D, Ortega M, Martinez O, Mungas DM, Reed BR, DeCarli CS. Extent and distribution of white matter hyperintensities in normal aging, MCI, and AD. Neurology 2007; 67:2192-8. [PMID: 17190943 PMCID: PMC3776588 DOI: 10.1212/01.wnl.0000249119.95747.1f] [Citation(s) in RCA: 309] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVE To analyze the extent and spatial distribution of white matter hyperintensities (WMH) in brain regions from cognitively normal older individuals (CN) and patients with mild cognitive impairment (MCI) and Alzheimer disease (AD). METHODS We studied 26 mild AD, 28 MCI, and 33 CN. MRI analysis included quantification of WMH volume, nonlinear mapping onto a common anatomic image, and spatial localization of each WMH voxel to create an anatomically precise frequency distribution map. Areas of greatest frequency of WMH from the WMH composite map were used to identify 10 anatomic regions involving periventricular areas and the corpus callosum (CC) for group comparisons. RESULTS Total WMH volumes were associated with age, extent of concurrent vascular risk factors, and diagnosis. After correcting for age, total WMH volumes remained significantly associated with diagnosis and extent of vascular risk. Regional WMH analyses revealed significant differences in WMH across regions that also differed significantly according to diagnosis. In post-hoc analyses, significant differences were seen between CN and AD in posterior periventricular regions and the splenium of the CC. MCI subjects had intermediate values at all regions. Repeated measures analysis including vascular risk factors in the model found a significant relationship between periventricular WMH and vascular risk that differed by region, but regional differences according to diagnosis remained significant and there was no interaction between diagnosis and vascular risk. CONCLUSIONS Differences in white matter hyperintensities (WMH) associated with increasing cognitive impairment appear related to both extent and spatial location. Multiple regression analysis of regional WMH, vascular risk factors, and diagnosis suggest that these spatial differences may result from the additive effects of vascular and degenerative injury. Posterior periventricular and corpus callosum extension of WMH associated with mild cognitive impairment and Alzheimer disease indicate involvement of strategic white matter bundles that may contribute to the cognitive deficits seen with these syndromes.
Collapse
Affiliation(s)
- M Yoshita
- Department of Neurology and Center for Neuroscience, University of California at Davis, 1544 Newton Ct., Davis, CA 95616, USA.
| | | | | | | | | | | | | | | |
Collapse
|
479
|
Bugg JM, DeLosh EL, Clegg BA. Physical Activity Moderates Time-of-Day Differences in Older Adults' Working Memory Performance. Exp Aging Res 2006; 32:431-46. [PMID: 16982572 DOI: 10.1080/03610730600875833] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Based on a synthesis of the literature on time of day and physical fitness effects on cognition, the current study examined whether physical activity moderated time-of-day differences in older adults' performance on a working memory task. Sedentary older adults' working memory performance declined significantly from morning to evening, whereas more active older adults performed similarly across the day. This interaction did not extend to performance on a simple reaction time task. A novel explanation based on the selective effect of mental fatigue on executive control processes is proposed.
Collapse
Affiliation(s)
- Julie M Bugg
- Department of Psychology, Colorado State University, Fort Collins, Colorado, USA.
| | | | | |
Collapse
|
480
|
Hannestad J, Taylor WD, McQuoid DR, Payne ME, Krishnan KRR, Steffens DC, Macfall JR. White matter lesion volumes and caudate volumes in late-life depression. Int J Geriatr Psychiatry 2006; 21:1193-8. [PMID: 16955447 DOI: 10.1002/gps.1640] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND Decreased caudate volumes and increased white matter lesions (WMLs) are associated both with aging and late-life depression, but the relationship between the two is unclear. We examined the association between WML and caudate volume, hypothesizing there would be a negative association, which would be stronger for WMLs located in anterior regions. We additionally hypothesized that this association would be stronger in depressed subjects. METHOD This MRI study included 182 elderly depressed and 64 elderly control subjects. Our imaging analysis procedures divided the brain into anterior and posterior halves. WML volume in each half was calculated, as were left and right caudate volumes. A statistical model incorporating WML volumes, age, total brain volume, diagnosis, and gender was used to examine caudate volumes. RESULTS WML volume was negatively associated with total and right caudate volume. This association was stronger for WMLs in the anterior half of the brain. Anterior WML volume was additionally negatively associated with right caudate volume in depressed subjects, but not in controls. CONCLUSIONS Using unadjusted levels of significance, WML volume is negatively associated with right caudate volume in both older populations, but with left caudate volume only in depressed individuals. When statistical corrections for multiple comparisons are used, the finding is limited to a negative association between WML volume and right caudate volume, primarily in depressed subjects. This study demonstrates one mechanism by which WMLs may disrupt frontostriatal circuits.
Collapse
Affiliation(s)
- Jonas Hannestad
- Departments of Psychiatry and Behavioral Sciences, Duke University Medical Center, Durham, NC 27710, USA
| | | | | | | | | | | | | |
Collapse
|
481
|
Abstract
Biological aging of the brain is partly attributable to aging of the cerebrovascular circulation and the effects of these vascular changes on the brain. A variety of techniques ranging from simple, clinical scores to complex radiological techniques have been used in an attempt to understand, describe and quantify this process. Simultaneously attempts have been made to relate these changes to cognitive and physical changes and the risk of dementia and stroke associated with brain aging. The most frequently used clinical scores are the Framingham Stroke Risk Profile and the Hachinski Ischemic Score for vascular dementia. Radiological techniques to estimate cerebrovascular burden include many varieties of ultrasonographic, computerized tomography (CT), magnetic resonance imaging (MRI) and nuclear medicine techniques. The radiological techniques evaluate the nature and extent of disease in the vessels supplying the brain and the pattern and extent of radiological evidence of damage to the brain both on static and dynamic imaging and are briefly outlined in this review. There are several studies using these techniques to study 'normal' aging populations, and the techniques used in the most widely known of these studies are briefly highlighted in this review.
Collapse
Affiliation(s)
- Sudha Seshadri
- Department of Neurology, School of Medicine, Boston University, Boston, USA.
| |
Collapse
|
482
|
Bugg JM, Zook NA, DeLosh EL, Davalos DB, Davis HP. Age differences in fluid intelligence: Contributions of general slowing and frontal decline. Brain Cogn 2006; 62:9-16. [PMID: 16603300 DOI: 10.1016/j.bandc.2006.02.006] [Citation(s) in RCA: 113] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2005] [Revised: 09/28/2005] [Accepted: 02/26/2006] [Indexed: 10/24/2022]
Abstract
The current study examined the contributions of general slowing and frontal decline to age differences in fluid intelligence. Participants aged 20-89 years completed Block Design, Matrix Reasoning, simple reaction time, choice reaction time, Wisconsin Card Sorting, and Tower of London tasks. Age-related declines in fluid intelligence, speed of processing, and frontal function were observed. Hierarchical regression analyses showed that the processing speed and frontal function measures accounted for significant variance in fluid intelligence performance, but there was also a residual effect of age after controlling for each variable individually as well as both variables. An additional analysis showed that the variance in fluid intelligence that was attributable to processing speed was not fully shared with the variance attributable to frontal function. These findings suggest that the age-related decline in fluid intelligence is due to general slowing and frontal decline, as well as other unidentified factors.
Collapse
Affiliation(s)
- Julie M Bugg
- Department of Psychology, Colorado State University, USA.
| | | | | | | | | |
Collapse
|
483
|
Brickman AM, Zimmerman ME, Paul RH, Grieve SM, Tate DF, Cohen RA, Williams LM, Clark CR, Gordon E. Regional white matter and neuropsychological functioning across the adult lifespan. Biol Psychiatry 2006; 60:444-53. [PMID: 16616725 DOI: 10.1016/j.biopsych.2006.01.011] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2005] [Revised: 01/05/2006] [Accepted: 01/10/2006] [Indexed: 11/28/2022]
Abstract
BACKGROUND The current study utilized magnetic resonance imaging (MRI) to more fully elucidate the relationship among age, regional white matter, and neuropsychological functioning. METHODS One hundred ninety-nine neurologically healthy adults received MRI and standardized neuropsychological assessment. MR images were spatially normalized and segmented by tissue type; relative white matter values in each of the four cerebral lobes in each hemisphere were computed. Subjects were divided into Younger (ages 21-30), Middle (ages 31-54), and Older (ages 55-79) age groups. RESULTS The Older group had significantly less overall relative white matter than the Middle group, who had significantly less overall relative white matter than the Younger participants (F (2, 193) = 5.42, p = 0.005). Differences in frontal lobe white matter were of largest magnitude, followed by temporal lobe (F (6, 579) = 3.32, p = 0.003). Age and frontal and temporal lobe white matter were primarily associated with performance on neuropsychological tests of executive functioning and memory. Mediational analysis suggested that frontal lobe white matter mediated the relationship between age and performance on tasks of executive functioning and memory. CONCLUSIONS The results confirm age-associated decline in frontal and temporal white matter, and age-related cognitive decline in several domains. Decline in neuropsychological functioning is, in part, mediated by a relative age-related reduction in frontal white matter.
Collapse
Affiliation(s)
- Adam M Brickman
- Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University Medical Center, New York, NY 10032, USA.
| | | | | | | | | | | | | | | | | |
Collapse
|
484
|
Sowell ER, Peterson BS, Kan E, Woods RP, Yoshii J, Bansal R, Xu D, Zhu H, Thompson PM, Toga AW. Sex differences in cortical thickness mapped in 176 healthy individuals between 7 and 87 years of age. Cereb Cortex 2006; 17:1550-60. [PMID: 16945978 PMCID: PMC2329809 DOI: 10.1093/cercor/bhl066] [Citation(s) in RCA: 466] [Impact Index Per Article: 25.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Findings from previous magnetic resonance imaging studies of sex differences in gray matter have been inconsistent, with some showing proportionally increased gray matter in women and some showing no differences between the sexes. Regional sex differences in gray matter thickness have not yet been mapped over the entire cortical surface in a large sample of subjects spanning the age range from early childhood to old age. We applied algorithms for cortical pattern matching and techniques for measuring cortical thickness to the structural magnetic resonance images of 176 healthy individuals between the ages of 7 and 87 years. We also mapped localized differences in brain size. Maps of sex differences in cortical thickness revealed thicker cortices in women in right inferior parietal and posterior temporal regions even without correcting for total brain volume. In these regions, the cortical mantle is up to 0.45 mm thicker, on average, in women than in men. Analysis of a subset of 18 female and 18 male subjects matched for age and brain volume confirmed the significance of thicker gray matter in temporal and parietal cortices in females, independent of brain size differences. Further analyses were conducted in the adult subjects where gender differences were evaluated using height as a covariate, and similar sex differences were observed even when body size differences between the sexes were controlled. Together, these results suggest that greater cortical thickness in posterior temporal inferior parietal regions in females relative to males are independent of differences in brain or body size. Age-by-sex interactions were not significant in the temporoparietal region, suggesting that sex differences in these regions are present from at least late childhood and then are maintained throughout life. Male brains were larger than female brains in all locations, though male enlargement was most prominent in the frontal and occipital poles, bilaterally. Given the large sample and the large range of ages studied, these results help to address controversies in the study of central nervous system sexual dimorphisms.
Collapse
Affiliation(s)
- Elizabeth R Sowell
- Laboratory of Neuro Imaging, Department of Neurology, University of California, Los Angeles, CA 90095-7334, USA.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
485
|
Abstract
Magnetic resonance diffusion tensor imaging (DTI) is a non-invasive in vivo method for characterizing the integrity of anatomical connections and white matter circuitry and provides a quantitative assessment of the brain's white matter microstructure. DTI studies reveal age-related declines in white matter fractional ansiotropy (FA) in normal healthy adults in whom volume declines are not necessarily detectable. The decline is equivalent in men and women, is linear from about age 20 years onwards, and has a frontal distribution. Studies combining regional DTI metrics and tests of specific cognitive and motor functions have shown that age-related declines in white matter integrity are associated with similar declines in interhemispheric transfer, especially dependent on frontal systems. Emerging from recent DTI findings and conceptualizations of neural causes of cognitive decline in aging, we propose three white matter-mediated neural system hypotheses of aging brain structure and function: (1) the anteroposterior gradient, (2) bilateral recruitment of brain systems via the corpus callosum for frontally based task execution, and (3) frontocerebellar synergism. These hypotheses are not mutually exclusive but establish a basis for posing testable questions about brain systems recruited when those used in youth are altered by aging.
Collapse
Affiliation(s)
- Edith V Sullivan
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, 401 Quarry Road, Stanford, CA 94305, USA.
| | | |
Collapse
|
486
|
Smith CD, Chebrolu H, Wekstein DR, Schmitt FA, Markesbery WR. Age and gender effects on human brain anatomy: a voxel-based morphometric study in healthy elderly. Neurobiol Aging 2006; 28:1075-87. [PMID: 16774798 DOI: 10.1016/j.neurobiolaging.2006.05.018] [Citation(s) in RCA: 244] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2005] [Revised: 04/19/2006] [Accepted: 05/03/2006] [Indexed: 10/24/2022]
Abstract
The adult human brain shrinks slowly with age, but the regional specificity and tissue class specificity of this loss is unclear. Subjects (n=122) were healthy aged participants in a longitudinal cohort who undergo periodic standardized cognitive and clinical examination. Multi-spectral segmentation of magnetic resonance images into grey matter (GM), white matter (WM) and CSF was performed on cross-sectional image data using a custom template and calculated prior probability maps. Global differences were evaluated by fitting a regression model for absolute and normalized subject GM, WM, and CSF values. Global and regional patterns of GM, WM and CSF differences were assessed using optimized voxel-based morphometry (VBM). GM volume decreased with age at a rate of 2.4 cm(3)/year (-0.18%/year); CSF increased by 2.5 cm(3)/year (0.20%/year). Regression analyses showed no significant decrease in WM volume, but a focal WM decrease with age was detected in the anterior corpus callosum using VBM. Diffuse reductions of GM volume were seen with age in the frontal, parietal, and temporal cortex, cerebellum and basal ganglia. Relative regional differences in cortical GM volume with age occurred in the frontal, parietal and temporal lobes, but not in medial temporal lobe or in posterior cingulate. We did not observe significant gender effects. These findings establish a baseline for comparison with pathologic changes in human brain volume between ages 58 and 95 years.
Collapse
Affiliation(s)
- Charles D Smith
- Department of Biomedical Engineering, University of Kentucky, Lexington, KY 40536-0098, United States.
| | | | | | | | | |
Collapse
|
487
|
Huh TJ, Kramer JH, Gazzaley A, Delis DC. Response bias and aging on a recognition memory task. J Int Neuropsychol Soc 2006; 12:1-7. [PMID: 16433938 DOI: 10.1017/s1355617706060024] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/06/2005] [Revised: 09/26/2005] [Accepted: 09/28/2005] [Indexed: 11/07/2022]
Abstract
UNLABELLED Response bias reflects the decision rule an individual uses when faced with uncertainty on recognition memory tasks. Recent studies indicate frontal regions may mediate response bias performance. One theory of aging also implicates frontal lobe contributions in age-related cognitive changes. This suggests that frontal lobe changes may mediate response bias in older adults. Consistent with this frontal aging hypothesis, we predicted that response bias would become more liberal with age. METHODS Participants were 181 younger (30-49) and 112 older normal adults (75+) that were part of the California Verbal Learning Test-second edition (CVLT-2) normative sample (total n = 1078). We used parametric measures of discriminability and response bias provided by the CVLT-2 scoring program. Groups were similar in IQ and education. Multi-level regression models were created to examine the effects of moderating variables. The interaction between age and age group significantly predicted response bias. Post hoc analysis indicated that increasing age was associated with more liberal bias in the older but not in the younger group. In the light of reported relationships between frontal regions and both aging and response bias, we hypothesize that frontal changes may be the underlying mechanism explaining the increase in liberal response bias with age.
Collapse
Affiliation(s)
- Terri J Huh
- Department of Psychiatry, Memory and Aging Center, University of California San Francisco, California 94143, USA.
| | | | | | | |
Collapse
|
488
|
Abstract
Background and Purpose—
This review considers the current state of knowledge of genetic factors underlying vascular cognitive impairment (VCI).
Summary of Review—
We argue here that genes conferring susceptibility to VCI must be of 2 nonmutually exclusive classes: (1) genes that confer susceptibility to cerebrovascular disease, and (2) genes that determine brain tissue responses to cerebrovascular disease (ie, render parenchymal tissue more or less susceptible to injury or able to repair itself after injury). Although some progress has been made in identifying genes of the first class, little has been done to explore genes of the second class. Evidence for the existence of such genes is presented. We discuss the advantages and disadvantages of different forms of cerebrovascular disease for studying these genes, and different study designs that might be used.
Conclusion—
The most critical challenge for genetic studies of VCI is to identify quantifiable phenotypes that can be reliably and effectively determined in large samples of subjects.
Collapse
Affiliation(s)
- Gabrielle G Leblanc
- The Neurogenetics Group, National Institute of Neurological Disorders and Stroke, Bethesda, MD 20892, USA.
| | | | | | | |
Collapse
|
489
|
Yoshita M, Fletcher E, DeCarli C. Current concepts of analysis of cerebral white matter hyperintensities on magnetic resonance imaging. Top Magn Reson Imaging 2005; 16:399-407. [PMID: 17088690 PMCID: PMC3771319 DOI: 10.1097/01.rmr.0000245456.98029.a8] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Cerebrovascular disease is common and associated with cognitive deficits and increased risk for dementia. Until recently, only limited attention has focused on advances in imaging techniques to better define and quantify the spectrum of asymptomatic cerebrovascular disease commonly seen on magnetic resonance imaging, such as abnormal white matter signals. Abnormal signals in cerebral white matter, although nonspecific, are increased in prevalence and severity in association with aging and cerebrovascular risk factors among older individuals. The ubiquitous occurrence of these abnormal white matter signals commonly referred to as white matter hyperintensities (WMHs) and the association with cerebrovascular risk and cognitive impairment among older individuals make scientific evaluation of WMHs an important and much needed avenue of research. In this section, we review current methods of WMH analysis. Strengths and limitation of both quantitative and qualitative methods are discussed initially, followed by a brief review of current magnetic resonance imaging segmentation and mapping techniques that make it possible to assess the anatomical location of WMHs. We conclude by discussing future analytic methods designed to better understand the pathophysiology and cognitive consequences of WMHs.
Collapse
Affiliation(s)
- Mitsuhiro Yoshita
- Imaging of Dementia and Aging Laboratory, Department of Neurology and Center for Neuroscience, University of California at Davis, Davis, CA 95817, USA
| | | | | |
Collapse
|
490
|
DeStefano AL, Atwood LD, Massaro JM, Heard-Costa N, Beiser A, Au R, Wolf PA, DeCarli C. Genome-wide scan for white matter hyperintensity: the Framingham Heart Study. Stroke 2005; 37:77-81. [PMID: 16322484 DOI: 10.1161/01.str.0000196987.68770.b3] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
BACKGROUND AND PURPOSE White matter hyperintensity (WMH) volume is associated with aging and cerebrovascular disease and has been demonstrated to have a high heritability in the Framingham Heart Study as well as in other studies. We performed a genome-wide linkage analysis to identify chromosomal regions that may harbor genes influencing WMH in a family-based sample of the Framingham Heart Study. METHODS Brain magnetic resonance scans were performed, and WMH and total cranial volume (TCV) were quantified as previously described on 2259 cohort and offspring participants. The outcome used for linkage analysis was an age specific (within 10-year age groups) z-score for the natural logarithm of the ratio of WMH to TCV. This z-score was based on 2230 individuals after excluding 26 participants with neurological conditions other than stroke and 3 individuals whose ages were out of range. Variance component linkage analysis included 747 individuals (mean age=62.16+/-12.43 years) with both magnetic resonance measure and genotype information in 237 families. Mean percent WMH to TCV was 0.098+/-0.175 with a range of 0.00025% to 1.37% in the linkage analysis subjects. RESULTS A maximum multipoint logarithm of the odds (LOD) score=3.69, which indicates significant evidence of linkage, was observed at 4 cM on chromosome 4. A suggestive peak with LOD=1.78 was observed at 95 cM on chromosome 17. CONCLUSIONS We have significant evidence that a gene influencing WMH volume is located on chromosome 4 of the human genome.
Collapse
Affiliation(s)
- Anita L DeStefano
- Department of Biostatistics, Boston University School of Public Health, Boston, MA 02118, USA.
| | | | | | | | | | | | | | | |
Collapse
|
491
|
Sachdev P, Wen W. Should we distinguish between periventricular and deep white matter hyperintensities? Stroke 2005; 36:2342-3; author reply 2343-4. [PMID: 16239634 DOI: 10.1161/01.str.0000185694.52347.6e] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
|
492
|
|
493
|
Persson J, Nyberg L, Lind J, Larsson A, Nilsson LG, Ingvar M, Buckner RL. Structure–Function Correlates of Cognitive Decline in Aging. Cereb Cortex 2005; 16:907-15. [PMID: 16162855 DOI: 10.1093/cercor/bhj036] [Citation(s) in RCA: 299] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
To explore neural correlates of cognitive decline in aging, we used longitudinal behavioral data to identify two groups of older adults (n = 40) that differed with regard to whether their performance on tests of episodic memory remained stable or declined over a decade. Analysis of structural and diffusion tensor imaging (DTI) revealed a heterogeneous set of differences associated with cognitive decline. Manual tracing of hippocampal volume showed significant reduction in those older adults with a declining memory performance as did DTI-measured fractional anisotropy in the anterior corpus callosum. Functional magnetic resonance imaging during incidental episodic encoding revealed increased activation in left prefrontal cortex for both groups and additional right prefrontal activation for the elderly subjects with the greatest decline in memory performance. Moreover, mean DTI measures in the anterior corpus callosum correlated negatively with activation in right prefrontal cortex. These results demonstrate that cognitive decline is associated with differences in the structure as well as function of the aging brain, and suggest that increased activation is either caused by structural disruption or is a compensatory response to such disruption.
Collapse
Affiliation(s)
- Jonas Persson
- Department of Psychology, Umeå University, S-901 87 Umeå, Sweden.
| | | | | | | | | | | | | |
Collapse
|
494
|
Pfefferbaum A, Adalsteinsson E, Sullivan EV. Frontal circuitry degradation marks healthy adult aging: Evidence from diffusion tensor imaging. Neuroimage 2005; 26:891-9. [PMID: 15955499 DOI: 10.1016/j.neuroimage.2005.02.034] [Citation(s) in RCA: 279] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2004] [Revised: 02/14/2005] [Accepted: 02/23/2005] [Indexed: 11/16/2022] Open
Abstract
In vivo study of white matter microstructural integrity through magnetic resonance diffusion tensor imaging (DTI) permits examination of degradation of axonal circuitry that may underlie functional decline of frontally-based processes in normal adult aging. Determination of the pattern of age-related degradation of white matter microstructure requires quantitative comparison of the rostral-caudal and superior-inferior extents of the brain's white matter. To date, this has not been accomplished, probably because of significant artifacts from spatial distortion and poor signal resolution that precludes accurate analysis in prefrontal and inferior brain regions. Here, we report a profile analysis of the integrity of white matter microstructure across the supratentorium and in selected focal regions using DTI data collected at high-field strength (3 T), with isotropic voxel acquisition, and an analysis based on a concurrently-acquired field map to permit accurate quantification of artifact-prone, anterior and inferior brain regions. The groups comprised 10 younger and 10 older individuals; all were high functioning, highly educated, and in excellent health. The DTI profile analysis revealed a robust frontal distribution of low white matter anisotropy and high bulk mean diffusivity in healthy older compared with younger adults. In contrast to frontal fiber systems, posterior systems were largely preserved with age. A second analysis, based on focal samples of FA, confirmed that the age-related FA decline was restricted to frontal regions, leaving posterior and inferior brain regions relatively intact. The selective decline of anterior anisotropy with advancing age provides evidence for the potential of a microstructural white matter mechanism for the commonly observed decline in frontally-based functions.
Collapse
|
495
|
Abstract
Our knowledge about the process of aging has continued to evolve as the methods used to study this process become more sophisticated. As more becomes known about the diagnostic criteria for dementia, the population of subjects taking part in aging studies has become more carefully screened minimizing the role of dementia as a confounding variable. Furthermore, advances in imaging techniques now allow us to view the anatomy of the brain in vivo better than any time in the past paving the way for longitudinal studies of the brain. It should not be surprising given the changes seen in studies of aging that our conventional wisdom of the aging process is being called into question.
Collapse
Affiliation(s)
- Ronald J Killiany
- Department of Anatomy and Neurobiology, Boston University School of Medicine, Boston, Massachusetts 02118, USA.
| | | | | |
Collapse
|