The impact of subcortical white matter disease on mood in euthymic older adults: a diffusion tensor imaging study

Late-life depressive symptoms and white matter structural integrity within older Black adults

Introduction

Older Black adults experience a high burden of depressive symptoms and cerebrovascular disease but the specific neurobiological substrates underlying the association between late-life depressive symptoms and brain integrity are understudied, particularly in within-group designs.

Methods

Using the Center for Epidemiologic Studies Depression Scale and diffusion-tensor imaging, within-Black variation in the association between late-life depressive symptoms and white matter structural integrity was examined in 297 older Black participants without dementia that were enrolled across three epidemiological studies of aging and dementia. Linear regression models were used to test associations with DTI metrics (fractional anisotropy, trace of the diffusion tensor) as the outcomes and depressive symptoms as the predictor, while adjusting for age, sex, education, scanner, serotonin-reuptake inhibitor use, total volume of white-matter hyperintensities normalized by intracranial volume, and presence of white-matter hyperintensities at the voxel level.

Results

Higher level of self-reported late-life depressive symptoms was associated with greater diffusion-tensor trace (reduced white matter integrity) in connections between commissural pathways and contralateral prefrontal regions (superior and middle frontal/dorsolateral prefrontal cortex), association pathways connecting dorsolateral prefrontal cortex with insular, striatal and thalamic regions, and association pathways connecting the parietal, temporal and occipital lobes and the thalamus.

Discussion

This study demonstrated a discernable pattern of compromised white matter structural integrity underlying late-life depressive symptoms within older Black adults.

Depressive symptoms in cognitively unimpaired older adults are associated with lower structural and functional integrity in a frontolimbic network

Subclinical depressive symptoms are associated with increased risk of Alzheimer's disease (AD), but the brain mechanisms underlying this relationship are still unclear. We aimed to provide a comprehensive overview of the brain substrates of subclinical depressive symptoms in cognitively unimpaired older adults using complementary multimodal neuroimaging data. We included cognitively unimpaired older adults from the baseline data of the primary cohort Age-Well (n = 135), and from the replication cohort ADNI (n = 252). In both cohorts, subclinical depressive symptoms were assessed using the 15-item version of the Geriatric Depression Scale; based on this scale, participants were classified as having depressive symptoms (>0) or not (0). Voxel-wise between-group comparisons were performed to highlight differences in gray matter volume, glucose metabolism and amyloid deposition; as well as white matter integrity (only available in Age-Well). Age-Well participants with subclinical depressive symptoms had lower gray matter volume in the hippocampus and lower white matter integrity in the fornix and the posterior parts of the cingulum and corpus callosum, compared to participants without symptoms. Hippocampal atrophy was recovered in ADNI, where participants with subclinical depressive symptoms also showed glucose hypometabolism in the hippocampus, amygdala, precuneus/posterior cingulate cortex, medial and dorsolateral prefrontal cortex, insula, and temporoparietal cortex. Subclinical depressive symptoms were not associated with brain amyloid deposition in either cohort. Subclinical depressive symptoms in ageing are linked with neurodegeneration biomarkers in the frontolimbic network including brain areas particularly sensitive to AD. The relationship between depressive symptoms and AD may be partly underpinned by neurodegeneration in common brain regions.

Diffusion tensor imaging pipeline measures of cerebral white matter integrity: An overview of recent advances and prospects

Cerebral small vessel disease (CSVD) is a leading cause of age-related microvascular cognitive decline, resulting in significant morbidity and decreased quality of life. Despite a progress on its key pathophysiological bases and general acceptance of key terms from neuroimaging findings as observed on the magnetic resonance imaging (MRI), key questions on CSVD remain elusive. Enhanced relationships and reliable lesion studies, such as white matter tractography using diffusion-based MRI (dMRI) are necessary in order to improve the assessment of white matter architecture and connectivity in CSVD. Diffusion tensor imaging (DTI) and tractography is an application of dMRI that provides data that can be used to non-invasively appraise the brain white matter connections via fiber tracking and enable visualization of individual patient-specific white matter fiber tracts to reflect the extent of CSVD-associated white matter damage. However, due to a lack of standardization on various sets of software or image pipeline processing utilized in this technique that driven mostly from research setting, interpreting the findings remain contentious, especially to inform an improved diagnosis and/or prognosis of CSVD for routine clinical use. In this minireview, we highlight the advances in DTI pipeline processing and the prospect of this DTI metrics as potential imaging biomarker for CSVD, even for subclinical CSVD in at-risk individuals.

Transverse Sinus Stenosis in Venous Pulsatile Tinnitus Patients May Lead to Brain Perfusion and White Matter Changes

Objective: Transverse sinus stenosis (TSS) is associated with various symptoms, but whether it can lead to pathological brain changes is unclear. This study aimed to investigate brain changes in venous pulsatile tinnitus (PT) patients with TSS.

Materials and Methods: In this study, fifty-five consecutive venous PT patients and fifty age- and gender-matched healthy controls (HCs) were investigated. In CT venography, the combined conduit score (CCS) was used to assess the degree of TSS in venous PT patients. Magnetic resonance venography was used to assess TSS in HCs. All the participants had undergone arterial spin labeling and structural MRI scans.

Results: Two patients without TSS and ten HCs with TSS were excluded. Fifty-three venous PT patients with TSS and 40 HCs without TSS were included in this study. All the patients had unilateral cases: 16 on the left and 37 on the right. Based on the CCS, the patients were divided into high-degree TSS (a score of 1–2) (n = 30) and low-degree TSS groups (a score of 3–4) (n = 23). In the whole brain and gray matter, the patients with high-degree TSS showed decreased cerebral blood flow (CBF) compared with patients with low-degree TSS as well as HCs (P < 0.05), and no significant difference in CBF was found in patients with low-degree TSS and HCs (P > 0.05). In white matter (WM) regions, the patients with high-degree TSS exhibited decreased CBF relative to the HCs (P < 0.05). The incidence of cloud-like WM hyperintensity was significantly higher in the above two patient groups than in the HC group (P < 0.05).

Conclusion: TSS in venous PT patients may lead to decreased CBF and cloud-like WM hyperintensity. These neuroimaging findings may provide new insights into pathological TSS in venous PT.

Vascular depression for radiology: A review of the construct, methodology, and diagnosis

Vascular depression (VD) as defined by magnetic resonance imaging (MRI) has been proposed as a unique subtype of late-life depression. The VD hypothesis posits that cerebrovascular disease, as characterized by the presence of MRI-defined white matter hyperintensities, contributes to and increases the risk for depression in older adults. VD is also accompanied by cognitive impairment and poor antidepressant treatment response. The VD diagnosis relies on MRI findings and yet this clinical entity is largely unfamiliar to neuroradiologists and is rarely, if ever, discussed in radiology journals. The primary purpose of this review is to introduce the MRI-defined VD construct to the neuroradiology community. Case reports are highlighted in order to illustrate the profile of VD in terms of radiological, clinical, and neuropsychological findings. A secondary purpose is to elucidate and elaborate on the measurement of cerebrovascular disease through visual rating scales and semi- and fully-automated volumetric methods. These methods are crucial for determining whether lesion burden or lesion severity is the dominant pathological contributor to VD. Additionally, these rating methods have implications for the growing field of computer assisted diagnosis. Since VD has been found to have a profile that is distinct from other types of late-life depression, neuroradiologists, in conjunction with psychiatrists and psychologists, should consider VD in diagnosis and treatment planning.

Depression related cerebral pathology and its relationship with cognitive functioning: A systematic review

BACKGROUND

Depression's relationship with cerebral abnormalities and cognitive decline is temporally dynamic. Despite clear clinical utility, understanding depression's effect on cerebral structures, cognitive impairment and the interaction between these symptoms has had limited consideration.

METHODS

This review summarised studies examining a clinical depression diagnosis or validated scales measuring depressive symptoms, data concerning amyloid-beta (Aβ) levels, brain structure and function focusing on hippocampal alterations, or white matter hyperintensities (WMH), and at least one validated neuropsychological test. Online database searches of: PsycINFO, EMBASE, MEDLINE, and Scopus were conducted to identify potential articles.

RESULTS

While depression was consistently associated with cross-sectionally cognitive decline across multiple domains, the neuropathological basis of this dysfunction remained unclear. Hippocampal, frontal, and limbic dysfunction as well as cortical thinning, WMH, and Aβ burden all provide inconsistent findings, likely due to depression subtypes. The consistency of these findings additionally decreases when examining this relationship longitudinally, as these results are further confounded by pre-dementia states. The therapeutic interventions examined were more efficacious in the younger compared with the older samples, who were characterised by greater WMH and Aβ burden.

LIMITATIONS

The limited number of longitudinal and interventional studies in addition to the heterogeneity of the samples restricts their generalisability.

CONCLUSIONS

Symptomatological differences between early-onset and late-onset depression (EOD and LOD) appear crucial in understanding whether late-life depression is the primary or secondary source of cerebral pathology. Though severe cognitive impairments and clearer neuropathological underpinnings are more characteristic of LOD than EOD, the inconsistency of valid biomarkers remains problematic.

Diffusion tensor imaging correlates of early markers of depression in youth at high-familial risk for bipolar disorder

BACKGROUND

Mood disorders are familial psychiatric diseases, in which patients show reduced white matter (WM) integrity. We sought to determine whether WM integrity was affected in young offspring at high-familial risk of mood disorder before they go on to develop major depressive disorder (MDD).

METHODS

The Bipolar Family study is a prospective longitudinal study examining young individuals (age 16-25 years) at familial risk of mood disorder on three occasions 2 years apart. This study used baseline imaging data, categorizing groups according to clinical outcome at follow-up. Diffusion tensor MRI data were acquired for 61 controls and 106 high-risk individuals, the latter divided into 78 high-risk subjects who remained well throughout the study ('high-risk well') and 28 individuals who subsequently developed MDD ('high-risk MDD'). Voxel-wise between-group comparison of fractional anisotropy (FA) based on diagnostic status was performed using tract-based spatial statistics (TBSS).

RESULTS

Compared to controls, both high-risk groups showed widespread decreases in FA (p_corr  < .05) at baseline. Although FA in the high-risk MDD group negatively correlated with subthreshold depressive symptoms at the time of scanning (p_corr  < .05), there were no statistically significant differences at p-corrected levels between the two high-risk groups.

CONCLUSIONS

These results suggest that decreased FA is related to the presence of familial risk for mood disorder along with subdiagnostic symptoms at the time of scanning rather than predictive of subsequent diagnosis. Due to the difficulties performing such longitudinal prospective studies, we note, however, that this latter analysis may be underpowered due to sample size within the high-risk MDD group. Further clinical follow-up may clarify these findings.

Association of Microvascular Dysfunction With Late-Life Depression: A Systematic Review and Meta-analysis

Importance

The etiologic factors of late-life depression are still poorly understood. Recent evidence suggests that microvascular dysfunction is associated with depression, which may have implications for prevention and treatment. However, this association has not been systematically reviewed.

Objective

To examine the associations of peripheral and cerebral microvascular dysfunction with late-life depression.

Data Sources

A systematic literature search was conducted in MEDLINE and EMBASE for and longitudinal studies published since inception to October 16, 2016, that assessed the associations between microvascular dysfunction and depression.

Study Selection

Three independent researchers performed the study selection based on consensus. Inclusion criteria were a study population 40 years of age or older, a validated method of detecting depression, and validated measures of microvascular function.

Data Extraction and Synthesis

This systematic review and meta-analysis has been registered at PROSPERO (CRD42016049158) and is reported in accordance with the PRISMA and MOOSE guidelines. Data extraction was performed by an independent researcher.

Main Outcomes and Measures

The following 5 estimates of microvascular dysfunction were considered in participants with or without depression: plasma markers of endothelial function, albuminuria, measurements of skin and muscle microcirculation, retinal arteriolar and venular diameter, and markers for cerebral small vessel disease. Data are reported as pooled odds ratios (ORs) by use of the generic inverse variance method with the use of random-effects models.

Results

A total of 712 studies were identified; 48 were included in the meta-analysis, of which 8 described longitudinal data. Data from 43 600 participants, 9203 individuals with depression, and 72 441 person-years (mean follow-up, 3.7 years) were available. Higher levels of plasma endothelial biomarkers (soluble intercellular adhesion molecule-1: OR, 1.58; 95% CI, 1.28-1.96), white matter hyperintensities (OR, 1.29; 95% CI, 1.19-1.39), cerebral microbleeds (OR, 1.18; 95% CI, 1.03-1.34), and cerebral (micro)infarctions (OR, 1.30; 95% CI, 1.21-1.39) were associated with depression. Among the studies available, no significant associations of albuminuria and retinal vessel diameters with depression were reported. Longitudinal data showed a significant association of white matter hyperintensities with incident depression (OR, 1.19; 95% CI, 1.09-1.30).

Conclusions and Relevance

This meta-analysis shows that both the peripheral and cerebral forms of microvascular dysfunction are associated with higher odds of (incident) late-life depression. This finding may have clinical implications because microvascular dysfunction might provide a potential target for the prevention and treatment of depression.

Sub-threshold depressive symptoms and brain structure: A magnetic resonance imaging study within the Whitehall II cohort

BACKGROUND

Late-life sub-threshold depressive symptoms (i.e. depressive symptoms that do not meet the criteria for a diagnosis of major depressive disorder) are associated with impaired physical health and function, and increased risk of major depressive disorder. Magnetic resonance imaging (MRI) studies examining late-life major depressive disorder find structural brain changes in grey and white matter. However, the extent to which late-life sub-threshold depression is associated with similar hallmarks is not well established.

METHODS

Participants with no history of major depressive disorder were selected from the Whitehall Imaging Sub-Study (n=358, mean age 69±5 years, 17% female). Depressive symptoms were measured using the Centre for Epidemiological Studies Depression Scale (CES-D) at three previous Whitehall II Study phases (2003-04, 2007-09 and 2012-13) and at the time of the MRI scan (2012-14). The relationships between current and cumulative depressive symptoms and MRI brain measures were explored using Voxel-Based Morphometry (VBM) for grey matter and Tract Based Spatial Statistics (TBSS) for white matter.

RESULTS

Current sub-threshold depressive symptoms were associated with significant reductions in fractional anisotropy and increases in axial and radial diffusivity. There were no significant relationships between current depressive symptoms and grey matter measures, or cumulative depressive symptoms and MRI measures.

LIMITATIONS

The prevalence (10%) of sub-threshold depressive symptoms means that analyses may be underpowered to detect subtle differences in brain structure.

CONCLUSIONS

Current sub-threshold depressive symptoms are associated with changes in white matter microstructure, indicating that even mild depressive symptoms are associated with similar MRI hallmarks to those in major depressive disorder.

Diffusion tensor imaging in euthymic bipolar disorder - A tract-based spatial statistics study

BACKGROUND

In the current DTI study we compared euthymic bipolar I disorder (BD-I) patients and healthy controls (HC). We subsequently divided the total patient group into lithium-users and non-lithium-users and estimated differences across the three groups.

METHODS

Twenty-one euthymic BD-I patients and twenty-two HC participants were included in psychiatric interviews and MRI image acquisition (diffusion-weighted (DW) and T1-weighted scans). Fractional anisotropy (FA), radial, mean and axial diffusivity (RD, MD, AD) were estimated from the DW data, using DTI. These measures were then compared between groups using FSL Tract Based Spatial Statistics (TBSS). Correlations with age at onset, number of episodes and depression score were analyzed.

RESULTS

A difference in FA, MD, RD and AD between the whole sample of euthymic BD-I patients and healthy controls could not be detected. Amongst others, lithium-using patients demonstrated a higher FA and lower RD when compared to non-lithium-using BD-I patients in the corpus callosum and left anterior corona radiata. Widespread clusters demonstrated negative FA associations and positive RD and MD associations with minor depressive symptoms.

LIMITATIONS

Patients were naturalistically treated. Although the sample size is comparable to several other DTI studies, a larger sample size would have been benificial. TBSS and DTI have their own limitations.

CONCLUSION

Our findings support the theory that previously described DTI-based microstructural differences between HC and BD patients could be less pronounced in euthymic BD patients. Differences in FA between patients using and not using lithium suggest a counteracting effect of lithium on white matter microstructural disturbances.

White matter microstructural damage and depressive symptoms in patients with mild cognitive impairment and cerebral small vessel disease: the VMCI-Tuscany Study

BACKGROUND AND PURPOSE

Disruption of cortical-subcortical circuits related to small vessel disease (SVD) may predispose to depression in the elderly. We aimed to determine the independent association between white matter (WM) microstructural damage, evaluated with diffusion tensor imaging (DTI), and depressive symptoms in a cohort of elderly subjects with mild cognitive impairment (MCI) and SVD.

METHODS

The vascular mild cognitive impairment (VMCI)-Tuscany Study is an observational multicentric longitudinal study that enrolled patients with MCI and moderate to severe degrees of WM hyperintensities on MRI. Lacunar infarcts, cortical atrophy, medial temporal lobe atrophy, microbleeds, and DTI-derived indices (mean diffusivity, MD and fractional anisotropy, FA) were evaluated on baseline MRI. Geriatric Depression Scale (GDS) (score 0-15) was used to assess depressive symptoms. An extensive neuropsychological battery, Instrumental Activities of Daily Living scale, and the Short Physical Performance Battery were used for cognitive, functional, and motor assessments, respectively.

RESULTS

Seventy-six patients (mean age: 75.1 ± 6.8 years) were included. Univariate analyses showed a significant association between GDS score and both DTI-derived indices (MD: r = 0.307, p = 0.007; FA: r = -0.245; p = 0.033). The association remained significant after adjustment for age, WM hyperintensities severity, global cognitive, functional and motor performances, and antidepressant therapy (MD: r = 0.361, p = 0.002; FA: r = -0.277; p = 0.021).

CONCLUSIONS

These results outline the presence of an association between WM microstructural damage and depressive symptoms in MCI patients with SVD. This relationship does not seem to be mediated by disability, cognitive, and motor impairment, thus supporting the vascular depression hypothesis.

White matter integrity and depressive symptoms in cerebral small vessel disease: The RUN DMC study

OBJECTIVE

Depressive symptoms are common in elderly with cerebral small vessel disease (SVD). As not every individual with SVD experiences depressive symptoms, other factors might play a role. We therefore investigated the white matter (WM) integrity of the white matter tracts in elderly with depressive symptoms, independent of global cognitive function, by applying the tract-based spatial statistics (TBSS).

DESIGN

Prospective cohort study with cross-sectional baseline data.

SETTING

Radboud University Nijmegen Medical Centre, The Netherlands.

PARTICIPANTS

438 individuals aged between 50-85 years, with SVD without dementia.

MEASUREMENTS

Diffusion tensor imaging parameters and depressive symptoms, assessed with the Center for Epidemiologic Studies Depression Scale.

RESULTS

Compared with non-depressed participants (N = 287), those with depressive symptoms (N = 151) had lower fractional anisotropy in the genu and body of the corpus callosum, bilateral inferior fronto-occipital fasciculus, uncinate fasciculus, and corona radiata. These differences disappeared after adjustment for white matter hyperintensities (WMH) and lacunar infarcts. Mean-, axial- and radial diffusivity were higher in these areas in participants with depressive symptoms. After additional adjustment for WMH and lacunar infarcts, the changes observed in radial diffusivity also disappeared. Adding global cognition as confounding variable altered the diffusion parameters only slightly.

CONCLUSION

This study indicates that elderly with depressive symptoms show a lower WM integrity, independent of global cognitive function, and that the presence of SVD is mostly responsible, affecting the fronto-subcortical regions and hereby disrupting the neural circuitry involved in mood regulation.

Ischemic brain injury in hemodialysis patients: which is more dangerous, hypertension or intradialytic hypotension?

Abnormalities of cognitive function and high levels of depression incidence are characteristic of hemodialysis patients. Although previously attributed to the humoral effects of uremia, it is becoming increasingly appreciated that many elements of the overall disease state in CKD patients contribute to functional disturbances and physical brain injury. These factors range from those associated with the underlying primary diseases (cardiovascular, diabetes etc.) to those specifically associated with the requirement for dialysis (including consequences of the hemodialysis process itself). They are, however, predominantly ischemic threats to the integrity of brain tissue. These evolving insights are starting to allow nephrologists to appreciate the potential biological basis of dependency and depression in our patients, as well as develop and test new therapeutic approaches to this increasingly prevalent and important issue. This review aims to summarize the current understanding of brain injury in this setting, as well as examine recent advances being made in the modification of dialysis-associated brain injury.

Depressive symptoms, symptom dimensions, and white matter lesion volume in older adults: a longitudinal study

OBJECTIVE

White matter lesions (WMLs) are associated with depressive symptoms in older adults. However, it is not clear whether different symptom dimensions of depression have distinct associations with WMLs. The authors assessed the longitudinal relationships of the Center for Epidemiologic Studies Depression Scale (CES-D) total score and subscale scores with WML volume in the Baltimore Longitudinal Study of Aging.

METHODS

Using a prospective observational design, the authors examined WML volume and depressive symptoms at 1- to 2-year intervals for up to 9 years in 116 dementia-free participants (mean age: 68.78 ± 7.68). At each visit, depressive symptoms were measured with the CES-D and WML volumes were quantified from structural magnetic resonance imaging scans.

RESULTS

Higher CES-D full-scale scores were associated with greater WML volume and with a faster rate of volume increases over time in women, especially at older ages. Higher depressed mood and somatic symptoms subscale scores were associated with greater increases in WML volume over time at older ages. In men, depressed mood and somatic symptoms were associated with larger WML volume at baseline.

CONCLUSION

Findings confirm an association between WMLs and depressive symptoms and suggest that depressed mood and somatic symptoms may be stronger predictors of depression-related brain changes than lack of well-being. Age and sex may moderate the relationships between depressive symptoms and WMLs. Understanding particular symptom dimensions of depressive symptoms has implications for treatment and may lead to targeted interventions and more precise knowledge of mechanisms underlying depression.

White matter integrity and late-life depression in community-dwelling individuals: diffusion tensor imaging study using tract-based spatial statistics

BACKGROUND

Late-life depression has been associated with white matter changes in studies using the regions of interest approach.

AIMS

To investigate the cross-sectional and longitudinal relationship between white matter integrity and depression in community-dwelling individuals using diffusion tensor imaging with tract-based spatial statistics.

METHOD

The sample comprised 381 participants aged between 72 and 92 years who were assessed twice within 2 years. Depressive symptoms were measured with the Geriatric Depression Scale. Tract-based spatial statistics were applied to investigate white matter integrity in currently depressed v. non-depressed elderly people and in those with a history of depression v. no history of depression. The relationship between white matter integrity and development of depressive symptoms after 2 years were analysed with logistic regression.

RESULTS

Individuals with current depression had widespread white matter integrity reduction compared with non-depressed elderly people. Significant fractional anisotropy reductions were found in 45 brain areas with the most notable findings in the frontal lobe, association and projection fibres. A history of depression was not associated with reduced fractional anisotropy. White matter changes in the superior frontal gyrus, posterior thalamic radiation, superior longitudinal fasciculus and in the body of corpus callosum predicted depression at follow-up.

CONCLUSIONS

Reduced white matter integrity is associated with late-life depression and predicts future depressive symptoms whereas a history of depression is not related to white matter changes. Disruption to white matter integrity may be a biomarker to predict late-life depression.

Associations between vascular risk and mood in euthymic older adults: preliminary findings

OBJECTIVES

Vascular risk has been associated with late-life depression, but it is less certain whether it is also associated with the endorsement of depressive symptoms among euthymic older adults. We explore whether vascular risk is associated with endorsement of depressive symptoms among euthymic older adults and examine associations with cognitive function.

METHODS

Fifty-seven adults (50-89 years), were assessed for: 1) vascular risk (Framingham Stroke Risk Profile, FSRP); 2) depressive mood (Center for Epidemiologic Studies Depression, CESD self-rating questionnaire; Hamilton Depression Rating Scale, HDRS clinical interview); and 3) cognitive domains, (Learning and Memory, L-M; Attention and Information Processing, AIP; Executive Function, EF; Semantic Language, SL).

RESULTS

Significant correlations were observed between FSRP and both depression scales, independent of age. No significant correlations were observed between HDRS and any cognitive domain; in contrast, CESD correlated significantly with L-M, AIP and EF but not SL. FSRP correlated significantly with L-M and EF measures only. Regression analyses revealed that 11.5% of the variance in HDRS scores was explained by FSRP, whereas CESD scores were explained by EF (20.8% of variance).

CONCLUSIONS

Vascular risk was associated with endorsement of depressive symptoms in euthymic older adults. However, the patterns of associations with the two depression scales are distinct and may reflect both differences in administration and item characteristics. A limitation of this study was the exclusion of individuals with subclinical depression, leading to a restricted range on depression scales; future studies should include a full population sample to more fully explore low mood in late-life.

Altered white-matter architecture in treatment-naive adolescents with clinical depression

BACKGROUND

Depressive disorders are highly prevalent in adolescence and confer a heightened risk of recurrence in adulthood. Insight into the developmental neurocircuitry of depression could advance our understanding of depression and aid the development of effective treatment strategies. Whereas white-matter (WM) abnormalities are strongly implicated in adult depression, we still lack a firm understanding of WM architecture in adolescent depression. Using diffusion tensor imaging (DTI), we set out to investigate WM microstructure in a sample of clinically depressed adolescents relative to matched controls.

METHOD

We employed tract-based spatial statistics (TBSS) to examine WM microstructure in 25 treatment-naive adolescents with clinical depression relative to 21 matched controls. Using TBSS, we examined fractional anisotropy (FA), axial diffusivity (AD), radial diffusivity (RD) and mean diffusivity (MD). Threshold-free cluster enhancement (TFCE) with family-wise error (FWE) correction was used to control for multiple comparisons.

RESULTS

Our analysis revealed abnormal WM microstructure in clinically depressed adolescents. More specifically, whole-brain analysis revealed that patients had lower FA values in the body of the corpus callosum (CC), coupled with elevated RD and MD, and preserved AD. Conversely, region-of-interest analysis revealed that patients had higher FA values in the uncinate fasciculus (UF), coupled with elevated AD, reduced RD and preserved MD.

CONCLUSIONS

In line with neurocircuitry models of depression, our findings suggest that WM abnormalities within pathways facilitating cognitive and emotional functioning are involved in the pathophysiology of depression. Importantly, our findings show that these WM abnormalities are already present early in the course of the disorder.

The relationship between interleukin-1 receptor antagonist and cognitive function in older adults with bipolar disorder

OBJECTIVE

Cognitive impairments are a feature of bipolar disorder (BD) and could be worsened by inflammatory cytokines. We determined whether (i) serum interleukin-1 receptor antagonist (IL-1RA) was increased in elderly BD subjects; (ii) whether IL-1RA was associated with worse neurocognitive function; and (iii) whether IL-1RA was associated with white matter integrity.

METHODS

Twenty-one euthymic BD patients (65 +/- 9 years) with serum available for IL-1RA measures by enzyme-linked immunoassays were compared with 26 similarly aged control participants. Four factor analysis-derived z-scores and a global z-score were obtained from a battery of 21 neurocognitive tests. Diffusion tensor images were used to obtain fractional anisotropy (FA), and an automated labeling pathway algorithm was used to obtain white matter hyperintensity burden.

RESULTS

Interleukin-1 receptor antagonist was elevated in BD subjects compared with controls (439+/-326 pg/mL vs. 269+/-109 pg/mL; p = 0.004). Moreover, IL-1RA was inversely correlated with three cognitive function factors and global cognition (r = -0.37; p = 0.01). IL-1RA continued to correlate with global cognitive function even when covarying for either IL-6 or brain-derived neurotrophic factor. Although FA was lower in BD subjects (0.368 +/- 0.02 vs. 0.381 +/- 0.01; p = 0.02), IL-1RA was not associated with FA or white matter hyperintensity burden.

CONCLUSION

Elevated serum levels of IL-1RA in BD subjects, even during euthymic states, were associated with worse cognitive function. This association was not explained by co-occurring increases in IL-6, by decreased brain-derived neurotrophic factor, nor by measures of white matter integrity. These cross-sectional findings support the possibility that the IL-1 family may contribute to cognitive impairments in BD.

White-matter tract integrity in late-life depression: associations with severity and cognition

BACKGROUND

Although significant changes in both gray and white matter have been noted in late-life depression (LLD), the pathophysiology of implicated white-matter tracts has not been fully described. In this study we examined the integrity of specific white-matter tracts in LLD versus healthy controls (HC).

METHOD

Participants aged ⩾60 years were recruited from the community. The sample included 23 clinically diagnosed individuals with LLD and 23 HC. White-matter integrity metrics [fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD) and radial diffusivity (RD)] were calculated in the bilateral cingulum and uncinate fasciculus. Depression severity was measured using the Center for Epidemiological Studies Depression Scale (CESD). Composite scores for learning and memory and executive function were created using standardized neuropsychological assessments.

RESULTS

White-matter integrity was lower in LLD versus HC in the bilateral cingulum and right uncinate fasciculus (p⩽0.05). In the whole sample, depression severity correlated with integrity in the bilateral cingulum and right uncinate fasciculus (p ⩽0.05). In patients, depression severity correlated with the integrity of the left uncinate fasciculus (p = 0.03); this tract also correlated with executive function (p = 0.02). Among HC, tract integrity did not correlate with depression scores; however, learning and memory correlated with integrity of the bilateral uncinate fasciculus and bilateral cingulum; executive function correlated with the right uncinate and left cingulum (p ⩽0.05).

CONCLUSIONS

White-matter tract integrity was lower in LLD than in HC and was associated with depression severity across all participants. Tract integrity was associated with cognition in both groups but more robustly among HC.

In vivo quantification of white matter microstructure for use in aging: a focus on two emerging techniques

Human brain imaging has seen many advances in the quantification of white matter in vivo. For example, these advances have revealed the association between white matter damage and vascular disease as well as their impact on risk for and development of dementia and depression in an aging population. Current neuroimaging methods to quantify white matter damage provide a foundation for understanding such age-related neuropathology; however, these methods are not as adept at determining the underlying microstructural abnormalities signaling at risk tissue or driving white matter damage in the aging brain. This review will begin with a brief overview of the use of diffusion tensor imaging (DTI) in understanding white matter alterations in aging before focusing in more detail on select advances in both diffusion-based methods and multi-component relaxometry techniques for imaging white matter microstructural integrity within myelin sheaths and the axons they encase. Although DTI greatly extended the field of white matter interrogation, these more recent technological advances will add clarity to the underlying microstructural mechanisms that contribute to white matter damage. More specifically, the methods highlighted in this review may prove more sensitive (and specific) for determining the contribution of myelin versus axonal integrity to the aging of white matter in brain.

Prefrontal vulnerabilities and whole brain connectivity in aging and depression

Studies exploring the underpinnings of age-related neurodegeneration suggest fronto-limbic alterations that are increasingly vulnerable in the presence of disease including late life depression. Less work has assessed the impact of this specific vulnerability on widespread brain circuitry. Seventy-nine older adults (healthy controls=45; late life depression=34) completed translational tasks shown in non-human primates to rely on fronto-limbic networks involving dorsolateral (Self-Ordered Pointing Task) or orbitofrontal (Object Alternation Task) cortices. A sub-sample of participants also completed diffusion tensor imaging for white matter tract quantification (uncinate and cingulum bundle; n=58) and whole brain tract-based spatial statistics (n=62). Despite task associations to specific white matter tracts across both groups, only healthy controls demonstrated significant correlations between widespread tract integrity and cognition. Thus, increasing Object Alternation Task errors were associated with decreasing fractional anisotropy in the uncinate in late life depression; however, only in healthy controls was the uncinate incorporated into a larger network of white matter vulnerability associating fractional anisotropy with Object Alternation Task errors using whole brain tract-based spatial statistics. It appears that the whole brain impact of specific fronto-limbic vulnerabilities in aging may be eclipsed in the presence of disease-specific neuropathology like that seen in late life depression.

The Iowa Gambling Task (IGT) in Brazil: a systematic review

Background: Decision-making is a complex, multidimensional cognitive function that requires the choice between two or more options and also the predictive analysis of its consequences. One of the tools most widely used to assess decision-making in neuropsychological research is the Iowa Gambling Task (IGT). Objective: To conduct a systematic review of articles reporting empirical IGT studies based in Brazil. Method: Articles were obtained from multiple journal databases including ISI Web of Knowledge, Scopus, SciELO, LILACS, and Scholar Google. Results: Thirty-six studies were included in this review and divided into four categories according to main subject matter (psychiatry & personality; demographic & cultural variables; medical/clinic; and psychometric properties & test administration standardization). In general, there was a significant growth in research employing IGT (Χ² = 17.6, df = 5, p = 0.0003), but this growth was restricted to a few geographic areas of Brazil. The psychiatry & personality subject matter was the most abundant, accounting for 14 publications (39% of the total sample). Conclusion: Since its first adaptation to Brazilian Portuguese in 2006, a growing interest in decision-making as measured by the IGT can be observed, with psychiatry & personality topics representing a large portion of the scientific inquiry to date. Nevertheless, in order to extend the initial results of Brazilian IGT decision-making research, more studies are necessary - across a more diverse range of topics, including demographic & cultural variables, and psychometric properties & test administration standardization, the areas least studied -, as is the dissemination of the IGT to more regions of the country.

Psychological symptoms and blood pressure among rural-dwellers

Rural-dwelling adults face different health concerns and risks than do adults living in urban areas, with reduced assess to care. Studies examining the associations between anxiety and/or depression and blood pressure have yielded mixed results. This study addressed this by examining the association of these symptoms to blood pressure in men compared to women, and for differing racial groups in a rural population in the western United States. Analyses indicate the association between depression and blood pressure differs by race. Further, depressive symptoms were associated with higher diastolic blood pressure for participants at or above the mean of anxiety.

White matter abnormalities and illness severity in major depressive disorder

BACKGROUND

White matter abnormalities have been implicated in the aetiology of major depressive disorder; however, the relationship between the severity of symptoms and white matter integrity is currently unclear.

AIMS

To investigate white matter integrity in people with major depression and healthy controls, and to assess its relationship with depressive symptom severity.

METHOD

Diffusion tensor imaging data were acquired from 66 patients with recurrent major depression and a control group of 66 healthy individuals matched for age, gender and IQ score, and analysed with tract-based spatial statistics. The relationship between white matter integrity and severity of depression as measured by the Beck Depression Inventory was examined.

RESULTS

Depressive illness was associated with widespread regions of decreased white matter integrity, including regions in the corpus callosum, superior longitudinal fasciculus and anterior corona radiata, compared with the control group. Increasing symptom severity was negatively correlated with white matter integrity, predominantly in the corpus callosum.

CONCLUSIONS

Widespread alterations in white matter integrity are evident in major depressive disorder. These abnormalities are heightened with increasing severity of depressive symptoms.

Are there neurological consequences of recurrent intradialytic hypotension?

Structural abnormalities of the brain are common in hemodialysis (HD) patients, as are a wide range of severe functional deficiencies of cerebral function. Both depression and increasing dependency are highly prevalent in HD patients and worsen severely within the first 12 months of dialysis initiation. HD, as it is commonly practiced, is associated with significant recurrent episodes of circulatory stress. This results in acute injury to the heart, skin, kidney and gut, and drives longer term end-organ chronic injury. This article aims to explore the hypothesis that the cerebral microcirculation is also sensitive to dialysis-based circulatory stress (and other multiorgan consequences of recurrent dialysis-induced ischemia), and that this may drive specific patterns of brain injury with resultant psychiatric and functional consequences.

Memory complaints with and without memory impairment: the impact of leukoaraiosis on cognition

White matter alterations, leukoaraiosis (LA) on structural MRI, are associated with cognitive deficits and increased risk of dementia. LA may also impact on subjective memory complaints in otherwise healthy older adults. Little is known about the interplay between LA memory complaints and cognition. We investigated cognitive phenotypes associated with LA in 42 non-demented older adults categorized as having subjective cognitive complaints with no objective cognitive impairment-the subjective cognitive impairment group (SCI; n = 12), amnesic mild cognitive impairment (aMCI; n = 20), or healthy controls (HC; n = 11). We measured LA severity on MRI with a 40-point visual rating scale. Controlling for age and Mini-Mental State Examination (MMSE) score, analyses revealed multiple between-group differences. Follow-up linear regression models investigating the underlying contributors to each clinic group's cognitive profile indicated that LA contributed to learning slope variance (after accounting for age and MMSE) but only for the SCI group. Although the SCI group showed a significantly steeper learning slope when compared to HC and aMCI, increasing LA severity negatively impacted this group's rate of learning. This, in conjunction with the significant contribution of age on SCI learning slope performance variance suggests that greater LA burden at a younger age may contribute to subtle changes in learning for individuals with subjective cognitive complaints.

Aging in autism spectrum disorders: a mini-review

This article addresses an important and barely researched topic: what happens to children with autism spectrum disorders when they grow old. We review the small published literature on aging in autism. We then consider the relevance of research on 'neurotypical' aging in core domains of autistic impairment: social cognition, executive function, cognitive style and memory. Research themes from the study of normal aging, including cognitive reserve, compensation, quality of life, loneliness and physical health are of relevance for future research on autism. Studies of aging in autism will be important not only to plan appropriate services, but also to shed light on the full developmental trajectory of this neurodevelopmental condition, and perhaps provide clues to neuropathology and etiology.

White matter: beyond focal disconnection

The complex phenomenology of white matter dementia and many neuropsychiatric disorders implies that they originate from involvement of distributed neural networks, and white matter neuropathology is increasingly implicated in the pathogenesis of these network disconnection syndromes. White matter disorders produce functional asynchrony of interdependent cerebral regions subserving normal cognitive and emotional functions. Accumulating evidence suggests that white matter dementia primarily reflects disturbed frontal systems connectivity, whereas disruption of frontal and temporal lobe systems is implicated in the pathogenesis of neuropsychiatric disorders. Continued study of normal and abnormal white matter promises to help resolve challenging problems in behavioral neurology and neuropsychiatry.

Recurrent circulatory stress: the dark side of dialysis

Current conventional hemodialysis (HD) is largely an industrialized process, with inadequate attention to the role that the dialysis treatment itself may play in the development and promulgation of uremic related disease states. HD is capable of exerting significant recurrent systemic circulatory stress. There is already an appreciation that this may be important in the development of cardiac disease, but it appears that this systemic insult is capable of resulting in perfusion-dependent injury of a wide range of vulnerable vascular beds. These include gut, brain, and potentially the kidney. This predominantly hemodynamic injury can therefore result a mixed picture of direct perfusion-related injury, local/systemic inflammation, and potentiation of further cycles of injury. This article aims to put forward a pathophysiological paradigm that places dialysis-induced acute injury at the center of much of the observed disease burden in HD patients.

Cerebral microbleeds and symptom severity of post-stroke depression: a magnetic resonance imaging study

BACKGROUND

Cerebral microbleeds (CMBs) are common in stroke survivors, although their clinical significance in the development of psychiatric conditions following stroke remains unknown. This study examines the association between post-stroke depression (PSD) symptom severity and CMBs.

METHODS

Amongst the 4088 patients with acute ischemic stroke who had been admitted to the acute stroke unit of a university-affiliated regional hospital in Hong Kong, between December 2004 and May 2009, 994 patients were recruited. A psychiatrist administered the Structural Clinical Interview for DSM-IV to all 994 patients and made a diagnosis of PSD three months after the index stroke. PSD symptom severity was assessed with the 15-item Geriatric Depression Scale (GDS). Seventy-eight patients were found to have PSD. The presence and location of CMBs were evaluated with magnetic resonance imaging (MRI).

RESULTS

Seventy-eight patients (7.8%) had PSD. CMBs were identified in 20 PSD patients. Relative to the no-CMB group, the mean GDS score of patients with lobar CMBs was significantly higher (12.6±2.6 versus 10.4±2.5, p=0.01 after adjusting for age, sex, global cognitive functions, neurological deficits and white matter hyperintensities).

LIMITATIONS

Patients with more severe stroke, those who died before the three-month follow-up and those who became depressed later were excluded, as were those unable to give their consent due to dementia or aphasia. These selection biases may limit the generalizability of the findings.

CONCLUSIONS

The results suggest that lobar CMBs may contribute to PSD symptom severity. The importance of CMBs in the pathogenesis of other psychiatric disorders in stroke survivors and other patient populations warrants further investigation.

White matter structural decline in normal ageing: a prospective longitudinal study using tract-based spatial statistics

Normal ageing is accompanied by a progressive decline in cognitive function but the mechanisms for this are not fully understood. Nevertheless, the importance of white matter degeneration is supported by diffusion tensor imaging (DTI) studies, although several important questions remain about the pattern and nature of age-related white matter degeneration. Firstly, there is a lack of longitudinal data determining the rate of change in DTI parameters with age, and whether this can be detected over short time periods. Secondly, it is unclear whether observed changes are uniform across the brain or whether accelerated white matter degeneration is localised to particular brain regions, as would support the frontal-ageing hypothesis. This study uses DTI techniques to quantify structural integrity change to determine whether regional differences are apparent in the rate of degeneration during longitudinal follow-up in a sample of healthy middle aged and older adults aged between 50 and 90years. Longitudinal differences in fractional anisotropy, axial and radial diffusivity are investigated using 1D coronal slice profiles, and 2D column maps in standard space, as well as using 3D tract-based spatial statistics (TBSS) to investigate local age-related structural changes on a voxel-by-voxel basis at baseline and two-year follow-up. Results indicate that DTI can detect age-related change in white matter structure over a relatively short follow-up period and that longitudinal analyses reveal significant changes in white matter integrity throughout the brain with no evidence of accelerated decline in the frontal lobe regions during a 2year period. Common changes across different diffusion characteristics are discussed.