White matter lesion volumes and caudate volumes in late-life depression

Alterations of the amplitude of low-frequency fluctuation induced by repetitive transcranial magnetic stimulation combined with antidepressants treatment for major depressive disorder

We investigated the neuroimaging changes and clinical efficacy of repetitive transcranial magnetic stimulation (rTMS) combined with antidepressants in major depressive disorder (MDD) patients. We scanned 35 patients with MDD and 27 healthy controls (HC) with resting-state functional magnetic resonance imaging (fMRI) before and after treatment. We analyzed amplitude of low-frequency fluctuation (ALFF) and the correlation with clinical variables. The rate of significant efficacy after treatment was higher in the combination treatment group than in the antidepressant group, although not statistically significant. At baseline, ALFF increased in the left middle temporal, brain stem, and left cerebellum and decreased in the right anterior cingulate (ACC), right orbital frontal cortex (OFC), and right caudate. ALFF increased in the left fusiform and decreased in the right lingual gyrus, left middle occipital gyrus, and left superior occipital gyrus after antidepressants. ALFF increased in the right ACC, right OFC, and right rectus after combination treatment. ALFF changes in the right ACC/OFC were negatively correlated with HAMD changes. After treatment, abnormal activity in some brain regions normalized, but these regions differed between the two treatment groups. rTMS combined with antidepressants therapy may improve MDD symptoms by improving neuronal activity levels in the right ACC and right OFC.

Challenges in Identifying Individualized Brain Biomarkers of Late Life Depression

Research into neuroimaging biomarkers for Late Life Depression (LLD) has identified neural correlates of LLD including increased white matter hyperintensities and reduced hippocampal volume. However, studies into neuroimaging biomarkers for LLD largely fail to converge. This lack of replicability is potentially due to challenges linked to construct variability, etiological heterogeneity, and experimental rigor. We discuss suggestions to help address these challenges, including improved construct standardization, increased sample sizes, multimodal approaches to parse heterogeneity, and the use of individualized analytical models.

Preliminary Comparison of Subcortical Structures in Elderly Subclinical Depression: Structural Analysis with 3T MRI

Depression in the elderly population has shown increased likelihood of neurological disorders due to structural changes in the subcortical area. However, further investigation into depression related subcortical changes is needed due to mismatches in structural analysis results between studies as well as scarcities in research regarding subcortical connectivity patterns of subclinical depression populations. This study aims to investigate structural differences in subcortical regions of aged participants with subclinical depression using 3Tesla MRI. In structural analysis, volumes of each subcortical region were measured to observe the volumetric difference and asymmetry between groups, but no significant difference was found. In addition, fractional anisotropy (FA) and apparent diffusion coefficient (ADC) did not show any significant differences between groups. Structural analysis using probabilistic tractography indicated that the connection strength between left nucleus accumbens-right hippocampus, and right thalamus-right caudate was higher in the control group than the subclinical depression group. The differences in subcortical connection strength of subclinical depression groups, have shown to correlate with emotional and cognitive disorders, such as anxiety and memory impairment. We believe that the analysis of structural differences and cross-regional network measures in subcortical structures can help identify neurophysiological changes occurring in subclinical depression.

Characteristic Biomarker and Cognitive Profile in Incipient Mixed Dementia

Background:

Research has shown that mixed dementia is more common than previously believed but little is known of its early stages.

Objective:

To examine if incipient mixed dementia can be differentiated from incipient Alzheimer’s disease (AD) and subcortical ischemic vascular dementia (SVD) using neuropsychological tests, cerebrospinal fluid (CSF) markers, and magnetic resonance imaging markers.

Methods:

We included 493 patients and controls from the Gothenburg MCI study and used the dementia groups for marker selection (CSF total-tau (T-tau), phospho-tau (P-tau), and amyloid-β₄₂ (Aβ₄₂), 11 neuropsychological tests, and 92 regional brain volumes) and to obtain cut-off values which were then applied to the MCI groups.

Results:

Incipient mixed dementia was best differentiated from incipient AD by the Word fluency F-A-S test and the Trail making test A. CSF T-tau, P-tau, and Aβ₄₂ differentiated incipient mixed dementia from incipient SVD.

Conclusion:

Incipient mixed dementia is characterized by an AD-like biomarker profile and an SVD-like cognitive profile. Incipient mixed dementia can be separated from incipient AD and incipient SVD using CSF markers and cognitive testing.

Altered directed functional connectivity of the right amygdala in depression: high-density EEG study

The cortico-striatal-pallidal-thalamic and limbic circuits are suggested to play a crucial role in the pathophysiology of depression. Stimulation of deep brain targets might improve symptoms in treatment-resistant depression. However, a better understanding of connectivity properties of deep brain structures potentially implicated in deep brain stimulation (DBS) treatment is needed. Using high-density EEG, we explored the directed functional connectivity at rest in 25 healthy subjects and 26 patients with moderate to severe depression within the bipolar affective disorder, depressive episode, and recurrent depressive disorder. We computed the Partial Directed Coherence on the source EEG signals focusing on the amygdala, anterior cingulate, putamen, pallidum, caudate, and thalamus. The global efficiency for the whole brain and the local efficiency, clustering coefficient, outflow, and strength for the selected structures were calculated. In the right amygdala, all the network metrics were significantly higher (p < 0.001) in patients than in controls. The global efficiency was significantly higher (p < 0.05) in patients than in controls, showed no correlation with status of depression, but decreased with increasing medication intake (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${{\bf{R}}}^{{\bf{2}}}{\boldsymbol{=}}{\bf{0.59}}\,{\bf{and}}\,{\bf{p}}{\boldsymbol{=}}{\bf{1.52}}{\bf{e}}{\boldsymbol{ \mbox{-} }}{\bf{05}}$$\end{document}R2=0.59andp=1.52e‐05). The amygdala seems to play an important role in neurobiology of depression. Practical treatment studies would be necessary to assess the amygdala as a potential future DBS target for treating depression.

Association of Depression With Functional Mobility in Schizophrenia

BACKGROUND

Functional immobility can cause functional disability in patients with schizophrenia and has been linked to prognosis and mortality. Although depression might be a barrier for physical activity engagement, scarce data are present on the relationship between depression and functional mobility (FM) in schizophrenia. Thus, we aimed to investigate the associations among FM, depression, and other clinical correlates in individuals with schizophrenia.

METHODS

FM was evaluated by the pedometer-assessed daily steps and Timed Up-and-Go (TUG) test in the daily-living and clinical settings, respectively. Psychiatric symptoms were assessed using the Beck Depression Inventory, Brief Psychiatric Rating Scale (BPRS), and State-Trait Anxiety Inventory. Cognitive function was evaluated using the Sternberg Working Memory (SWM) Task. Multiple regression analyses were performed to identify predictive factors associated with FM, with adjustment for relevant covariates.

RESULTS

Sixty patients were enrolled in this study. Depression was the most consistent explanatory variable for both pedometer (β = -0.34, p = 0.011) and TUG time (β = 0.32, p = 0.018). Additionally, SWM accuracy (β = -0.29, p = 0.018), BPRS-Withdrawal (β = 0.19, p = 0.139), and fasting blood sugar (β = 0.34, p = 0.008) were associated with TUG time. However, psychotic symptoms and anxiety were not associated with pedometer and TUG.

CONCLUSIONS

We identified an association between depression and FM after adjusting for other disorder-related correlates in schizophrenia. Since the intervention goal is functional recovery, improving FM by treating depression may have considerable therapeutic value.

MR-based age-related effects on the striatum, globus pallidus, and thalamus in healthy individuals across the adult lifespan

While numerous studies have used magnetic resonance imaging (MRI) to elucidate normative age‐related trajectories in subcortical structures across the human lifespan, there exists substantial heterogeneity among different studies. Here, we investigated the normative relationships between age and morphology (i.e., volume and shape), and microstructure (using the T1‐weighted/T2‐weighted [T1w/T2w] signal ratio as a putative index of myelin and microstructure) of the striatum, globus pallidus, and thalamus across the adult lifespan using a dataset carefully quality controlled, yielding a final sample of 178 for the morphological analyses, and 162 for the T1w/T2w analyses from an initial dataset of 253 healthy subjects, aged 18–83. In accordance with previous cross‐sectional studies of adults, we observed age‐related volume decrease that followed a quadratic relationship between age and bilateral striatal and thalamic volumes, and a linear relationship in the globus pallidus. Our shape indices consistently demonstrated age‐related posterior and medial areal contraction bilaterally across all three structures. Beyond morphology, we observed a quadratic inverted U‐shaped relationship between T1w/T2w signal ratio and age, with a peak value occurring in middle age (at around 50 years old). After permutation testing, the Akaike information criterion determined age relationships remained significant for the bilateral globus pallidus and thalamus, for both the volumetric and T1w/T2w analyses. Our findings serve to strengthen and expand upon previous volumetric analyses by providing a normative baseline of morphology and microstructure of these structures to which future studies investigating patients with various disorders can be compared.

Deformities of the Globus Pallidus are Associated with Severity of Suicidal Ideation and Impulsivity in Patients with Major Depressive Disorder

Neuroimaging research increasingly suggests there are biological features related to suicidal risk, including brain morphometric features, leading to an elaborate suicide risk assessment. However, few studies have focused on the severity of suicidal ideation and its association with subcortical anatomy in patients with major depressive disorder (MDD). Here, we mainly investigated whether specific structural differences were present in MDD patients with and without suicidal ideation; and supplemented comparison with and without suicidal attempt. We hypothesized that structures associated with suicidal ideation would be derived from a combination of depression and impulsivity. Local atrophy of subcortical structures in 48 patients with MDD (24 with suicidal ideation and 24 without) and 25 age- and sex-matched healthy controls were compared using a surface-based shape analysis method. There was no difference in brain volume between MDD patients with or without suicidal ideations; or MDD patients with or without suicidal attempt. However, the atrophy level in the left pallidum showed a positive correlation with severity of suicidal risk in MDD patients with suicidal ideation. Local atrophy of the left hippocampus, right caudate, and right pallidum had a positive correlation with total impulsivity. These findings possibly suggest that vulnerability to suicidal attempt can be derived from suicidal ideation combined with depression and impulsivity, related to reduced motivational control.

Mild Prenatal Stress Causes Emotional and Brain Structural Modifications in Rats of Both Sexes

Stress or high levels of glucocorticoids (GCs) during developmental periods is known to induce persistent effects in the neuroendocrine circuits that control stress response, which may underlie individuals’ increased risk for developing neuropsychiatric conditions later in life, such as anxiety or depression. We developed a rat model (Wistar han) of mild exposure to unpredictable prenatal stress (PS), which consists in a 4-h stressor administered three times per week on a random basis; stressors include strobe lights, noise and restrain. Pregnant dams subjected to this protocol present disrupted circadian corticosterone secretion and increased corticosterone secretion upon acute stress exposure. Regarding progeny, both young adult (2 months old) male and female rats present increased levels of circulating corticosterone and hyperactivity of the hypothalamus-pituitary-adrenal axis to acute stress exposure. Both sexes present anxious- and depressive-like behaviors, shown by the decreased time spent in the open arms of the elevated plus maze (EPM) and in the light side of the light-dark box (LDB), and by increased immobility time in the forced swim test, respectively. Interestingly, these results were accompanied by structural modifications of the bed nucleus of stria terminalis (BNST) and hippocampus, as well as decreased norepinephrine and dopamine levels in the BNST, and serotonin levels in the hippocampus. In summary, we characterize a new model of mild PS, and show that stressful events during pregnancy can lead to long-lasting structural and neurochemical effects in the offspring, which affect behavior in adulthood.

Warping an atlas derived from serial histology to 5 high-resolution MRIs

Previous work from our group demonstrated the use of multiple input atlases to a modified multi-atlas framework (MAGeT-Brain) to improve subject-based segmentation accuracy. Currently, segmentation of the striatum, globus pallidus and thalamus are generated from a single high-resolution and -contrast MRI atlas derived from annotated serial histological sections. Here, we warp this atlas to five high-resolution MRI templates to create five de novo atlases. The overall goal of this work is to use these newly warped atlases as input to MAGeT-Brain in an effort to consolidate and improve the workflow presented in previous manuscripts from our group, allowing for simultaneous multi-structure segmentation. The work presented details the methodology used for the creation of the atlases using a technique previously proposed, where atlas labels are modified to mimic the intensity and contrast profile of MRI to facilitate atlas-to-template nonlinear transformation estimation. Dice's Kappa metric was used to demonstrate high quality registration and segmentation accuracy of the atlases. The final atlases are available at https://github.com/CobraLab/atlases/tree/master/5-atlas-subcortical.

Is episodic memory performance more vulnerable to depressive affect in older adulthood?

This study examined how age, depressive symptoms, demographic variables, frailty, and health factors jointly influence episodic memory across the lifespan in two large, diverse samples. Hierarchical regression analyses from both samples showed that depressive symptoms negatively impacted episodic memory performance with the effect being more pronounced for older adults. Health and frailty tended not to be associated with episodic memory. However, the main effect of depressive symptoms tended to remain significant over and above other predictors, while the interaction with age was weakened with the addition of demographic variables. The unique contribution of this study is demonstrating that the relationship between depressive symptoms and episodic memory is moderated by age across relatively large non-clinical lifespan samples of adults. The findings indicate the importance of measuring and studying depressive symptoms during the course of aging in order to better understand the complex relationship between age, affect, physical functioning, and memory.

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.

Episodic memory in depression: the unique contribution of the anterior caudate and hippocampus

BACKGROUND

Learning and memory impairments in older adults with depression are linked to hippocampal atrophy. However, other subcortical regions may also be contributing to these deficits. We aimed to examine whether anterior caudate nucleus volume is significantly reduced in older adults with depression compared to controls; whether anterior caudate volume is associated with performance on tasks of episodic learning and memory, and if so, whether this association is independent of the effects of the hippocampus.

METHOD

Eighty-four health-seeking participants meeting criteria for lifetime major depressive disorder (mean age = 64.2, s.d. = 9.1 years) and 27 never-depressed control participants (mean age = 63.9, s.d. = 8.0 years) underwent neuropsychological assessment including verbal episodic memory tests [Rey Auditory Verbal Learning Test and Logical Memory (WMS-III)]. Magnetic resonance imaging was conducted, from which subregions of the caudate nucleus were manually demarcated bilaterally and hippocampal volume was calculated using semi-automated methods.

RESULTS

Depressed subjects had smaller right anterior caudate (RAC) (t = 2.3, p = 0.026) and poorer memory compared to controls (t = 2.5, p < 0.001). For depressed subjects only, smaller RAC was associated with poorer verbal memory (r = 0.3, p = 0.003) and older age (r = -0.46, p < 0.001). Multivariable regression showed that the RAC and hippocampus volume uniquely accounted for 5% and 3% of the variance in memory, respectively (β = 0.25, t = 2.16, p = 0.033; β = 0.19, t = 1.71, p = 0.091).

CONCLUSIONS

In older people with depression, the anterior caudate nucleus and the hippocampus play independent roles in mediating memory. While future studies examining this structure should include larger sample sizes and adjust for multiple comparisons, these findings support the critical role of the striatum in depression.

The Effect of Aging in Inhibitory Control of Major Depressive Disorder Revealed by Event-Related Potentials

Elderly depressed patients manifest pronounced executive dysfunction compared with younger subjects with depressive disorder. Aging-related brain changes may result in executive dysfunction in geriatric depression. We investigated the neural correlates of inhibitory control processing in depressed subjects at different ages using event-related potentials (ERPs). A equiprobable visual Go/Nogo task was used in 19 young (27.4 ± 5.0 years) and 18 elderly (70.8 ± 6.9 years) depressed subjects and their age-matched healthy controls (20 young subjects, 26.2 ± 3.7 years, and 18 elderly subjects, 68.1 ± 4.8 years). The responses were based on two types of equilateral triangular figures of upright (Go) and inverted triangle (Nogo). The elderly subjects exhibited later N2 and P3 latencies, and larger Go-N2 and P3 amplitudes, compared with the younger subjects. Further, the elderly controls displayed smaller P3 in the central and parietal regions, and yielded larger Nogo-P3 amplitude in the frontal region compared with younger controls. While the young depressed patients yielded smaller P3 amplitude than the controls across frontal, central and parietal regions, elderly depressed patients yielded smaller P3 than the elderly controls only in the frontal region. Our results suggest that the inhibitory control subprocesses are differentially affected by depression and aging. The stimulus response speed and the effort intensity of inhibition control are specifically impaired in the elderly depressed patients. And the diminished amplitudes of frontal P3 in the elderly depression imply a frontal dysfunction mechanism.

Reduced volume of the nucleus accumbens in heroin addiction

The neural mechanisms of heroin addiction are still incompletely understood, even though modern neuroimaging techniques offer insights into disease-related changes in vivo. While changes on cortical structure have been reported in heroin addiction, evidence from subcortical areas remains underrepresented. Functional imaging studies revealed that the brain reward system and particularly the nucleus accumbens (NAcc) play a pivotal role in the pathophysiology of drug addiction. The aim of this study was to investigate whether there was a volume difference of the NAcc in heroin addiction in comparison to healthy controls. A further aim was to correlate subcortical volumes with clinical measurements on negative affects in addiction. Thirty heroin-dependent patients under maintenance treatment with diacetylmorphine and twenty healthy controls underwent structural MRI scanning at 3T. Subcortical segmentation analysis was performed using FMRIB's Integrated Registration and Segmentation Tool function of FSL. The State-Trait Anxiety Inventory and the Beck Depression Inventory were used to assess trait anxiety and depressive symptoms, respectively. A decreased volume of the left NAcc was observed in heroin-dependent patients compared to healthy controls. Depression score was negatively correlated with left NAcc volume in patients, whereas a positive correlation was found between the daily opioid dose and the volume of the right amygdala. This study indicates that there might be structural differences of the NAcc in heroin-dependent patients in comparison with healthy controls. Furthermore, correlations of subcortical structures with negative emotions and opioid doses might be of future relevance for the investigation of heroin addiction.

White Matter Hyperintensity Accumulation During Treatment of Late-Life Depression

White matter hyperintensities (WMHs) have been shown to be associated with the development of late-life depression (LLD) and eventual treatment outcomes. This study sought to investigate longitudinal WMH changes in patients with LLD during a 12-week antidepressant treatment course. Forty-seven depressed elderly patients were included in this analysis. All depressed subjects started pharmacological treatment for depression shortly after a baseline magnetic resonance imaging (MRI) scan. At 12 weeks, patients underwent a follow-up MRI scan, and were categorized as either treatment remitters (n=23) or non-remitters (n=24). Among all patients, there was as a significant increase in WMHs over 12 weeks (t(46)=2.36, P=0.02). When patients were stratified by remission status, non-remitters demonstrated a significant increase in WMHs (t(23)=2.17, P=0.04), but this was not observed in remitters (t(22)=1.09, P=0.29). Other markers of brain integrity were also investigated including whole brain gray matter volume, hippocampal volume, and fractional anisotropy. No significant differences were observed in any of these markers during treatment, including when patients were stratified based on remission status. These results add to existing literature showing the association between WMH accumulation and LLD treatment outcomes. Moreover, this is the first study to demonstrate similar findings over a short interval (ie 12 weeks), which corresponds to the typical length of an antidepressant trial. These findings serve to highlight the acute interplay of cerebrovascular ischemic disease and LLD.

A decade from discovery to therapy: Lingo-1, the dark horse in neurological and psychiatric disorders

Leucine-rich repeat and immunoglobulin domain-containing protein (Lingo-1) is a potent negative regulator of neuron and oligodendrocyte survival, neurite extension, axon regeneration, oligodendrocyte differentiation, axonal myelination and functional recovery; all processes highly implicated in numerous brain-related functions. Although playing a major role in developmental brain functions, the potential application of Lingo-1 as a therapeutic target for the treatment of neurological disorders has so far been under-estimated. A number of preclinical studies have shown that various methods of antagonizing Lingo-1 results in neuronal and oligodendroglial survival, axonal growth and remyelination; however to date literature has only detailed applications of Lingo-1 targeted therapeutics with a focus primarily on myelination disorders such as multiple sclerosis and spinal cord injury; omitting important information regarding Lingo-1 signaling co-factors. Here, we provide for the first time a complete and thorough review of the implications of Lingo-1 signaling in a wide range of neurological and psychiatric disorders, and critically examine its potential as a novel therapeutic target for these disorders.

Effect of white matter lesions on manual dexterity in healthy middle-aged persons

OBJECTIVES

We hypothesized that integrated motor-visual functions measured by manipulative manual dexterity are affected by white matter lesion (WML) burden as measured on cranial MRI across relevant brain regions in subjects at risk of preclinical occult vascular disease.

METHODS

A real-time cross-sectional study of healthy subjects aged 29 to 74 years with a family history of early-onset coronary artery disease (n = 714; mean age, 51 ± 11 years; mean education, 14 ± 3 years; 42% male; 38% black) were identified from probands with coronary artery disease diagnosed before age 60 years. WMLs on 3-tesla brain MRI and Grooved Pegboard scores were measured.

RESULTS

WMLs were observed at all ages. Mean pegboard scores were 108 ± 18, similar to normal populations. In unadjusted analysis, WMLs and pegboard scores were significantly correlated by region (total WMLs, r = 0.34, p = 0.0001; frontal [r = 0.34, p < 0.0001], insula [r = 0.31, p < 0.0001], parietal [r = 0.31, p < 0.0001], and temporal [r = 0.17, p < 0.0001]). In multivariate analysis predicting (log) pegboard score adjusted for age, sex, race, education, regional or total volumes, and familial non-independence, total WML volume (p = 5.79E - 05) and regional WML volumes (p < 0.01) retained statistical significance in all but the youngest age quartile (29-43 years).

CONCLUSIONS

Greater WML volumes in different brain regions are associated with higher pegboard scores (worse performance) independent of age, sex, race, education, and total or regional volumes. This suggests that small vessel cerebrovascular disease may be present in healthy individuals in a preclinical state with measurable impact on complex integrative functions in individuals with excess risk of clinical vascular disease.

White matter lesions and depression: a systematic review and meta-analysis

We sought to determine if an association exists between overall, deep, and periventricular white matter hyperintensities and depression. We searched PubMed (Medline) and Scopus (Embase) from April-October 2012 using the MeSH terms: "White matter lesions" OR "white matter disease" OR "Cerebrovascular Disease" OR "Leukoencephalopathies" AND "Depressive Disorder" AND "magnetic resonance imaging," and "Depression" AND "leukoaraiosis." No language limits were implemented. Hand searching was performed of all included studies and relevant review articles. 913 PubMed and 188 Scopus citations were identified. Relevant, human, non-overlapping magnetic resonance imaging studies were eligible for inclusion if they reported generic data. We extracted the most adjusted odds ratios reported generated from comparing depression across severe (determined either volumetrically or visually) and mild/no white matter lesion groups. 19 reports were included. Cross-sectional subgroup analyses showed that deep white matter hyperintensities significantly associated with depression (N = 2261, odds ratio 1.02, 95% confidence interval 1.00-1.04, p = 0.02), whereas periventricular (N = 3813, odds ratio 1.08, 95% confidence interval 0.99-1.17, p = 0.07) and overall did not (N = 5876, odds ratio 1.12, 95% confidence interval 0.96-1.30, p = 0.14). Overall longitudinal analysis revealed a pooled odds ratio of 1.12 (N = 2015; 95% confidence interval 0.97-1.29; p = 0.13; Q = 7.19, p = 0.07; I2 = 58.3%). Longitudinal subgroup analyses revealed that overall white matter hyperintensities (N = 1882, odds ratio 1.22, 95% confidence interval, 1.06-1.4, p < 0.01) significantly associated with depression but deep did not (N = 660, odds ratio 2.02, 95% confidence interval, 0.56-7.22, p = 0.281). No significant heterogeneity was present in subgroup analyses. In conclusion, we found a significant, but weak association between white matter hyperintensities and depression.

Depression in the elderly: brain correlates, neuropsychological findings, and role of vascular lesion load

PURPOSE OF REVIEW

Late-life depression (LLD) presents in older adults as a heterogeneous mood disorder. Because of the diverse outcomes and symptomatology of LLD, several theories, especially the vascular depression hypothesis, have been proposed to identify its cause. This review outlines the features of LLD and explores the recent advances in characterizing this disorder through studies of brain functioning and cognition, with an emphasis on how vascular changes may mediate this disorder.

RECENT FINDINGS

LLD is associated with brain changes, including atrophy of hippocampus, independent of other neurodegenerative states. White matter lesions (WMLs) are frequently found in patients with LLD. Functional imaging has revealed both distinct characteristics of LLD and overlap of some cognitive symptoms with other dementias. Executive dysfunction and impaired processing speeds are at the core of the cognitive deficits in LLD and are associated with the development of WMLs in specific fiber tracts in the brain.

SUMMARY

LLD is associated with brain changes in both gray matter and white matter, including cerebrovascular changes, atrophy, and loss of myelin integrity. These brain changes are associated with age of onset of depression, as well as cumulative life-time depression burden, and can explain the increased dementia risk associated with LLD.

Vascular lesions and functional limitations among older adults: does depression make a difference?

ABSTRACT Background: The association between disability and depression is complex, with disability well established as a correlate and consequence of late life depression. Studies in community samples report that greater volumes of cerebral white matter hyperintensities (WMHs) seen on brain imaging are linked with functional impairment. These vascular changes are also associated with late life depression, but it is not known if depression is a modifier in the relationship between cerebrovascular changes and functional impairment. Methods: The study sample was 237 older adults diagnosed with major depression and 140 never depressed comparison adults, with both groups assessed at study enrollment. The dependent variable was the number of limitations in basic activities of daily living (ADL), instrumental ADLs, and mobility tasks. The independent variable was the total volume of cerebral white matter lesions or hyperintensities assessed though magnetic resonance imaging. Results: In analyses controlling for age, sex, race, high blood pressure, and cognitive status, a greater volume of WMH was positively associated with the total number of functional limitations as well as the number of mobility limitations among those older adults with late life depression but not among those never depressed, suggesting the association between WMH volume and functional status differs in the presence of late life depression. Conclusions: These findings suggest older patients with both depression and vascular risk factors may be at an increased risk for functional decline, and may benefit from management of both cerebrovascular risk factors and depression.

Cellular morphometry in late-life depression: a review of postmortem studies

The impact of major depression in late life is considerable and set to intensify with a worldwide shift in demographic profile toward an elderly population. Although the precise neurobiological mechanisms are not fully understood, a significant body of clinical, epidemiological, and imaging data have suggested divergent pathophysiological pathways underlie depression in late life, when compared with younger patients. Neuroimaging studies have demonstrated significant increases in white matter hyperintensities in late-life depression in several key areas involved in affective circuitry. Postmortem cellular morphometry studies have played a vital role in the identification of discrete changes in the brain microstructure in depression. This review draws together such postmortem studies, which have utilized tissue from younger/mixed age and late-life depressed patients. These findings have suggested varying neuronal and glial cell pathology in depression between different age cohorts. This age-related disparity may suggest different pathophysiological basis for depression, with vascular factors playing a potentially greater role in late life.

Differences in prefrontal, limbic, and white matter lesion volumes according to cognitive status in elderly patients with first-onset subsyndromal depression

The purpose of this preliminary study was to test the hypothesis that subsyndromal depression is associated with the volume of medial prefrontal regional gray matter and that of white matter lesions (WMLs) in the brains of cognitively normal older people. We also explored the relationships between subsyndromal depression and medial prefrontal regional gray matter volume, limbic regional gray matter volume, and lobar WMLs in the brains of patients with mild cognitive impairment (MCI) and Alzheimer's disease (AD). We performed a cross-sectional study comparing patients with subsyndromal depression and nondepressed controls with normal cognition (n = 59), MCI (n = 27), and AD (n = 27), adjusting for sex, age, years of education, and results of the Mini-Mental State Examination. Frontal WML volume was greater, and right medial orbitofrontal cortical volume was smaller in cognitively normal participants with subsyndromal depression than in those without subsyndromal depression. No volume differences were observed in medial prefrontal, limbic, or WML volumes according to the presence of subsyndromal depression in cognitively impaired patients. The absence of these changes in patients with MCI and AD suggests that brain changes associated with AD pathology may override the changes associated with subsyndromal depression.

Cognitive deficits in geriatric depression: clinical correlates and implications for current and future treatment

The purpose of this article is to identify the cognitive deficits commonly associated with geriatric depression and describe their clinical significance. The complex relationship between geriatric depression and dementia is summarized and possible shared mechanisms discussed. Evidence regarding whether the cognitive deficits in depression may be mitigated with medication or with computerized cognitive remediation is presented.

Executive dysfunction correlates with caudate nucleus atrophy in patients with white matter changes on MRI: a subset of LADIS

White matter changes (WMC) are common magnetic resonance imaging (MRI) findings, particularly in the elderly. Recent studies such as the Leukoaraiosis and Disability Study (LADIS) have found that WMC relate to adverse outcomes including cognitive impairment, depression, disability, unsteadiness and falls in cross-sectional and follow-up studies. Frontostriatal (or frontosubcortical) brain circuits may serve many of these functions, with the caudate nuclei playing a role in convergence of cognitive functions. This study aimed to determine whether reduced caudate volume relates to cognitive functions (executive functions, memory functions and speed of processing) and WMC. We determined caudate nuclei volumes, through manual tracing, on a subgroup of the LADIS study (n=66) from four centres with baseline and 3-year follow-up MRI scans. Regression analysis was used to assess relationships between caudate volume, cognitive function and WMC. Severity of WMC did not relate to caudate volume. Smaller caudate volumes were significantly associated with poorer executive functioning at baseline and at 3 years, but were not associated with scores of memory or speed of processing. Thus, in patients with WMC, a surrogate of small vessel disease, caudate atrophy relates to the dysexecutive syndrome, supporting the role of caudate as an important part of the frontostriatal circuit.

The effect of subsyndromal symptoms of depression and white matter lesions on disability for individuals with mild cognitive impairment

OBJECTIVE

To assess the effect of subsyndromal symptoms of depression (SSD) on ratings of disability for individuals with mild cognitive impairment (MCI).

METHODS

Data from 405 MCI participants from the Alzheimer's Disease Neuroimaging Initiative (ADNI) study were analyzed. Participants were evaluated at baseline and at 6-month intervals over 2 years. Severity of depressive symptoms was rated utilizing the Geriatric Depression Scale. Disability was assessed utilizing the Functional Assessment Questionnaire (FAQ). Other clinical variables included white matter lesion (WML) and intracranial brain (ICV) volumes derived from magnetic resonance imaging, ratings of overall cognitive function (Alzheimer's Disease Assessment Scale, ADAS), and apolipoprotein E (ApoE) status. Demographic variables included age, education, and gender.

RESULTS

SSD individuals had a lower volume of WML and higher frequency of ApoE ε4 alleles than nondepressed participants but the two groups did not differ with respect to other clinical or demographic variables. At baseline, SSD individuals were 1.77 times more likely to have poorer FAQ scores than individuals with no symptoms of depression after controlling for the effect of cognitive functioning, ICV, WML, and ApoE status. The presence of SSD at baseline was not associated with a poorer course of disability outcomes, cognitive functioning, or conversion to dementia over 24 months.

CONCLUSIONS

SSD demonstrated a significant impact on disability for MCI individuals, who are also at high risk for functional limitations related to neurodegenerative disease. Therefore, the treatment of SSD may represent a significant avenue to reduce the burden of disability in this vulnerable patient population.

The brain reward circuitry in mood disorders

Mood disorders are common and debilitating conditions characterized in part by profound deficits in reward-related behavioural domains. A recent literature has identified important structural and functional alterations within the brain's reward circuitry--particularly in the ventral tegmental area-nucleus accumbens pathway--that are associated with symptoms such as anhedonia and aberrant reward-associated perception and memory. This Review synthesizes recent data from human and rodent studies from which emerges a circuit-level framework for understanding reward deficits in depression. We also discuss some of the molecular and cellular underpinnings of this framework, ranging from adaptations in glutamatergic synapses and neurotrophic factors to transcriptional and epigenetic mechanisms.

A systematic review and meta-analysis of magnetic resonance imaging studies in late-life depression

Gray matter abnormalities within frontal-subcortical and limbic networks are hypothesized to play a key role in the pathophysiology of late-life depression. In this work, gray matter abnormalities in late-life depression are examined in a systematic review and meta-analysis of magnetic resonance imaging studies. In the systematic review, 27 articles were identified that compared participants with late-life depression with comparison group participants, and 17 studies were suitable for inclusion in meta-analyses of volumes of the whole brain, orbitofrontal cortex, caudate, hippocampus, putamen, and thalamus. Volume reductions were detected in 7 of 15 comparisons of the hippocampus and a meta-analysis revealed a significant, but small, effect size. Although examined by fewer studies, meta-analyses also revealed significant volume reductions in the orbitofrontal cortex, putamen, and thalamus. A more systematic and comprehensive analysis of the global distribution of gray matter abnormalities, and an examination of subcortical abnormalities were identified as key areas for future research.

Organic bases of late-life depression: a critical update

Late-life depression (LLD) is frequently associated with cognitive impairment and increases the risk of subsequent dementia. Cerebrovascular disease, deep white matter lesions, Alzheimer disease (AD) and dementia with Lewy bodies (DLB) have all been hypothesized to contribute to this increased risk, and a host of studies have looked at the interplay between cerebrovascular disease and LLD. This has resulted in new concepts of LLD, such as "vascular depression", but despite multiple magnetic resonance imaging (MRI) studies in this field, the relationship between structural changes in human brain and LLD is still controversial. While pathological findings of suicide in some elderly persons revealed multiple lacunes, small vessel cerebrovascular disease, AD-related lesions or multiple neurodegenerative pathologies, recent autopsy data challenged the role of subcortical lacunes and white matter lesions as major morphological substrates of depressive symptoms as well as poorer executive function and memory. Several neuropathological studies, including a personal clinico-pathological study in a small cohort of elderly persons with LLD and age-matched controls confirmed that lacunes, periventricular and deep white matter demyelination as well as AD-related lesions are usually unrelated to the occurrence of LLD. In the same line, neuropathological data show that early-onset depression is not associated with an acceleration of age-related neurodegenerative changes. Very recent data on the critical role of glia-modulating neuronal dysfunction and degeneration in depression are discussed.

Towards automated detection of depression from brain structural magnetic resonance images

INTRODUCTION

Depression is a major issue worldwide and is seen as a significant health problem. Stigma and patient denial, clinical experience, time limitations, and reliability of psychometrics are barriers to the clinical diagnoses of depression. Thus, the establishment of an automated system that could detect such abnormalities would assist medical experts in their decision-making process. This paper reviews existing methods for the automated detection of depression from brain structural magnetic resonance images (sMRI).

METHODS

Relevant sources were identified from various databases and online sites using a combination of keywords and terms including depression, major depressive disorder, detection, classification, and MRI databases. Reference lists of chosen articles were further reviewed for associated publications.

RESULTS

The paper introduces a generic structure for representing and describing the methods developed for the detection of depression from sMRI of the brain. It consists of a number of components including acquisition and preprocessing, feature extraction, feature selection, and classification.

CONCLUSION

Automated sMRI-based detection methods have the potential to provide an objective measure of depression, hence improving the confidence level in the diagnosis and prognosis of depression.

Meta-analysis of volumetric abnormalities in cortico-striatal-pallidal-thalamic circuits in major depressive disorder

BACKGROUND

Abnormalities in cortico-striatal-pallidal-thalamic (CSPT) circuits have been implicated in major depressive disorder (MDD). However, the robustness of these findings across studies is unclear, as is the extent to which they are influenced by demographic, clinical and pharmacological factors.

METHOD

With the aim of clarifying these questions, we conducted a meta-analysis to map the volumetric abnormalities that were most robustly identified in CSPT circuits of individuals with MDD. A systematic search identified 41 studies meeting our inclusion criteria.

RESULTS

There were significant volume reductions in prefrontal (especially orbitofrontal) and anterior cingulate cortices, and also in subcortical structures such as the caudate nucleus and putamen, with effect sizes ranging from small to moderate. The subgenual anterior cingulate and orbitofrontal cortices were significantly smaller in antidepressant-free samples compared to medicated patients. Late-life depression (LLD) tended to be associated with smaller volumes in circumscribed frontal and subcortical structures, with the most robust differences being found in thalamic volume.

CONCLUSIONS

Individuals with major depression demonstrate volumetric abnormalities of CSPT circuits. However, these observations may be restricted to certain subgroups, highlighting the clinical heterogeneity of the disorder. On the basis of this meta-analysis, CSPT abnormalities were more prominent in those with LLD whereas antidepressant use seemed to normalize certain cortical volumetric abnormalities.

Magnetic resonance imaging studies in unipolar depression: systematic review and meta-regression analyses

Previous meta-analyses of structural MRI studies have shown diffuse cortical and sub-cortical abnormalities in unipolar depression. However, the presence of duplicate publications, recruitment of particular age groups and the selection of specific regions of interest means that there is uncertainty about the balance of current research. Moreover, the lack of systematic exploration of highly significant heterogeneity has prevented the generalisability of finding. A systematic review and random-effects meta-analysis was carried out to estimate effect sizes. Possible publication bias, and the impact of various study design characteristics on the magnitude of the observed effect size were systematically explored. The aim of this study was 1) to include structural MRI studies systematically comparing unipolar depression with bipolar disorder and healthy volunteers; 2) to consider all available structures of interest without specific age limits, avoiding data duplication, and 3) to explore the influence of factors contributing to the measured effect sizes systematically with meta-regression analyses. Unipolar depression was characterised by reduced brain volume in areas involved in emotional processing, including the frontal cortex, orbitofrontal cortex, cingulate cortex, hippocampus and striatum. There was also evidence of pituitary enlargement and an excess of white matter hyperintensity volume in unipolar depression. Factors which influenced the magnitude of the observed effect sizes were differences in methods, clinical variables, pharmacological interventions and sample age.

Relationship of orthostatic blood pressure to white matter hyperintensities and subcortical volumes in late-life depression

BACKGROUND

Structural brain abnormalities are associated with late-life major depression, with numerous studies reporting increased white matter hyperintensities (WMH) and reduced cortical/subcortical grey matter volumes. There is strong evidence linking vascular disease to WMH, but limited evidence on its association with subcortical volumes.

AIMS

To investigate the relationship of orthostatic blood pressure changes to WMH and subcortical grey matter volumes in late-life depression.

METHOD

Thirty-eight people with depression and a similarly aged comparison group (n = 30) underwent fluid attenuated inversion recovery (FLAIR) and T(1)-weighted magnetic resonance imaging as well as systematic orthostatic blood pressure assessments. Volumetric estimates of WMH and subcortical grey matter were obtained for each participant and the relationship to blood pressure drop on active stand was examined.

RESULTS

An association between orthostatic systolic blood pressure drop and WMH volumes in temporal and parietal regions was found in the depression group (age-corrected partial correlation r' = 0.31-0.35, P<0.05). Subcortical volumes were not related to blood pressure changes or WMH volumes in either group.

CONCLUSIONS

We found evidence for an association between the degree of orthostatic systolic blood pressure drop and WMH volume in the depression group. Since blood pressure drops lead to WMH in animals our findings suggest systolic blood pressure drops may be a factor contributing to these lesions in late-life depression.

MRI-defined vascular depression: a review of the construct

OBJECTIVE

To review the construct of MRI-defined vascular depression and to examine the substantive and methodological issues that bear on its validity as a distinct subtype of depression in late life.

DESIGN

Literature review.

RESULTS

We identified three areas that are critical to establishing the validity of MRI-defined vascular depression: (1) understanding and delineating the relationship between MRI hyperintensities, executive dysfunction, and antidepressant treatment outcome; (2) understanding the relationship between, and establishing the validity of, qualitative and quantitative approaches to the measurement of MRI hyperintensities (the primary feature of the proposed subtype); (3) establishing the clinical presentation and course of the subtype in the context of other late-life disorders.

CONCLUSIONS

Despite considerable data supporting the validity of MRI-defined vascular depression, there are a number of critical issues that remain, including establishing a causal relationship between cerebrovascular disease and late-life depression, establishing consistent diagnostic criteria, determining the importance of lesion type and location, and understanding the course of the disorder.

Abnormal functional connectivity in patients with vascular cognitive impairment, no dementia: a resting-state functional magnetic resonance imaging study

The functional connectivity (FC) method was used to investigate the changes in the resting state of patients with vascular cognitive impairment, no dementia (VCIND). Resting-state functional magnetic resonance images (fMRIs) were acquired from 16 patients with subcortical ischemic vascular disease (SIVD) who fulfilled the criteria for VCIND, as well as 18 age- and sex-matched subjects with SIVD with no cognitive impairment (control group). Posterior cingulate cortex connectivity was gathered by investigating synchronic low-frequency fMRI signal fluctuations with a temporal correlation method. Compared with the control group, the patients showed FC decrease in the left middle temporal gyrus, the left anterior cingulate/left middle frontal gyrus, the right caudate, the right middle frontal gyrus, and the left medial frontal gyrus/paracentral lobule. There were also some regions that showed increased connectivity. These regions included the right inferior temporal gyrus, the left middle temporal gyrus, the left precentral gyrus, and the left superior parietal lobule. Our findings revealed the change in resting-state patterns of neuronal activity in patients with VCIND. This change may be caused by subcortical white matter lesions that destroyed direct and indirect fiber tract connectivity across the cerebral white matter and influenced the cortical FC and hypoperfusion resulted from small vascular disease. The results of the increased connectivity may be evoked by the compensatory recruitment and plasticity mechanism. Our findings suggest that the simplicity and noninvasiveness of this method makes it a potential tool to help thoroughly understand the pathogenesis of VCIND.

Morphometric analysis of neuronal and glial cell pathology in the caudate nucleus in late-life depression

OBJECTIVE

To assess glial and neuronal density and neuronal volume in two areas of the caudate nucleus in late-life major depression.

DESIGN

A postmortem study using the disector and nucleator methods to estimate neuronal density and volume and glial density of cells from human brain tissue from the anterior portion (dorsolateral and ventromedial aspects) of the caudate nucleus.

SETTING

Brain tissues were obtained from the Newcastle Brain Tissue Resource at Newcastle University, UK.

PARTICIPANTS

The study group consisted of 13 subjects with late-life major depression and nine comparison subjects of similar age.

RESULTS

Evidence of moderate reductions in neuronal density was found in the depressed group in both the dorsolateral and ventromedial areas of the caudate nucleus. There were no significant changes in glial density or neuronal volume in either area nor was there any evidence of differences in depression in early and late-onset subgroups.

CONCLUSIONS

Neuroimaging abnormalities in frontal and subcortical areas including ischemic hyperintensities and a reduction in volume and metabolism in the caudate nucleus have been reported in late-life depression, and previous morphometric studies have reported neuronal changes in prefrontal cortical areas. The findings in this study extend these morphometric investigations in late-life depression to the caudate nucleus, suggesting that neuronal abnormalities are present in this subcortical nucleus as well as in these related prefrontal areas.

The vascular depression hypothesis: an update

Since being proposed as a unique subtype of late-life depression (LLD), the vascular depression hypothesis has received considerable research attention. Although this effort has generated considerable empirical support for the validity of the subtype, fundamental questions remain including how the illness is defined, whether cerebrovascular disease and executive dysfunction (ED) define two separate entities or one underlying subtype, and whether ED is responsible for poor response to antidepressant treatment. In this guest editorial, we explore these and other issues (i.e., the role of personality and social support, psychosocial treatments targeting cognitive abilities frequently impaired in LLD) using a number of important papers that are either directly or indirectly related to the vascular depression hypothesis. In so doing we highlight a range of critical problems facing the vascular depression hypothesis and the effort to establish the illness as a unique diagnostic entity in late-life.

Functional connectivity in late-life depression using resting-state functional magnetic resonance imaging

OBJECTIVE

To investigate whether there are differences in brain connectivity in late-life depression (LLD) and nondepressed subjects using the left and right heads of caudate nuclei (hCN) as the seed regions.

DESIGN

Resting-state functional magnetic resonance imaging (fMRI) data were collected using a 3-Tesla MRI System.

SETTING

Subjects were recruited from primary or secondary care services in the Newcastle area.

PARTICIPANTS

Thirty-three subjects aged 65 years and older; 16 who had a recent episode of LLD and 17 nondepressed subjects.

MEASUREMENTS

Functional connectivity was analyzed by extracting the temporal signal variation from the left and right hCN and cross correlating with the rest of the brain.

RESULTS

Significant connectivity between the hCN and frontal areas was observed in the nondepressed group, whereas in LLD, connectivity was seen over a much wider area. Regions showing significantly greater connectivity (p < or =0.05) in LLD compared with the nondepressed group were frontal (precentral, subgyral, middle frontal, and paracentral lobule), sublobar (thalamus and insula), limbic (cingulate), parietal (postcentral gyrus, precuneus, inferior parietal lobule, and supramarginal gyrus), and temporal (superior temporal gyrus). Conversely, no brain regions showed greater connectivity in the nondepressed group than LLD. In both groups, the right hCN showed significantly greater connectivity than the left in numerous brain regions, but connectivity for the left hCN did not exceed the right in any brain regions.

CONCLUSIONS

This resting-state study showed increased connectivity in specific brain regions in LLD compared with the nondepressed group, which supports the view that functional connectivity is altered in depression.

Increased neural response to fear in patients recovered from depression: a 3T functional magnetic resonance imaging study

BACKGROUND

Previous imaging studies have revealed that acute major depression is characterized by altered neural responses to negative emotional stimuli. Typically, responses in limbic regions such as the amygdala are increased while activity in cortical regulatory regions such as the dorsolateral prefrontal cortex (DLPFC) is diminished. Whether these changes persist in unmedicated recovered patients is unclear.

METHOD

We used functional magnetic resonance imaging to examine neural responses to emotional faces in a facial expression-matching task in 16 unmedicated recovered depressed patients and 21 healthy controls.

RESULTS

Compared with controls, recovered depressed patients had increased responses bilaterally to fearful faces in the DLPFC and right caudate. Responses in the amygdala did not distinguish the groups.

CONCLUSIONS

Our findings indicate that clinical recovery from depression is associated with increased activity in the DLPFC to negative emotional stimuli. We suggest that this increase may reflect a compensatory cortical control mechanism with the effect of limiting emotional dysregulation in limbic regions such as the amygdala.

Brain volume abnormalities in major depressive disorder: a meta-analysis of magnetic resonance imaging studies

OBJECTIVE

So far, there have been no attempts to integrate the growing number of all brain volumetric magnetic resonance imaging studies in depression. In this comprehensive meta-analysis the magnitude and extent of brain volume differences between 2,418 patients with major depressive disorder and 1,974 healthy individuals from 64 studies was determined.

METHODS

A systematic research was conducted for volumetric magnetic resonance imaging studies of patients with major depressive disorder in relation to healthy control subjects. Studies had to report sufficient data for computation of effect sizes. For each study, the Cohen's d was calculated. All analyses were performed using the random effects model. Additionally, meta-regression analyses were done to explore the effects of potential sources of heterogeneity.

RESULTS

Patients showed large volume reductions in frontal regions, especially in the anterior cingulate and orbitofrontal cortex with smaller reductions in the prefrontal cortex. The hippocampus, the putamen and caudate nucleus showed moderate volume reductions.

CONCLUSIONS

This is the first comprehensive meta-analysis in major depressive disorder demonstrating structural brain abnormalities, particularly in those brain areas that are involved in emotion processing and stress-regulation.

Imaging phenotypes of major depressive disorder: genetic correlates

Imaging techniques are a potentially powerful method of identifying phenotypes that are associated with, or are indicative of, a vulnerability to developing major depressive disorder (MDD). Here we identify seven promising MDD-associated traits identified by magnetic resonance imaging (MRI) or positron emission tomography (PET). We evaluate whether these traits are state-independent, heritable endophenotypes, or state-dependent phenotypes that may be useful markers of treatment efficacy. In MDD, increased activity of the amygdala in response to negative stimuli appears to be a mood-congruent phenomenon, and is likely moderated by the 5-HT transporter gene (SLC6A4) promoter polymorphism (5-HTTLPR). Hippocampal volume loss is characteristic of elderly or chronically-ill samples and may be impacted by the val66met brain-derived neurotrophic factor (BDNF) gene variant and the 5-HTTLPR SLC6A4 polymorphism. White matter pathology is salient in elderly MDD cohorts but is associated with cerebrovascular disease, and is unlikely to be a useful marker of a latent MDD diathesis. Increased blood flow or metabolism of the subgenual anterior cingulate cortex (sgACC), together with gray matter volume loss in this region, is a well-replicated finding in MDD. An attenuation of the usual pattern of fronto-limbic connectivity, particularly a decreased temporal correlation in amygdala-anterior cingulate cortex (ACC) activity, is another MDD-associated trait. Concerning neuroreceptor PET imaging, decreased 5-HT(1A) binding potential in the raphe, medial temporal lobe, and medial prefrontal cortex (mPFC) has been strongly associated with MDD, and may be impacted by a functional single nucleotide polymorphism in the promoter region of the 5-HT(1A) gene (HTR1A: -1019 C/G; rs6295). Potentially indicative of inter-study variation in MDD etiology or mood state, both increased and decreased binding potential of the 5-HT transporter has been reported. Challenges facing the field include the problem of phenotypic and etiological heterogeneity, technological limitations, the confounding effects of medication, and non-disease related inter-individual variation in brain morphology and function. Further advances are likely as epigenetic, copy-number variant, gene-gene interaction, and genome-wide association (GWA) approaches are brought to bear on imaging data.

Caudate nucleus volumes in stroke and vascular dementia

We aimed to assess the volume of the nucleus caudatus as a neuroanatomical substrate of fronto-subcortical circuits, in stroke patients with/without dementia, and the relationship to potential determinants of neural circuit integrity such as white matter hyperintensities (WMH) and stroke volume. Stroke only (Stroke) (n=19) and stroke with Vascular Dementia (VaD) (n=16) and healthy control (n=20) subjects, matched on demographic variables, underwent extensive neuropsychiatric assessments and manual MRI-based volumetric measurements for intracranial area (ICA), stroke volume, and bilateral caudate volume. WMH on MRI were quantified using an automated algorithm. Multivariate analysis of covariance (controlling for age and ICA), revealed that across the three groups, caudate volumes were significantly different. There was a significant difference in bilateral caudate nucleus volume between subjects by diagnosis (Stroke, VaD, control). The control group was largest in overall mean volume of the diagnostic groups, followed by the Stroke group (86% of controls), and finally, the VaD group (72%). There was a partial correlation between total caudate volume and the total volume of deep WMH including periventricular regions and brainstem, controlling for ICA; and for total stroke volume. Stroke patients with VaD have smaller caudate nuclei compared to those without dementia and healthy controls, with the stroke-only patients being intermediate in their caudate volume status. There was preliminary evidence of negative correlation of caudate volume with volume of deep WMH and total stroke volume, suggesting cerebrovascular disease contributes to caudate atrophy,which, in turn may disrupt fronto-subcortical circuits.

Assessment of depression in three medically ill, elderly populations: Alzheimer's disease, Parkinson's disease, and stroke

Prevalence rates of depression in medically ill elderly people are strikingly high. In particular, the prevalences of depression at any given time in Alzheimer's, Parkinson's, and stroke are as high as 87%, 75%, and 79%, respectively. Proper detection and management of depression in primary care is imperative. The present review examines the risk factors, peculiarities, and etiologies of depression in these populations. We suggest that certain features of depression be considered in assessing depression in these populations and provide guidelines for distinguishing depression from medical, psychosocial, and physical complaints common in elderly people. Additionally, we explore the use of self-report instruments of depression and provide guidelines regarding the specific measures and cutoffs most appropriate for use with these populations. To this end, we hope that readers acquire a greater appreciation for the experience of depression of those suffering from these neurological disorders to aid in their assessment.

Caudate volumes in public transportation workers exposed to trauma in the Stockholm train system

The caudate nucleus is a structure implicated in the neural circuitry of psychological responses to trauma. This study aimed to quantify the volume of the caudate in persons exposed to trauma. Thirty-six subjects under 65 were recruited from transport workers in Stockholm who reported having been unintentionally responsible for a person-under-the-train accident or among employees having experienced an assault in their work (1999-2001) between 3 months and 6 years before MRI scanning. In those exposed to the trauma, a DSM-IV diagnosis of post-traumatic stress disorder (PTSD) was made by an independent psychiatrist, with subjects being classified as PTSD or no PTSD. MRI data were analyzed blindly to all clinical information by an experienced rater using a standardized manual tracing protocol to quantify the volume of the caudate. Within-group comparisons of PTSD (n=19) and no PTSD (n=17) found the right caudate nucleus to be significantly (9%) larger than the left: a right hemisphere baseline asymmetry. A multivariate analysis of covariance (MANCOVA) was conducted to assess the volume of the caudate nucleus (right and left) in relation to the diagnosis of no PTSD (n=17) or PTSD (n=19). After adjustment for the covariates (age, sex, intracranial volume, years since trauma, and number of trauma episodes), there was a significant difference in raw right caudate nucleus volume between subjects with PTSD compared with those without PTSD. Volume of the left caudate nucleus was not significantly different between the PTSD and no PTSD groups. The right caudate volume in the PTSD group was 9% greater compared with the no PTSD group. There is a larger right hemisphere volume of the caudate within those exposed to trauma with active PTSD compared with those without PTSD, superimposed upon a baseline caudate asymmetry.

Bipolar and major depressive disorder: neuroimaging the developmental-degenerative divide

Both major depressive disorder and bipolar disorder are the subject of a voluminous imaging and genetics literature. Here, we attempt a comprehensive review of MRI and metabolic PET studies conducted to date on these two disorders, and interpret our findings from the perspective of developmental and degenerative models of illness. Elevated activity and volume loss of the hippocampus, orbital and ventral prefrontal cortex are recurrent themes in the literature. In contrast, dorsal aspects of the PFC tend to display hypometabolism. Ventriculomegaly and white matter hyperintensities are intimately associated with depression in elderly populations and likely have a vascular origin. Important confounding influences are medication, phenotypic and genetic heterogeneity, and technological limitations. We suggest that environmental stress and genetic risk variants interact with each other in a complex manner to alter neural circuitry and precipitate illness. Imaging genetic approaches hold out promise for advancing our understanding of affective illness.

Three-dimensional surface mapping of the caudate nucleus in late-life depression

OBJECTIVE

To compare the volumes of the caudate nucleus, using traditional volumetry and a three-dimensional brain mapping technique, in a group of individuals with late-life depression and a group of age- and education-equated nondepressed comparison subjects.

DESIGN

Cross-sectional.

SETTING

University Medical Center.

PARTICIPANTS

Twenty-three nondemented subjects with late-life depression and 15 age- and education-equated elderly comparison subjects (depressed mean years of age: 70.5 +/- 5.7 SD, comparison subjects = 69.9 years +/- 6.4) with no history of psychiatric or neurologic disease.

MEASUREMENTS

Structural magnetic resonance imaging. Three-dimensional (3-D) surface models were created from manually traced outlines of the caudate nucleus from spoiled gradient echo images. Models were geometrically averaged across subjects and statistical maps created to localize any regional volume differences between groups.

RESULTS

Relative to comparison subjects, depressed subjects had significantly lower mean volumes for both the left (p = 0.029) and right (p = 0.052) caudate nucleus as well as total caudate volume (p = 0.032). Total volumes were 13.1% less in the depressed group (13.5% on the left and 12.6% on the right). 3-D maps further localized these reductions to the caudate head. Volume reductions were correlated with depression severity, as measured by the 17-item Hamilton Depression Rating Scale.

CONCLUSION

Late-life depression is associated with left and right caudate nucleus reduction especially in anterior portions. Among depressed subjects, greater caudate reduction was associated with more severe depression. These results are consistent with growing evidence that the anterior caudate nucleus, especially the head, may be structurally and functionally abnormal in affective disorders.

Anterior cingulate dysfunction in geriatric depression

BACKGROUND

Although several brain abnormalities have been identified in geriatric depression, their relationship to the pathophysiological mechanisms leading to the development and perpetuation of this syndrome remain unclear.

METHODS

This paper reviews findings on the anterior cingulate cortex (ACC) function and on the relationship of ACC abnormalities to the clinical presentation and the course of geriatric depression in order to elucidate the pathophysiological role of ACC in this disorder.

RESULTS

The ACC is responsible for conflict detection and emotional evaluation of error and is connected to brain structures that regulate mood, emotional valence of thought and autonomic and visceral responses, which are functions disturbed in depression. Geriatric depression often is accompanied by abnormalities in some executive functions and has a clinical presentation consistent with ACC abnormalities. Indices of ACC dysfunction are associated with adverse outcomes of geriatric depression.

CONCLUSIONS

Converging findings suggest that at least some ACC functions are abnormal in depression and these abnormalities are pathophysiologically meaningful. Indices of ACC dysfunction may be used to identify subgroups of depressed elderly patients with distinct illness course and treatment needs and serve as the theoretical background for novel treatment development.