Depression in small-vessel disease relates to white matter ultrastructural damage, not disability

Vascular depression: A comprehensive exploration of the definition, mechanisms, and clinical challenges

Vascular depression (VaDep), which was proposed over two decades ago, is a distinct subtype of depression primarily observed in patients with stroke and cerebral small-vessel disease and is characterized by white matter hyperintensities; however, the lack of standardized diagnostic criteria and consensus limits its clinical application. This review explores the pathological conditions and vascular risk factors that may precipitate VaDep, particularly in relation to stroke and cerebral small-vessel disease. VaDep is distinguished by unique pathophysiological mechanisms and treatment responses. We categorize these mechanisms into three groups: 1) macroscopic mechanisms, including vascular aging, cerebral hypoperfusion, blood-brain barrier disruption, and neural circuit dysfunction; 2) microscopic mechanisms, involving the inflammatory response, hypothalamic-pituitary-adrenal axis dysregulation, impaired monoamine synthesis, and mitochondrial dysfunction; and 3) undetermined mechanisms, such as microbiota-gut-brain axis dysbiosis. These insights support VaDep as a distinct depression subtype, differentiating it from late-life depression and major depressive disorder. Treatment is challenging, as patients with VaDep often exhibit resistance to conventional antidepressants. Addressing vascular risk factors and protecting vascular integrity are essential for effective management. Future research should validate these mechanisms and develop novel diagnostic and therapeutic approaches to improve VaDep outcomes.

Prevalence of Fatigue and Associations With Depression and Cognitive Impairment in Patients With CADASIL

BACKGROUND AND OBJECTIVES

Fatigue is a common and disabling symptom in cerebrovascular disease and has been associated with white matter damage, but the underlying disease mechanisms are poorly understood. Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is the most common genetic form of stroke and causes a cerebral small vessel disease arteriopathy with white matter ischemia. We determined the prevalence of fatigue in CADASIL, the factors associated with it, and its relationship with both depression and cognitive impairment.

METHODS

Prospectively recruited genetically confirmed patients with CADASIL were assessed using the Fatigue Severity Scale. The prevalence of fatigue in CADASIL was compared with that of healthy controls from the community. We determined associations between fatigue and clinical features, cardiovascular risk factors, MRI parameters, cognition, and depression. Cognition was measured using the Brief Memory and Executive Test (BMET) and depression using the Geriatric Depression Scale (GDS). Mediation and path analyses were performed to determine relationships between fatigue, depression, and cognitive impairment.

RESULTS

One hundred seventy-four patients with CADASIL (mean age [SD] of 51.3 [12.30] years, 59.66% female) and 50 healthy controls were included in the analysis (mean age [SD] of 51.42 [12.58] years, 38.0% female). Fatigue was present in 51.7% of patients with CADASIL and was almost 5 times more common than in controls (OR: 4.99, 95% CI [2.28-10.95], p < 0.001). There was no association of fatigue with history of stroke or MRI parameters including white matter hyperintensity lesion volume. Logistic regression showed both GDS total score (OR: 1.11 [1.05-1.17], p = 0.0002) and BMET total score (OR: 0.86 [0.75-0.98], p = 0.02) to be predictors of fatigue. Fatigue, depression, and cognition were frequently comorbid. Mediation analysis showed depression to have a greater effect on fatigue prevalence than cognitive impairment. Path analysis confirmed depression to be the largest predictor of fatigue and found this relationship to be bidirectional.

DISCUSSION

Fatigue was present in over half of the patients with CADASIL. Depression and cognition were the main predictors of fatigue, and all 3 symptoms were frequently comorbid. The relationship between depression and fatigue was the strongest and was bidirectional. This suggests targeting depressive symptoms may have benefit in fatigue management.

Age matters when improving symptoms of anxiety, depression, and sleepiness in patients with obstructive sleep apnea treated with continuous positive airway pressure

Obstructive sleep apnea (OSA) is a prevalent sleep disorder linked to significant daytime sleepiness and mood disturbances. Continuous positive airway pressure (CPAP) therapy is the standard treatment for OSA, but its effects on mental health outcomes, are not well understood. This study aimed to evaluate the impact of CPAP on daytime sleepiness, depressive symptoms, and anxiety symptoms while assessing how improvements vary with age. A total of 98 participants diagnosed with OSA were included in this study. Pretreatment and posttreatment scores for daytime sleepiness [Epworth Sleepiness Scale (ESS)], depression [Patient Health Questionnaire (PHQ)], and anxiety [Generalized Anxiety Disorder (GAD)] were collected. Improvements were calculated as the difference between pretreatment and posttreatment scores. Age, sex, ethnicity, apnea-hypopnea index, and CPAP compliance, were analyzed. Significant improvements were observed across all age groups after CPAP treatment: ESS scores improved by a mean of 5.6 points (P < 0.001), PHQ scores improved by 6.3 points (P < 0.001), and GAD scores improved by 1.1 points (P = 0.002). CPAP therapy effectively reduced daytime sleepiness, depression, and anxiety in patients with OSA, with significant age-related differences in outcomes. Younger individuals benefited most from treatment.

Vascular risk, gait, behavioral, and plasma indicators of VCID

INTRODUCTION

Cost-effective screening tools for vascular contributions to cognitive impairment and dementia (VCID) has significant implications. We evaluated non-imaging indicators of VCID using magnetic resonance imaging (MRI)-measured white matter (WM) damage and hypothesized that these indicators differ based on age.

METHODS

In 745 participants from the Mayo Clinic Study of Aging (≥50 years of age) with serial WM assessments from diffusion MRI and fluid-attenuated inversion recovery (FLAIR)-MRI, we examined associations between baseline non-imaging indicators (demographics, vascular risk factors [VRFs], gait, behavioral, plasma glial fibrillary acidic protein [GFAP], and plasma neurofilament light chain [NfL]) and WM damage across three age tertiles.

RESULTS

VRFs and gait were associated with diffusion changes even in low age strata. All measures (VRFs, gait, behavioral, plasma GFAP, plasma NfL) were associated with white matter hyperintensities (WMHs) but mainly in intermediate and high age strata.

DISCUSSION

Non-imaging indicators of VCID were related to WM damage and may aid in screening participants and assessing outcomes for VCID.

HIGHLIGHTS

Non-imaging indicators of VCID can aid in prediction of MRI-measured WM damage but their importance differed by age. Vascular risk and gait measures were associated with early VCID changes measured using diffusion MRI. Plasma markers explained variability in WMH across age strata. Most non-imaging measures explained variability in WMH and vascular WM scores in intermediate and older age groups. The framework developed here can be used to evaluate new non-imaging VCID indicators proposed in the future.

Characteristic patterns of functional connectivity-mediated cerebral small vessel disease-related cognitive impairment and depression

Cerebral small vessel disease is common in most individuals aged 60 years or older, and it is associated with cognitive dysfunction, depression, anxiety disorder, and mobility problems. Currently, many cerebral small vessel disease patients have both cognitive impairment and depressive symptoms, but the relationship between the 2 is unclear. The present research combined static and dynamic functional network connectivity methods to explore the patterns of functional networks in cerebral small vessel disease individuals with cognitive impairment and depression (cerebral small vessel disease-mild cognitive impairment with depression) and their relationship. We found specific functional network patterns in the cerebral small vessel disease-mild cognitive impairment with depression individuals (P < 0.05). The cerebral small vessel disease individuals with depression exhibited unstable dynamic functional network connectivity states (transitions likelihood: P = 0.040). In addition, we found that the connections within the lateral visual network between the sensorimotor network and ventral attention network could mediate white matter hyperintensity-related cognitive impairment (indirect effect: 0.064; 95% CI: 0.003, 0.170) and depression (indirect effect: -0.415; 95% CI: -1.080, -0.011). Cognitive function can negatively regulate white matter hyperintensity-related depression. These findings elucidate the association between cognitive impairment and depression and provide new insights into the underlying mechanism of cerebral small vessel disease-related cognitive dysfunction and depression.

Vascular risk factors, white matter microstructure, and depressive symptoms: a longitudinal analysis in the UK Biobank

BACKGROUND

Cumulative burden from vascular risk factors (VRFs) has been associated with an increased risk of depressive symptoms in mid- and later life. It has been hypothesised that this association arises because VRFs disconnect fronto-subcortical white matter tracts involved in mood regulation, which puts older adults at higher risk of developing depressive symptoms. However, evidence for the hypothesis that disconnection of white matter tracts underlies the association between VRF burden and depressive symptoms from longitudinal studies is scarce.

METHODS

This preregistered study analysed longitudinal data from 6,964 middle-aged and older adults from the UK Biobank who participated in consecutive assessments of VRFs, brain imaging, and depressive symptoms. Using mediation modelling, we directly tested to what extend white matter microstructure mediates the longitudinal association between VRF burden and depressive symptoms.

RESULTS

VRF burden showed a small association with depressive symptoms at follow-up. However, there was no evidence that fractional anisotropy (FA) of white matter tracts mediated this association. Additional analyses also yielded no mediating effects using alternative operationalisations of VRF burden, mean diffusivity (MD) of single tracts, or overall average of tract-based white matter microstructure (global FA, global MD, white matter hyperintensity volume).

CONCLUSIONS

Our results lend no support to the hypothesis that disconnection of white matter tracts underlies the association between VRF burden and depressive symptoms, while highlighting the relevance of using longitudinal data to directly test pathways linking vascular and mental health.

Is later-life depression a risk factor for Alzheimer's disease or a prodromal symptom: a study using post-mortem human brain tissue?

BACKGROUND

Depression and dementia are both common diseases. Although new cases of depression are more common in younger adults, there is a second peak at the age of 50 years suggesting a different pathological process. Late-life depression (LLD) is associated with dementia. However, it remains unclear whether depression represents a dementia prodrome or is a true risk factor for its development. LLD is thought to have a vascular component and this may be a possible link between depression and dementia. We hypothesised that later-life depression is a prodromal manifestation of dementia and would therefore be associated with more AD, and/or ischaemic brain abnormalities that are present in earlier-life depression or in age- and sex-matched controls.

METHODS

We assessed post-mortem orbitofrontal cortex and dorsolateral pre-frontal cortex from 145 individuals in 4 groups: 28 18-50-year-olds with depression, 30 older individuals (ages 51-90) with depression, 28 with early AD (Braak tangle stages III-IV) and 57 matched controls (17 early-life, 42 later-life). Levels of Aβ, phospho-tau and α-synuclein were assessed by immunohistochemistry and ELISA. To quantify chronic ischaemia, VEGF, MAG and PLP1 were measured by ELISA. To assess pericyte damage, PDGFRB was measured by ELISA. For blood-brain barrier leakiness, JAM-A, claudin 5 and fibrinogen were measured by ELISA. To quantity endothelial activation, the ratio of ICAM1:collagen IV was assessed by immunohistochemistry.

RESULTS

There was no evidence of chronic cerebral hypoperfusion or increased Aβ/tau in either depression group. There was also no indication of pericyte damage, increased blood-brain barrier leakiness or endothelial activation in the OFC or DLPFC in the depression groups.

CONCLUSIONS

Contrary to some previous findings, we have not found evidence of impaired vascular function or increased Aβ in LLD. Our study had a relatively small sample size and limitations in the availability of clinical data. These results suggest that depression is a risk factor for dementia rather than an early manifestation of AD or a consequence of cerebral vascular insufficiency.

Associations of neuroimaging markers with depressive symptoms over time in middle-aged and elderly persons

BACKGROUND

Cerebrovascular disease is regarded as a potential cause of late-life depression. Yet, evidence for associations of neuroimaging markers of vascular brain disease with depressive symptoms is inconclusive. We examined the associations of neuroimaging markers and depressive symptoms in a large population-based study of middle-aged and elderly persons over time.

METHODS

A total of 4943 participants (mean age = 64.6 ± 11.1 years, 55.7% women) from the Rotterdam Study were included. At baseline, total brain volume, gray matter volume, white matter volume, white matter hyperintensities volume, cortical infarcts, lacunar infarcts, microbleeds, white matter fractional anisotropy, and mean diffusivity (MD) were measured with a brain MRI (1.5T). Depressive symptoms were assessed twice with the Center for Epidemiologic Studies Depression scale (median follow-up time: 5.5 years, IQR = 0.9). To assess temporal associations of neuroimaging markers and depressive symptoms, linear mixed models were used.

RESULTS

A smaller total brain volume (β = -0.107, 95% CI -0.192 to -0.022), larger white matter hyperintensities volume (β = 0.047, 95% CI 0.010-0.084), presence of cortical infarcts (β = 0.194, 95% CI 0.047-0.341), and higher MD levels (β = 0.060, 95% CI 0.022-0.098) were cross-sectionally associated with more depressive symptoms. Longitudinal analyses showed that small total brain volume (β = -0.091, 95% CI -0.167 to -0.015) and presence of cortical infarcts (β = 0.168, 95% CI 0.022-0.314) were associated with increasing depressive symptoms over time. After stratification on age, effect sizes were more pronounced at older ages.

CONCLUSIONS

Neuroimaging markers of white matter microstructural damage were associated with depressive symptoms longitudinally in this study of middle-aged and elderly persons. These associations were more pronounced at older ages, providing evidence for the role of white matter structure in late-life depressive symptomatology.

A new nomogram including total cerebral small vessel disease burden for individualized prediction of early-onset depression in patients with acute ischemic stroke

Objectives

The present study was designed to evaluate the effects of total cerebral small vessel disease (CSVD) on early-onset depression after acute ischemic stroke (AIS), and to develop a new nomogram including total CSVD burden to predict early-onset post-stroke depression (PSD).

Methods

We continuously enrolled patients with AIS who were hospitalized at the First Affiliated Hospital of Soochow University between October 2017 and June 2019. All patients were assessed for depressive symptoms using the 17-item Hamilton Depression Scale (HAMD-17) at 14 ± 2 days after the onset of AIS. The diagnosis for depression was made according to the American Diagnostic and Statistical Manual of Mental Disorders Version 5 (DSM-5). The demographic and clinical data were collected including total CSVD burden. On the basis of a multivariate logistic model, the independent factors of early-onset PSD were identified and the predictive nomogram was generated. The performance of the nomogram was evaluated by Harrell's concordance index (C-index) and calibration plot.

Results

A total of 346 patients were enrolled. When contrasted to a 0 score of total CSVD burden, the score ≥2 (moderate to severe total CSVD burden) was an independent risk factor for early-onset PSD. Besides, gender, cognitive impairments, baseline Barthel Index (BI), and plasma fibrinogen were independently associated with early-onset PSD. The nomogram based on all these five independent risk factors was developed and validated with an Area Under Curve (AUC) of 0.780. In addition, the calibration plot revealed an adequate fit of the nomogram in predicting the risk of early-onset depression in patients with AIS.

Conclusions

Our study found the total CSVD burden score of 2–4 points was an independent risk factor of early-onset PSD. The proposed nomogram based on total CSVD burden, gender, cognitive impairments, baseline BI, and plasma fibrinogen concentration gave rise to a more accurate and more comprehensive prediction for early-onset PSD.

Neuropsychiatric symptoms are associated with exacerbated cognitive impairment in covert cerebral small vessel disease

OBJECTIVES

Neuropsychiatric symptoms are related to disease progression and cognitive decline over time in cerebral small vessel disease (SVD) but their significance is poorly understood in covert SVD. We investigated neuropsychiatric symptoms and their relationships between cognitive and functional abilities in subjects with varying degrees of white matter hyperintensities (WMH), but without clinical diagnosis of stroke, dementia or significant disability.

METHODS

The Helsinki Small Vessel Disease Study consisted of 152 subjects, who underwent brain magnetic resonance imaging (MRI) and comprehensive neuropsychological evaluation of global cognition, processing speed, executive functions, and memory. Neuropsychiatric symptoms were evaluated with the Neuropsychiatric Inventory Questionnaire (NPI-Q, n = 134) and functional abilities with the Amsterdam Instrumental Activities of Daily Living questionnaire (A-IADL, n = 132), both filled in by a close informant.

RESULTS

NPI-Q total score correlated significantly with WMH volume (r_s = 0.20, p = 0.019) and inversely with A-IADL score (r_s = -0.41, p < 0.001). In total, 38% of the subjects had one or more informant-evaluated neuropsychiatric symptom. Linear regressions adjusted for age, sex, and education revealed no direct associations between neuropsychiatric symptoms and cognitive performance. However, there were significant synergistic interactions between neuropsychiatric symptoms and WMH volume on cognitive outcomes. Neuropsychiatric symptoms were also associated with A-IADL score irrespective of WMH volume.

CONCLUSIONS

Neuropsychiatric symptoms are associated with an accelerated relationship between WMH and cognitive impairment. Furthermore, the presence of neuropsychiatric symptoms is related to worse functional abilities. Neuropsychiatric symptoms should be routinely assessed in covert SVD as they are related to worse cognitive and functional outcomes.

Contrast agent-free state-of-the-art magnetic resonance imaging on cerebral small vessel disease - Part 2: Diffusion tensor imaging and functional magnetic resonance imaging

Cerebral small vessel disease (cSVD) has been widely studied using conventional magnetic resonance imaging (MRI) methods, although the association between MRI findings and clinical features of cSVD is not always concordant. We assessed the additional contribution of contrast agent-free, state-of-the-art MRI techniques, particularly diffusion tensor imaging (DTI) and functional magnetic resonance imaging (fMRI), to understand brain damage and structural and functional connectivity impairment related to cSVD. We performed a review following the PICOS worksheet and Search Strategy, including 152 original papers in English, published from 2000 to 2022. For each MRI method, we extracted information about their contributions regarding the origins, pathology, markers, and clinical outcomes in cSVD. In general, DTI studies have shown that changes in mean, radial, and axial diffusivity measures are related to the presence of cSVD. In addition to the classical deficit in executive functions and processing speed, fMRI studies indicate connectivity dysfunctions in other domains, such as sensorimotor, memory, and attention. Neuroimaging metrics have been correlated with the diagnosis, prognosis, and rehabilitation of patients with cSVD. In short, the application of contrast agent-free, state-of-the-art MRI techniques has provided a complete picture of cSVD markers and tools to explore questions that have not yet been clarified about this clinical condition. Longitudinal studies are desirable to look for causal relationships between image biomarkers and clinical outcomes.

Structural brain network measures in elderly patients with cerebral small vessel disease and depressive symptoms

Objectives

To investigate the relationship between diffusion tensor imaging (DTI) indicators and cerebral small vessel disease (CSVD) with depressive states, and to explore the underlying mechanisms of white matter damage in CSVD with depression.

Method

A total of 115 elderly subjects were consecutively recruited from the neurology clinic, including 36 CSVD patients with depressive state (CSVD+D), 34 CSVD patients without depressive state (CSVD-D), and 45 controls. A detailed neuropsychological assessment and multimodal magnetic resonance imaging (MRI) were performed. Based on tract-based spatial statistics (TBSS) analysis and structural network analysis, differences between groups were compared, including white matter fiber indicators (fractional anisotropy and mean diffusivity) and structural brain network indicators (global efficiency, local efficiency and network strength), in order to explore the differences and correlations of DTI parameters among the three groups.

Results

There were no significant differences in terms of CSVD burden scores and conventional imaging findings between the CSVD-D and CSVD+D groups. Group differences were found in DTI indicators (p <  0.05), after adjusting for age, gender, education level, and vascular risk factors (VRF), there were significant correlations between TBSS analysis indicators and depression, including: fractional anisotropy (FA) (r = − 0.291, p <  0.05), mean diffusivity (MD) (r = 0.297, p < 0.05), at the same time, between structural network indicators and depression also show significant correlations, including: local efficiency (E_Local) (r = − 0.278, p < 0.01) and network strength (r = − 0.403, p < 0.001).

Conclusions

Changes in FA, MD values and structural network indicators in DTI parameters can predict the depressive state of CSVD to a certain extent, providing a more direct structural basis for the hypothesis of abnormal neural circuits in the pathogenesis of vascular-related depression. In addition, abnormal white matter alterations in subcortical neural circuits probably affect the microstructural function of brain connections, which may be a mechanism for the concomitant depressive symptoms in CSVD patients.

The enigma of vascular depression in old age: a critical update

Depression is common in older individuals and is associated with high disability and increased mortality, yet the factors predicting late-life depression (LLD) are poorly understood. The relationship between of depressive disorder, age- and disease-related processes have generated pathogenic hypotheses and provided new treatment options. LLD syndrome is often related to a variety of vascular mechanisms, in particular hypertension, cerebral small vessel disease, white matter lesions, subcortical vascular impairment, and other processes (e.g., inflammation, neuroimmune regulatory dysmechanisms, neurodegenerative changes, amyloid accumulation) that may represent etiological factors by affecting frontolimbic and other neuronal networks predisposing to depression. The "vascular depression" hypothesis suggests that cerebrovascular disease (CVD) and vascular risk factors may predispose, induce or perpetuate geriatric depressive disorders. It is based on the presence of various cerebrovascular risk factors in many patients with LLD, its co-morbidity with cerebrovascular lesions, and the frequent development of depression after stroke. Other findings related to vascular depression are atrophy of the medial temporal cortex or generalized cortical atrophy that are usually associated with cognitive impairment. Other pathogenetic hypotheses of LLD, such as metabolic or inflammatory ones, are briefly discussed. Treatment planning should consider there may be a modest response to antidepressants, but several evidence-based and novel treatment options for LLD exist, such as electroconvulsive therapy, transcranial magnetic stimulation, neurobiology-based psychotherapy, as well as antihypertension and antiinflammatory drugs. However, their effectiveness needs further investigation, and new methodologies for prevention and treatment of depression in older individuals should be developed.

Pathomechanisms of Vascular Depression in Older Adults

Depression in older individuals is a common complex mood disorder with high comorbidity of both psychiatric and physical diseases, associated with high disability, cognitive decline, and increased mortality The factors predicting the risk of late-life depression (LLD) are incompletely understood. The reciprocal relationship of depressive disorder and age- and disease-related processes has generated pathogenic hypotheses and provided various treatment options. The heterogeneity of depression complicates research into the underlying pathogenic cascade, and factors involved in LLD considerably differ from those involved in early life depression. Evidence suggests that a variety of vascular mechanisms, in particular cerebral small vessel disease, generalized microvascular, and endothelial dysfunction, as well as metabolic risk factors, including diabetes, and inflammation that may induce subcortical white and gray matter lesions by compromising fronto-limbic and other important neuronal networks, may contribute to the development of LLD. The "vascular depression" hypothesis postulates that cerebrovascular disease or vascular risk factors can predispose, precipitate, and perpetuate geriatric depression syndromes, based on their comorbidity with cerebrovascular lesions and the frequent development of depression after stroke. Vascular burden is associated with cognitive deficits and a specific form of LLD, vascular depression, which is marked by decreased white matter integrity, executive dysfunction, functional disability, and poorer response to antidepressive therapy than major depressive disorder without vascular risk factors. Other pathogenic factors of LLD, such as neurodegeneration or neuroimmune regulatory dysmechanisms, are briefly discussed. Treatment planning should consider a modest response of LLD to antidepressants, while vascular and metabolic factors may provide promising targets for its successful prevention and treatment. However, their effectiveness needs further investigation, and intervention studies are needed to assess which interventions are appropriate and effective in clinical practice.

Rich-Club Analysis of the Structural Brain Network in Cases with Cerebral Small Vessel Disease and Depression Symptoms

BACKGROUND

Altered white matter brain networks have been extensively studied in cerebral small vessel disease (SVD). However, there exists currently a deficiency of comprehending the performance of changes within the structural networks of the brain in cases with cerebral SVD and depression symptoms. The main aim of the present research is to study the network topology behaviors and features of rich-club organization in SVD patients using graph theory and diffusion tensor imaging (DTI) to characterize changes in the microstructure of the brain.

METHODS

DTI datasets were acquired from 26 SVD patients with symptoms of depression (SVD + D) and 26 SVD patients without symptoms of depression (SVD - D), and a series of neuropsychological assessments were completed. A structural network was created using a deterministic fiber tracking method. The analysis of rich-club was performed in company with analysis of the global network features of the network to characterize the topological properties of all subjects.

RESULTS

DTI data were obtained from SVD patients who manifested symptoms of depression (SVD + D) and from control SVD patients (SVD - D). In comparison with SVD - D patients, SVD + D cases demonstrated a diminished coefficient of clustering along with lower global efficiencies and longer path length characteristics. Rich-club analysis showed SVD + D patients had decreased feeder connectivity and local connectivity strengths compared to SVD - D patients. Our data also showed that the feeder connections in the brain correlated significantly with the severity of depression in SVD + D patients.

CONCLUSIONS

Our study revealed that SVD patients with depressive symptoms have disrupted white matter networks that characteristically have reduced network efficiency compared to the networks in other SVD patients. Disrupted information interactions among the regions of nonrich-club and rich-club in SVD cases are related to the severity of depression. Our data suggest that DTI may be utilized as an appropriate biomarker for the diagnosis of depression in comorbid SVD patients.

Depression, dementia and immune dysregulation

Major depression is a prevalent illness that increases the risk of several neurological conditions. These include stroke, cardiovascular disease, and dementia including Alzheimer's disease. In this review we ask whether certain types of depression and associated loneliness may be a harbinger of cognitive decline and possibly even dementia. We propose that chronic stress and inflammation combine to compromise vascular and brain function. The resulting increases in proinflammatory cytokines and microglial activation drive brain pathology leading to depression and mild cognitive impairment, which may progress to dementia. We present evidence that by treating the inflammatory changes, depression can be reversed in many cases. Importantly, there is evidence that anti-inflammatory and antidepressant treatments may reduce or prevent dementia in people with depression. Thus, we propose a model in which chronic stress and inflammation combine to increase brain permeability and cytokine production. This leads to microglial activation, white matter damage, neuronal and glial cell loss. This is first manifest as depression and mild cognitive impairment, but can eventually evolve into dementia. Further research may identify clinical subgroups with inflammatory depression at risk for dementia. It would then be possible to address in clinical trials whether effective treatment of the depression can delay the onset of dementia.

Individual markers of cerebral small vessel disease and domain-specific quality of life deficits

BACKGROUND

Cerebral small vessel disease (SVD) leads to reduced quality of life (QOL), but the mechanisms underlying this relationship remain unknown. This study investigated multivariate relationships between radiological markers of SVD and domain-specific QOL deficits, as well as potential mediators, in patients with SVD.

METHODS

Clinical and neuroimaging measures were obtained from a pooled sample of 174 SVD patients from the St. George's Cognition and Neuroimaging in Stroke and PRESsure in established cERebral small VEssel disease studies. Lacunes, white matter hyperintensities, and microbleeds were defined as radiological markers of SVD and delineated using MRI. QOL was assessed using the Stroke-Specific Quality of Life Scale. Multivariate linear regression was used to determine whether SVD markers were associated with domain-specific QOL deficits. Significant associations were further investigated using mediation analysis to examine whether functional disability or cognition was potential mediators.

RESULTS

Multivariate regression analyses revealed that lacunes were associated with total QOL score (β = -8.22, p = .02), as well as reductions in mobility (β = -1.41, p = .008) and language-related subdomains (β = -0.69, p = .033). White matter hyperintensities and microbleeds showed univariate correlations with QOL, but these became nonsignificant during multivariate analyses. Mediation analyses revealed that functional disability, defined as reduced activities of daily living, and executive function, partially mediated the relationship between lacunes and total QOL, as well as mobility-related QOL, but not language-related QOL.

CONCLUSIONS

Lacunar infarcts have the most detrimental effect on QOL in SVD patients, particularly in the mobility and language-related subdomains. These effects may be partially explained by a reduction in activities of daily living. These results may inform targeted interventions to improve QOL in patients with SVD.

Oligodendrocyte lineage cells and depression

Depression is a common mental illness, affecting more than 300 million people worldwide. Decades of investigation have yielded symptomatic therapies for this disabling condition but have not led to a consensus about its pathogenesis. There are data to support several different theories of causation, including the monoamine hypothesis, hypothalamic-pituitary-adrenal axis changes, inflammation and immune system alterations, abnormalities of neurogenesis and a conducive environmental milieu. Research in these areas and others has greatly advanced the current understanding of depression; however, there are other, less widely known theories of pathogenesis. Oligodendrocyte lineage cells, including oligodendrocyte progenitor cells and mature oligodendrocytes, have numerous important functions, which include forming myelin sheaths that enwrap central nervous system axons, supporting axons metabolically, and mediating certain forms of neuroplasticity. These specialized glial cells have been implicated in psychiatric disorders such as depression. In this review, we summarize recent findings that shed light on how oligodendrocyte lineage cells might participate in the pathogenesis of depression, and we discuss new approaches for targeting these cells as a novel strategy to treat depression.

Subclinical Cognitive and Neuropsychiatric Correlates and Hippocampal Volume Features of Brain White Matter Hyperintensity in Healthy People

White matter hyperintensities (WMH) are associated with brain aging and behavioral symptoms as a possible consequence of disrupted white matter pathways. In this study, we investigated, in a cohort of asymptomatic subjects aged 50 to 80, the relationship between WMH, hippocampal atrophy, and subtle, preclinical cognitive and neuropsychiatric phenomenology. Thirty healthy subjects with WMH (WMH+) and thirty individuals without (WMH−) underwent comprehensive neuropsychological and neuropsychiatric evaluations and 3 Tesla Magnetic Resonance Imaging scan. The presence, degree of severity, and distribution of WMH were evaluated with a semi-automated algorithm. Volumetric analysis of hippocampal structure was performed through voxel-based morphometry. A multivariable logistic regression analysis indicated that phenomenology of subclinical apathy and anxiety was associated with the presence of WMH. ROI-based analyses showed a volume reduction in the right hippocampus of WMH+. In healthy individuals, WMH are associated with significant preclinical neuropsychiatric phenomenology, as well as hippocampal atrophy, which are considered as risk factors to develop cognitive impairment and dementia.

An Exploratory Study of Pathways from White Matter Hyperintensities to Cognitive Impairment through Depressive Symptoms Using Structural Equation Modeling: A Cross Sectional Study in Patients with Dementia

OBJECTIVE

The aim of this study was to model the relationships among white matter hyperintensities (WMHs), depressive symptoms, and cognitive function and to examine the mediating effect of depressive symptoms on the relationship between WMHs and cognitive impairment.

METHODS

We performed structural equation modeling using cross-sectional data from 1158 patients from the Clinical Research for Dementia of South Korea (CREDOS) registry who were diagnosed with mild-to-moderate dementia. Periventricular white matter hyperintensities (PWMHs) and deep white matter hyperintensities (DWMHs) were obtained separately on the protocol of magnetic resonance imaging (MRI). Depression and cognitive function were assessed using the Korean Form of the Geriatric Depression Scale (KGDS) and the Seoul Neuropsychological Screening Battery (SNSB), respectively.

RESULTS

The model that best reflected the relationships among the variables was the model in which DWMHs affected cognitive function directly and indirectly through the depressive symptoms; on the other hand, PWMHs only directly affected cognitive function.

CONCLUSIONS

This study presents the mediation model including the developmental pathway from DWMHs to cognitive impairment through depressive symptoms and suggests that the two types of WMHs may affect cognitive impairment through different pathways.

Anti-mouse CX3CR1 Antibody Alleviates Cognitive Impairment, Neuronal Loss and Myelin Deficits in an Animal Model of Brain Ischemia

White matter lesions are common when global cerebral ischemia (GCI) occurs in the elderly, and cause damage to neurological and psychological functions. Remyelination often fails because of the limited recruitment of oligodendrocyte progenitor cells (OPCs) to the demyelinated site or the inefficient differentiation of OPCs to mature oligodendrocytes (OLs). The activation of microglia, the most important immune cells in the central nervous system, and subsequent inflammation have been implicated in myelination repair disorder. Little is known about the role of the Fractalkine/CX3CR1 signaling pathway, the key regulator of microglia activation, on myelin in microglia. In this study, a GCI animal model was generated through bilateral common carotid artery occlusion to induce ischemic inflammation and white matter damage; then, we downregulated CX3CR1 by intracerebroventricular administration of neutralizing antibody anti-FKR. Downregulation of CX3CR1 significantly reversed the depression-like behavior and cognitive impairment in GCI mice. Activation of microglia was inhibited, and the peripheral inflammatory responses were also ameliorated as revealed by decreased serum levels of IL-1β, IL-6 and TNF-α. CX3CR1 block substantially reversed demyelination in striatum, cortex and hippocampus and promoted differentiation and maturation of OPCs into mature OLs in the hippocampus. No effect was found on myelin in the corpus callosum. Besides, hippocampal neurons were protected by anti-FKR treatment after GCI. Collectively, our data demonstrated that downregulating of the Fractalkine/CX3CR1 signaling pathway had an anti-depressant and cognition-improvement effect by inhibiting microglia activation, promoting OPCs maturation and remyelination.

Small Vessel Disease

Small vessel disease (SVD) refers to conditions where damage to arterioles and capillaries is predominant, leading to reduced, or interrupted perfusion of the affected organ. Data suggest that when this condition is evident in any organ, it is already systemic in its occurrence and consequences. SVD affects primarily organs that receive significant portions of cardiac output such as the brain, the kidney, and the retina. Thus, SVD is a major etiologic cause in debilitating conditions such as renal failure, blindness, lacunar infarcts, and dementia. The factors that lead to this devastating condition include all the known vascular risk factors when they are not strictly controlled, but lifestyles that include sedentary existence, obesity, and poor sleep patterns are also recognized drivers of SVD. In addition, depression is now recognized as a vascular risk factor. Inflammation is a mediator of SVD, but it is not known which factor(s) predominate in its etiology. This article emphasizes the need for more investigations to define this link further and suggests clinical and societal responses that might reduce the major impacts of this condition on populations.

Contributions of cardiovascular risk and smoking to chronic obstructive pulmonary disease (COPD)-related changes in brain structure and function

Background

Brain damage and cardiovascular disease are extra-pulmonary manifestations of chronic obstructive pulmonary disease (COPD). Cardiovascular risk factors and smoking are contributors to neurodegeneration. This study investigates whether there is a specific, COPD-related deterioration in brain structure and function independent of cardiovascular risk factors and smoking.

Materials and methods

Neuroimaging and clinical markers of brain structure (micro- and macro-) and function (cognitive function and mood) were compared between 27 stable COPD patients (age: 63.0±9.1 years, 59.3% male, forced expiratory volume in 1 second [FEV1]: 58.1±18.0% pred.) and 23 non-COPD controls with >10 pack years smoking (age: 66.6±7.5 years, 52.2% male, FEV1: 100.6±19.1% pred.). Clinical relationships and group interactions with brain structure were also tested. All statistical analyses included correction for cardiovascular risk factors, smoking, and aortic stiffness.

Results

COPD patients had significantly worse cognitive function (p=0.011), lower mood (p=0.046), and greater gray matter atrophy (p=0.020). In COPD patients, lower mood was associated with markers of white matter (WM) microstructural damage (p<0.001), and lower lung function (FEV1/forced vital capacity and FEV1) with markers of both WM macro (p=0.047) and microstructural damage (p=0.028).

Conclusion

COPD is associated with both structural (gray matter atrophy) and functional (worse cognitive function and mood) brain changes that cannot be explained by measures of cardiovascular risk, aortic stiffness, or smoking history alone. These results have important implications to guide the development of new interventions to prevent or delay progression of neuropsychiatric comorbidities in COPD. Relationships found between mood and microstructural abnormalities suggest that in COPD, anxiety, and depression may occur secondary to WM damage. This could be used to better understand disabling symptoms such as breathlessness, improve health status, and reduce hospital admissions.

Exploring causal pathways linking cerebral small vessel diseases burden to poststroke depressive symptoms with structural equation model analysis

BACKGROUND

Cerebral small vessel diseases (SVD) are associated with poststroke depressive symptoms (PDS). The mechanisms underlying the association between SVD burden and PDS are unclear. This study investigated the clinical pathways linking SVD burden to PDS.

METHOD

A cohort of 563 patients with acute ischemic stroke were examined at three and fifteen months after stroke. PDS was measured with the 15-item Geriatric Depression Scale (GDS). Cognitive and physical functions were assessed with the Mini-Mental State Examination and the modified Rankin Scale, respectively. All patients received MRI scans at baseline. Infarct volumes and the four SVD markers (lacunae, white matter hyperintensities, cerebral microbleeds, and perivascular spaces) were assessed on magnetic resonance imaging. SVD burden was defined as a latent variable encompassing the information about all four SVD markers in structural equation modeling (SEM). SEM was further employed to examine the direct and indirect linking pathways between SVD burden, infarct volumes, stroke severity, poststroke cognitive and physical dysfunctions, and PDS.

RESULTS

The latent SVD burden was directly associated with more severe PDS at the 3-month follow-up (path coefficient=0.11), while SVD burden and PDS at the 15-month were mainly linked through PDS at the 3-month follow-up (path coefficient=0.48). The volume of acute infarcts and impaired physical functions predominantly mediated the association between SVD burden and PDS at 3-month follow-up. Physical and cognitive functions 15 months after stroke mainly bridged the link between SVD burden and the PDS at the 15-month follow-up.

LIMITATIONS

The study included patients with mild stroke, which reduced the generalizability of the findings.

CONCLUSIONS

SVD burden not only directly determines poststroke depressive symptoms, but also worsens acute stroke lesions, stroke severity, and poststroke neurological deficits, thereby contributing further to the development of PDS over the first 15 months after stroke.

Low-Grade Inflammation Is Associated with Apathy Indirectly via Deep White Matter Lesions in Community-Dwelling Older Adults: The Sefuri Study

Low-grade inflammation is implicated in the pathogenesis of atherosclerosis, metabolic syndrome, and apathy as a form of vascular depression. We analyzed the brain magnetic resonance imaging findings in 259 community-dwelling older adults (122 men and 137 women, with a mean age of 68.4 years). The serum concentrations of high-sensitivity C-reactive protein (hsCRP) were measured by a quantitative enzyme-linked immunosorbent assay. Logistic regression analysis revealed that the log₁₀ hsCRP value and the presence of a metabolic syndrome were independently associated with confluent but not punctate deep white matter lesions (DWMLs). Path analysis based on structural equation modeling (SEM) indicated that the direct path from the log₁₀ hsCRP to the DWMLs was significant (β = 0.119, p = 0.039). The direct paths from the metabolic syndrome to the log₁₀ hsCRP and to the DWMLs were also significant. The direct path from the DWMLs to apathy (β = −0.165, p = 0.007) was significant, but the direct path from the log₁₀ hsCRP to apathy was not significant. Inflammation (i.e., elevated serum hsCRP levels) was associated with DWMLs independent of common vascular risk factors, while DWMLs were associated with apathy. The present analysis with SEM revealed the more realistic scheme that low-grade inflammation was associated with apathy indirectly via DWMLs in community-dwelling older adults.

Apathy is associated with large-scale white matter network disruption in small vessel disease

OBJECTIVE

To investigate whether white matter network disruption underlies the pathogenesis of apathy, but not depression, in cerebral small vessel disease (SVD).

METHODS

Three hundred thirty-one patients with SVD from the Radboud University Nijmegen Diffusion Tensor and Magnetic Resonance Cohort (RUN DMC) study completed measures of apathy and depression and underwent structural MRI. Streamlines reflecting underlying white matter fibers were reconstructed with diffusion tensor tractography. First, path analysis was used to determine whether network measures mediated associations between apathy and radiologic markers of SVD. Next, we examined differences in whole-brain network measures between participants with only apathy, only depression, and comorbid apathy and depression and a control group free of neuropsychiatric symptoms. Finally, we examined regional network differences associated with apathy.

RESULTS

Path analysis demonstrated that network disruption mediated the relationship between apathy and SVD markers. Patients with apathy, compared to all other groups, were impaired on whole-brain measures of network density and efficiency. Regional network analyses in both the apathy subgroup and the entire sample revealed that apathy was associated with impaired connectivity in premotor and cingulate regions.

CONCLUSIONS

Our results suggest that apathy, but not depression, is associated with white matter tract disconnection in SVD. The subnetworks delineated suggest that apathy may be driven by damage to white matter networks underlying action initiation and effort-based decision making.

Cerebral small vessel disease: neuroimaging markers and clinical implication

Cerebral small vessel disease (CSVD) is a broad category of cerebrovascular diseases which primarily affect the perforating arterioles, capillaries and venules with multiple distinct etiologies. In spite of distinctive pathogenesis, CSVD shares similar neuroimaging markers, including recent small subcortical infarct, lacune of presumed vascular origin, white matter hyperintensity of presumed vascular origin, perivascular space and cerebral microbleeds. The radiological features of neuroimaging markers are indicative for etiological analysis. Furthermore, in sporadic arteriosclerotic pathogenesis associated CSVD, the total CSVD burden is a significant predictor for stroke events, global cognitive impairment, psychiatric disorders and later life quality. This review aims to summarize the radiological characteristics as well as the clinical implication of CSVD markers and neuroimaging interpretation for CSVD symptomatology.

Structural network connectivity impairment and depressive symptoms in cerebral small vessel disease

BACKGROUND

Cerebral small vessel disease (SVD) can disrupt mood regulation circuits and cause depressive symptoms which may occur prior to onset of other symptoms. However, the topological network alterations in SVD with depressive symptoms remained unclear. We aim to investigate how these changes in structural network were related to depressive symptoms in SVD.

METHODS

We recruited 20 SVD with depressive symptoms (SVD+D), 20 SVD without depressive symptoms (SVD-D) and 16 healthy control (HC) individuals. Graph theory and diffusion tensor imaging (DTI) were applied to construct a structural network. We compared networks between groups, and examined the relationships between network properties, conventional measures of MRI, and depressive symptoms.

RESULTS

The structural network was significantly disrupted in global and regional levels in both SVD groups. SVD+D group showed more severe impairment of global network efficiency, and lower nodal efficiency and less connections within multiple regions like hippocampus, amygdala and several cortical structures. The disruption of network connectivity was associated with depressive symptoms and MRI measures of SVD, however, no mediation effect of network efficiency was detected between MRI measures and depressive symptoms.

LIMITATION

The relatively small sample size and lower spatial resolution of DTI-based network limited our power of investigation.

CONCLUSIONS

The brain structural network is significantly disrupted in SVD+D and the impairment is related to severity of vascular damages and depressive symptoms. The study provides evidence for the role of structural network damage in SVD-related depressive symptoms and might be a potential novel disease marker for SVD and comorbid depression.

Small vessel disease, neurovascular regulation and cognitive impairment: post-mortem studies reveal a complex relationship, still poorly understood

The contribution of vascular disease to cognitive impairment is under-recognized and the pathogenesis is poorly understood. This information gap has multiple causes, including a lack of post-mortem validation of clinical diagnoses of vascular cognitive impairment (VCI) or vascular dementia (VaD), the exclusion of cases with concomitant neurodegenerative disease when diagnosing VCI/VaD, and a lack of standardization of neuropathological assessment protocols for vascular disease. Other contributors include a focus on end-stage destructive lesions to the exclusion of more subtle types of diffuse brain injury, on structural abnormalities of arteries and arterioles to the exclusion of non-structural abnormalities and capillary damage, and the use of post-mortem sampling strategies that are biased towards the identification of neurodegenerative pathologies. Recent studies have demonstrated the value of detailed neuropathology in characterizing vascular contributions to cognitive impairment (e.g. in diabetes), and highlight the importance of diffuse white matter changes, capillary damage and vasoregulatory abnormalities in VCI/VaD. The use of standardized, evidence-based post-mortem assessment protocols and the inclusion of biochemical as well as morphological methods in neuropathological studies should improve the accuracy of determination of the contribution of vascular disease to cognitive impairment and clarify the relative contribution of different pathogenic processes to the tissue damage.

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.

Vascular depression consensus report - a critical update

BACKGROUND

Vascular depression is regarded as a subtype of late-life depression characterized by a distinct clinical presentation and an association with cerebrovascular damage. Although the term is commonly used in research settings, widely accepted diagnostic criteria are lacking and vascular depression is absent from formal psychiatric manuals such as the Diagnostic and Statistical Manual of Mental Disorders, 5^th edition - a fact that limits its use in clinical settings. Magnetic resonance imaging (MRI) techniques, showing a variety of cerebrovascular lesions, including extensive white matter hyperintensities, subcortical microvascular lesions, lacunes, and microinfarcts, in patients with late life depression, led to the introduction of the term "MRI-defined vascular depression".

DISCUSSION

This diagnosis, based on clinical and MRI findings, suggests that vascular lesions lead to depression by disruption of frontal-subcortical-limbic networks involved in mood regulation. However, despite multiple MRI approaches to shed light on the spatiotemporal structural changes associated with late life depression, the causal relationship between brain changes, related lesions, and late life depression remains controversial. While postmortem studies of elderly persons who died from suicide revealed lacunes, small vessel, and Alzheimer-related pathologies, recent autopsy data challenged the role of these lesions in the pathogenesis of vascular depression. Current data propose that the vascular depression connotation should be reserved for depressed older patients with vascular pathology and evident cerebral involvement. Based on current knowledge, the correlations between intra vitam neuroimaging findings and their postmortem validity as well as the role of peripheral markers of vascular disease in late life depression are discussed.

CONCLUSION

The multifold pathogenesis of vascular depression as a possible subtype of late life depression needs further elucidation. There is a need for correlative clinical, intra vitam structural and functional MRI as well as postmortem MRI and neuropathological studies in order to confirm the relationship between clinical symptomatology and changes in specific brain regions related to depression. To elucidate the causal relationship between regional vascular brain changes and vascular depression, animal models could be helpful. Current treatment options include a combination of vasoactive drugs and antidepressants, but the outcomes are still unsatisfying.

Persistent post-stroke depression in mice following unilateral medial prefrontal cortical stroke

Post-stroke depression (PSD) is a common outcome following stroke that is associated with poor recovery. To develop a preclinical model of PSD, we targeted a key node of the depression-anxiety circuitry by inducing a unilateral ischemic lesion to the medial prefrontal cortex (mPFC) stroke. Microinjection of male C57/BL6 mice with endothelin-1 (ET-1, 1600 pmol) induced a small (1 mm(3)) stroke consistently localized within the left mPFC. Compared with sham control mice, the stroke mice displayed a robust behavioral phenotype in four validated tests of anxiety including the elevated plus maze, light-dark, open-field and novelty-suppressed feeding tests. In addition, the stroke mice displayed depression-like behaviors in both the forced swim and tail suspension test. In contrast, there was no effect on locomotor activity or sensorimotor function in the horizontal ladder, or cylinder and home cage activity tests, indicating a silent stroke due to the absence of motor abnormalities. When re-tested at 6 weeks post stroke, the stroke mice retained both anxiety and depression phenotypes. Surprisingly, at 6 weeks post stroke the lesion site was infiltrated by neurons, suggesting that the ET-1-induced neuronal loss in the mPFC was reversible over time, but was insufficient to promote behavioral recovery. In summary, unilateral ischemic lesion of the mPFC results in a pronounced and persistent anxiety and depression phenotype with no evident sensorimotor deficits. This precise lesion of the depression circuitry provides a reproducible model to study adaptive cellular changes and preclinical efficacy of novel interventions to alleviate PSD symptoms.

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.

Obstructive Sleep Apnea is Linked to Depression and Cognitive Impairment: Evidence and Potential Mechanisms

Obstructive sleep apnea (OSA) is highly prevalent but very frequently undiagnosed. OSA is an independent risk factor for depression and cognitive impairment/dementia. Herein the authors review studies in the literature pertinent to the effects of OSA on the cerebral microvascular and neurovascular systems and present a model to describe the key pathophysiologic mechanisms that may underlie the associations, including hypoperfusion, endothelial dysfunction, and neuroinflammation. Intermittent hypoxia plays a critical role in initiating and amplifying these pathologic processes. Hypoperfusion and impaired cerebral vasomotor reactivity lead to the development or progression of cerebral small vessel disease (C-SVD). Hypoxemia exacerbates these processes, resulting in white matter lesions, white matter integrity abnormalities, and gray matter loss. Blood-brain barrier (BBB) hyperpermeability and neuroinflammation lead to altered synaptic plasticity, neuronal damage, and worsening C-SVD. Thus, OSA may initiate or amplify the pathologic processes of C-SVD and BBB dysfunction, resulting in the development or exacerbation of depressive symptoms and cognitive deficits. Given the evidence that adequate treatment of OSA with continuous positive airway pressure improves depression and neurocognitive functions, it is important to identify OSA when assessing patients with depression or cognitive impairment. Whether treatment of OSA changes the deteriorating trajectory of elderly patients with already-diagnosed vascular depression and cognitive impairment/dementia remains to be determined in randomized controlled trials.

Associations between the Brief Memory and Executive Test (BMET), Activities of Daily Living, and Quality of Life in Patients with Cerebral Small Vessel Disease

OBJECTIVES

In addition to neuropsychological difficulties, patients with cerebral small vessel disease (SVD) can have reduced activities of daily living and a poorer quality of life compared to healthy adults. The Brief Memory and Executive Test (BMET), is a cognitive screening tool designed to be sensitive to the neuropsychological profile of patients with SVD. While the BMET is sensitive to the cognitive consequences of SVD, it is unclear how well scores on this measure relate to functional outcomes. The aims of this study are to investigate the relationship between scores on the BMET and functional outcomes (activities of daily living and quality of life) in SVD, and to compare this with other commonly used cognitive screening tools.

METHODS

This study included 184 participants with SVD (mean age=63.2; SD=9.9) and 299 healthy controls (mean age=62.4; SD=13.8) who were tested using the BMET, Montreal Cognitive Assessment (MoCA), Mini-Mental State Examination (MMSE), Stroke Specific - Quality of Life Scale (SS-QoL), Geriatric Depression Scale (GDS), and measures of both instrumental activities of daily living (IADL) and basic activities of daily living (BADL).

RESULTS

After controlling for covariates the scores on the BMET, but not the MoCA or MMSE, were significantly related to poorer IADL and quality of life in the SVD group. In addition to the BMET scores, symptoms of depression were found to be significant associated with functional outcome.

CONCLUSION

These results support the clinical utility of using of the BMET, in combination with a standardized depression questionnaire, during the early assessment of patients with SVD.

Neuropsychiatric sequelae of stroke

Stroke survivors are often affected by psychological distress and neuropsychiatric disturbances. About one-third of stroke survivors experience depression, anxiety or apathy, which are the most common neuropsychiatric sequelae of stroke. Neuropsychiatric sequelae are disabling, and can have a negative influence on recovery, reduce quality of life and lead to exhaustion of the caregiver. Despite the availability of screening instruments and effective treatments, neuropsychiatric disturbances attributed to stroke are currently underdiagnosed and undertreated. Stroke severity, stroke-related disabilities, cerebral small vessel disease, previous psychiatric disease, poor coping strategies and unfavourable psychosocial environment influence the presence and severity of the psychiatric sequelae of stroke. Although consistent associations between psychiatric disturbances and specific stroke locations have yet to be confirmed, functional MRI studies are beginning to unveil the anatomical networks that are disrupted in stroke-associated psychiatric disorders. Evidence regarding biochemical and genetic biomarkers for stroke-associated psychiatric disorders is still limited, and better understanding of the biological determinants and pathophysiology of these disorders is needed. Investigation into the management of these conditions must be continued, and should include pilot studies to assess the benefits of innovative behavioural interventions and large-scale cooperative randomized controlled pharmacological trials of drugs that are safe to use in patients with stroke.

Baseline characteristic of patients presenting with lacunar stroke and cerebral small vessel disease may predict future development of depression

OBJECTIVE

Cerebral small vessel disease (SVD) is associated with late-onset depression and increases the risk for depression after stroke. We aimed to investigate baseline predictors of depression after long-term follow-up in patients with SVD, initially presenting with first-ever lacunar stroke, free of depression and cognitive impairment.

METHODS

A total of 294 patients with SVD were evaluated 3-5 years after the qualifying event. We analyzed baseline demographic data, vascular risk factors, functional status expressed as a score on modified Rankin Scale (mRS), cognitive status, presence of depression, total number of lacunar infarcts and severity of white matter hyperintensities (WMH) on MRI with Age-Related White Matter Changes scale total score (tARWMC) and Fazekas scale periventricular and deep subcortical scores.

RESULTS

On follow-up, depression was registered in 117 (39.8%) SVD patients. At the baseline, patients with depression compared with non-depressed were older (64.4 vs 60.9 years; p = 0.007), had higher mRS score (2.8 ± 0.7 vs 1.5 ± 0.7; p < 0.0001) and had more severe lesions on MRI scales (p < 0.0001 for all parameters). On follow-up, depressed patients more frequently exhibited cognitive decline (75.2% depressed vs 56.5% non-depressed; p = 0.003). No difference was detected in risk factor frequency between groups. Multivariate Cox regression analysis adjusted by age and gender revealed independent predictors of depression: baseline mRS >2 (HR 2.17, 95%CI 1.74-2.72; p < 0.0001) and tARWMC (HR 1.05, 95%CI 1.02-1.09; p = 0.005), and cognitive decline on follow-up (HR 1.80, 95%CI 1.12-2.89; p = 0.015).

CONCLUSIONS

Baseline functional status and severity of WMH and development of cognitive decline predict the occurence of late-onset depression in patients with SVD.

Recovery Potential After Acute Stroke

In acute stroke, the major factor for recovery is the early use of thrombolysis aimed at arterial recanalization and reperfusion of ischemic brain tissue. Subsequently, neurorehabilitative training critically improves clinical recovery due to augmention of postlesional plasticity. Neuroimaging and electrophysiology studies have revealed that the location and volume of the stroke lesion, the affection of nerve fiber tracts, as well as functional and structural changes in the perilesional tissue and in large-scale bihemispheric networks are relevant biomarkers of post-stroke recovery. However, associated disorders, such as mood disorders, epilepsy, and neurodegenerative diseases, may induce secondary cerebral changes or aggravate the functional deficits and, thereby, compromise the potential for recovery.

Differential relationships between apathy and depression with white matter microstructural changes and functional outcomes

Small vessel disease is a stroke subtype characterized by pathology of the small perforating arteries, which supply the sub-cortical structures of the brain. Small vessel disease is associated with high rates of apathy and depression, thought to be caused by a disruption of white matter cortical-subcortical pathways important for emotion regulation. It provides an important biological model to investigate mechanisms underlying these key neuropsychiatric disorders. This study investigated whether apathy and depression can be distinguished in small vessel disease both in terms of their relative relationship with white matter microstructure, and secondly whether they can independently predict functional outcomes. Participants with small vessel disease (n = 118; mean age = 68.9 years; 65% male) defined as a clinical and magnetic resonance imaging confirmed lacunar stroke with radiological leukoaraiosis were recruited and completed cognitive testing, measures of apathy, depression, quality of life and diffusion tensor imaging. Healthy controls (n = 398; mean age = 64.3 years; 52% male) were also studied in order to interpret the degree of apathy and depression found within the small vessel disease group. Firstly, a multilevel structural equation modelling approach was used to identify: (i) the relationships between median fractional anisotropy and apathy, depression and cognitive impairment; and (ii) if apathy and depression make independent contributions to quality of life in patients with small vessel disease. Secondly, we applied a whole-brain voxel-based analysis to investigate which regions of white matter were associated with apathy and depression, controlling for age, gender and cognitive functioning. Structural equation modelling results indicated both apathy (r = -0.23, P ≤ 0.001) and depression (r = -0.41, P ≤ 0.001) were independent predictors of quality of life. A reduced median fractional anisotropy was significantly associated with apathy (r = -0.38, P ≤ 0.001), but not depression (r = -0.16, P = 0.09). On voxel-based analysis, apathy was associated with widespread reduction in white matter integrity, with the strongest effects in limbic association tracts such as the anterior cingulum, fornix and uncinate fasciculus. In contrast, when controlling for apathy, we found no significant relationship between our white matter parameters and symptoms of depression. In conclusion, white matter microstructural changes in small vessel disease are associated with apathy but not directly with depressive symptoms. These results suggest that apathy, but not depression, in small vessel disease is related to damage to cortical-subcortical networks associated with emotion regulation, reward and goal-directed behaviour.

Transcranial Parenchymal Sonographic Findings in Patients With Cerebral Small Vessel Disease: A Preliminary Study

OBJECTIVES

Patients with cerebral small vessel disease often present with various motor, cognitive, and emotional changes, including gait disturbances, parkinsonism, and depression. Substantia nigra hyperechogenicity, brain stem raphe hypoechogenicity, ventricle diameters, and sonographic characteristics of other brain structures on transcranial sonography have been increasingly used as biomarkers in a range of neurologic diseases. We aimed to explore the frequency and clinical correlates of transcranial sonographic findings in symptomatic patients with small vessel disease.

METHODS

In a cross-sectional study, neurologic, cognitive, and emotional statuses and transcranial sonographic and magnetic resonance imaging findings were compared between 102 patients with small vessel disease and 45 healthy age- and sex-matched control participants.

RESULTS

Compared to healthy controls, small vessel disease cases had more frequent brain stem raphe hypoechogenicity (55.9% versus 11.1%; P < .0001), substantia nigra hyperechogenicity (30.4% versus 11.1%; P = .022), and enlarged third ventricles (P < .0001). Substantia nigra hyperechogenicity correlated with gait disturbances, extrapyramidal features, and cognitive impairment. Brain stem raphe hypoechogenicity was associated with the diagnosis of depression. Enlargement of the third and lateral ventricles was more frequent in patients with cognitive impairment. Pathologic substantia nigra hyperechogenicity and enlarged ventricles were associated with the severity of cerebral ischemic lesions.

CONCLUSIONS

Transcranial sonography shows pathologic findings in a substantial number of patients with small vessel disease, probably reflecting disruption of frontostriatal pathways.

Leisure-Time Physical Inactivity Associated with Vascular Depression or Apathy in Community-Dwelling Elderly Subjects: The Sefuri Study

BACKGROUND

Although physical inactivity is a major public health problem, the causative factors for physical inactivity per se are poorly understood. To address this issue, we investigated the relationship between deep white matter lesions (DWMLs) on magnetic resonance imaging, apathy, and physical activities using structural equation modeling (SEM).

METHODS

We examined 317 community-dwelling elderly subjects (137 men and 180 women with a mean age of 64.5 years) without dementia or clinically apparent depression. Physical activity was assessed with a questionnaire consisting of 3 components (leisure-time, work, and sport activities).

RESULTS

The mean score from the apathy scale (a visual analogue version of Starkstein's apathy scale) of the Grades 2-3 DWML group was 420 (95% confidence interval [CI] 379-461), which was lower (more apathetic) than the Grade 0 DWML group score of 478 (95% CI 463-492) after adjustment for education as a covariate. SEM showed that the direct paths from DWMLs or education to apathy were significant, and the direct path from apathy to leisure-time activity was highly significant (β = .25, P < .001). The degree of apathetic behavior was negatively associated with sport activity in female subjects and positively associated with TV watching in male subjects.

CONCLUSIONS

The results of the study show that DWMLs are one of the major factors that cause apathetic behavior and that apathy has significant negative effects on leisure-time physical activity in community-dwelling elderly subjects. Even a minor level of apathy without major depression would have a significant impact on activities of daily living and quality of life.