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

Major depressive disorder and the development of cerebral small vessel disease: A Mendelian randomization study

BACKGROUND

Although observational studies indicate a complex, bidirectional association between major depressive disorder (MDD) and cerebral small vessel disease (CSVD), the results are frequently inconsistent. This study investigated the potential correlation of MDD with both CSVD clinical outcomes and radiological markers, utilizing a bidirectional Mendelian randomization (MR) study design.

METHODS

Instrumental variables for MDD were obtained from the latest and largest genome-wide association study (GWAS). For CSVD, we extracted genetic instruments from GWAS datasets corresponding to both clinical outcomes and radiological markers, including intracerebral hemorrhage, small vessel ischemic stroke, white matter hyperintensities volume, mean diffusivity (MD), fractional anisotropy, brain microbleeds, and enlarged perivascular space (PVS). We employed the inverse variance weighting method as the primary analysis, complemented by conducting extensive sensitivity and heterogeneity tests.

RESULTS

In the forward MR analyses, we discovered that the genetically predicted risk of MDD exhibits a potential causal relationship with two CSVD phenotypes demonstrating microscopic white matter (WM) damage: mean diffusivity (β = 0.784, 95 % CI 0.285-1.283, p = 0.002) and WM-PVS (OR = 1.053, 95%CI 1.010-1.097, p = 0.015). A single SNP (rs2232423) was identified as significantly influencing the causal relationship between MDD and WM. After excluding this SNP, our estimated association between MDD and increased MD (β = 0.516, 95%CI -0.001-1.033, p = 0.048) remained. The effects of MDD on WM-PVS passed all the tests for heterogeneity and pleiotropy. Reverse MR analyses showed no evidence of reverse causality between MDD and an altered CSVD risk.

CONCLUSIONS

This study supports a potential causal association between MDD and CSVD-related indicators of impaired WM microstructure. These insights hold promise for improving risk assessment methods in CSVD.

Cerebrovascular Disease and Late-Life Depression: A Scoping Review

Cerebral small-vessel disease (CSVD) is an umbrella term encompassing chronic, progressive conditions that affect the brain's vasculature. Diverse pathological and neurological factors lead to various clinical and neuroimaging patterns in elderly patients. While depression in the elderly is not uncommon, the connection between CSVD and late-life depression (LLD) remains unclear. CSVD is significant because it is closely linked to chronic hypertension, contributing to microvascular damage and impaired cerebral perfusion. Our objective was to synthesize evidence, evaluate relevant literature to synthesize, and present information relating to the underlying pathophysiology and factors linking CSVD to depression in older adults. Three databases were searched, EMBASE, Ovid MEDLINE, and Web of Science, with the articles selected for inclusion needing to be peer-reviewed, written in English, and published between 1998 and 2022 and have a primary focus on people aged 50 and above who had depression and had a documented history of CSVD. Twenty papers met these criteria and were analyzed, including using statistical correlation. Of the 20 studies, 15 reported a statistically significant correlation between CVSD and LLD, whereas five of the studies found no significant correlation. In the 15 studies that reported a significant relationship between CSVD and LLD, there were a total of 15,158 participants, or an average of approximately 1,011 participants per study. The five studies that did not find a correlation included 2,222 participants, averaging about 444 participants per study. Thus, this review's overall findings are consistent with a significant relationship between CSVD and LLD. White matter hyperintensities (WMHs), one of the findings of CSVD, were found to be a common finding in patients with CSVD and LLD. Increased WMH volume led to an increase in depressive symptoms. However, some studies highlight counterpoints, emphasizing the complexity of the relationship and the influence of non-vascular factors such as neuroinflammation, neurodegeneration, and systemic comorbidities. These findings underscore the importance of early detection of CSVD and interdisciplinary approaches to mitigate the burden of depression and cognitive decline in aging populations. Future research should focus on advanced neuroimaging, genetic profiling, and longitudinal studies to unravel the multifaceted mechanisms linking CSVD and LLD and improve clinical outcomes.

Trajectories in depressive symptoms and midlife brain health

Depressive symptoms may either be a risk factor or prodromal to dementia. Investigating this association in midlife may help clarify the role of depression in cognitive aging. We aimed to identify trajectories in depressive symptoms in early to mid-life and related cognitive and brain outcomes in midlife. This study includes 3944 Black and White participants (ages 26-45 years at baseline) from the Coronary Artery Risk Development in Young Adults (CARDIA) study with 20 years of follow-up. Depressive symptoms were assessed using the Center for Epidemiological Studies Depression scale at five time points over 20 years. Growth mixture modeling (GMM) was used to identify depressive symptom trajectories. Participants completed a neuropsychological battery 20 years after baseline, including the Digit Symbol Substitution Test (DSST), Rey-Auditory Verbal Learning Test (RAVLT), Stroop Test, Montreal Cognitive Assessment (MoCA), and category and letter fluency tests. A sub-sample of participants (n = 662) underwent brain magnetic resonance imaging (MRI) to characterize gray matter volumes and white matter hyperintensities (WMHs). We identified four classes of depressive symptom trajectories: a "declining" class (n = 286, 7.3%) with initially high symptoms and subsequent decline, a class with consistently high symptoms ("steady high"; n = 264, 6.7%), a class with late increases in symptoms ("increasing"; n = 277, 7%), and a class with consistently low symptoms ("steady low"; n = 3117, 79.0%). The steady high and the increasing classes had poorer performance on all cognitive tests, while the declining class had poorer performance on the DSST, verbal fluency, and MoCA. Compared to the steady low symptom class, the steady high class had lower volumes in the entorhinal cortex (β: -180.80, 95% CI: -336.69 to -24.91) and the amygdala (β: -40.97, 95% CI: -74.09 to -7.85), the increasing class had more WMHs (β: 0.55, 95% CI: 0.22 to 0.89), and the declining class was not significantly different in any brain measures. Trajectories in depressive symptoms in young to mid-adulthood show distinct cognitive and brain phenotypes in midlife. Steady high depressive symptoms may represent a group that is at risk for dementia, whereas increasing symptoms in midlife may be associated with white matter damage.

The Rotterdam Study. Design update and major findings between 2020 and 2024

The Rotterdam Study is a population-based cohort study, started in 1990 in the district of Ommoord in the city of Rotterdam, the Netherlands, with the aim to describe the prevalence and incidence, unravel the etiology, and identify targets for prediction, prevention or intervention of multifactorial diseases in mid-life and elderly. The study currently includes 17,931 participants (overall response rate 65%), aged 40 years and over, who are examined in-person every 3 to 5 years in a dedicated research facility, and who are followed-up continuously through automated linkage with health care providers, both regionally and nationally. Research within the Rotterdam Study is carried out along two axes. First, research lines are oriented around diseases and clinical conditions, which are reflective of medical specializations. Second, cross-cutting research lines transverse these clinical demarcations allowing for inter- and multidisciplinary research. These research lines generally reflect subdomains within epidemiology. This paper describes recent methodological updates and main findings from each of these research lines. Also, future perspective for coming years highlighted.

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.

The heterogeneity of late-life depression and its pathobiology: a brain network dysfunction disorder

Depression is frequent in older individuals and is often associated with cognitive impairment and increasing risk of subsequent dementia. Late-life depression (LLD) has a negative impact on quality of life, yet the underlying pathobiology is still poorly understood. It is characterized by considerable heterogeneity in clinical manifestation, genetics, brain morphology, and function. Although its diagnosis is based on standard criteria, due to overlap with other age-related pathologies, the relationship between depression and dementia and the relevant structural and functional cerebral lesions are still controversial. LLD has been related to a variety of pathogenic mechanisms associated with the underlying age-related neurodegenerative and cerebrovascular processes. In addition to biochemical abnormalities, involving serotonergic and GABAergic systems, widespread disturbances of cortico-limbic, cortico-subcortical, and other essential brain networks, with disruption in the topological organization of mood- and cognition-related or other global connections are involved. Most recent lesion mapping has identified an altered network architecture with "depressive circuits" and "resilience tracts", thus confirming that depression is a brain network dysfunction disorder. Further pathogenic mechanisms including neuroinflammation, neuroimmune dysregulation, oxidative stress, neurotrophic and other pathogenic factors, such as β-amyloid (and tau) deposition are in discussion. Antidepressant therapies induce various changes in brain structure and function. Better insights into the complex pathobiology of LLD and new biomarkers will allow earlier and better diagnosis of this frequent and disabling psychopathological disorder, and further elucidation of its complex pathobiological basis is warranted in order to provide better prevention and treatment of depression in older individuals.

Chronic Cough-Related Differences in Brain Morphometry in Adults: A Population-Based Study

BACKGROUND

Individuals with cough hypersensitivity have increased central neural responses to tussive stimuli, which may result in maladaptive morphometric changes in the central cough processing systems.

RESEARCH QUESTION

Are the volumes of the brain regions implicated in cough hypersensitivity different in adults with chronic cough compared with adults without chronic cough?

STUDY DESIGN AND METHODS

Between 2009 and 2014, participants in the Rotterdam Study, a population-based cohort, underwent brain MRI and were interviewed for chronic cough, which was defined as daily coughing for at least 3 months. Regional brain volumes were quantified with the use of parcellation software. Based on literature review, we identified and studied seven brain regions that previously had been associated with altered functional brain activity in chronic cough. The relationship between chronic cough and regional brain volumes was investigated with the use of multivariable regression models.

RESULTS

Chronic cough was prevalent in 9.6% (No. = 349) of the 3,620 study participants (mean age, 68.5 ± 9.0 years; 54.6% women). Participants with chronic cough had significantly smaller anterior cingulate cortex volume than participants without chronic cough (mean difference, -126.16 mm³; 95% CI, -245.67 to -6.66; P = .039). Except for anterior cingulate cortex, there were no significant difference in the volume of other brain regions based on chronic cough status. The volume difference in the anterior cingulate cortex was more pronounced in the left hemisphere (mean difference, -88.11 mm³; 95% CI, -165.16 to -11.06; P = .025) and in men (mean difference, -242.58 mm³; 95% CI, -428.60 to -56.55; P = .011).

INTERPRETATION

Individuals with chronic cough have a smaller volume of the anterior cingulate cortex, which is a brain region involved in cough suppression.

CLINICAL TRIAL REGISTRATION

The Netherlands National Trial Registry (NTR; www.trialregister.nl) and the World Health Organization's International Clinical Trials Registry Platform (ICTRP; www.who.int/ictrp/network/primary/en/) under the joint catalogue number NTR6831.

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.