Association of trajectories of depressive symptoms with vascular risk, cognitive function and adverse brain outcomes: The Whitehall II MRI sub-study

Depressive symptoms and cognitive decline in older adults

OBJECTIVES

Few studies have examined the impact of late-life depression trajectories on specific domains of cognitive function. This study aims to delineate how different depressive symptom trajectories specifically affect cognitive function in older adults.

DESIGN

Prospective longitudinal cohort study.

SETTING

Australia and the United States of America.

PARTICIPANTS

In total, 11,035 community-dwelling older adults with a mean age of 75 years.

MEASUREMENTS

Depressive trajectories were modelled from depressive symptoms according to annual Centre for Epidemiological Studies Depression Scale 10 (CES-D-10) surveys. Four trajectories of depressive symptoms were identified: low ("nondepressed"), consistently mild ("subthreshold depression"), consistently moderate ("persistent depression"), and initially low but increasing ("emerging depression"). Global cognition (Modified Mini-Mental State Examination [3MS]), verbal fluency (Controlled Oral Word Association Test [COWAT]), processing speed (Symbol Digit Modalities Test [SDMT]), episodic memory (Hopkins Verbal Learning Test - Revised [HVLT-R]), and a composite z-score were assessed over a subsequent median 2 years.

RESULTS

Subthreshold depression predicted impaired performance on the SDMT (Cohen's d -0.04) and composite score (-0.03); emerging depression predicted impaired performance on the SDMT (-0.13), HVLT-R (-0.09), 3 MS (-0.08) and composite score (-0.09); and persistent depression predicted impaired performance on the SDMT (-0.08), 3 MS (-0.11), and composite score (-0.09).

CONCLUSIONS

Depressive symptoms are associated with later impaired processing speed. These effects are small. Diverse depression trajectories have different impacts on cognitive function.

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.

Performance of probable dementia classification in a European multi-country survey

Feasibility constraints limit availability of validated cognitive assessments in observational studies. Algorithm-based identification of 'probable dementia' is thus needed, but no algorithm developed so far has been applied in the European context. The present study sought to explore the usefulness of the Langa-Weir (LW) algorithm to detect 'probable dementia' while accounting for country-level variation in prevalence and potential underreporting of dementia. Data from 56 622 respondents of the Survey of Health, Ageing and Retirement in Europe (SHARE, 2017) aged 60 years and older with non-missing data were analyzed. Performance of LW was compared to a logistic regression, random forest and XGBoost classifier. Population-level 'probable dementia' prevalence was compared to estimates based on data from the Organisation for Economic Co-operation and Development. As such, application of the prevalence-specific LW algorithm, based on recall and limitations in instrumental activities of daily living, reduced underreporting from 61.0 (95% CI, 53.3-68.7%) to 30.4% (95% CI, 19.3-41.4%), outperforming tested machine learning algorithms. Performance in other domains of health and cognitive function was similar for participants classified 'probable dementia' and those self-reporting physician-diagnosis of dementia. Dementia classification algorithms can be adapted to cross-national cohort surveys such as SHARE and help reduce underreporting of dementia with a minimal predictor set.

Effects of Health-Promoting Lifestyle on Late-Onset Depression in Older Adults: Mediating Effect of Meaning in Life and Interleukin-6 (IL-6)

Purpose

Late-onset depression (LOD) with poor treatment response has high incidence and mortality in the China's aged people, this study aims to explore the correlation between health-promoting lifestyle, meaning in life, interleukin-6 (IL-6) and LOD for providing scientific basis of LOD prevention and rehabilitation.

Patients and Methods

A total of 496 LOD patients (study group) and healthy older adults (control group) were enrolled and investigated by using the Health-promoting lifestyle Profile-II, revised (HPLP-IIR), Meaning in Life Questionnaire-Chinese Version (MLQ-C), and Hamilton Depression Scale (HAMD). The interleukin-6 (IL-6) in the circulating blood was detected by utilizing ELISA kit.

Results

The results showed that the scores of all factors in HPLP-IIR and MLQ were significantly lower and IL-6 level was higher in the study group than the control group. Scores of most factors in HPLP-IIR and MLQ negatively and IL-6 positively correlated with scores of subscales and total HAMD score. Meaning in life and IL-6 partially mediated the relationship between health-promoting lifestyles and depression severity in the study group, with the mediating effect explains 15.76% and 22.64% of the total effect, respectively.

Conclusion

Health-promoting lifestyles, meaning in life, and IL-6 are predictors of LOD, and an unhealthy lifestyle could induce LOD through the mediating effect of meaning in life and IL-6 in older adults.

Artificial intelligence for dementia prevention

INTRODUCTION

A wide range of modifiable risk factors for dementia have been identified. Considerable debate remains about these risk factors, possible interactions between them or with genetic risk, and causality, and how they can help in clinical trial recruitment and drug development. Artificial intelligence (AI) and machine learning (ML) may refine understanding.

METHODS

ML approaches are being developed in dementia prevention. We discuss exemplar uses and evaluate the current applications and limitations in the dementia prevention field.

RESULTS

Risk-profiling tools may help identify high-risk populations for clinical trials; however, their performance needs improvement. New risk-profiling and trial-recruitment tools underpinned by ML models may be effective in reducing costs and improving future trials. ML can inform drug-repurposing efforts and prioritization of disease-modifying therapeutics.

DISCUSSION

ML is not yet widely used but has considerable potential to enhance precision in dementia prevention.

HIGHLIGHTS

Artificial intelligence (AI) is not widely used in the dementia prevention field. Risk-profiling tools are not used in clinical practice. Causal insights are needed to understand risk factors over the lifespan. AI will help personalize risk-management tools for dementia prevention. AI could target specific patient groups that will benefit most for clinical trials.

Depression Trajectories, Genetic Risk, and Cognitive Performance in Older Adults: Multilevel Model with a 10-Year Longitudinal Cohort

INTRODUCTION

Cognitive performance in older ages is strongly affected by individuals' genetic predispositions. We investigated whether depression trajectories were associated with subsequent cognitive performance independent of participants' genetic predispositions.

METHODS

Participants from the Health and Retirement Study with European ancestry and aged over 50 were included in the analysis. Depressive symptoms were evaluated using the Center for Epidemiologic Studies Depression Scale, and the 6-year trajectories were fitted using latent class linear mixed models. Linear multilevel regression was applied to model the associations between depression trajectory and subsequent cognitive performance. Stratified analyses were performed to investigate these associations in participants with different genetic predispositions of cognitive performance and APOE ε4 allelic status.

RESULTS

A total of 5,942 eligible participants were included in the study. Four depression trajectories were identified. Compared with the nondepression trajectory, all other depression trajectories were associated with worse cognitive performance (β [95% CI]: mild-depression trajectory: -0.20 [-0.56, -0.06], p = 0.007; worsening-depression trajectory: -0.29 [-0.47, -0.12], p = 0.001; persistent-depression trajectory: -0.32 [-0.53, -0.13], p = 0.001). Although these associations were independent of participants' inherent genetic risk, the participants with a low polygenetic score for cognitive performance were more likely to have an enhanced association between depression trajectories and cognitive decline. Similar relationships were also found in APOE ε4 noncarriers.

CONCLUSION

Among older participants with European ancestry, even a mild-depression trajectory was associated with worse cognitive performance. Early intervention in participants with any degree of depression might benefit regarding preventing cognitive performance decline.

10-Year trajectories of depressive symptoms and subsequent brain health in middle-aged adults

Depressive symptoms differ in severity and stability over time. Trajectories depicting these changes, particularly those with high late-life depressive symptoms, have been associated with poor brain health at old age. To better understand these associations across the lifespan, we examined depressive symptoms trajectories in relation to brain health in middle age. We included 1676 participants from the ORACLE Study, all were expecting a child at baseline (mean age 32.8, 66.6% women). Depressive symptoms were assessed at baseline, 3 years and 10 years after baseline. Brain health (global brain volume, subcortical structures volume, white matter lesions, cerebral microbleeds, cortical thickness, cortical surface area) was assessed 15 years after baseline. Using k-means clustering, four depressive symptoms trajectories were identified: low, low increasing, decreasing, and high increasing symptoms. The high increasing trajectory was associated with smaller brain volume compared to low symptoms, not surviving multiple testing correction. The low increasing trajectory was associated with more cortical thickness in a small region encompassing the right lateral occipital cortex compared to low symptoms. These findings show that longitudinal depressive symptoms trajectories are only minimally associated with brain health in middle age, suggesting that associations may only emerge later in life.

Distinct depressive symptom trajectories are associated with incident diabetes among Chinese middle-aged and older adults: The China Health and Retirement Longitudinal Study

OBJECTIVE

Previous studies have reported that depression and depressive symptom are associated with diabetes incident. However, the association between long-term depressive symptom patterns and risk of diabetes remains unknown. The aim of present study was to evaluate the association between depressive symptom trajectories and risk of diabetes.

METHODS

We used data of 8806 participants (≥45 years old) from the China Health and Retirement Longitudinal Study (CHARLS). Trajectories of depressive symptom were identified by latent mixture modeling. Multivariable logistic regression model was used to examine the association of depressive symptom trajectories with diabetes.

RESULTS

Five depressive symptom trajectories were identified, characterizing by maintaining a low CES-D scores throughout the follow-up (low-stable; 3227 participants [36.65%]); maintaining a moderate CES-D scores throughout the follow-up (moderate-stable; 3402 participants [38.63%]); moderate starting CES-D scores then increasing scores (moderate-increasing; 681 participants [7.73%%]); high starting CES-D scores but then decreasing scores (high-decreasing; 1061 participants [12.05%]); and maintained high CES-D scores throughout the follow-up (high-stable; 435 participants [4.94%]). During 2015 to 2018 (Wave 3 to Wave 4), a total of 312 respondents experienced diabetes. Compared with participants in the low-stable depressive symptom trajectory, those following a high-decreasing (ORs = 2.04; 95%CIs 1.48-2.98) and high-stable depressive symptom trajectories (ORs = 3.26; 95%CIs 2.06-5.16) were at substantially higher risk of developing diabetes.

CONCLUSIONS

Individuals with high-decreasing and high-stable depressive symptom trajectories over time were associated with increased risk of incident diabetes. Long-term depressive symptom may be a strong predictor of having diabetes.

Mapping of machine learning approaches for description, prediction, and causal inference in the social and health sciences

Machine learning (ML) methodology used in the social and health sciences needs to fit the intended research purposes of description, prediction, or causal inference. This paper provides a comprehensive, systematic meta-mapping of research questions in the social and health sciences to appropriate ML approaches by incorporating the necessary requirements to statistical analysis in these disciplines. We map the established classification into description, prediction, counterfactual prediction, and causal structural learning to common research goals, such as estimating prevalence of adverse social or health outcomes, predicting the risk of an event, and identifying risk factors or causes of adverse outcomes, and explain common ML performance metrics. Such mapping may help to fully exploit the benefits of ML while considering domain-specific aspects relevant to the social and health sciences and hopefully contribute to the acceleration of the uptake of ML applications to advance both basic and applied social and health sciences research.

Associations of depression and regional brain structure across the adult lifespan: Pooled analyses of six population-based and two clinical cohort studies in the European Lifebrain consortium

OBJECTIVE

Major depressive disorder has been associated with lower prefrontal thickness and hippocampal volume, but it is unknown whether this association also holds for depressive symptoms in the general population. We investigated associations of depressive symptoms and depression status with brain structures across population-based and patient-control cohorts, and explored whether these associations are similar over the lifespan and across sexes.

METHODS

We included 3,447 participants aged 18-89 years from six population-based and two clinical patient-control cohorts of the European Lifebrain consortium. Cross-sectional meta-analyses using individual person data were performed for associations of depressive symptoms and depression status with FreeSurfer-derived thickness of bilateral rostral anterior cingulate cortex (rACC) and medial orbitofrontal cortex (mOFC), and hippocampal and total grey matter volume (GMV), separately for population-based and clinical cohorts.

RESULTS

Across patient-control cohorts, depressive symptoms and presence of mild-to-severe depression were associated with lower mOFC thickness (r_symptoms = -0.15/ r_status = -0.22), rACC thickness (r_symptoms = -0.20/ r_status = -0.25), hippocampal volume (r_symptoms = -0.13/ r_status = 0.13) and total GMV (r_symptoms = -0.21/ r_status = -0.25). Effect sizes were slightly larger for presence of moderate-to-severe depression. Associations were similar across age groups and sex. Across population-based cohorts, no associations between depression and brain structures were observed.

CONCLUSIONS

Fitting with previous meta-analyses, depressive symptoms and depression status were associated with lower mOFC, rACC thickness, and hippocampal and total grey matter volume in clinical patient-control cohorts, although effect sizes were small. The absence of consistent associations in population-based cohorts with mostly mild depressive symptoms, suggests that significantly lower thickness and volume of the studied brain structures are only detectable in clinical populations with more severe depressive symptoms.

The trajectories of depressive symptoms and subsequent incident dementia, coronary heart diseases, stroke and all-cause mortality

BACKGROUND

Evidence suggests the occurrence of depressive symptoms in mid- to late-life inflates the risk for ageing-related morbidity compared to people without depressive symptoms. The eventual association between depressive symptoms in mid- to late-life and long-term (over 10-year) risks for incident dementia, coronary heart disease (CHD), stroke, and morbidity is to be established.

METHODS

This longitudinal cohort study utilized Health and Retirement Study (HRS) of U.S residents aged ≥ 50 years who were interviewed every 2-year during follow-up (average follow-up: 11.6 ± 2.85 years). Trajectories of depressive symptoms were assessed by the Center for Epidemiologic Studies Depression (CES-D) scale from 1994 to 2000 at baseline. Incident dementia, CHD, stroke and all-cause mortality were determined from 2000 to 2018.

RESULTS

Among 7810 individuals who were free from dementia, CHD and stroke, five trajectories of depressive symptoms were identified: non-depressed (36.7 %), mild (48.8 %), worsening (7.8 %), improving (4.1 %) and persistent (2.7 %). Compared with those in the non-depressed group, participants with mild, worsening and persistent depressive symptoms had significantly greater hazards of incident dementia (multivariable adjusted hazard ratios and 95 % confidence intervals: 1.32 [1.17-1.48], 1.58 [1.30-1.93], 2.82 [2.17-3.67], respectively), CHD (1.13 [1.03-1.24], 1.47 [1.25-1.73], 1.34 [1.03-1.74], respectively), stroke (1.30 [1.12-1.52], 1.58 [1.23-2.04], 1.71 [1.16-2.53], respectively) and all-cause mortality (1.17 [1.07-1.27], 1.46 [1.27-1.68], 1.66 [1.35-2.06], respectively). The hazards of incident events, except for CHD, were not significantly greater in individuals with improving depressive symptoms.

CONCLUSIONS

The present findings suggest even sub-clinical threshold depressive symptoms were associated with the hazards of ageing related diseases while such associations were not significant with managed depressive symptoms.

Gender differences in the association of depression trajectories with executive and memory functions: Evidence from the longitudinal study of the Survey of Health, Ageing and Retirement in Europe (2004-2017)

Gender differences in depression trajectories and their effects on cognitive function are poorly understood. This article aims to identify depression trajectories in both genders and further explore the association of depression trajectories with executive and memory functions by gender. A total 3990 participants aged 50 years or older with repeated measurements from waves 1 to 7 (wave 3 excluded) of the Study of the Survey of Health, Ageing and Retirement in Europe (SHARE) were included. Group-based trajectory modeling (GBTM) was conducted to identify the optimal number of depression trajectories. Generalized estimating equation (GEE) models were used to examine the relation of depression trajectories to cognitive function after stratification by gender. Three distinct depression trajectories were identified in both genders, but the patterns of trajectories among genders were nonidentical. The trajectories of depression in males were characterized by non-low, moderate, persistent-depressive symptoms but with an unstable trend, while in females, they were characterized by non-low, moderate, persistent-depressive symptoms and with a worsening trend. The prevalence of persistent high depression in women (20.08%) was higher than that in men (3.13%). Moderate and persistent high depression trajectories were negatively associated with episodic memory (β = -0.53 and -0.72, respectively, p < 0.001) and verbal fluency in females (β = -0.96 and -1.47, p=0.01 and < 0.001, respectively). Older women had a greater frequency of developing depression than older men. Gender differences in depression trajectories existed. Moderate and persistent high depression trajectories exerted a negative effect on some domains of cognitive impairment only in females.

Trajectories of depressive symptoms in older adults and associated health outcomes

With the progressive aging of the world's population, prolongation of a healthy lifespan in old age has become a medical research priority. The presence of depressive symptoms in later life is associated with poor health prognosis and increased mortality^1,2. Here we explore distinct trajectories of depressive symptoms in later life and their association with several health-related outcomes in 19,110 older individuals followed for a median of 4.7 years. Using a latent class, mixed-modeling approach we identified four distinct trajectories of depressive symptoms with scoring patterns of consistently low, moderate, emerging and persistently high. Compared to those with minimal depressive symptoms, membership of any other class was associated with specific patterns of baseline sociodemographic and medical factors. Membership of any group with depressive symptoms was associated with a higher likelihood of health events, including physical disability, cancer and major bleeding episodes. Membership of the persistently depressed class was associated with increased mortality, while a diagnosis of dementia was generally limited to the class with initially low and progressively rising symptoms. The course of depressive symptoms in older individuals can vary widely and depend on several factors. The presence of depressive symptoms, including those that do not meet criteria for major depression, can flag a poor prognosis and risk for specific health conditions. Systematic assessment of depressive symptoms may facilitate early identification of at-risk populations.

Retinal Microvascular Caliber and Incident Depressive Symptoms: The Multi-Ethnic Study of Atherosclerosis

Cerebral microvascular dysfunction may contribute to depression via disruption of brain structures involved in mood regulation, but evidence is limited. The retina allows for visualization of a microvascular bed that shares similarities with the cerebral microvasculature. We investigated the associations between baseline retinal arteriolar and venular calibers (central retinal arteriolar equivalent (CRAE) and central retinal venular equivalent (CRVE), respectively) and incident depressive symptoms in the Multi-Ethnic Study of Atherosclerosis (MESA). We used longitudinal data on 4,366 participants (mean age = 63.2 years; 48.5% women, 28.4% Black) without baseline depressive symptoms. Depressive symptoms, defined as Center for Epidemiologic Studies Depression Scale score ≥16 and/or use of antidepressant medication, were determined between 2002 and 2004 (baseline; MESA visit 2) and at 3 follow-up examinations conducted every 1.5–2 years thereafter. Fundus photography was performed at baseline. After a mean follow-up period of 6.1 years, 21.9% (n = 958) had incident depressive symptoms. After adjustment for sociodemographic, lifestyle, and cardiovascular factors, a 1–standard-deviation larger baseline CRVE was associated with a higher risk of depressive symptoms (hazard ratio = 1.10, 95% confidence interval: 1.02, 1.17), and a 1–standard-deviation larger baseline CRAE was not statistically significantly associated with incident depressive symptoms (hazard ratio = 1.04, 95% confidence interval: 0.97, 1.11). In this study, larger baseline CRVE, but not CRAE, was associated with a higher incidence of depressive symptoms.

Incidence of neurological and psychiatric comorbidity over time: a population-based cohort study in Ontario, Canada

INTRODUCTION

Comprehensive, population-based investigations of the extent and temporality of associations between common neurological and psychiatric disorders are scarce.

METHODS

This retrospective cohort study used linked health administrative data for Ontarians aged 40-85 years on 1 April 2002, to estimate the adjusted rate of incident dementia, Parkinson's disease (PD), stroke or mood/anxiety disorder (over 14 years) according to the presence and time since diagnosis of a prior disorder. Sex differences in the cumulative incidence of a later disorder were also examined.

RESULTS

The cohort included 5,283,546 Ontarians (mean age 56.2 ± 12.1 years, 52% female). The rate of dementia was significantly higher for those with prior PD (adjusted hazard ratio [adjHR] 4.05, 95% confidence interval [CI] 3.99-4.11); stroke (adjHR 2.49, CI 2.47-2.52) and psychiatric disorder (adjHR 1.79, CI 1.78-1.80). The rate of PD was significantly higher for those with prior dementia (adjHR 2.23, CI 2.17-2.30) and psychiatric disorder (adjHR 1.77, CI 1.74-1.81). The rate of stroke was significantly higher among those with prior dementia (adjHR 1.56, CI 1.53-1.58). Prior dementia (adjHR 2.36, CI 2.33-2.39), PD (adjHR 1.80, CI 1.75-1.85) and stroke (adjHR 1.47, CI 1.45-1.49) were associated with a higher rate of an incident psychiatric disorder. Generally, associations were strongest in the 6 months following a prior diagnosis and demonstrated a J-shape relationship over time. Significant sex differences were evident in the absolute risks for several disorders.

CONCLUSIONS

The observed nature of bidirectional associations between these neurological and psychiatric disorders indicates opportunities for earlier diagnosis and interventions to improve patient care.

Trajectories of depressive symptoms and subsequent cognitive decline in older adults: a pooled analysis of two longitudinal cohorts

BACKGROUND

the course of depression is variable, but it is unknown how this variability over time affects long-term cognitive decline.

OBJECTIVE

to examine the relationship of different trajectories of depressive symptoms on rates of subsequent cognitive decline in older adults.

DESIGN

population-based cohort study.

SETTING

communities in the USA and England.

SUBJECTS

17,556 older adults from the Health and Retirement Study and the English Longitudinal Study of Ageing.

METHODS

depressive symptoms were assessed using the Center for Epidemiologic Studies Depression Scale, and trajectories were calculated using group-based trajectory modelling. Global cognitive function and three cognitive domains of memory, executive function and temporal orientation were assessed for up to 18 years.

RESULTS

five trajectories of depressive symptoms were identified. Compared with the 'non-depressed' trajectory, the 'worsening depressive symptoms' trajectory (pooled β = -0.016 standard deviation (SD)/year, 95% confidence interval (CI): -0.021 to -0.010), 'persistent depressive symptoms' trajectory (pooled β = -0.016 SD/year, 95% CI: -0.024 to -0.008), and 'mild depressive symptoms' trajectory (pooled β = -0.008 SD/year, 95% CI: -0.014 to -0.003) were associated with faster rates of cognitive decline, while no such association was found for the 'improving depressive symptoms' trajectory (pooled β = 0.001 SD/year, 95% CI: -0.010 to 0.012).

CONCLUSIONS

subthreshold depressive symptoms are associated with an increased rate of cognitive decline, while individuals who show improving depressive symptoms do not exhibit accelerated cognitive decline. These findings raise the possibility that maintaining depressive symptoms as low as possible and ignoring the clinical threshold, might mitigate cognitive decline in older adults.

Microvascular Contribution to Late-Onset Depression: Mechanisms, Current Evidence, Association With Other Brain Diseases, and Therapeutic Perspectives

Depression is common in older individuals and is associated with high disability and mortality. A major problem is treatment resistance: >50% of older patients do not respond to current antidepressants. Therefore, new effective interventions for prevention and treatment of depression in older individuals need to be developed, which requires a better understanding of the mechanisms underlying depression. The pathophysiology of depression is multifactorial and complex. Microvascular dysfunction may be an early and targetable mechanism in the development of depression, notably depression that initiates in late life (late-onset depression). Late-onset depression commonly co-occurs with other diseases or syndromes that may share a microvascular origin, including apathy, cognitive impairment, dementia, and stroke. Together, these disabilities may all be part of one large phenotype resulting from global cerebral microvascular dysfunction. In this review, we discuss the pathophysiology of microvascular dysfunction-related late-onset depression, summarize recent epidemiological evidence on the association between cerebral microvascular dysfunction and depression, and indicate potential drivers of cerebral microvascular dysfunction. We also propose the hypothesis that depression may be a manifestation of a larger phenotype of cerebral microvascular dysfunction, highlight potential therapeutic targets and interventions, and give directions for future research.

Prominent health problems, socioeconomic deprivation, and higher brain age in lonely and isolated individuals: A population-based study

Loneliness is linked to increased risk for Alzheimer's disease, but little is known about factors potentially contributing to adverse brain health in lonely individuals. In this study, we used data from 24,867 UK Biobank participants to investigate risk factors related to loneliness and estimated brain age based on neuroimaging data. The results showed that on average, individuals who self-reported loneliness on a single yes/no item scored higher on neuroticism, depression, social isolation, and socioeconomic deprivation, performed less physical activity, and had higher BMI compared to individuals who did not report loneliness. In line with studies pointing to a genetic overlap of loneliness with neuroticism and depression, permutation feature importance ranked these factors as the most important for classifying lonely vs. not lonely individuals (ROC AUC = 0.83). While strongly linked to loneliness, neuroticism and depression were not associated with brain age estimates. Conversely, objective social isolation showed a main effect on brain age, and individuals reporting both loneliness and social isolation showed higher brain age relative to controls - as part of a prominent risk profile with elevated scores on socioeconomic deprivation and unhealthy lifestyle behaviours, in addition to neuroticism and depression. While longitudinal studies are required to determine causality, this finding may indicate that the combination of social isolation and a genetic predisposition for loneliness involves a risk for adverse brain health. Importantly, the results underline the complexity in associations between loneliness and adverse health outcomes, where observed risks likely depend on a combination of interlinked variables including genetic as well as social, behavioural, physical, and socioeconomic factors.

Depressive Symptoms Imputed Across the Life Course Are Associated with Cognitive Impairment and Cognitive Decline

BACKGROUND

Depressive symptoms may increase risk for dementia, but findings are controversial because late-life depression may be a prodromal dementia symptom. Life course data on depression and dementia risk may clarify this association; however, data is limited.

OBJECTIVE

To impute adult depressive symptoms trajectories across adult life stages and estimate the association with cognitive impairment and decline.

METHODS

Using a pooled study of 4 prospective cohorts (ages 20-89), we imputed adult life course depressive symptoms trajectories based on Center for Epidemiologic Studies Depression Scale-10 (CESD-10) and calculated time-weighted averages for early adulthood (ages 20-49), mid-life (ages 50-69), and late-life (ages 70-89) for 6,122 older participants. Adjusted pooled logistic and mixed-effects models estimated associations of imputed depressive symptoms with two cognitive outcomes: cognitive impairment defined by established criteria and a composite cognitive score.

RESULTS

In separate models, elevated depressive symptoms in each life stage were associated with cognitive outcomes: early adulthood OR for cognitive impairment = 1.59 (95%CI: 1.35,1.87); mid-life OR = 1.94 (95%CI:1.16, 3.26); and late-life OR = 1.77 (95%CI:1.42, 2.21). When adjusted for depressive symptoms in the other life-stages, elevated depressive symptoms in early adulthood (OR = 1.73; 95%CI: 1.42,2.11) and late-life (OR = 1.43; 95%CI: 1.08,1.89) remained associated with cognitive impairment and were also associated with faster rates of cognitive decline (p < 0.05).

CONCLUSION

Imputing depressive symptom trajectories from pooled cohorts may help expand data across the life course. Our findings suggest early adulthood depressive symptoms may be a risk factor for cognitive impairment independent of mid- or late-life depressive symptoms.