History of depression as a risk factor for dementia: an updated review

Neutrophil activation and related disrupted frontolimbic circuit may contribute to cognitive progression of minimal depressive symptoms in non-dementia elderly

BACKGROUND

As a more common but easily neglected disorder, minimal depressive symptoms (MDS), it is unclear whether and why it increases the risk of cognitive progression in non-dementia elderly.

METHODS

The Alzheimer's disease Neuroimaging Initiative (ADNI) database was used to assign 1065 non-dementia elderly into normal control (n = 380) and MDS (n = 685) groups via the Geriatric Depression Scale (GDS). Blood neutrophils, transcriptomics and metabolomics, cerebrospinal fluid (CSF) proteomics, and magnetic resonance imaging (MRI) data were analyzed.

RESULTS

MDS was found to increase the risk of cognitive progression independently of multiple psychological symptoms. Increased levels of blood neutrophils were associated with cognitive progression in MDS, as supported by neutrophil-related pathways by transcriptomic enrichment analysis and multi-omics joint analysis. A disrupted frontolimbic circuit was associated with neutrophil activation in MDS.

LIMITATIONS

The heterogeneity of the sample limited the generalizability of results, and the lack of follow-up data limited the research on the mechanism of neutrophil activation influencing cognitive function in MDS.

CONCLUSIONS

Cognitive progression occurs as early as the MDS stage. And this phenomenon may attribute to the neutrophil activation and the related disrupted frontolimbic circuit.

Cross-sectional and longitudinal associations between late-life depressive symptoms and cognitive deficits: 20-year follow-up of the Kuakini Honolulu-Asia aging study

OBJECTIVE

To examine depressed affect, somatic complaints, and positive affect as longitudinal predictors of fluid, crystallized and global cognitive performance in the Kuakini Honolulu-Asia Aging Study (HAAS), a large prospective cohort study of Japanese-American men.

METHODS

We assessed 3,088 dementia-free Kuakini-HAAS participants aged 71-93 (77.1 ± 4.2) years at baseline (1991-1993). Depressive symptoms were evaluated by the Center for Epidemiologic Studies Depression (CES-D) Scale. Baseline CES-D depression subscales (depressed and positive affects; somatic complaints) were computed. The Cognitive Abilities Screening Instrument (CASI) measured cognitive performance on a 100-point scale; fluid and crystallized cognitive abilities were derived from CASI factor analysis. Cognition was also evaluated at 4 follow-up examinations over a 20-year period. Multiple regression assessed baseline CES-D subscales as predictors of cognitive change. The baseline covariates analyzed were CASI, age, education, prevalent stroke, APOE ε4 presence, and the longevity-associated FOXO3 genotype.

RESULTS

Cross-sectionally, baseline CES-D subscales were related to cognitive measures; e.g., higher depressed affect was associated with lower crystallized ability (β = -0.058, p ≤ 0.01), and somatic complaints were linked to poorer fluid ability (β = -0.045, p ≤ 0.05) and to worse global cognitive function as measured by total CASI score (β = -0.038, p ≤ 0.05). However, depression subscales did not significantly or consistently predict fluid ability, crystallized ability, or global cognitive performance over time.

CONCLUSION

Psychological and physical well-being were associated with contemporaneous but not subsequent cognitive functioning. Assessment of depressive symptoms may identify individuals who are likely to benefit from interventions to improve mood and somatic health and thereby maintain or enhance cognition.

Increased nocturnal urinary cortisol levels in the elderly patients with depression, coexisting major geriatric syndromes and combined pathogenetic mechanisms

BACKGROUND

The mechanisms at the basis of depression are still matter of debate, but several studies in the literature suggest common pathways with dementia (genetic predispositions, metabolic and inflammatory mechanisms, neuropathological changes) and other geriatric syndromes.

AIMS

To evaluate the role of cortisol (as marker of the HPA, hypothalamus-pituitary-adrenal axis hyperactivity) in elderly subjects with depressive symptoms (by the means of the AGICO, AGIng and COrtisol, study), in relationship to the presence of the major geriatric syndromes.

METHODS

The AGICO study enrolled patients from ten Geriatric Units in Italy. Every subject received a comprehensive geriatric assessment or CGA (including the Mini Mental State Examination or MMSE, Geriatric Depression Scale or GDS and Cornell Scale for Depression in Dementia or CSDD), the neurological examination (with a computed tomography scan or magnetic resonance imaging of the brain), the assessment of the metabolic syndrome (MetS), the evaluation of the cortisol activity by two consecutive urine collections (diurnal and nocturnal), a CGA-derived frailty index (FI) and a modified measure of allostatic load (AL).

RESULTS

The MMSE scores were significantly and inversely related to the values of GDS (p < 0.001) and CSDD (p < 0.05), respectively. The patients with depressive symptoms (GDS/CSDD > 8) showed significantly increased disability, MetS, inflammation, FI and AL and significantly reduced MMSE and renal function. The diurnal and nocturnal urinary cortisol levels in the patients with depressive symptoms (GDS/CSDD > 8) were higher with respects to controls (p < 0.05 for nocturnal difference).

DISCUSSION

The AGICO study showed that the stress response is activated in the patients with depression.

CONCLUSION

The depression in elderly patient should be reconsidered as a systemic disease, with coexisting major geriatric syndromes (disability, dementia, frailty) and combined pathogenetic mechanisms (metabolic syndrome, impaired renal function, low-grade inflammation, and allostatic load). Cortisol confirmed its role as principal mediator of the aging process in both dementia and metabolic syndrome.

Multimorbidity patterns and health-related quality of life among community-dwelling older adults: evidence from a rural town in Suzhou, China

PURPOSE

The high prevalence of multimorbidity in aging societies has posed tremendous challenges to the healthcare system. The aim of our study was to comprehensively assess the association of multimorbidity patterns and health-related quality of life (HRQOL) among rural Chinese older adults.

METHODS

This was a cross-sectional study. Data from 4,579 community-dwelling older adults aged 60 years and above was collected by the clinical examination and questionnaire survey. Information on 10 chronic conditions was collected and the 3-Level EQ-5D (EQ-5D-3L) was adopted to measure the HRQOL of older adults. An exploratory factor analysis was performed to determine multimorbidity patterns. Regression models were fitted to explore the associations of multimorbidity patterns with specific health dimensions and overall HRQOL.

RESULTS

A total of 2,503 (54.7%) participants suffered from multimorbidity, and they reported lower HRQOL compared to those without multimorbidity. Three kinds of multimorbidity patterns were identified including cardiovascular-metabolic diseases, psycho-cognitive diseases and organic diseases. The associations between psycho-cognitive diseases/organic diseases and overall HRQOL assessed by EQ-5D-3L index score were found to be significant (β = - 0.097, 95% CI - 0.110, - 0.084; β = - 0.030, 95% CI - 0.038, - 0.021, respectively), and psycho-cognitive diseases affected more health dimensions. The impact of cardiovascular-metabolic diseases on HRQOL was largely non-significant.

CONCLUSION

Multimorbidity was negatively associated with HRQOL among older adults from rural China. The presence of the psycho-cognitive diseases pattern or the organic diseases pattern contributed to worse HRQOL. The remarkable negative impact of psycho-cognitive diseases on HRQOL necessiates more attention and relevant medical assistance to older rural adults.

Combining artificial neural networks and a marginal structural model to predict the progression from depression to Alzheimer's disease

Introduction

Decades of research in population health have established depression as a likely precursor to Alzheimer's disease. A combination of causal estimates and machine learning methods in artificial intelligence could identify internal and external mediating mechanisms that contribute to the likelihood of progression from depression to Alzheimer's disease.

Methods

We developed an integrated predictive model, combining the marginal structural model and an artificial intelligence predictive model, distinguishing between patients likely to progress from depressive states to Alzheimer's disease better than each model alone.

Results

The integrated predictive model achieved substantial clinical relevance when using the area under the curve measure. It performed better than the traditional statistical method or a single artificial intelligence method alone.

Discussion

The integrated predictive model could form a part of a clinical screening tool that identifies patients who are likely to progress from depression to Alzheimer's disease for early behavioral health interventions. Given the high costs of treating Alzheimer's disease, our model could serve as a cost-effective intervention for the early detection of depression before it progresses to Alzheimer's disease.

The prevalence of mild cognitive impairment in Gulf War veterans: a follow-up study

Introduction

Gulf War Illness (GWI), also called Chronic Multisymptom Illness (CMI), is a multi-faceted condition that plagues an estimated 250,000 Gulf War (GW) veterans. Symptoms of GWI/CMI include fatigue, pain, and cognitive dysfunction. We previously reported that 12% of a convenience sample of middle aged (median age 52 years) GW veterans met criteria for mild cognitive impairment (MCI), a clinical syndrome most prevalent in older adults (e.g., ≥70 years). The current study sought to replicate and extend this finding.

Methods

We used the actuarial neuropsychological criteria and the Montreal Cognitive Assessment (MoCA) to assess the cognitive status of 952 GW veterans. We also examined regional brain volumes in a subset of GW veterans (n = 368) who had three Tesla magnetic resonance images (MRIs).

Results

We replicated our previous finding of a greater than 10% rate of MCI in four additional cohorts of GW veterans. In the combined sample of 952 GW veterans (median age 51 years at time of cognitive testing), 17% met criteria for MCI. Veterans classified as MCI were more likely to have CMI, history of depression, and prolonged (≥31 days) deployment-related exposures to smoke from oil well fires and chemical nerve agents compared to veterans with unimpaired and intermediate cognitive status. We also replicated our previous finding of hippocampal atrophy in veterans with MCI, and found significant group differences in lateral ventricle volumes.

Discussion

Because MCI increases the risk for late-life dementia and impacts quality of life, it may be prudent to counsel GW veterans with cognitive dysfunction, CMI, history of depression, and high levels of exposures to deployment-related toxicants to adopt lifestyle habits that have been associated with lowering dementia risk. With the Food and Drug Administration's recent approval of and the VA's decision to cover the cost for anti-amyloid β (Aβ) therapies, a logical next step for this research is to determine if GW veterans with MCI have elevated Aβ in their brains.

Age-Related Alterations in Gray Matter Microstructure in Older People With Remitted Major Depression at Risk for Dementia

Background

Major depressive disorder (MDD) in late life is a risk factor for mild cognitive impairment (MCI) and Alzheimer's disease. However, studies of gray matter changes have produced varied estimates of which structures are implicated in MDD and dementia. Changes in gray matter volume and cortical thickness are macrostructural measures for the microstructural processes of free water accumulation and dendritic spine loss.

Methods

We conducted multishell diffusion imaging to assess gray matter microstructure in 244 older adults with remitted MDD (n = 44), MCI (n = 115), remitted MDD+MCI (n = 61), or without psychiatric disorders or cognitive impairment (healthy control participants; n = 24). We estimated measures related to neurite density, orientation dispersion, and free water (isotropic volume fraction) using a biophysically plausible model (neurite orientation dispersion and density imaging).

Results

Results showed that increasing age was correlated with an increase in isotropic volume fraction and a decrease in orientation dispersion index, which is consistent with neuropathology dendritic loss. In addition, this relationship between age and increased isotropic volume fraction was more disrupted in the MCI group than in the remitted MDD or healthy control groups. However, the association between age and orientation dispersion index was similar for all 3 groups.

Conclusions

The findings suggest that the neurite orientation dispersion and density imaging measures could be used to identify biological risk factors for Alzheimer's disease, signifying both conventional neurodegeneration observed with MCI and dendritic loss seen in MDD.

Glymphatic System and Psychiatric Disorders: A Rapid Comprehensive Scoping Review

BACKGROUND

Since discovering the glymphatic system, there has been a looming interest in exploring its relationship with psychiatric disorders. Recently, increasing evidence suggests an involvement of the glymphatic system in the pathophysiology of psychiatric disorders. However, clear data are still lacking. In this context, this rapid comprehensive PRISMA-ScR (Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews) scoping review aims to identify and analyze current evidence about the relation between the glymphatic system and psychiatric disorders.

METHODS

We conducted a comprehensive review of the literature and then proceeded to discuss the findings narratively. Tables were then constructed and articles were sorted according to authors, year, title, location of study, sample size, psychiatric disorder, the aim of the study, principal findings, implications.

RESULTS

Twenty papers were identified as eligible, among which 2 articles on Schizophrenia, 1 on Autism Spectrum Disorders, 2 on Depression, 1 on Depression and Trauma-related Disorders, 1 on Depression and Anxiety, 2 on Anxiety and Sleep Disorders, 8 on Sleep Disorders, 2 on Alcohol use disorder and 1 on Cocaine Use Disorder.

CONCLUSION

This review suggests a correlation between the glymphatic system and several psychiatric disorders: Schizophrenia, Depression, Anxiety Disorders, Sleep Disorders, Alcohol Use Disorder, Cocaine Use Disorder, Trauma-Related Disorders, and Autism Spectrum Disorders. Impairment of the glymphatic system could play a role in Trauma-Related Disorders, Alcohol Use Disorders, Cocaine Use Disorders, Sleep Disorders, Depression, and Autism Spectrum Disorders. It is important to implement research on this topic and adopt standardized markers and radio diagnostic tools.

Bidirectional associations between memory and depression moderated by sex and age: Findings from the CLSA

BACKGROUND

Research has struggled to understand the temporal relationship between cognition and depression. Some literature suggests that depression may be a risk factor for memory decline, while other work indicates that memory decline may precede depression symptoms. The purpose of this study was to clarify the temporal relationship between memory and depression, examining the moderating role of sex and age.

METHODS

Data were drawn from two time points in the Canadian Longitudinal Study on Aging (CLSA). Memory was measured using a composite of immediate and delayed verbal recall scores, and depressive symptoms were measured using the Center for Epidemiologic Studies Short Depression Scale (CESD-10). Separate cross-lagged panel models (CLPMs) were run based on age (i.e., ages 45-64; ages 65+) and sex (n = 51,338).

RESULTS

Results indicated bidirectional associations between depressive symptoms and memory such that depressive symptoms at baseline predicted memory at follow-up (β= 0.029-0.068, with all p-values <0.01) and memory at baseline predicted depressive symptoms at follow-up (β= 0.025-0.033, with all p-values <0.05). The only exception was in the older female group, where memory did not predict depressive symptoms (β= -0.006, p = 0.543). Depressive symptoms at baseline were a stronger predictor of memory at follow-up than memory at baseline was for depressive symptoms at follow-up in all groups except for older males.

FINDINGS

The findings suggest small but consistent bidirectional associations between depression and memory in almost all sex/age groupings. Depressive symptoms tended to be a stronger predictor of memory than memory was for future depressive symptoms.

Comparison of the 10-, 14- and 20-Item CES-D Scores as Predictors of Cognitive Decline

The association between depressive symptomatology and cognitive decline has been examined using the Centre for Epidemiologic Studies-Depression Scale (CES-D); however, concerns have been raised about this self-report measure. Here, we examined how the CES-D total score from the 14- and 10-item versions compared to the 20-item version in predicting progression to cognitive decline from a cognitively unimpaired baseline. Data from 1054 participants were analysed using ordinal logistic regression, alongside moderator and receiver-operating characteristics curve analyses. All baseline total scores significantly predicted progression to cognitive decline. The 14-item version was better than the 20-item version in predicting consensus diagnosis, as shown by their AICs, while also showing the highest accuracy when discriminating between participants by diagnosis at last visit. We did not find sex to moderate the relationship between CES-D score and cognitive decline. Current findings suggest the 10- and 14-item versions of the CES-D are comparable to the 20-item version, and that the 14-item version may be better at predicting longitudinal consensus diagnosis compared to the 20-item version.

Neuropsychological Performance in Alzheimer's Disease versus Late-Life Depression: A Systematic Review and Meta-Analysis

OBJECTIVE

Despite decades of research, neuropsychological tests (NPTs) that clearly differentiate between Alzheimer's disease (AD) and late-life depression (LLD) have yet to be agreed upon. Given this gap in knowledge and the rapid deployment of disease-modifying drugs for the two disorders, accurate clinical diagnosis using evidence-based assessment is essential. This study aims to systematically examine the literature to identify NPTs that would be able to differentiate AD and LLD.

METHOD

Databases and bibliographies were searched to identify articles for analysis. Two major inclusion criteria were that the studies compared neuropsychological functioning of AD versus LLD using normed NPTs and provided data for effect size calculation. Risk of bias was minimized by having independent coders for all steps in the review.

RESULTS

Forty-one studies met inclusion criteria (N = 2,797) and provided effect sizes for tests that were classified as belonging to 15 domains of functioning. The two groups were well differentiated by tasks of delayed contextual verbal memory as compared to immediate or non-contextual memory, recognition cueing, confrontation naming, visuospatial construction, and conceptualization. Specific NPTs that appear to be useful for differential diagnosis include the Rey Auditory Verbal Learning Test-Delayed Recognition; Boston Naming Test; the Dementia Rating Scale's memory, conceptualization, and construction subscales; and the CERAD Constructional Praxis.

CONCLUSIONS

The NPTs highlighted in this systematic review could be used as a relatively simple and cost-effective method to differentiate between patients with cognitive dysfunction due to AD versus LLD.

Minimal amount of exercise prevents incident dementia in cognitively normal older adults with osteoarthritis: a retrospective longitudinal follow-up study

Robust evidence suggests that regular exercise, including walking more than 6000 steps, is effective for preventing dementia; however, such activity is less feasible in older people with osteoarthritis (OA) or other motor disabilities. Therefore, we aimed to test whether the minimal amount of exercise (MAE) could help prevent dementia in older adults with OA. A retrospective longitudinal study was performed and a non-demented cohort (≥ 50-years-old) of 242 people (155 [64.0%] non-converters and 87 [36.0%] converters) from three centers in Taiwan was analyzed with a mean follow-up of 3.1 (range 0.3-5.9) and 2.9 (range 0.5-6.0) years, respectively. MAE was defined as walking for approximately 15-30 min or 1500-3000 steps. Rate of MAE (0, 1-2, or ≥ 3) within one week were defined as MAE-no, MAE-weekly, or MAE-daily, respectively. The incidence rates of dementia were compared between groups. Multivariate logistic regression and Cox proportional hazards analyses were used to study the influence of MAE on dementia occurrence. Age, education, sex, activities of daily living, neuropsychiatric symptoms, cognition, multiple vascular risk factors, and related medications were adjusted. Compared to the MAE-no group, the odds ratios for the incidents of dementia were 0.48 and 0.19 in the MAE-weekly and MAE-daily groups, respectively. In addition, older age, poorer cognition, poorer ADL performance, and congestive heart failure increased the incidence of dementia. Daily and weekly MAE prevented dementia in older adults with OA. As such, an informative public health policy may help promote adequate exercise in at-risk groups.

Associations between psychological therapy outcomes for depression and incidence of dementia

BACKGROUND

Depression is an important, potentially modifiable dementia risk factor. However, it is not known whether effective treatment of depression through psychological therapies is associated with reduced dementia incidence. The aim of this study was to investigate associations between reduction in depressive symptoms following psychological therapy and the subsequent incidence of dementia.

METHODS

National psychological therapy data were linked with hospital records of dementia diagnosis for 119808 people aged 65+. Participants received a course of psychological therapy treatment in Improving Access to Psychological Therapies (IAPT) services between 2012 and 2019. Cox proportional hazards models were run to test associations between improvement in depression following psychological therapy and incidence of dementia diagnosis up to eight years later.

RESULTS

Improvements in depression following treatment were associated with reduced rates of dementia diagnosis up to 8 years later (HR = 0.88, 95% CI 0.83-0.94), after adjustment for key covariates. Strongest effects were observed for vascular dementia (HR = 0.86, 95% CI 0.77-0.97) compared with Alzheimer's disease (HR = 0.91, 95% CI 0.83-1.00).

CONCLUSIONS

Reliable improvement in depression across psychological therapy was associated with reduced incidence of future dementia. Results are consistent with at least two possibilities. Firstly, psychological interventions to improve symptoms of depression may have the potential to contribute to dementia risk reduction efforts. Secondly, psychological therapies may be less effective in people with underlying dementia pathology or they may be more likely to drop out of therapy (reverse causality). Tackling the under-representation of older people in psychological therapies and optimizing therapy outcomes is an important goal for future research.

Brain structure and phenotypic profile of superagers compared with age-matched older adults: a longitudinal analysis from the Vallecas Project

BACKGROUND

Cognitive abilities, particularly memory, normally decline with age. However, some individuals, often designated as superagers, can reach late life with the memory function of individuals 30 years younger. We aimed to characterise the brain structure of superagers and identify demographic, lifestyle, and clinical factors associated with this phenotype.

METHODS

We selected cognitively healthy participants from the Vallecas Project longitudinal cohort recruited between Oct 10, 2011, and Jan 14, 2014, aged 79·5 years or older, on the basis of their delayed verbal episodic memory score. Participants were assessed with the Free and Cued Selective Reminding Test and with three non-memory tests (the 15-item version of the Boston Naming Test, the Digit Symbol Substitution Test, and the Animal Fluency Test). Participants were classified as superagers if they scored at or above the mean values for a 50-56-year-old in the Free and Cued Selective Reminding Test and within one standard deviation of the mean or above for their age and education level in the three non-memory tests, or as typical older adults if they scored within one standard deviation of the mean for their age and education level in the Free and Cued Selective Reminding Test. Data acquired as per protocol from up to six yearly follow-ups were used for longitudinal analyses.

FINDINGS

We included 64 superagers (mean age 81·9 years; 38 [59%] women and 26 [41%] men) and 55 typical older adults (82·4 years; 35 [64%] women and 20 [36%] men). The median number of follow-up visits was 5·0 (IQR 5·0-6·0) for superagers and 5·0 (4·5-6·0) for typical older adults. Superagers exhibited higher grey matter volume cross-sectionally in the medial temporal lobe, cholinergic forebrain, and motor thalamus. Longitudinally, superagers also showed slower total grey matter atrophy, particularly within the medial temporal lobe, than did typical older adults. A machine learning classification including 89 demographic, lifestyle, and clinical predictors showed that faster movement speed (despite no group differences in exercise frequency) and better mental health were the most differentiating factors for superagers. Similar concentrations of dementia blood biomarkers in superager and typical older adult groups suggest that group differences reflect inherent superager resistance to typical age-related memory loss.

INTERPRETATION

Factors associated with dementia prevention are also relevant for resistance to age-related memory decline and brain atrophy, and the association between superageing and movement speed could provide potential novel insights into how to preserve memory function into the ninth decade.

FUNDING

Queen Sofia Foundation, CIEN Foundation, Spanish Ministry of Science and Innovation, Alzheimer's Association, European Research Council, MAPFRE Foundation, Carl Zeiss Foundation, and the EU Comission for Horizon 2020.

TRANSLATION

For the Spanish translation of the abstract see Supplementary Materials section.

Putative pathological mechanisms of late-life depression and Alzheimer's Disease

Alzheimer's disease (AD) is a neurodegenerative disorder that is characterized by progressive impairment in cognition and memory. AD is accompanied by several neuropsychiatric symptoms, with depression being the most prominent. Although depression has long been known to be associated with AD, controversial findings from preclinical and clinical studies have obscured the precise nature of this association. However recent evidence suggests that depression could be a prodrome or harbinger of AD. Evidence indicates that the major central serotonergic nucleus-the dorsal raphe nucleus (DRN)-shows very early AD pathology: neurofibrillary tangles made of hyperphosphorylated tau protein and degenerated neurites. AD and depression share common pathophysiologies, including functional deficits of the serotonin (5-HT) system. 5-HT receptors have modulatory effects on the progression of AD pathology i.e., reduction in Aβ load, increased hyper-phosphorylation of tau, decreased oxidative stress etc. Moreover, preclinical models show a role for specific channelopathies that result in abnormal regional activational and neuroplasticity patterns. One of these concerns the pathological upregulation of the small conductance calcium-activated potassium (SK) channel in corticolimbic structure. This has also been observed in the DRN in both diseases. The SKC is a key regulator of cell excitability and long-term potentiation (LTP). SKC over-expression is positively correlated with aging and cognitive decline, and is evident in AD. Pharmacological blockade of SKCs has been reported to reverse symptoms of depression and AD. Thus, aberrant SKC functioning could be related to depression pathophysiology and diverts its late-life progression towards the development of AD. We summarize findings from preclinical and clinical studies suggesting a molecular linkage between depression and AD pathology. We also provide a rationale for considering SKCs as a novel pharmacological target for the treatment of AD-associated symptoms.

Frailty transition and depression among community-dwelling older adults: the Korean Longitudinal Study of Aging (2006-2020)

BACKGROUND

Frailty is recognized as a geriatric syndrome associated with depression. The consequences and mechanism of frailty transitions are still understudied. This study assessed the influence of frailty transitions on new-onset depressive symptomology using longitudinal, nationwide data of Korean community-dwelling older adults.

METHODS

Longitudinal population-based study conducted in every even-numbered year starting from 2006 to 2020 (eight waves) with a sample of older adults aged ≥ 60 years old. After the application of exclusion criteria, a total of 2,256 participants were included in the 2008 baseline year. Frailty transition was determined through the biennial assessment of change in frailty status using the frailty instrument (FI); depression was measured using the Center for Epidemiological Studies Depression 10 Scale. We employed the lagged general estimating equations to assess the temporal effect of frailty transition on obtaining depressive symptoms.

RESULTS

Compared to non-frail individuals, the risk of depression was higher in transitioned into frailty and constantly frail participants over a 2-year interval: men (odds ratio (OR) 1.26, 95% confidence interval (CI) 1.21-1.32; OR 1.29, 95% CI 1.21-1.38), women (OR 1.34, 95% CI 1.28-1.40; OR 1.51, 95% CI 1.41-1.62), respectively.

CONCLUSIONS

Frailty transition is found to be associated with new-onset depressive symptoms. Frail individuals and those who transitioned into frailty were associated with a higher risk of depression. Particular attention should be paid to these frailty transitioned groups. Early intervention and implementation of prevention strategies at physical, nutritional, and social levels are warranted to ameliorate frailty and depression in late life.

Chronic Stress, Depression, and Alzheimer's Disease: The Triangle of Oblivion

Chronic stress and high levels of the main stress hormones, and glucocorticoids (GC), are implicated in susceptibility to brain pathologies such as depression and Alzheimer's disease (AD), as they promote neural plasticity damage and glial reactivity, which can lead to dendritic/synaptic loss, reduced neurogenesis, mood deficits, and impaired cognition. Moreover, depression is implicated in the development of AD with chronic stress being a potential link between both disorders via common neurobiological underpinnings. Hereby, we summarize and discuss the clinical and preclinical evidence related to the detrimental effect of chronic stress as a precipitator of AD through the activation of pathological mechanisms leading to the accumulation of amyloid β (Aβ) and Tau protein. Given that the modern lifestyle increasingly exposes individuals to high stress loads, it is clear that understanding the mechanistic link(s) between chronic stress, depression, and AD pathogenesis may facilitate the treatment of AD and other stress-related disorders.

Age- and sex-specific modifiable risk factor profiles of dementia: evidence from the UK Biobank

Dementia constitutes a worldwide concern. To characterize the age- and sex-specific modifiable risk factor profiles of dementia, we included 497,401 UK Biobank participants (mean age = 56.5 years) without dementia at baseline (2006-2010) and followed them until March 2021. Cox proportional hazard models were used to estimate the age- and sex-specific hazard ratios (HRs) of incident dementia associated with socioeconomic (less education and high Townsend deprivation index), lifestyle (non-moderate alcohol intake, current smoking, suboptimal diet, physical inactivity, and unhealthy sleep duration), and health condition factors (hypertension, diabetes, cardiovascular diseases, and depressive symptoms). We also calculated the population attributable fractions (PAFs) of these factors. During follow-up (mean = 11.6 years), we identified 6564 dementia cases. HRs for the risk factors were similar between the sexes, while most factors showed stronger associations among younger participants. For example, the HRs of smoking were 1.74 (95% CI: 1.23, 2.47) for individuals aged < 50 years, and 1.18 (1.05, 1.33) for those aged ≥ 65 years. Overall, 46.8% (37.4%, 55.2%) of dementia cases were attributable to the investigated risk factors. The PAFs of the investigated risk factors also decreased with age, but that for health condition risk factors decreased with lower magnitude than socioeconomic and lifestyle risk factors. The stronger associations and greater PAFs of several modifiable risk factors for dementia among younger adults than older participants underscored the importance of dementia prevention from an earlier stage across the adult life course.

Lifestyle Adjustment: Influential Risk Factors in Cognitive Aging

Cognitive aging is inevitable. However, researchers have demonstrated that lifestyle adjustments can reduce the risk of cognitive impairment. A healthy diet style, the Mediterranean diet, has been proven to benefit the elderly. Oil, salt, sugar, and fat are, on the contrary, risk factors for cognitive dysfunction because of the resultant high caloric intake. Physical and mental exercises, especially cognitive training, are also beneficial for aging. At the same time, several risk factors need to be noted, such as smoking, alcohol consumption, insomnia, and excessive daytime sleeping, which are highly relative to cognitive impairment, cardiovascular diseases, and dementia.

Multi-stage classification of Alzheimer's disease from 18F-FDG-PET images using deep learning techniques

The study aims to implement a convolutional neural network framework that uses the 18F-FDG PET modality of brain imaging to detect multiple stages of dementia, including Early Mild Cognitive Impairment (EMCI) and Late Mild Cognitive Impairment (LMCI), and Alzheimer's disease (AD) from Cognitively Normal (CN), and assess the results. 18F-FDG PET imaging modality for brain were procured from Alzheimer's disease neuroimaging initiative's (ADNI) repository. The ResNet50V2 model layers were utilised for feature extraction, with the final convolutional layers fine-tuned for this dataset's multi-classification objectives. Multiple metrics and feature maps were utilized to scrutinize and evaluate the model's statistical and qualitative inference. The multi-classification model achieved an overarching accuracy of 98.44% and Area under the receiver operating characteristic curve of 95% on the testing set. Feature maps aided in deducing finer aspects of the model's overall operation. This framework helped classifying from the 18F-FDG PET brain images, the subtypes of Mild Cognitive Impairment (MCI) which include EMCI, LMCI, from AD, CN groups and achieved an all-inclusive sensitivity of 94% and specificity of 95% respectively.

Fluctuation of depressive symptoms in cognitively unimpaired participants and the risk of mild cognitive impairment 5 years later: Results of the Heinz Nixdorf Recall study

BACKGROUND

Depression might be an independent risk factor for cognitive decline, a prodromal dementia symptom or a reaction to cognitive/functional impairment.

OBJECTIVE

To investigate the association between (1) depressive symptoms and (2) depressive symptom patterns over 13 years with incident mild cognitive impairment (MCI) 5 years later.

MATERIALS AND METHODS

We included 724/823 cognitively unimpaired men/women who participated in the population-based Heinz Nixdorf Recall study (t1: 2005-2008, ø62.9 years; t2: 2010-2015, ø68.1 years). Depressive symptoms were assessed in the study center and during six postal follow-ups using the short form of the Center for Epidemiologic Studies Depression Scale (CES-D). Relative risks (RR; 95% confidence intervals) for MCI at t2 (men/women: 71/76) were estimated for CES-D at t1 (linear and dichotomized at ≥17, cut-off for clinically relevant depressive symptoms) and CES-D fluctuations over 13 years (stable low, large fluctuations, stable high/stable around cut-off) using log-linear regression models with Poisson working likelihood adjusted for age, sex, education, diabetes mellitus, coronary heart disease, and stroke.

RESULTS

Fully adjusted risk for MCI at t2 (per CES-D point increase at t1) was elevated for the total cohort (1.053, 1.031-1.076), men (1.046, 1.012-1.081), and women (1.059, 1.029-1.090). Applying the dichotomized CES-D, risk for MCI was substantially increased for the total cohort [2.22 (1.38-3.58)] and in women [2.59 (1.46-4.58)]. Large CES-D fluctuations and stable high/stable around cut-off were associated with increased RR for MCI in the total cohort and in women compared to stable low symptoms.

CONCLUSION

Depressive symptoms predicted MCI in cognitively unimpaired participants of our population-based study. Adequate treatment of depression may therefore contribute to the maintenance of normal cognition and delay dementia onset.

A smart healthcare-based system for classification of dementia using deep learning

Objectives

This study aims to develop a deep learning-based classification model for early detection of dementia using a wearable device that can measure the electrical conductivity of the skin, temperature, and movement as factors related to dementia, interlocking them with an application, and analyzing the collected data.

Methods

This study was conducted on 18 elderly individuals (5 males, 13 females) aged 65 years or older who consented to the study. The Korean Mini-Mental State Examination survey for cognitive function tests was conducted by well-trained researchers. The subjects were first grouped into high- or low-risk group for dementia based on their Korean Mini-Mental State Examination score. Data obtained by wearable devices of each subject were then used for the classification of the high- and low-risk groups of dementia through a smart healthcare-based system implementing a deep neural network with scaled principal component analysis. The correlation coefficients between the Korean Mini-Mental State Examination score and the featured data were also investigated.

Results

Our study showed that the proposed system using a deep neural network with scaled principal component analysis was effective in detecting individuals at high risk for dementia with up to 99% accuracy and which performance was better compared with commonly used classification algorithms. In addition, it was found that the electrical conductivity of skin had the closest correlation with the results of the Korean Mini-Mental State Examination score among data collected through wearable devices in this study.

Conclusions

Our proposed system can contribute to effective early detection of dementia for the elderly, using a non-invasive and easy-to-wear wearable device and classification algorithms with a simple cognitive function test. In the future, we intend to have more subjects participate in the experiment, to include more relevant variables in the wearable device, and to analyze the effectiveness of the smart healthcare-based dementia classification system over the long term.

Plasma Amyloid-β dynamics in late-life major depression: a longitudinal study

Depressed individuals are twice as likely to develop Alzheimer's disease (AD) as compared to controls. Brain amyloid-β (Aβ) deposition is believed to have a major role in AD pathogenesis but studies also suggest associations of Aβ dynamics and depression. The aim of this study was to test if plasma Aβ levels are longitudinally associated to late-life depression. We measured plasma levels of amyloid-β_1-40 (Aβ40) and amyloid-β_1-42 (Aβ42) peptides longitudinally for three consecutive years in 48 cognitively intact elderly subjects with late-life major depressive disorder (LLMD) and 45 age-matched cognitively healthy controls. We found that the Aβ42/Aβ40 plasma ratio was significantly and steadily lower in depressed subjects compared to controls (p < 0.001). At screening, Aβ42/Aβ40 plasma did not correlate with depression severity (as measured with Hamilton Depression Scale) or cognitive performance (as measured with Mini-Mental State Examination) but was associated to depression severity at 3 years after adjustment for age, education, cognitive performance, and antidepressants use. This study showed that reduced plasma Aβ42/Aβ40 ratio is consistently associated with LLMD diagnosis and that increased severity of depression at baseline predicted low Aβ42/Aβ40 ratio at 3 years. Future studies are needed to confirm these findings and examine if the consistently lower plasma Aβ42/Aβ40 ratio in LLMD reflects increased brain amyloid deposition, as observed in AD subjects, and an increased risk for progressive cognitive decline and AD.

An analytical pathway of consumption expenditure with neighborhood deprivation and depression on cognitive health among elderly in India: A moderated mediation approach

BACKGROUND

This study aims to find the linkage between neighborhood deprivation and cognition with depression as a mediating factor while economic condition as a moderator.

METHODS

We have used the recent baseline wave-1 data of Longitudinal Aging Study in India (LASI), 2017-2018. The study was restricted to 60 and above population, consisting of males (14,931) and females (16,533). We have used moderated mediating model to understand the relationship between deprivation (X), cognition (Y) mediated through depression (M), moderated by economic condition (W), while controlling all possible confounders.

RESULTS

Neighborhood deprivation was positively associated with depression (β: 0.12; SE: 0.01) and inversely linked to cognition (β: -0.4; SE: 0.02). Deprivation had a strong indirect effect on cognition that was mediated by depression. Further, interaction of depression (M) and economic condition (W) was negatively associated (β = -0.03; SE: 0.01) with cognition (Y), indicating that lower economic section being more depressed with lower cognitive function.

LIMITATIONS

The study failed to capture other mental health aspects like stress and anxiety using the Depression, Anxiety and Stress Scale-21 items (DASS-21).

CONCLUSIONS

This study has found a link between higher economic condition with low deprivation and depression. Older individuals with better financial situation have improved cognitive level than their counterparts, who are also depressed. This study provides an opportunity to conduct future research on cognitive health in the face of population aging in India.

Decreased Cerebral Amyloid-β Depositions in Patients With a Lifetime History of Major Depression With Suspected Non-Alzheimer Pathophysiology

Cerebral amyloid-β (Aβ) depositions in depression in old age are controversial. A substantial proportion of individuals with late-life major depressive disorder (MDD) could be classified as having suspected non-Alzheimer’s disease pathophysiology (SNAP) by a negative test for the biomarker amyloid-β (Aβ−) but positive neurodegeneration (ND+). This study aimed to evaluate subthreshold Aβ loads in amyloid-negative MDD, particularly in SNAP MDD patients. This study included 46 amyloid-negative MDD patients: 23 SNAP (Aβ−/ND+) MDD and 23 Aβ−/ND− MDD, and 22 Aβ−/ND− control subjects. All subjects underwent ¹⁸F-florbetapir PET, FDG-PET, and MRI. Regions of interest (ROIs) and voxel-wise group comparisons were performed with adjustment for age, gender, and level of education. The SNAP MDD patients exhibited significantly deceased ¹⁸F-florbetapir uptakes in most cortical regions but not the parietal and precuneus cortex, as compared with the Aβ−/ND− MDD and control subjects (FDR correction, p < 0.05). No correlations of neuropsychological tests or depression characteristics with global cortical uptakes, but significant positive correlations between cognitive functions and adjusted hippocampal volumes among different groups were observed. The reduced Aβ depositions in the amyloid-negative MDD patients might be attributed mainly to the SNAP MDD patients. Our results indicated that meaningfully low amounts of subclinical Aβ might contain critical information on the non-amyloid-mediated pathogenesis.

Cognitive, Functional, and Emotional Changes During the COVID-19 Pandemic in Greek Patients with Neurocognitive Disorders

BACKGROUND

Prolonged periods of social deprivation, such as COVID-19-related lockdowns, are associated with deleterious effects on cognitive functions.

OBJECTIVE

The aim of this study was to gauge the effect of prolonged social isolation on the cognitive function of older adults with neurocognitive disorders.

METHODS

We recruited 125 older adults with minor or major neurocognitive disorders divided into two groups. The control group was tested at the first period of the study (October 2018-May 2019), whereas the experimental group was evaluated at the second chronological period of the study (October 2020-May 2021) during the second wave of COVID-19. Neuropsychological tests were performed at baseline and six months after baseline.

RESULTS

In the control group, significant changes in the scores from the Montreal Cognitive Assessment (MoCA; p = 0.049) and the Functional Rating Scale for Symptoms of Dementia (FRSSD; p = 0.005) were found between baseline and follow-up assessments, whereas no changes were identified in Mini-Mental State Examination (MMSE; p = 0.229) and Geriatric Depression Scale (GDS; p = 0.619) scores. In the experimental group, the scores from all neuropsychological tests (MoCA, MMSE, GDS, and FRSSD; p < 0.001 for all) were significantly different at follow-up when compared with those at baseline measurements. Moreover, significant deterioration of specific functions assessed in MMSE and FRSSD was detected, especially in the experimental group.

CONCLUSION

This study highlights cognitive functions directly affected by social deprivation of individuals with neurocognitive disorders. The findings can be used in the rehabilitation from confinement and its negative consequences.

Adipose Tissue Compartments, Inflammation, and Cardiovascular Risk in the Context of Depression

The neurobiological and behavioral underpinnings linking mental disorders, in particular, major depressive disorder (MDD), with cardiovascular disorders are a matter of debate. Recent research focuses on visceral (intra-abdominal and epicardial) adipose tissue and inflammation and their impact on the development of cardiometabolic disorders. Intra-abdominal adipose tissue is defined as an endocrine active fat compartment surrounding inner organs and is associated with type 2 diabetes mellitus, a risk factor for the later development of cardiovascular disorders. Epicardial (pericardial) adipose tissue is a fat compartment surrounding the heart with close proximity to the arteries supporting the heart. Visceral adipose tissue (VAT) is an important source of inflammatory mediators that, in concert with other risk factors, plays a leading role in cardiovascular diseases. In conjunction with the behavioral (physical inactivity, sedentary lifestyle), psychological (adherence problems), and hormonal (dysfunction of the hypothalamus-pituitary-adrenal axis with subsequent hypercortisolism) alterations frequently accompanying MDD, an enhanced risk for cardiovascular disorders results.

Examining heterogeneity in depression symptoms and associations with cognition and everyday function in MCI

INTRODUCTION

Although there is some evidence that different symptoms of depression have differential effects on cognition in older adults, these relationships remain understudied in older adults with mild cognitive impairment (MCI).

METHOD

Older adults (>50 years old) were classified as having MCI by Alzheimer's Disease Research Centers (ADRCs). Exploratory factor analyses and factor mixture modeling were used to determine depression symptom classes. Classes were then compared across different domains of cognition (i.e., memory, attention, language, and executive function) and informant-rated everyday function.

RESULTS

Analyses revealed six, distinct symptom classes (i.e., somatic symptoms, severely depressed, anhedonic symptoms, cognitive symptoms, minimally depressed, and low life satisfaction symptoms). Classes significantly varied on all measures of cognition and everyday function. In particular, the anhedonic class often showed the most substantial decline (on par with the severely depressed class), while the low life satisfaction class often showed the least (on par with the minimally depressed class).

CONCLUSIONS

To our knowledge, this is the first study to examine the relationship between depression symptom profiles and cognitive and everyday function in those with MCI. Our findings show that depression symptoms greatly differ in their associations with cognitive and everyday function. It may be beneficial for clinicians to specifically note if patients with MCI are reporting anhedonic and somatic symptoms of depression specifically.

Counterfactual analysis of differential comorbidity risk factors in Alzheimer's disease and related dementias

Alzheimer's disease and related dementias (ADRD) is a multifactorial disease that involves several different etiologic mechanisms with various comorbidities. There is also significant heterogeneity in the prevalence of ADRD across diverse demographics groups. Association studies on such heterogeneous comorbidity risk factors are limited in their ability to determine causation. We aim to compare counterfactual treatment effects of various comorbidity in ADRD in different racial groups (African Americans and Caucasians). We used 138,026 ADRD and 1:1 matched older adults without ADRD from nationwide electronic health records, which extensively cover a large population's long medical history in breadth. We matched African Americans and Caucasians based on age, sex, and high-risk comorbidities (hypertension, diabetes, obesity, vascular disease, heart disease, and head injury) to build two comparable cohorts. We derived a Bayesian network of 100 comorbidities and selected comorbidities with potential causal effect to ADRD. We estimated the average treatment effect (ATE) of the selected comorbidities on ADRD using inverse probability of treatment weighting. Late effects of cerebrovascular disease significantly predisposed older African Americans (ATE = 0.2715) to ADRD, but not in the Caucasian counterparts; depression significantly predisposed older Caucasian counterparts (ATE = 0.1560) to ADRD, but not in the African Americans. Our extensive counterfactual analysis using a nationwide EHR discovered different comorbidities that predispose older African Americans to ADRD compared to Caucasian counterparts. Despite the noisy and incomplete nature of the real-world data, the counterfactual analysis on the comorbidity risk factors can be a valuable tool to support the risk factor exposure studies.

An optimized MRI and PET based clinical protocol for improving the differential diagnosis of geriatric depression and Alzheimer's disease

Amyloid positron emission tomography (PET) and hippocampal volume derived from magnetic resonance imaging may be useful clinical biomarkers for differentiating between geriatric depression and Alzheimer's disease (AD). Here we investigated the incremental value of using hippocampal volume and 18F-flutemetmol amyloid PET measures in tandem and sequentially to improve discrimination in unclassified participants. Two approaches were compared in 41 participants with geriatric depression and 27 participants with probable AD: (1) amyloid and hippocampal volume combined in one model and (2) classification based on hippocampal volume first and then subsequent stratification using standardized uptake value ratio (SUVR)-determined amyloid positivity. Hippocampal volume and amyloid SUVR were significant diagnostic predictors of depression (sensitivity: 95%, specificity: 89%). 51% of participants were correctly classified according to clinical diagnosis based on hippocampal volume alone, increasing to 87% when adding amyloid data (sensitivity: 94%, specificity: 78%). Our results suggest that hippocampal volume may be a useful gatekeeper for identifying depressed individuals at risk for AD who would benefit from additional amyloid biomarkers when available.

Annual Incidence of Dementia from 2003 to 2018 in Metropolitan Seoul, Korea: A Population-Based Study

National dementia plans were applied in dementia support centers established in Seoul, Korea between 2007 and 2009. However, the annual incidence rates of dementia in Seoul have not been reported. We investigated this annual incidence and the characteristics of incident cases from 2003 to 2018. The customized research database of the Korean National Health Insurance Services was used. The annual crude and age-standardized incidence of dementia patients and their characteristics were analyzed. This study analyzed 108,596 incident dementia cases aged ≥60 years. The incidence rate increased from 2003 to 2011, including a rapid increment from 2007 to 2011. From 2011 to 2018, the crude (age-standardized) incidence per 105 person-years decreased from 641.51 (577.12) to 448.26 (361.23). The proportion of incident dementia cases was highest in the highest income group every year. However, the proportion of incident dementia cases in the lowest income group increased from 10.4% in 2003 to 25.8% in 2011. The annual incidence rate of dementia showed a sharp increase immediately after 2007, the year dementia support centers began to be introduced, and then stabilized after 2011. The characteristics of incident dementia cases have changed, including the proportion in the low-income group.

Serum amyloid P component level is associated with clinical response to escitalopram treatment in patients with major depressive disorder

Serum amyloid P component (SAP) is a universal constituent of human amyloid deposits, which has been implicated in Alzheimer's disease and major depressive disorder (MDD). However, the relationship between SAP level and depression severity remains obscure. The aims of this study were to investigate how SAP is involved in depression and to explore the association between SAP level and antidepressant treatment response. Patients with MDD (n = 85) who received escitalopram monotherapy for 8-12 weeks were selected from a multicenter open-label randomized clinical trial. The same number of healthy controls was recruited. Depression severity was measured according to the Hamilton Depression Rating Scale (HAMD-17) at baseline and weeks 4, 8, and 12. The plasma levels of SAP were measured at baseline, week 2 and week 12. As a result, baseline levels of SAP were significantly higher in depressed patients than in control subjects (p < 0.001). SAP levels at baseline were negatively associated with depression severity after escitalopram treatment (p < 0.05), and the changes in SAP levels from baseline to week 12 were highly correlated with the severity of depressive symptoms based on the HAMD-17 score (p < 0.05). Interestingly, treatment with escitalopram significantly decreased the plasma levels of SAP in females, but not in males. Altogether, our results suggest that SAP not only involved in the pathobiology of depression but also mediates the action of antidepressant medications.

Worldwide Occurrence of HIV-Associated Neurocognitive Disorders and Its Associated Factors: A Systematic Review and Meta-Analysis

BACKGROUND

HIV-associated neurocognitive disorders are common in people living with HIV/AIDS and affect the adherence of patients to prescriptions, activities of daily living, and quality of life of patients. However, there is a lack of summative evidence in the area. The present meta-analysis was therefore addressing this gap.

METHODS

We did our electronic search in Psych-Info, EMBASE, Scopus, and PubMed. The retrieved articles were stored with the endnote reference manager and data was extracted using Meta-XL version 5.3. The quality of studies was evaluated with the modified Newcastle-Ottawa Scale (NOS). A random-effect model and STATA-16 were used to compute the average estimate of HAND. Heterogeneity was weighed with I² statistics. A sensitivity analysis and subgroup analysis were employed. The existence/nonexistence of a publication bias was checked with the Eggers test of publication bias.

RESULTS

The average prevalence of HAND was 50.41% (95% CI: 45.56, 55.26). The average estimate of HAND in Europe was found to be 50.015% whereas in Africa, Asia, and the United States of America (USA) it was 49.566, 52.032, and 50.407% respectively. The prevalence of HAND in studies that used the HIV Dementia Scale (IHDS) was 36.883% and 59.956% at cutoff points of IHDS <9.5 and IHDS <10 respectively. Besides, the estimated average of HAND with the global dementia scale (GDS) was 40.766%. The prevalence of HAND in cross-sectional, cohort, and case-control studies was 49.52, 54.087, and 44.45% in that order. Socio-demographic variables; low level of education and older age, clinical and HIV related variables; the advanced stage of the illness and CD4 count of 500 cells/dl or less and psychological variables such as comorbidity of depression increases the risk of HAND.

CONCLUSION

The prevalence of HIV-associated neurocognitive disorders was about 50.41%. Low level of education and older age, clinical and HIV related variables such as the advanced stage of the illness and CD4 count of 500 cells/dl or less, and comorbidity of depression were associated with HIV associated neurocognitive disorders. Public health interventions for HIV patients should target these essential problems.

Different Sides of Depression in the Elderly: An In-depth View on the Role of Aβ Peptides

BACKGROUND

Late-onset depression (LOD) is the most common neuropsychiatric disorder associated with Alzheimer's disease (AD), often associated with structural and functional brain changes, neuropsychological impairments and negative family history for affective disorders. LOD could be a risk factor or a prodromal phase of AD; this has led to the investigation of the link between depression and amyloid-β (Aβ) peptides by measuring Aβ levels in plasma, cerebrospinal fluid (CSF) and brains of elderly depressed subjects.

OBJECTIVE

Clarify the complex relationship between depression, Aβ peptides and AD.

METHOD

We evaluated all articles published up to 2019 in PubMed in which Aβ was measured in serum (or plasma), CSF or brain in elderly with Major Depressive Disorder or depressive symptoms evaluated with standard scales.

RESULTS

Low plasma Aβ42 levels are strongly associated with depression severity. Plasma Aβ40 levels are higher in younger depressed, drug-resistant and those with more severe symptoms. CSF Aβ42 levels are lower in depressed than controls. PET-detected global and region-specific increases in Aβ deposition are sometimes associated with LOD, cognitive impairment, anxiety but not with Cardiovascular Diseases (CVDs)/CVD risk factors. Elderly depressed with CVDs/CVD risk factors have more frequently high plasma Aβ40 levels and drug-resistance; those without these co-morbidities have low plasma Aβ42 levels and a greater cognitive impairment.

CONCLUSION

Two specific Aβ profiles emerge in elderly depressed. One is associated with Aβ42 reductions in plasma and CSF, possibly reflecting increased brain amyloid deposition and prodromal AD. The other one is characterized by high plasma Aβ40 levels, cerebrovascular disease and clinically associated with increased AD risk.

Cognitive impairment and depression: Meta-analysis of structural magnetic resonance imaging studies

Longitudinal comorbidity of depression and cognitive impairment has been reported by number of epidemiological studies but the underlying mechanisms explaining the link between affective problems and cognitive decline are not very well understood. Imaging studies have typically investigated patients with major depressive disorder (MDD) and mild cognitive impairment (MCI) separately and thus have not identified a structural brain signature common to these conditions that may illuminate potentially targetable shared biological mechanisms. We performed a meta-analysis of. 48 voxel-based morphometry (VBM) studies of individuals with MDD, MCI, and age-matched controls and demonstrated that MDD and MCI patients had shared volumetric reductions in a number of regions including the insula, superior temporal gyrus (STG), inferior frontal gyrus, amygdala, hippocampus, and thalamus. We suggest that the shared volumetric reductions in the insula and STG might reflect communication deficits and infrequent participation in mentally or socially stimulating activities, which have been described as risk factors for both MCI and MDD. We also suggest that the disease-specific structural changes might reflect the disease-specific symptoms such as poor integration of emotional information, feelings of helplessness and worthlessness, and anhedonia in MDD. These findings could contribute to better understanding of the origins of MDD-MCI comorbidity and facilitate development of early interventions.

Estrogen Receptor α Agonist is Beneficial for Young Female Rats Against Chronic Unpredicted Mild Stress-Induced Depressive Behavior and Cognitive Deficits

BACKGROUND

Women are reported more likely to develop depression and dementia. However, the involved mechanism is poorly understood.

OBJECTIVE

Here, we clarified the role of estrogen receptor α (ERα) in depression and cognitive deficit in young female rats.

METHODS

After being exposed to 7-weeks' chronic unpredicted mild stress (CUMS), the depression resilient rats (Res rats) and depressed rats (Dep rats) were selected according to their records in sucrose preference test, forced swimming test, and open field test. Their cognition abilities were tested by Morris water maze. Proteomic assay, immunoprecipitation, western blotting, immunohistochemical, and Nissl staining were also used to understand the involved mechanism.

RESULTS

Compared with control rats and Res rats, Dep rats showed cognitive deficits and hippocampal impairments revealed by proteomic data, neuron losses, increased cleaved caspase-3, β-catenin phosphorylation, and glycogen synthase kinase3β (GSK3β) activation. As ERα, but not ERβ, was found declined in hippocampi of Dep rats, 4,4k,4a-(4-propyl-[1H]-pyrazole-1,3,5-triyl) trisphenol (PPT, an ERα agonist, 1 mg/kg/day), was used to treat Dep rats (Dep + PPT). Twenty days later, the depressive behaviors, cognition deficits, and hippocampal neuron loss were rescued in Dep + PPT rats. Furthermore, Res and Dep + PPT rats had higher levels of β-catenin combined with ERα and lower levels of β-catenin combined with GSK3β than Dep rats in hippocampi.

CONCLUSION

These results demonstrated hippocampal ERα is an important pro-resilient factor in CUMS-induced depressive behaviors and cognitive deficits. It was also given that the neuroprotection afforded by hippocampal ERα/Wnt interactions have significant implications for cognition and emotion in young females.

Bidirectional relation between affective symptoms and cognitive function from middle to late adulthood: a population-based birth cohort study

OBJECTIVES

There is an association between affective symptoms and cognition. However, the direction of this association remains unclear. This study aimed to test bidirectional relationships between affective symptoms and cognition from middle to late adulthood.

METHOD

Data were available from the MRC National Survey of Health and Development (NSHD), a prospective birth cohort of 5362 people born in 1946. Affective symptoms and cognition were measured at ages 53, 60-64, and 69. Latent scores of affective symptoms were derived and cross-lagged models were fitted for affective symptoms with verbal memory and processing speed.

RESULTS

Results revealed an inverse cross-sectional association between affective symptoms and verbal memory (β=-0.18, SE=0.04, p<.001) and processing speed (β=-0.13, SE=0.06, p=.05) at age 53, but not at ages 60-64 or 69. Affective symptoms at age 53 predicted lower verbal memory at age 60-64 (β=-0.58, SE=0.27, p=.03), and affective symptoms at age 60-64 predicted lower verbal memory (β=-0.64, SE=0.29, p=.03) and processing speed (β=-1.27, SE=0.41, p=.002) at age 69. Verbal memory and processing speed did not predict subsequent affective symptoms.

CONCLUSION

Affective symptoms predict poorer verbal memory and processing speed over a period of 16 years, but not vice versa.

Be Fit, Be Sharp, Be Well: The Case for Exercise as a Treatment for Cognitive Impairment in Late-life Depression

OBJECTIVE

To lay out the argument that exercise impacts neurobiological targets common to both mood and cognitive functioning, and thus more research should be conducted on its use as an alternative or adjunctive treatment for cognitive impairment in late-life depression (LLD).

METHOD

This narrative review summarizes the literature on cognitive impairment in LLD, describes the structural and functional brain changes and neurochemical changes that are linked to both cognitive impairment and mood disruption, and explains how exercise targets these same neurobiological changes and can thus provide an alternative or adjunctive treatment for cognitive impairment in LLD.

RESULTS

Cognitive impairment is common in LLD and predicts recurrence of depression, poor response to antidepressant treatment, and overall disability. Traditional depression treatment with medication, psychotherapy, or both, is not effective in fully reversing cognitive impairment for most depressed older adults. Physical exercise is an ideal treatment candidate based on evidence that it 1) is an effective treatment for depression, 2) enhances cognitive functioning in normal aging and in other patient populations, and 3) targets many of the neurobiological mechanisms that underlie mood and cognitive functioning. Results of the limited existing clinical trials of exercise for cognitive impairment in depression are mixed but overall support this contention.

CONCLUSIONS

Although limited, existing evidence suggests exercise may be a viable alternative or adjunctive treatment to address cognitive impairment in LLD, and thus more research in this area is warranted. Moving forward, additional research is needed in large, diverse samples to translate the growing research findings into clinical practice.

Longitudinal Relationships Between Subjective Cognitive Decline and Objective Memory: Depressive Symptoms Mediate Between-Person Associations

BACKGROUND

Subjective cognitive decline (SCD) may be an early indicator of cognitive impairment, but depressive symptoms can confound this relationship. Associations may be influenced by differences between individuals (i.e., between-persons) or how each individual changes in their experiences over time (i.e., within-persons).

OBJECTIVE

We examined depressive symptoms as a mediator of the between- and within-person associations of SCD and objective memory in older adults.

METHODS

Coordinated analyses were conducted across four datasets drawn from large longitudinal studies. Samples (range: n = 1,889 to n = 15,841) included participants 65 years of age or older with no dementia at baseline. We used multilevel structural equation modeling to examine the mediation of SCD and objective memory through depressive symptoms, as well as direct relationships among SCD, objective memory, and depressive symptoms.

RESULTS

Older adults who were more likely to report SCD had lower objective memory on average (between-person associations), and depressive symptoms partially mediated this relationship in three of four datasets. However, changes in depressive symptoms did not mediate the relationship between reports of SCD and declines in objective memory in three of four datasets (within-person associations).

CONCLUSION

Individual differences in depressive symptoms, and not changes in an individual's depressive symptoms over time, partially explain the link between SCD and objective memory. Older adults with SCD and depressive symptoms may be at greater risk for poor cognitive outcomes. Future research should explore how perceived changes in memory affect other aspects of psychological well-being, and how these relationships influence cognitive decline and Alzheimer's disease risk.

Depressive symptoms with cognitive dysfunction increase the risk of cognitive impairment: analysis of the Korean Longitudinal Study of Aging (KLoSA), 2006-2018

OBJECTIVES

Geriatric depression complicates cognitive health in older adults. This study aims to investigate the impact of depressive symptoms on cognitive impairment in community-dwelling older adults, depending on whether cognitive dysfunction accompanied.

DESIGN

A community-based longitudinal cohort study.

SETTING

This study analyzed data from the Korean Longitudinal Study of Aging (KLoSA) from 2006 to 2018.

PARTICIPANTS

Among 10,254 individuals who were registered in the KLoSA study, a total of 9119 subjects met the criteria, and 4547 subjects were included in the final analysis. The subjects were grouped into 4 categories based on depressive symptoms and cognitive dysfunction at baseline assessment: "normal control" (NC, n = 3341), "depression only" (Dep-only, n = 652), "cognitive dysfunction only" (CD-only, n = 393), and "depression with cognitive dysfunction" (Dep-CD, n = 161).

MEASUREMENTS

Cognitive impairment 10 years later was defined as K-MMSE scores below two percentile on demographically adjusted norms.

RESULTS

Ten-year survival, that is, not experiencing cognitive impairment, was 80 $$ \pm \,$$1% in NC group, 72 $$ \pm $$ 2% in Dep-only group, 52 $$ \pm $$ 3% in CD-only group, and 44 $$ \pm $$ 5% in Dep-CD group. The hazard ratio (HR) of the Dep-only group (HR = 1.18, 95% CI, 0.97-1.43, n.s.) did not differ from that of the NC group, but the HR of the Dep-CD group was significantly higher (HR = 2.85, 95% CI, 2.23-3.66, p < 0.001) than the NC group. When the Dep-CD group was compared to the CD-only group, the HR was 1.13 (95% CI, 0.85-1.49, n.s.), which indicates that it did not significantly differ from the CD-only group.

CONCLUSIONS

Our findings suggest that depressive symptoms with cognitive dysfunction are associated with a higher risk of cognitive impairment. Furthermore, cognitive dysfunction occurring with depressive symptoms is as much a risk for cognitive impairment as is pure cognitive dysfunction. Thus, healthcare providers should pay close attention to the community-dwelling elderly when depressive symptoms occur with cognitive dysfunction.

A Link Between Brain Insulin Resistance and Cognitive Dysfunctions: Targeting Ca2+/cAMP Signalling

BACKGROUND

A correlation between cognitive dysfunctions and brain insulin resistance has been established by several clinical and experimental studies. Consistent data support that people diagnosed with brain insulin resistance, resulted from diabetes, have shown an increased risk of presenting cognitive dysfunctions, clinical signs of dementia and depression, then speculating a role of dysregulations related to insulin signalling in these diseases. Furthermore, it is currently discussed that Ca2+ signalling, and its dysregulations, may be a factor which could correlate with brain insulin resistance and cognitive dysfunctions.

OBJECTIVE

Following this, revealing this interplay between these diseases may provide novel insights into the pathogenesis of such diseases.

METHODS

Publications covering topics such as Ca2+ signalling, diabetes, depression and dementia (alone or combined) were collected by searching PubMed and EMBASE.

RESULTS

The controlling of both neurotransmitters/hormones release and neuronal death could be achieved through modulating Ca2+ and cAMP signalling pathways (Ca2+/cAMP signalling).

CONCLUSION

Taking into account our previous reports on Ca2+/cAMP signalling, and considering a limited discussion in the literature on the role of Ca2+/cAMP signalling in the link between cognitive dysfunctions and brain insulin resistance, this article has comprehensively discussed the role of these signalling pathways in this link (between cognitive dysfunctions and brain insulin resistance).

Chronic colitis exacerbates NLRP3-dependent neuroinflammation and cognitive impairment in middle-aged brain

BACKGROUND

Neuroinflammation is a major driver of age-related brain degeneration and concomitant functional impairment. In patients with Alzheimer's disease, the most common form of age-related dementia, factors that enhance neuroinflammation may exacerbate disease progression, in part by impairing the glymphatic system responsible for clearance of pathogenic beta-amyloid. Inflammatory bowel diseases (IBDs) induce neuroinflammation and exacerbate cognitive impairment in the elderly. The NACHT-LRR and pyrin (PYD) domain-containing protein 3 (NLRP3) inflammasome has been implicated in neuroinflammation. Therefore, we examined if the NLRP3 inflammasome contributes to glymphatic dysfunction and cognitive impairment in an aging mouse model of IBD.

METHODS

Sixteen-month-old C57BL/6J and NLRP3 knockout (KO) mice received 1% wt/vol dextran sodium sulfate (DSS) in drinking water to model IBD. Colitis induction was confirmed by histopathology. Exploratory behavior was examined in the open field, associative memory by the novel-object recognition and Morris water maze tests, glymphatic clearance by in vivo two-photon imaging, and neuroinflammation by immunofluorescence and western blotting detection of inflammatory markers.

RESULTS

Administration of DSS induced colitis, impaired spatial and recognition memory, activated microglia, and increased A1-like astrocyte numbers. In addition, DSS treatment impaired glymphatic clearance, aggravated amyloid plaque accumulation, and induced neuronal loss in the cortex and hippocampus. These neurodegenerative responses were associated with increased NLRP3 inflammasome expression and accumulation of gut-derived T lymphocytes along meningeal lymphatic vessels. Conversely, NLRP3 depletion protected against cognitive dysfunction, neuroinflammation, and neurological damage induced by DSS.

CONCLUSIONS

Colitis can exacerbate age-related neuropathology, while suppression of NLRP3 inflammasome activity may protect against these deleterious effects of colitis.

Genetic Overlap Between Alzheimer's Disease and Depression Mapped Onto the Brain

Background: Alzheimer's disease (AD) and depression are debilitating brain disorders that are often comorbid. Shared brain mechanisms have been implicated, yet findings are inconsistent, reflecting the complexity of the underlying pathophysiology. As both disorders are (partly) heritable, characterising their genetic overlap may provide aetiological clues. While previous studies have indicated negligible genetic correlations, this study aims to expose the genetic overlap that may remain hidden due to mixed directions of effects. Methods: We applied Gaussian mixture modelling, through MiXeR, and conjunctional false discovery rate (cFDR) analysis, through pleioFDR, to genome-wide association study (GWAS) summary statistics of AD (n = 79,145) and depression (n = 450,619). The effects of identified overlapping loci on AD and depression were tested in 403,029 participants of the UK Biobank (UKB) (mean age 57.21, 52.0% female), and mapped onto brain morphology in 30,699 individuals with brain MRI data. Results: MiXer estimated 98 causal genetic variants overlapping between the 2 disorders, with 0.44 concordant directions of effects. Through pleioFDR, we identified a SNP in the TMEM106B gene, which was significantly associated with AD (B = -0.002, p = 9.1 × 10-4) and depression (B = 0.007, p = 3.2 × 10-9) in the UKB. This SNP was also associated with several regions of the corpus callosum volume anterior (B > 0.024, p < 8.6 × 10-4), third ventricle volume ventricle (B = -0.025, p = 5.0 × 10-6), and inferior temporal gyrus surface area (B = 0.017, p = 5.3 × 10-4). Discussion: Our results indicate there is substantial genetic overlap, with mixed directions of effects, between AD and depression. These findings illustrate the value of biostatistical tools that capture such overlap, providing insight into the genetic architectures of these disorders.

Dementia Syndrome of Depression: Diagnostic Challenges and Clinical Relevance

Late-life depression is frequently associated with cognitive impairment. Because of the overlap of symptoms, however, it can be challenging to discern a neurocognitive disorder (NCD) from a late-life depressive disorder. Although neuropsychological testing provides evidence, there are limited neurochemical or neuroimaging biomarkers for the etiological classification of NCD versus late-life depression. Without formal DSM-5 criteria for a dementia syndrome of depression (DSD), patients may be incorrectly diagnosed as having an NCD. Without recognition and appropriate aggressive treatment, patients may develop severe depression with cognitive impairment leading to significant morbidity. It is crucial that clinicians become aware of and assess for elements that differentiate DSD from neurocognitive disorders. In so doing, this syndrome can be identified and treated early in its course, allowing for the best patient outcomes. In this article, the authors demonstrate, through a case presentation, the diagnostic challenges and clinical value of accurately identifying and treating DSD.

Association of late-life depression with cognitive impairment: evidence from a cross-sectional study among older adults in India

BACKGROUND

Late-life depression (LLD) is considered as a prodrome to dementia and plays a major role in the development of long-term cognitive disabilities. We aimed to estimate the prevalence and correlates of LLD and cognitive impairment and to explore their associations among older adults in India.

METHODS

Data for this study was derived from the Longitudinal Ageing Study in India (LASI) Wave 1 (2017-18). The total sample included 31,464 (15,098 male and 16,366 female) older individuals aged 60 years and above. Cognitive impairment measured from various domains derived from the cognitive module of the Health and Retirement Study (HRS), and major depression measured by the CIDI-SF (Composite International Diagnostic Interview- Short Form) were the outcome variables. Descriptive, bivariate, and multivariable analyses were performed to fulfill the objectives of the study.

RESULTS

The overall prevalence of LLD and cognitive impairment for the current sample was 8.7% and 13.7 % respectively. Among older individuals who have rated their health status as poor were 2.59 times more likely to suffer from LLD [OR: 2.59, CI: 2.24-2.99] as compared to their counterparts. The older adults who had difficulty in activities of daily living (ADL) and instrumental activities of daily living (IADL) were 74% and 69 % more likely to suffer from LLD. Similarly, older adults who were depressed had higher odds of cognitive impairment [OR: 1.22, CI: 1.01-1.48] compared to their counterparts. Also, older adults who were depressed and belonged to rural areas were 2.58 times [AOR: 2.58, CI: 1.95-3.41] more likely to be cognitively impaired than those who were not depressed and resided in urban areas.

CONCLUSIONS

Depression is linked to an increased risk of cognitive decline and dementia; therefore, failing to diagnose and treat LLD in later life may have significant health implications. Moreover, treatment under the care of a cognitive neurologist or geriatric psychiatrist is recommended for people with LLD and cognitive disability due to both the disorders' complex existence.