Traumatic life events and risk for dementia: a systematic review and meta-analysis

OBJECTIVES: To systematically review the association between traumatic life events (TLE) and dementia risk. DESIGN: Systematic review and meta-analysis. DATA SOURCES: APA, PsychINFO, Embase and MEDLINE from their inception to 29.05.21 and updated on 20.04.22. ELIGIBILITY CRITERIA FOR SELECTING STUDIES: Original research articles published in peer reviewed journals examining the association between TLE and all cause dementia in individuals aged 60 and over. Two researchers independently assessed the risk of bias using the Newcastle-Ottawa Scale. We conducted a generic inverse variance random effects meta-analysis to provide an overall estimate of TLE impact on dementia risk. MAIN OUTCOME MEASURES: Risk, odds and hazards ratios relating to dementia risk. RESULTS: Initially, 3,487 studies were retrieved in the search and seven studies were included in the meta-analysis with data being used from 276,570 participants. TLE were associated with increased dementia risk. Trauma in general had a pooled HR of 1.21, (95% CI 1.03, 1.43, P = 0.0001). War/ Holocaust trauma and childhood trauma were also associated with increased dementia risk (HR = 1.28 (95% CI 1.01-1.63, P = 0.02) and HR = 1.76 (95% CI 1.17-2.64, P = 0.007) respectively). CONCLUSIONS: We have found an association between TLE and dementia risk. Future research exploring the dimensions of TLE and individual level factors are needed to better understand the relationship between TLE and dementia. TRIAL REGISTRATION: PROSPERO CRD42021253090

Trait Mindfulness Is Associated With Less Amyloid, Tau, and Cognitive Decline in Individuals at Risk for Alzheimer's Disease

BACKGROUND: Mindfulness, defined as nonjudgmental awareness of the present moment, has been associated with an array of mental and physical health benefits. Mindfulness may also represent a protective factor for Alzheimer's disease (AD). Here, we tested the potential protective effect of trait mindfulness on cognitive decline and AD pathology in older adults at risk for AD dementia. METHODS: Measures of trait mindfulness, longitudinal cognitive assessments, and amyloid-β (Aβ) and tau positron emission tomography scans were collected in 261 nondemented older adults with a family history of AD dementia from the PREVENT-AD (Pre-symptomatic Evaluation of Experimental or Novel Treatments for AD) observational cohort study. Multivariate partial least squares analyses were used to examine relationships between combinations of different facets of trait mindfulness and 1) cognitive decline, 2) Aβ, and 3) tau. RESULTS: Higher levels of mindful nonjudgment, describing, and nonreactivity were associated with less cognitive decline in attention, global cognition, and immediate and delayed memory. Higher levels of mindful nonjudgment and nonreactivity were related to less Aβ positron emission tomography signal in bilateral medial and lateral temporoparietal and frontal regions. Higher levels of mindful acting with awareness, describing, nonjudgment, and nonreactivity were associated with less tau positron emission tomography signal in bilateral medial and lateral temporal regions. CONCLUSIONS: Trait mindfulness was associated with less cognitive decline and less Aβ and tau in the brain in older adults at risk for AD dementia. Longitudinal studies examining the temporal relationship between trait mindfulness and AD markers, along with mindfulness intervention studies, will be important for further clarifying the potential protective benefits of mindfulness on AD risk

Examining the Lancet Commission risk factors for dementia using Mendelian randomisation

BACKGROUND: Dementia incidence is increasing across the globe and currently there are no disease-modifying pharmaceutical treatments. The Lancet Commission on dementia identified 12 modifiable risk factors which explain 40% of dementia incidence. However, whether these associations are causal in nature is unclear. OBJECTIVE: To examine the modifiable risk factors for dementia as identified in the Lancet Commission review using Mendelian randomisation (MR) to establish if, based on genetic evidence, these associations with different dementia subtypes are causal in nature. METHODS: Publicly available genome-wide association study data were used for 10 risk factors and Alzheimer’s disease (AD), frontotemporal dementia and dementia with Lewy bodies. Two-sample MR using the inverse varianceweighted method was conducted to test for causal relationships. Weighted median MR and MR-Egger were used to test for pleiotropic effects. RESULTS: Genetic proxied risk for higher levels of smoking (OR: 0.80 (95% CI: 0.69; 0.92), p=0.002), obesity (OR: 0.87 (95% CI: 0.82; 0.92), p<0.001) and blood pressure (OR: 0.90 (95% CI: 0.82; 0.99), p=0.035) appeared to be protective against the risk of AD. Post hoc analyses indicated these associations had pleiotropic effects with the risk of coronary artery disease. Genetic proxied risk of educational attainment was found to be inconsistently associated with the risk of AD. CONCLUSIONS AND IMPLICATIONS: Post hoc analysis indicated that the apparent protective effects of smoking, obesity and blood pressure were a result of survivor bias. The findings from this study did not support those presented by the Lancet Commission. Evidence from causal inference studies should be considered alongside evidence from epidemiological studies and incorporated into reviews of the literature

Depressive Symptoms Have Distinct Relationships With Neuroimaging Biomarkers Across the Alzheimer's Clinical Continuum

Background: Depressive and anxiety symptoms are frequent in Alzheimer’s disease and associated with increased risk of developing Alzheimer’s disease in older adults. We sought to examine their relationships to Alzheimer’s disease biomarkers across the preclinical and clinical stages of the disease. Method: Fifty-six healthy controls, 35 patients with subjective cognitive decline and 56 amyloid-positive cognitively impaired patients on the Alzheimer’s continuum completed depression and anxiety questionnaires, neuropsychological tests and neuroimaging assessments. We performed multiple regressions in each group separately to assess within group associations of depressive and anxiety symptoms with either cognition (global cognition and episodic memory) or neuroimaging data (gray matter volume, glucose metabolism and amyloid load). Results: Depressive symptoms, but not anxiety, were higher in patients with subjective cognitive decline and cognitively impaired patients on the Alzheimer’s continuum compared to healthy controls. Greater depressive symptoms were associated with higher amyloid load in subjective cognitive decline patients, while they were related to higher cognition and glucose metabolism, and to better awareness of cognitive difficulties, in cognitively impaired patients on the Alzheimer’s continuum. In contrast, anxiety symptoms were not associated with brain integrity in any group. Conclusion: These data show that more depressive symptoms are associated with greater Alzheimer’s disease biomarkers in subjective cognitive decline patients, while they reflect better cognitive deficit awareness in cognitively impaired patients on the Alzheimer’s continuum. Our findings highlight the relevance of assessing and treating depressive symptoms in the preclinical stages of Alzheimer’s disease

Association between anxiety symptoms and Alzheimer's disease biomarkers in cognitively healthy adults: A systematic review and meta-analysis

Objective: Anxiety has been identified as both a risk factor and prodromal symptom for Alzheimer's disease (AD) and related dementias, however, the underlying neurobiological correlates remain unknown. The aim of this systematic review and meta-analysis was to examine the association between anxiety symptoms and two defining markers of AD neuropathology: amyloid-beta (Aβ) and tau. Methods: Systematic literature searches were conducted across 5 databases. Studies investigating the relationship between anxiety and AD neuropathology (i.e., Aβ and/or tau) in cognitively healthy adults were eligible. Where possible, effect sizes were combined across studies, for Aβ and tau separately, using random-effects meta-analyses. Sensitivity analyses were performed to assess whether results differed according to anxiety type (i.e., state and trait) and biomarker assessment modality (i.e., positron emission tomography and cerebrospinal fluid). Results: Twenty-seven studies reporting data from 14 unique cohorts met eligibility criteria. Random-effects meta-analyses revealed no associations between self-reported anxiety symptoms and either Aβ (13 studies, Fisher's z = 0.02, 95% confidence interval [CI] -0.01–0.05, p = 0.194) or tau (4 studies, Fisher's z = 0.04, 95% CI -0.02–0.09, p = 0.235). Results remained unchanged across sensitivity analyses. Conclusions: In cognitively healthy adults, meta-analytic syntheses revealed no associations between anxiety symptoms and either Aβ or tau. There is a critical need, however, for larger studies with follow-up periods to examine the effect of anxiety symptom onset, severity, and chronicity on AD neuropathology. Additionally, further research investigating other potential neurobiological correlates is crucial to advance scientific understanding of the relationship between anxiety and dementia

Psychological therapies for depression and cardiovascular risk: evidence from national healthcare records in England

Aims: People with depression are up to 72% more at risk to develop cardiovascular disease (CVD) in their lifetime. Evidence-based psychotherapies are first-line interventions for the treatment of depression and are delivered nationally in England through the National Health Service via the Improving Access to Psychological Therapy (IAPT) primary care programme. It is currently unknown whether positive therapy outcomes may be associated with cardiovascular risk reduction. This study aimed to examine the association between psychotherapy outcomes for depression and incident CVD. Methods and results: A cohort of 636 955 individuals who have completed a course of psychotherapy was built from linked electronic healthcare record databases of national coverage in England: the national IAPT database, the Hospital Episode Statistics (HES) database, and the HES–ONS (Office of National Statistics) mortality database. Multivariable Cox models adjusting for clinical and demographic covariates were run to estimate the association between reliable improvement from depression and the risk of subsequent incidence of cardiovascular events. After a median follow-up of 3.1 years, reliable improvement from depression symptoms was associated with a lower risk of new onset of any CVD [hazard ratio (HR): 0.88, 95% confidence interval (CI): 0.86, 0.89], coronary heart disease (HR: 0.89, 95% CI: 0.86, 0.92), stroke (HR: 0.88, 95% CI: 0.83, 0.94), and all-cause mortality (HR: 0.81, 95% CI: 0.78, 0.84). This association was stronger in the under 60 compared with the over 60 for all outcomes. Results were confirmed in sensitivity analyses. Conclusion: Management of depression through psychological interventions may be associated with reduced risk of CVD. More research is needed to understand the causality of these associations

Salivary cortisol in longitudinal associations between affective symptoms and midlife cognitive function: A British birth cohort study

Affective disorders are associated with accelerated cognitive ageing. However, current understanding of biological mechanisms which underlie these observed associations is limited. The aim of this study was to test: 1) Whether cortisol acts as a pathway in the association between depressive or anxiety symptoms across adulthood and midlife cognitive function; 2) Whether cortisol is associated with later depressive or anxiety symptoms, and cognitive function. Data were used from the National Child Development Study, a sample of infants born in mainland UK during one week of 1958. A measure of the accumulation of affective symptoms was derived from data collected from age 23 to 42 using the Malaise Inventory Scale. Salivary cortisol measures were available at age 44–45. Cognitive function (memory, fluency, information processing) and affective symptoms were assessed at the age of 50. Path models were run to test whether salivary cortisol explained the longitudinal association between depressive or anxiety disorder symptoms and cognitive function. Direct effects of affective symptoms are shown across early to middle adulthood on cognitive function in midlife (memory and information processing errors). However, there were no effects of affective symptoms on cognitive function through cortisol measures. Additionally, cortisol measures were not significantly associated with subsequent affective symptoms or cognitive function at the age of 50. These results do not provide clear evidence to suggest that cortisol plays a role in the association between affective symptoms and cognitive function over this period of time. These findings contribute to our understanding of how the association between affective symptoms and cognitive function operates over time

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