Psychological distress and risk for dementia

The dynamic and reciprocal relationship between perceived everyday discrimination and cognitive function in later life

OBJECTIVES

This study, based on socioemotional selectivity theory and cognitive theory, investigates the dynamic and reciprocal relationship between perceived discrimination and cognitive function in later life.

METHODS

Data were drawn from four waves of the Health and Retirement Study (HRS 2006, 2010, 2014, and 2018). A total of 4,125 people who were 51 and older were included. Cognitive function was measured by the telephone interview for cognitive status (TICS-27). Perceived discrimination was measured using scores of the perceived everyday discrimination scale. Random intercept cross-lagged panel model (RI-CLPM) was utilized. The model was adjusted for a range of covariates. Subgroup analysis by ethnoracial groups was conducted.

RESULTS

Cross-sectionally, while lower cognitive function was associated with higher perceived discrimination, this relationship was unidirectional. Longitudinally, higher perceived discrimination predicted lower cognitive function in later waves only among non-Hispanic White individuals.

CONCLUSION

Results suggested that a decline in cognitive function may precede and contribute to the worsening of perceived discrimination, which may result in further decline in cognitive function. Lifetime experience of discrimination was discussed as a possible source of the racial/ethnic variations in the relationship. Further study is needed to examine whether this relationship holds among people with cognitive impairment and dementia.

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.

Common Neuropsychiatric S ymptoms in Alzheimer's Disease, Mild Cognitive Impairment, and Subjective Memory Complaints: A Unified Framework

The Alzheimer's disease (AD) continuum is a unique spectrum of cognitive impairment that typically involves the stages of subjective memory complaints (SMC), mild cognitive impairment (MCI), and AD dementia. Neuropsychiatric symptoms (NPS), such as apathy, anxiety, stress, and depression, are highly common throughout the AD continuum. However, there is a dearth of research on how these NPS vary across the AD continuum, especially SMC. There is also disagreement on the effects of specific NPS on each stage of the AD continuum due to their collinearity with other NPS, cognitive decline, and environmental factors (e.g., stress). In this article, we conduct a novel perspective review of the scientific literature to understand the presence of NPS across the AD continuum. Specifically, we review the effects of apathy, depression, anxiety, and stress in AD, MCI, and SMC. We then build on this knowledge by proposing two theories of NPS' occurrence across the AD continuum. Consequently, we highlight the current landscape, limitations (e.g., differing operationalization), and contentions surrounding the NPS literature. We also outline theories that could clear up contention and inspire future NPS research.

The Association between Resilience and Psychological Distress during the COVID-19 Pandemic: A Systematic Review and Meta-Analysis

This study examined the association between resilience and psychological distress in healthcare workers, the general population, and patients during the COVID-19 pandemic. We searched the PubMed, Web of Science, PsycInfo, Science Direct, and Nursing and Allied Health databases. Included articles examined healthcare workers (e.g., physicians and nurses), the general population, and patients during the COVID-19 pandemic. Studies of exposure to other infectious diseases related to epidemics or pandemics (e.g., SARS and MERS) were excluded. This study was performed following the Cooper matrix review method and PRISMA guidelines, followed by a meta-analysis of study results using R version 4.1.2. A random effect model was used for the pooled analysis. This study was registered with PROSPERO (registration No. CRD42021261429). Based on the meta-analysis, we found a moderate negative relationship between overall resilience and psychological distress (r = -0.42, 95% confidence interval [CI]: -0.45 to -0.38, p < 0.001). For the subgroup analysis, a moderately significant negative relationship between overall resilience and psychological distress was found among healthcare workers (r = -0.39, 95% CI: -0.44 to -0.33, p < 0.001), which was weaker than in the general population (r = -0.45, 95% CI: -0.50 to -0.39, p < 0.001) and in patients (r = -0.43; 95% CI: -0.52 to -0.33; p < 0.001). This association was robust, although the heterogeneity among individual effect sizes was substantial (I² = 94%, 99%, and 74%, respectively). This study revealed a moderate negative relationship between resilience and psychological distress in healthcare workers, the general population, and patients. For all these populations, interventions and resources are needed to improve individuals' resilience and ability to cope with psychological distress during the COVID-19 pandemic and in future disease outbreaks.

Does Shiftwork Impact Cognitive Performance? Findings from the Canadian Longitudinal Study on Aging (CLSA)

Few large nationwide studies have investigated the relationship between shiftwork and cognitive performance, and little is known about whether and how psychological distress may impact this relationship. This study aimed to examine: (1) the cross-sectional relationship between shiftwork (yes/no) and some aspects of cognitive performance (declarative memory and executive functioning) and (2) the potential moderating effect of psychological distress among 20,610 community-dwelling adults from the comprehensive cohort of the Canadian Longitudinal Study on Aging (CLSA). Differences by sex and retirement status were also explored. Shiftwork was significantly associated with poorer performance for executive functioning (interference condition: ß = 0.47, 95% CI: 0.31 to 0.63; MAT: ß = -0.85, 95% CI: -1.21 to -0.50) but not for declarative memory. Completely and not/partly retired males showed poorer cognitive performance on executive functioning. However, no evidence of a moderating effect by psychological distress was found. Our findings confirm the association between shiftwork and cognitive performance and highlight important health correlates of shiftwork.

Older Workers with Unpredictable Schedules: Implications for Well-being and Job Retention

BACKGROUND AND OBJECTIVES

A substantial portion of the service sector workforce is middle aged or older, but little is known about the scheduling conditions of these older workers. This study describes the quality of work schedules in the service sector by age and tests associations of unpredictable schedules with well-being and job retention among workers ages 50-80.

RESEARCH DESIGN AND METHODS

The Shift Project collected survey data on detailed working conditions and health from 121,408 service sector workers, recruited in 2017-2020 using social media advertisements. Survey weights aligned sample demographics with the American Community Survey, and multiple imputation addressed missingness. Ordinary least squares regression models were used to examine associations between age and schedule stability, and ordinary least squares, ordinal logit, and logit regression models tested associations between schedule stability and well-being and job retention outcomes for older workers.

RESULTS

Scheduling conditions were more stable and predictable for older compared to younger workers; however, more than 80% of workers ages 50-80 experienced one or more types of routine schedule instability. Among workers ages 50-80, unpredictable schedules were associated with psychological distress, poor quality sleep, work-family conflict, economic insecurity, job dissatisfaction, and intentions to look for a new job. Canceled and back-to-back closing and opening ("clopening") shifts were most strongly associated with negative outcomes.

DISCUSSION AND IMPLICATIONS

Policies aimed at improving scheduling conditions hold promise to benefit older service workers' well-being. As the population ages, improving work schedules in the years approaching retirement may be important to longer working lives.

Implication of Covid-19 on Neurological Complications with Specific Emphasis on Alzheimer's and Parkinson's Disease

It is noticeable how the novel coronavirus has spread from the Wuhan region of China to the whole world, devastating the lives of people worldwide. All the data related to the precautionary measures, diagnosis, treatment, and even the epidemiological data are being made freely accessible and reachable in a very little time as well as being rapidly published to save humankind from this pandemic. There might be neurological complications of COVID-19 and patients suffering from neurodegenerative conditions like Alzheimer's disease and Parkinson's disease might have repercussions as a result of the pandemic. In this review article, we have discussed the effect of SARS-CoV-2 viral infection on the people affected with neurodegenerative disorders such as Parkinson's and Alzheimer's. It primarily emphasizes two issues, i.e., vulnerability to infection and modifications of course of the disease concerning the clinical neurological manifestations, the advancement of the disease and novel approaches to support health care professionals in disease management, the susceptibility to these diseases, and impact on the severity of disease and management.

Psychosocial and Trauma-Related Stress and Risk of Dementia: A Meta-Analytic Systematic Review of Longitudinal Studies

Stress has deleterious effects on brain health and yet, the prognostic value of psychosocial stress regarding the most common types of dementias, including Alzheimer disease, is still unclear. The primary aim of this systematic review was to explore the association between psychosocial stress and late onset dementia. We classified 24articles from Medline, PsycINFO, CINAHL, and Web of Science, as pertaining toxic categories of psychosocial and trauma-related stress (low socio-economic status [SES] related inequalities, marital status, posttraumatic stress disorder, work stress, "vital exhaustion" [VE], and, combined stressors). Using the Quality of Prognosis Studies in Systematic Reviews tool, we judged the quality of evidence to be low. This systematic review provided some non-robust, yet suggestive evidence that the above psychosocial types of stress are associated with increased risk of dementia in later life. Future robust, longitudinal studies with repeated validated measures of psychosocial stress and dementiaare required to strengthen or refute these findings.

Neuropsychiatric Profile as a Predictor of Cognitive Decline in Mild Cognitive Impairment

Introduction: Mild cognitive impairment is often associated with affective and other neuropsychiatric symptoms (NPS). This co-occurrence might have a relevant impact on disease progression, from MCI to dementia.

Objective: The aim of this study was to explore the trajectories of cognitive decline in an MCI sample from a memory clinic, taking into consideration a perspective of isolated cognitive functions and based on NPS clusters, accounting for the different comorbid symptoms collected at their baseline visit.

Methods: A total of 2,137 MCI patients were monitored over a 2.4-year period. Four clusters of NPS (i.e., Irritability, Apathy, Anxiety/Depression and Asymptomatic) were used to run linear mixed models to explore the interaction of cluster with time on cognitive trajectories using a comprehensive neuropsychological battery (NBACE) administered at baseline and at the three subsequent follow-ups.

Results: A significant interaction between cluster and time in cognitive decline was found when verbal learning and cued-recall were explored (p = 0.002 for both memory functions). For verbal learning, the Irritability cluster had the largest effect size (0.69), whereas the Asymptomatic cluster showed the smallest effect size (0.22). For cued-recall, the Irritability cluster had the largest effect size among groups (0.64), and Anxiety/Depression had the smallest effect size (0.21).

Conclusions: In MCI patients, the Irritability and Apathy NPS clusters shared similar patterns of worsening in memory functioning, which could point to these NPS as risk factors of a faster cognitive decline, acting as early prognostic markers and helping in the diagnostic process.

Auditory evoked brain potentials as markers of chronic effects of mild traumatic brain injury in mid-life

OBJECTIVE

Auditory event-related potential (ERP) correlates of pre-dementia in late-life may also be sensitive to chronic effects of mild traumatic brain injury (mTBI) in mid-life. In addition to mTBI history, other clinical factors may also influence ERP measures of brain function. This study's objective was to evaluate the relationship between mTBI history, auditory ERP metrics, and common comorbidities.

METHODS

ERPs elicited during an auditory target detection task, psychological symptoms, and hearing sensitivity were collected in 152 combat-exposed veterans and service members, as part of a prospective observational cohort study. Participants, with an average age of 43.6 years, were grouped according to positive (n = 110) or negative (n = 42) mTBI history. Positive histories were subcategorized into repetitive mTBI (3 + ) (n = 40) or non-repetitive (1-2) (n = 70).

RESULTS

Positive history of mTBI was associated with reduced N200 amplitude to targets and novel distractors. In participants with repetitive mTBI compared to non-repetitive and no mTBI, P50 was larger in response to nontargets and N100 was smaller in response to nontargets and targets. Changes in N200 were mediated by depression and anxiety symptoms and hearing loss, with no evidence of a supplementary direct mTBI pathway.

CONCLUSIONS

Auditory brain function differed between the positive and negative mTBI groups, especially for repetitive injury, which implicated more basic, early auditory processing than did any mTBI exposure. Symptoms of internalizing psychopathology (depression and anxiety) and hearing loss are implicated in mTBI's diminished brain responses to behaviorally relevant and novel stimuli.

SIGNIFICANCE

A mid-life neurologic vulnerability conferred by mTBI, particularly repetitive mTBI, may be detectable using auditory brain potentials, and so auditory ERPs are a target for study of dementia risk in this population.

Allosteric modulation of AMPA receptors counteracts Tau-related excitotoxic synaptic signaling and memory deficits in stress- and Aβ-evoked hippocampal pathology

Despite considerable progress in the understanding of its neuropathology, Alzheimer's disease (AD) remains a complex disorder with no effective treatment that counteracts the memory deficits and the underlying synaptic malfunction triggered by the accumulation of amyloid beta (Aβ) and Tau protein. Mounting evidence supports a precipitating role for chronic environmental stress and glutamatergic excitotoxicity in AD, suggesting that targeting of glutamate receptor signaling may be a promising approach against both stress and AD pathologies. In light of the limited cognitive benefit of the direct antagonism of NMDA receptors in AD, we here focus on an alternative way to modify glutamatergic signaling through positive allosteric modulation of AMPA receptors, by the use of a PAM-AMPA compound. Using non-transgenic animal model of Aβ oligomer injection as well as the combined stress and Aβ i.c.v. infusion, we demonstrate that positive allosteric modulation of AMPA receptors by PAM-AMPA treatment reverted memory, but not mood, deficits. Furthermore, PAM-AMPA treatment reverted stress/Aβ-driven synaptic missorting of Tau and associated Fyn/GluN2B-driven excitotoxic synaptic signaling accompanied by recovery of neurotransmitter levels in the hippocampus. Our findings suggest that positive allosteric modulation of AMPA receptors restores synaptic integrity and cognitive performance in stress- and Aβ-evoked hippocampal pathology. As the prevalence of AD is increasing at an alarming rate, novel therapeutic targeting of glutamatergic signaling should be further explored against the early stages of AD synaptic malfunction with the goal of attenuating further synaptic damage before it becomes irreversible.

Risk of Suicide Attempt in Patients With Recent Diagnosis of Mild Cognitive Impairment or Dementia

IMPORTANCE

Little is known about the association between mild cognitive impairment (MCI) and suicide. Most studies have focused on dementia and suicidal behavior, with inconsistent results.

OBJECTIVES

To examine the association between diagnoses of MCI and dementia and suicide attempt and explore potential psychiatric moderators and to assess whether the association differs based on recency of diagnosis.

DESIGN, SETTING, AND PARTICIPANTS

This nationwide cohort study integrated 5 national databases from the Department of Veterans Affairs (VA) and Centers for Medicare & Medicaid Services and included all VA medical centers in the US. US veterans 50 years or older with MCI diagnoses at baseline (October 1, 2011, to September 30, 2013) or earlier (October 1, 2007, to September 30, 2011) were propensity matched 1:3 with (1) patients with dementia diagnoses and (2) patients without either diagnosis based on demographic characteristics and the Charlson Comorbidity Index. Diagnoses of MCI or dementia were defined as recent if there were no diagnosis codes before baseline. Data were analyzed from March 16, 2020, to January 15, 2021.

MAIN OUTCOMES AND MEASURES

Information on suicide attempts through December 31, 2016, provided by the National Suicide Prevention Applications Network (nonfatal) and Mortality Data Repository (fatal).

RESULTS

The study population of 147 595 participants included 21 085 patients with MCI, 63 255 with dementia, and 63 255 in the propensity-matched comparison group. Participants had a mean (SD) age of 74.7 (10.3) years, 143 353 (97.1%) were men, 4242 (2.9%) were women, and 127 065 (86.1%) were non-Hispanic White. A total of 138 patients with MCI (0.7%) and 400 patients with dementia (0.6%) attempted suicide during follow-up, compared with 253 patients without MCI or dementia (0.4%). Exploratory analyses revealed that no psychiatric comorbidity moderated the association between MCI or dementia and suicide attempt. After adjustment for demographic details and medical and psychiatric comorbidities, risk of suicide attempt was consistently highest for patients with a recent MCI or dementia diagnosis, with adjusted hazard ratios (HRs) of 1.73 (95% CI, 1.34-2.22; P < .001) for recent MCI and 1.44 (95% CI, 1.17-1.77; P = .001) for recent dementia. Risk associated with prior diagnosis was not significant (HR for prior MCI, 1.03 [95% CI, 0.78-1.36; P = .84]; HR for prior dementia, 1.14 [95% CI, 0.95-1.36; P = .15]).

CONCLUSIONS AND RELEVANCE

This study found that older adults with recent MCI or dementia diagnoses were at increased risk of attempting suicide. These findings suggest that involvement of supportive services at the time of or soon after diagnoses of MCI or dementia may help mitigate risk of suicide attempts.

Coping with Dementia in the Middle of the COVID-19 Pandemic

Multiple neurological complications have been associated with the coronavirus disease-19 (COVID-19), which is caused by severe acute respiratory syndrome coronavirus 2. This is a narrative review to gather information on all aspects of COVID-19 in elderly patients with cognitive impairment. First, the following three mechanisms have been proposed to underlie the neurological complications associated with COVID-19: 1) direct invasion, 2) immune and inflammatory reaction, and 3) hypoxic brain damage by COVID-19. Next, because the elderly dementia patient population is particularly vulnerable to COVID-19, we discussed risk factors and difficulties associated with cognitive disorders in this vulnerable population. We also reviewed the effects of the patient living environment in COVID-19 cases that required intensive care unit (ICU) care. Furthermore, we analyzed the impact of stringent social restrictions and COVID-19 pandemic-mediated policies on dementia patients and care providers. Finally, we provided the following strategies for working with elderly dementia patients: general preventive methods; dementia care at home and nursing facilities according to the activities of daily living and dementia characteristics; ICU care after COVID-19 infection; and public health care system and government response. We propose that longitudinal follow-up studies are needed to fully examine COVID-19 associated neurological complications, such as dementia, and the efficacy of telemedicine/telehealth care programs.

The mediating effect of psychological distress on cognitive function and physical frailty among the elderly: Evidence from rural Shandong, China

BACKGROUND

Few studies have explored the underlying mechanism between physical frailty and cognitive function. The aim of this study is to explore the mediating role of psychological distress (PD) for the association between cognitive function and physical frailty among the elderly in rural China.

METHODS

A total of 3,242 rural older adults were included in the analysis. Logistic regression and Bootstrap analyses were employed to explore the association between cognitive function, PD and frailty, and the mediating role of PD.

RESULTS

This study found that the prevalence of frailty and cognitive impairment among the elderly in rural China was 18.0%, 22.4%. After adjusted for controlling variables, cognitive function was significantly associated with high level of PD, and elderly with higher level of PD had a higher probability of suffering from frailty. PD played a partially mediating effect in cognitive function and frailty and the mediating effect of PD can explain the 11.0% of the total effect of cognitive function on frailty.

LIMITATIONS

The data were cross-sectional, thus the causal relationship between variables could not be determined. The main variables in this study were measured by self-report information, which might result in recall bias.

CONCLUSIONS

This study provide evidence that the effect of cognitive function on physical frailty was partially mediated by PD among the elderly in rural China. Primary health care should strengthen the screening of PD characterized by depression and anxiety, and strive to improve the physical and psychological well-being of rural elderly in China.

Vital Exhaustion and Incidence of Dementia: Results from the Copenhagen City Heart Study

BACKGROUND

Psychological distress is potentially linked to the risk of dementia through neurologic and cardiovascular mechanisms. Vital exhaustion (VE) is a mental state of psychological distress, which could be a risk factor for dementia.

OBJECTIVE

To investigate whether VE is a risk factor for dementia in later life.

METHODS

We used data from 6,807 participants attending the third survey of the Copenhagen City Heart Study in 1991-1994. VE was assessed by 17 symptoms (score: 0-17) from the Maastricht Questionnaire. Information on dementia was obtained from national registers. Risk time for dementia was counted from five years after VE assessment for participants > 55 years at the time of VE assessment. For younger participants, risk time for dementia was counted from the year they turned 60 years and onwards. Participants were followed until 2016. We used Poisson regression to calculate incidence rate ratios (IRR) and their 95% confidence intervals (CI).

RESULTS

During an average follow-up of 10 years, 872 participants were registered with dementia. We found a dose-response relation between the number of VE symptoms and the incidence of dementia. For every additional VE symptom, the dementia incidence increased by 2% (IRR = 1.024; 95% CI: 1.004-1.043). Adjustment for socio-demographic and health-related factors did not change the results substantially. Neither did stratification by age, sex, educational level, and marital status.

CONCLUSION

We found evidence that VE is a risk factor for dementia. Our sensitivity analyses supported that this association was not only due to VE being a potential prodromal sign of dementia.

A Review of Minority Stress as a Risk Factor for Cognitive Decline in Lesbian, Gay, Bisexual, and Transgender (LGBT) Elders

Lesbian, gay, bisexual, and transgender (LGBT) older adults comprise a unique and growing subset of the aging population. The historical context in which they came of age was imbued with victimization and discrimination. These experiences are subjectively stressful and collectively known as minority stress. Older LGBT adults continue to face stressors related to their gender and sexual identities in their daily lives. Importantly, chronic minority stress (CMS), like other forms of chronic stress, is harmful to health and well-being. CMS contributes to LGBT health disparities, including cardiovascular disease and depression, conditions that in turn increase risk for premature cognitive decline. Furthermore, long-term exposure to stress hormones is associated with accelerated brain aging. Yet, the cognitive functioning of LGBT elders and the influence of CMS on their cognition is all but unexplored. In this review, we examine the influences of CMS in LGBT elders and connect those influences to existing research on stress and cognitive aging. We propose a testable model describing how CMS in LGBT elders heightens risk for premature cognitive aging and how ameliorating factors may help protect from CMS risk. Research is desperately needed to calibrate this model toward improving LGBT quality of life and mental health practices.

Alpha-synuclein at the nexus of genes and environment: the impact of environmental enrichment and stress on brain health and disease

Accumulation of alpha‐synuclein protein aggregates is the hallmark neuropathologic feature of synucleinopathies such as Parkinson’s disease. Rare point mutations and multiplications in SNCA, the gene encoding alpha‐synuclein, as well as other genetic alterations are linked to familial Parkinson’s disease cases with high penetrance and hence constitute major genetic risk factors for Parkinson’s disease. However, the preponderance of cases seems sporadic, most likely based on a complex interplay between genetic predispositions, aging processes and environmental influences. Deciphering the impact of these environmental factors and their interactions with the individual genetic background in humans is challenging and often requires large cohorts, complicated study designs, and longitudinal set‐ups. In contrast, rodent models offer an ideal system to study the influence of individual environmental aspects under controlled genetic background and standardized conditions. In this review, we highlight findings from studies examining effects of environmental enrichment mimicking stimulation of the brain by its physical and social surroundings as well as of environmental stressors on brain health in the context of Parkinson’s disease. We discuss possible internal molecular transducers of such environmental cues in Parkinson’s disease rodent models and emphasize their potential in developing novel avenues to much‐needed therapies for this still incurable disease.

This article is part of the Special Issue “Synuclein”

Distinct Stress Response and Altered Striatal Transcriptome in Alpha-Synuclein Overexpressing Mice

Parkinson's disease (PD) is a progressive neurodegenerative disorder with motor symptoms and a plethora of non-motor and neuropsychiatric features that accompany the disease from prodromal to advanced stages. While several genetic defects have been identified in familial forms of PD, the predominance of cases are sporadic and result from a complex interplay of genetic and non-genetic factors. Clinical evidence, moreover, indicates a role of environmental stress in PD, supported by analogies between stress-induced pathological consequences and neuronal deterioration observed in PD. From this perspective, we set out to investigate the effects of chronic stress exposure in the context of PD by using a genetic mouse model that overexpresses human wildtype SNCA. Mimicking chronic stress was achieved by adapting a chronic unpredictable mild stress protocol (CUMS) comprising eight different stressors that were applied randomly over a period of eight weeks starting at an age of four months. A distinctive stress response with an impact on anxiety-related behavior was observed upon SNCA overexpression and CUMS exposure. SNCA-overexpressing mice showed prolonged elevation of cortisol metabolites during CUMS exposure, altered anxiety-related traits, and declined motor skills surfacing with advanced age. To relate our phenotypic observations to molecular events, we profiled the striatal and hippocampal transcriptome and used a 2 × 2 factorial design opposing genotype and environment to determine differentially expressed genes. Disturbed striatal gene expression and minor hippocampal gene expression changes were observed in SNCA-overexpressing mice at six months of age. Irrespective of the CUMS-exposure, genes attributed to the terms neuroinflammation, Parkinson's signaling, and plasticity of synapses were altered in the striatum of SNCA-overexpressing mice.

Stress and the Etiopathogenesis of Alzheimer's Disease and Depression

Alzheimer's disease (AD) is a multifactorial neurodegenerative disorder with a complex physiopathology whose initiators are poorly defined. Accumulating clinical and experimental evidence suggests a causal role of lifetime stress in AD. This chapter summarizes current knowledge about how chronic stress and its accompanying high levels of glucocorticoid (GC) secretion, trigger the two main pathomechanisms of AD: (i) misprocessing of amyloid precursor protein (APP) and the generation of amyloid beta (Aβ) and (ii) Tau hyperphosphorylation and aggregation. Given that depression is a well-known stress-related illness, and the evidence that depression may precede AD, this chapter also explores neurobiological mechanisms that may be common to depressive and AD pathologies. This review also discusses emerging insights into the role of Tau and its malfunction in disrupting neuronal cascades and neuroplasticity and, thus triggering brain pathology.

Dysregulation of autophagy and stress granule-related proteins in stress-driven Tau pathology

Imbalance of neuronal proteostasis associated with misfolding and aggregation of Tau protein is a common neurodegenerative feature in Alzheimer's disease (AD) and other Tauopathies. Consistent with suggestions that lifetime stress may be an important AD precipitating factor, we previously reported that environmental stress and high glucocorticoid (GC) levels induce accumulation of aggregated Tau; however, the molecular mechanisms for such process remain unclear. Herein, we monitor a novel interplay between RNA-binding proteins (RBPs) and autophagic machinery in the underlying mechanisms through which chronic stress and high GC levels impact on Tau proteostasis precipitating Tau aggregation. Using molecular, pharmacological and behavioral analysis, we demonstrate that chronic stress and high GC trigger mTOR-dependent inhibition of autophagy, leading to accumulation of Tau aggregates and cell death in P301L-Tau expressing mice and cells. In parallel, we found that environmental stress and GC disturb cellular homeostasis and trigger the insoluble accumulation of different RBPs, such as PABP, G3BP1, TIA-1, and FUS, shown to form stress granules (SGs) and Tau aggregation. Interestingly, an mTOR-driven pharmacological stimulation of autophagy attenuates the GC-driven accumulation of Tau and SG-related proteins as well as the related cell death, suggesting a critical interface between autophagy and the response of the SG-related protein in the neurodegenerative potential of chronic stress and GC. These studies provide novel insights into the RNA-protein intracellular signaling regulating the precipitating role of environmental stress and GC on Tau-driven brain pathology.

Mindfulness mechanisms and psychological effects for aMCI patients: A comparison with psychoeducation

Amnestic mild cognitive impairment (aMCI), an Alzheimer's disease prodrome, is characterized by cognitive and psychological symptoms, the latter aggravating prognosis. A mindfulness-based intervention (MBI) represents a promising non-pharmacological framework for Alzheimer's disease prevention. The Monitoring + Acceptance Theory (MAT) postulates that MBI improves cognition through monitoring, and psychological well-being, through acceptance. This single-blind preliminary randomized-controlled study investigated the effects of a MBI on anxio-depressive symptoms, quality of life, and memory, compared to a psychoeducation-based intervention in older adults with aMCI. The contribution of MAT components and of ruminations' reduction to intervention efficacy were examined. Participants assigned to both conditions experienced similar benefits regarding anxio-depressive symptoms and aging-related quality of life. General quality of life and memory remained unchanged. A partial support of the MAT and of ruminations reduction to the MBI's efficacy was found. The findings provide new insights on the effects and mechanisms of a MBI on aMCI symptoms.

Stress and Corticosteroids Modulate Muscarinic Long Term Potentiation (mLTP) in the Hippocampus

Stress influences synaptic plasticity, learning and memory in a steroid hormone receptor dependent manner. Based on these findings it has been proposed that stress could be a major risk factor for the development of cognitive decline and dementia. Interestingly, evidence has been provided that stress also affects muscarinic, i.e., acetylcholine (ACh)-mediated neurotransmission. To learn more about the impact of stress and steroids on synaptic plasticity, in this study, we investigated the effects of stress on muscarinic long term potentiation (mLTP). We report that multiple, unpredictable exposure to stress depresses carbachol (0.5 μM)-induced mLTP, while this effect of stress is not observed in hippocampal slices prepared from mice exposed only to a single stressful procedure. Furthermore, we demonstrate that activation of distinct steroid hormone receptors is involved in stress-mediated alterations of mLTP. Activation of mineralocorticoid receptors (MR) promotes mLTP, while glucocorticoid receptor (GR) activity impairs mLTP. These effects of multiple unpredictable stress on mLTP are long-lasting since they are detected even two weeks after the last stressful experience. Thus, multiple unpredictable events rather than a single stressful experience affect mLTP in a steroid hormone receptor dependent manner, suggesting that chronic unpredictable stress can lead to lasting alterations in hippocampal cholinergic plasticity.

Design and Implementation of an Intervention Development Study: Retaining Cognition While Avoiding Late-Life Depression (ReCALL)

OBJECTIVE

To discuss the design, rationale, and implementation of an intervention development study addressing indicated and selective prevention of depression and anxiety in individuals 60 years and older with mild cognitive impairment (MCI) and in their caregivers.

METHODS

In Phase I, now completed, we developed and standardized problem-solving therapy (PST) and the combined PST + moderate-intensity physical exercise (PE) intervention to be administered to participants with MCI and their caregivers together, dyadically, with both participants working with the same interventionist in the same therapy sessions. In Phase II we have been testing the interventions against enhanced usual care (EUC) and have addressed challenges to recruitment. Randomization was to one of three cells: PST + PE, PST, or EUC.

RESULTS

Although we set out to intervene dyadically, many individuals with MCI lived alone or did not have a support person who could participate in the study with them. Consequently, we modified the study to include MCI participants with and without support persons. Ninety-four participants were enrolled: 20 with MCI together with their support persons (N = 20 dyads) and 54 MCI participants without accompanying support persons. Most participants have been satisfied with the usefulness of the interventions in managing stress and cognitive problems.

CONCLUSION

PST and moderate-intensity PE are acceptable interventions for depression and anxiety prevention in older adults with MCI and their available caregivers.

Perceived Stress Is Differentially Related to Hippocampal Subfield Volumes among Older Adults

INTRODUCTION

Chronic exposure to stress has been shown to impact a wide range of health-related outcomes in older adults. Despite extensive animal literature revealing deleterious effects of biological markers of stress on the dentate gyrus subfield of the hippocampus, links between hippocampal subfields and psychological stress have not been studied in humans. This study examined the relationship between perceived stress and hippocampal subfield volumes among racially/ethnically diverse older adults.

METHODS AND MATERIALS

Between July 2011 and March 2014, 116 nondemented participants were consecutively drawn from the Einstein Aging Study, an ongoing community-based sample of individuals over the age of 70 residing in Bronx, New York. All participants completed the Perceived Stress Scale, Geriatric Depression Scale, and underwent 3.0 T MRI. FreeSurfer was used to derive total hippocampal volume, hippocampal subfield volumes (CA1, CA2/CA3, CA4/Dentate Gyrus (CA4/DG), and subiculum), entorhinal cortex volume, whole brain volume, and total intracranial volume.

RESULTS

Linear regression analyses revealed that higher levels of perceived stress were associated with smaller total hippocampal volume (β = -0.20, t = -2.40, p = 0.02), smaller CA2/CA3 volumes (β = -0.18, t = -2.24, p = 0.03) and smaller CA4/DG volumes (β = -0.19, t = -2.28, p = 0.03) after controlling for total intracranial volume, age, gender, and race. These findings remained unchanged after removal of individuals with clinically significant symptoms of depression.

DISCUSSION

Our findings provide evidence of a relationship between a direct indicator of psychological stress and specific hippocampal subfield volumes in elderly individuals. These results highlight the importance of clinical screening for chronic stress in otherwise healthy older adults.

Chronic Stress and Glucocorticoids: From Neuronal Plasticity to Neurodegeneration

Stress and stress hormones, glucocorticoids (GCs), exert widespread actions in central nervous system, ranging from the regulation of gene transcription, cellular signaling, modulation of synaptic structure, and transmission and glial function to behavior. Their actions are mediated by glucocorticoid and mineralocorticoid receptors which are nuclear receptors/transcription factors. While GCs primarily act to maintain homeostasis by inducing physiological and behavioral adaptation, prolonged exposure to stress and elevated GC levels may result in neuro- and psychopathology. There is now ample evidence for cause-effect relationships between prolonged stress, elevated GC levels, and cognitive and mood disorders while the evidence for a link between chronic stress/GC and neurodegenerative disorders such as Alzheimer's (AD) and Parkinson's (PD) diseases is growing. This brief review considers some of the cellular mechanisms through which stress and GC may contribute to the pathogenesis of AD and PD.

Potential benefits of mindfulness-based interventions in mild cognitive impairment and Alzheimer's disease: an interdisciplinary perspective

The present article is based on the premise that the risk of developing Alzheimer's disease (AD) from its prodromal phase (mild cognitive impairment; MCI) is higher when adverse factors (e.g., stress, depression, and metabolic syndrome) are present and accumulate. Such factors augment the likelihood of hippocampal damage central in MCI/AD aetiology, as well as compensatory mechanisms failure triggering a switch toward neurodegeneration. Because of the devastating consequences of AD, there is a need for early interventions that can delay, perhaps prevent, the transition from MCI to AD. We hypothesize that mindfulness-based interventions (MBI) show promise with regard to this goal. The present review discusses the associations between modifiable adverse factors and MCI/AD decline, MBI's impacts on adverse factors, and the mechanisms that could underlie the benefits of MBI. A schematic model is proposed to illustrate the course of neurodegeneration specific to MCI/AD, as well as the possible preventive mechanisms of MBI. Whereas regulation of glucocorticosteroids, inflammation, and serotonin could mediate MBI's effects on stress and depression, resolution of the metabolic syndrome might happen through a reduction of inflammation and white matter hyperintensities, and normalization of insulin and oxidation. The literature reviewed in this paper suggests that the main reach of MBI over MCI/AD development involves the management of stress, depressive symptoms, and inflammation. Future research must focus on achieving deeper understanding of MBI's mechanisms of action in the context of MCI and AD. This necessitates bridging the gap between neuroscientific subfields and a cross-domain integration between basic and clinical knowledge.

Depressive, functional status, and neuropsychiatric symptom trajectories before an Alzheimer's disease diagnosis

OBJECTIVES

This short report relied on multiyear data from the National Alzheimer's Coordinating Center - Uniform Data Set (NACC-UDS) to examine whether significant changes occurred in functional status, neuropsychiatric symptoms, and depressive symptoms in the years before receiving an Alzheimer's disease (AD) diagnosis.

METHOD

The secondary analysis used a retrospective cohort design. The NACC-UDS is a publicly accessible, longitudinal database that includes standardized data on neuropsychiatric symptoms, functional status, and depressive symptoms for Alzheimer's Disease Center (ADC) participants in the USA based on their annual visits from 2005 to 2011. ADC participants were considered diagnosed with AD if a follow-up data form indicated an affirmative response to whether the ADC participant had 'probable AD (National Institute of Neurological and Communicative Disorders and Stroke (NINCDS)/Alzheimer's Disease and Related Disorders Association (ADRDA))' or 'possible AD (NINCDS/ADRDA).' This yielded an analytic sample of 2478 individuals (139 with an eventual probable AD diagnosis, 109 individuals with an eventual possible AD diagnosis, and 2230 without any AD diagnosis) representing a total of 11,358 visits/points of data.

RESULTS

Multilevel linear models revealed significant decreases (p < 0.05) in functional status prior to a probable or possible AD diagnosis and significant increases in depressive symptoms prior to a probable AD diagnosis.

DISCUSSION

Changes in functional and depressive symptoms were partly independent of cognitive decline. The longitudinal results lend additional support to conceptual and empirical models of pre-diagnosis declines in AD.

The influence of chronic stress on dementia-related diagnostic change in older adults

Increased susceptibility of the aging brain to both chronic stress and incipient dementia-related neuropathology may accelerate cognitive decline. We investigated associations between chronic stress and diagnostic change in 62 individuals (mean age, 78.7 y) participating in an Alzheimer disease research center longitudinal study. The subjects, diagnosed at baseline as cognitively normal (CN) or with mild cognitive impairment (MCI), were followed for an average of 2.5 years. Senior neurologists, blind to detailed measures of stress and cognition, assigned diagnoses annually. Logistic regression analyses assessed the accuracy with which measures of stress (event-based ratings, cortisol levels) predicted the conversion to MCI and dementia. Eleven individuals with MCI at baseline received a dementia diagnosis during follow-up. Sixteen converted from cognitively normal to MCI. Prolonged, highly stressful experiences were associated with conversion from MCI to dementia. The cortisol awakening response, with age and education, was associated with a diagnostic change to MCI. Cortisol measures were not associated with the progression from MCI to dementia, and there was no association between stressful experiences and the change to MCI. Mechanisms associated with the transition from normal cognition to MCI may differ from those associated with a diagnostic change to dementia. These findings could facilitate the identification of interventional strategies to reduce the risk of decline at different stages of susceptibility.

Neuroimmunoendocrine regulation of the prion protein in neutrophils

The prion protein (PrP(C)) is a cell surface protein expressed mainly in the nervous system. In addition to the role of its abnormal conformer in transmissible spongiform encephalopathies, normal PrP(C) may be implicated in other degenerative conditions often associated with inflammation. PrP(C) is also present in cells of hematopoietic origin, including T cells, dendritic cells, and macrophages, and it has been shown to modulate their functions. Here, we investigated the impact of inflammation and stress on the expression and function of PrP(C) in neutrophils, a cell type critically involved in both acute and chronic inflammation. We found that systemic injection of LPS induced transcription and translation of PrP(C) in mouse neutrophils. Up-regulation of PrP(C) was dependent on the serum content of TGF-β and glucocorticoids (GC), which, in turn, are contingent on the activation of the hypothalamic-pituitary-adrenal axis in response to systemic inflammation. GC and TGF-β, either alone or in combination, directly up-regulated PrP(C) in neutrophils, and accordingly, the blockade of GC receptors in vivo curtailed the LPS-induced increase in the content of PrP(C). Moreover, GC also mediated up-regulation of PrP(C) in neutrophils following noninflammatory restraint stress. Finally, neutrophils with up-regulated PrP(C) presented enhanced peroxide-dependent cytotoxicity to endothelial cells. The data demonstrate a novel interplay of the nervous, endocrine, and immune systems upon both the expression and function of PrP(C) in neutrophils, which may have a broad impact upon the physiology and pathology of various organs and systems.

The relation between depressive symptoms and semantic memory in amnestic mild cognitive impairment and in late-life depression

Semantic deficits have been documented in the prodromal phase of Alzheimer's disease, but it is unclear whether these deficits are associated with non-cognitive manifestations. For instance, recent evidence indicates that cognitive deficits in elders with amnestic mild cognitive impairment (aMCI) are modulated by concomitant depressive symptoms. The purposes of this study were to (i) investigate if semantic memory impairment in aMCI is modulated according to the presence (aMCI-D group) or absence (aMCI group) of depressive symptoms, and (ii) compare semantic memory performance of aMCI and aMCI-D groups to that of patients with late-life depression (LLD). Seventeen aMCI, 16 aMCI-D, 15 LLD, and 26 healthy control participants were administered a semantic questionnaire assessing famous person knowledge. Results showed that performance of aMCI-D patients was impaired compared to the control and LLD groups. However, in the aMCI group performance was comparable to that of all other groups. Overall, these findings suggest that semantic deficits in aMCI are somewhat associated with the presence of concomitant depressive symptoms. However, depression alone cannot account solely for the semantic deficits since LLD patients showed no semantic memory impairment in this study. Future studies should aim at clarifying the association between depression and semantic deficits in older adults meeting aMCI criteria. (JINS, 2011, 17, 865-874).

3xTgAD mice exhibit altered behavior and elevated Aβ after chronic mild social stress

Chronic stress may be a risk factor for developing Alzheimer's disease (AD), but most studies of the effects of stress in models of AD utilize acute adverse stressors of questionable clinical relevance. The goal of this work was to determine how chronic psychosocial stress affects behavioral and pathological outcomes in an animal model of AD, and to elucidate underlying mechanisms. A triple-transgenic mouse model of AD (3xTgAD mice) and nontransgenic control mice were used to test for an affect of chronic mild social stress on blood glucose, plasma glucocorticoids, plasma insulin, anxiety, and hippocampal amyloid β-particle (Aβ), phosphorylated tau (ptau), and brain-derived neurotrophic factor (BDNF) levels. Despite the fact that both control and 3xTgAD mice experienced rises in corticosterone during episodes of mild social stress, at the end of the 6-week stress period 3xTgAD mice displayed increased anxiety, elevated levels of Aβ oligomers and intraneuronal Aβ, and decreased brain-derived neurotrophic factor levels, whereas control mice did not. Findings suggest 3xTgAD mice are more vulnerable than control mice to chronic psychosocial stress, and that such chronic stress exacerbates Aβ accumulation and impairs neurotrophic signaling.

Dietary patterns during pregnancy and the risk of postpartum depression: the mother-child 'Rhea' cohort in Crete, Greece

OBJECTIVE

To identify and describe dietary patterns in a cohort of pregnant women, and investigate whether dietary patterns during pregnancy are related to postpartum depression (PPD).

DESIGN

The study uses data from the prospective mother-child cohort 'Rhea' study. Pregnant women completed an FFQ in mid-pregnancy and the Edinburg Postpartum Depression Scale (EPDS) at 8-10 weeks postpartum. Dietary patterns during pregnancy ('health conscious', 'Western') were identified using principal component analysis. Associations between dietary patterns categorized in tertiles and PPD symptoms were investigated by multivariable regression models after adjusting for confounders.

SETTING

Heraklion, Crete, Greece, 2007-2010.

SUBJECTS

A total of 529 women, participating in the 'Rhea' cohort.

RESULTS

High adherence to a 'health conscious' diet, characterized by vegetables, fruit, pulses, nuts, dairy products, fish and olive oil, was associated with lower EPDS scores (highest v. lowest tertile: β-coefficient = -1·75, P = 0·02). Women in the second (relative risk (RR) = 0·52, 95 % CI 0·30, 0·92) or third tertile (RR = 0·51, 95 % CI 0·25, 1·05) of the 'health conscious' dietary pattern were about 50 % less likely to have high levels of PPD symptoms (EPDS ≥ 13) compared with those in the lowest tertile.

CONCLUSIONS

This is the first prospective study showing that a healthy diet during pregnancy is associated with reduced risk for PPD. Additional longitudinal studies and trials are needed to confirm these findings.

Path dependence in social and psychological risk factors for dementia

This article focuses on social and psychological risk factors for Alzheimer’s disease, dementia, and cognitive impairment and presents some key points for prevention in developing countries based on previous studies, a social science theory, and our preliminary survey. Previous population-based studies found that educational and occupational attainment, income, participation in social and mental activities, and psychological distress were associated with dementia risk. According to the theory of path dependence, earlier factors largely determine successive ones, where education is one of these early experiences in life. Our preliminary survey suggested that education sets a path that several psychosocial risk factors are dependent on. The expansion of basic education is indispensable. Resources for prevention should be concentrated on individuals with a low level of education. In order to break from a path creating self-reinforcement of risk factors, it is necessary to implement early and active interventions.

Anxiety and related symptoms in older persons with dementia: directions for practice

Anxiety disorders and related symptoms commonly occur in older people with cognitive impairment or dementia, significantly worsening functioning and reducing quality of life. This review of the literature outlines the extent of the problem, and focuses on current best practices in psychosocial interventions anxiety in persons with dementia. Discussion follows on promising nonpharmacological interventions that are recommended for further consideration and future research.

Occurrence of neuropsychiatric symptoms and psychiatric disorders in mild Alzheimer's disease and mild cognitive impairment subtypes

BACKGROUND

Neuropsychiatric disorders are common in cognitively impaired older persons, and associated with institutionalization and caregiver stress in Alzheimer's disease (AD). Few studies have compared the occurrence of both psychiatric disorders and neuropsychiatric symptoms in patients with AD and mild cognitive impairment (MCI) subtypes. We aimed to investigate the frequency of psychiatric disorders and neuropsychiatric symptoms in AD and MCI patients, compared to controls.

METHODS

We included 245 outpatients of a memory clinic in Rome, Italy (119 AD; 68 multidomain-MCI; 58 amnestic-MCI) and 107 controls. Categorical disorders of depression and apathy were diagnosed with structured interviews. Symptoms were evaluated with the Neuropsychiatric Inventory (NPI). The odds ratios (OR) of patients having neuropsychiatric symptoms compared to controls were calculated with logistic regression, adjusted for sociodemographic and clinical variables.

RESULTS

A large proportion of AD (49.6%) and multidomain-MCI (44.1%) patients had depression disorder. Apathy disorder was common in AD (51.3%) but less frequent in amnestic-MCI (6.9%) and multidomain-MCI (14.7%). AD patients were three times more likely to have depression disorders (OR = 3.0, CI = 1.1-7.6) or apathy (OR = 16.9, CI = 4.6-61.8) compared to amnestic-MCI, and seven times more likely to have apathy disorder than multidomain-MCI (OR = 7.5, CI = 3.0-19.2). After apathy and depression, the most prevalent neuropsychiatric symptoms in AD and MCI were anxiety, agitation, irritability, night-time behaviors, and appetite disturbances. There was an increasing prevalence of many neuropsychiatric symptoms with increasing severity of cognitive syndromes.

CONCLUSIONS

Clinicians should consider the relevance of neuropsychiatric disorders and symptoms in patients with cognitive disturbances, and incorporate a thorough psychiatric examination in the evaluation of patients.

Depression and Alzheimer's disease: neurobiological links and common pharmacological targets

Depression is one of the most prevalent and life-threatening forms of mental illnesses, whereas Alzheimer's disease is a neurodegenerative disorder that affects more than 37 million people worldwide. Recent evidence suggests a strong relationship between depression and Alzheimer's disease. A lifetime history of major depression has been considered as a risk factor for later development of Alzheimer's disease. The presence of depressive symptoms can affect the conversion of mild cognitive impairment into Alzheimer's disease. Neuritic plaques and neurofibrillary tangles, the two major hallmarks of Alzheimer's disease brain, are more pronounced in the brains of Alzheimer's disease patients with comorbid depression as compared with Alzheimer's disease patients without depression. On the other hand, neurodegenerative phenomena have been observed in different brain regions of patients with a history of depression. Recent evidence suggests that molecular mechanisms and cascades that underlie the pathogenesis of major depression, such as chronic inflammation and hyperactivation of hypothalamic-pituitary-adrenal (HPA) axis, are also involved in the pathogenesis of Alzheimer's disease. In particular, a specific impairment in the signaling of some neurotrophins such as transforming-growth-factor beta1 (TGF-beta1) and brain-derived neurotrophic factor (BDNF) has been observed both in depression and Alzheimer's disease. In the present review we will examine the evidence on the common molecular pathways between depression and Alzheimer's disease and we will discuss these pathways as new pharmacological targets for the treatment of both major depression and Alzheimer's disease.