Investigation of possible risk factors for depression in Alzheimer's disease: A systematic review of the evidence

Risk of depression in persons with Alzheimer's disease: A national cohort study

INTRODUCTION

Depression is a risk factor and possible prodromal symptom of Alzheimer's disease (AD), but little is known about subsequent risk of developing depression in persons with AD.

METHODS

National matched cohort study was conducted of all 129,410 persons diagnosed with AD and 390,088 with all-cause dementia during 1998-2017 in Sweden, and 3,900,880 age- and sex-matched controls without dementia, who had no prior depression. Cox regression was used to compute hazard ratios (HRs) for major depression through 2018.

RESULTS

Cumulative incidence of major depression was 13% in persons with AD and 3% in controls. Adjusting for sociodemographic factors and comorbidities, risk of major depression was greater than two-fold higher in women with AD (HR, 2.21; 95% confidence interval [CI], 2.11-2.32) or men with AD (2.68; 2.52-2.85), compared with controls. Similar results were found for all-cause dementia.

DISCUSSION

Persons diagnosed with AD or related dementias need close follow-up for timely detection and treatment of depression.

Highlights

In a large cohort, women and men with AD had >2-fold subsequent risk of depression.Risks were highest in the first year (>3-fold) but remained elevated ≥3 years later.Risk of depression was highest in persons aged ≥85 years at AD diagnosis.Persons with AD need close follow-up for detection and treatment of depression.

Depression and thoughts of self-harm and suicide among people living with dementia: results of a cross-sectional survey

BACKGROUND

Depression is common among people with dementia. Despite most people with dementia living in the community, there have been few investigations of self-reported depressive symptoms and suicidal ideation among community-dwelling people with dementia in Australia. This study aimed to explore the proportion of people with mild, moderate and severe levels of depressive symptoms, and suicidal ideation among a sample of people living with dementia in Australia. Correlates of reporting depressive symptoms were also explored.

METHODS

Adults diagnosed with dementia by a medical professional who were English speaking and community-dwelling were asked to complete a paper and pencil survey. Those who were unable to provide independent consent were excluded. Depression was assessed using the Geriatric Depression Scale -15, and suicidal ideation was assessed using two study-specific items. Multivariable analyses examined quality of life, unmet needs and sociodemographic factors associated with having a score of five or more on the Geriatric Depression Scale-15.

RESULTS

Ninety-four people participated in the study. Thirty-seven percent (n = 35) reported some level of depressive symptoms, with most of these (21%, n = 20) classified as having mild depressive symptoms. Five participants (5%) reported they had had thoughts of being better off dead or hurting themselves, while three (3%) reported having had a plan to end their life. For each additional unmet need, the odds of being depressed increased by 25%(P < 0.001). For each point increase in quality of life, the odds of being depressed decreased by 48% (P < 0.001).

CONCLUSIONS

The high proportion of people with dementia who report depressive symptoms suggests the need to routinely assess depressive symptoms among this group. There may also be benefits in assessing unmet needs and addressing these where possible as part of an approach to reducing depression among people living with dementia in the community.

Characterization of Depressive Symptoms in Dementia and Examination of Possible Risk Factors

Background

Depression in individuals with Alzheimer's disease (AD) is common, distressing, difficult to treat, and inadequately understood. It occurs more frequently in AD than in older adults without dementia. The reasons why some patients develop depression during AD and others do not remain obscure.

Objective

We aimed to characterize depression in AD and to identify risk factors.

Methods

We used data from three large dementia focused cohorts: ADNI (n = 665 with AD, 669 normal cognition), NACC (n = 698 with AD, 711 normal cognition), and BDR (n = 757 with AD). Depression ratings were available using the GDS and NPI and in addition for BDR the Cornell. A cut-off of≥8 was used for the GDS and the Cornell Scale for Depression in Dementia,≥6 for the NPI depression sub-scale, and≥2 for the NPI-Q depression sub-scale. We used logistic regression to examine potential risk factors and random effects meta-analysis and an interaction term to look for interactions between each risk factor and the presence of cognitive impairment.

Results

In individual studies there was no evidence of a difference in risk factors for depressive symptoms in AD. In the meta-analysis the only risk factor which increased the risk of depressive symptoms in AD was previous depression, but information on this was only available from one study (OR 7.78 95% CI 4.03-15.03).

Conclusion

Risk factors for depression in AD appear to differ to those for depression per se supporting suggestions of a different pathological process, although a past history of depression was the strongest individual risk factor.

Perceived availability of home- and community-based services and self-reported depression among Chinese older adults: A cross-sectional study

Few studies have assessed the association between perceived availability of home- and community-based services (HCBSs) and self-reported depression among Chinese older adults, which the present study attempts to rectify. This cross-sectional study enrolled 11,941 participants aged 65 and older from the Chinese Longitudinal Healthy Longevity Survey 2018 wave. The 10-item Center for Epidemiologic Studies Depression Scale (CESD-10) was used to evaluate depression, and perceived availability was measured for four categories of HCBSs: daily life assistance, medical care services, emotional support and social services, and other. These four categories and the number of services in each were used to represent the perceived availability of service provision. Binary logistic models were used to explore the relationship between perceived availability of HCBSs and depression in older adults. Perceived daily life assistance was found to be negatively associated with depression symptoms among Chinese older adults in both urban and rural areas [rural: OR (95%CI) = 0.66 (0.55-0.78), p < 0.001; urban: OR (95% CI) = 0.69(0.60-0.79), p < 0.001], while perceived levels of medical care services, emotional support and social services, and other were not associated with depression symptoms in rural or urban areas. Our primary finding was that providing daily life assistance at the community level may help to meet more older adults' daily needs, thus potentially decreasing the risk of depression.

Psychological treatments for depression and anxiety in dementia and mild cognitive impairment

BACKGROUND

Experiencing anxiety and depression is very common in people living with dementia and mild cognitive impairment (MCI). There is uncertainty about the best treatment approach. Drug treatments may be ineffective and associated with adverse effects. Guidelines recommend psychological treatments. In this updated systematic review, we investigated the effectiveness of different psychological treatment approaches.

OBJECTIVES

Primary objective To assess the clinical effectiveness of psychological interventions in reducing depression and anxiety in people with dementia or MCI. Secondary objectives To determine whether psychological interventions improve individuals' quality of life, cognition, activities of daily living (ADL), and reduce behavioural and psychological symptoms of dementia, and whether they improve caregiver quality of life or reduce caregiver burden.

SEARCH METHODS

We searched ALOIS, the Cochrane Dementia and Cognitive Improvement Group's register, MEDLINE, Embase, four other databases, and three trials registers on 18 February 2021.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that compared a psychological intervention for depression or anxiety with treatment as usual (TAU) or another control intervention in people with dementia or MCI.

DATA COLLECTION AND ANALYSIS

A minimum of two authors worked independently to select trials, extract data, and assess studies for risk of bias. We classified the included psychological interventions as cognitive behavioural therapies (cognitive behavioural therapy (CBT), behavioural activation (BA), problem-solving therapy (PST)); 'third-wave' therapies (such as mindfulness-based cognitive therapy (MBCT)); supportive and counselling therapies; and interpersonal therapies. We compared each class of intervention with control. We expressed treatment effects as standardised mean differences or risk ratios. Where possible, we pooled data using a fixed-effects model. We used GRADE methods to assess the certainty of the evidence behind each result.

MAIN RESULTS

We included 29 studies with 2599 participants. They were all published between 1997 and 2020. There were 15 trials of cognitive behavioural therapies (4 CBT, 8 BA, 3 PST), 11 trials of supportive and counselling therapies, three trials of MBCT, and one of interpersonal therapy. The comparison groups received either usual care, attention-control education, or enhanced usual care incorporating an active control condition that was not a specific psychological treatment. There were 24 trials of people with a diagnosis of dementia, and five trials of people with MCI. Most studies were conducted in community settings. We considered none of the studies to be at low risk of bias in all domains.  Cognitive behavioural therapies (CBT, BA, PST) Cognitive behavioural therapies are probably slightly better than treatment as usual or active control conditions for reducing depressive symptoms (standardised mean difference (SMD) -0.23, 95% CI -0.37 to -0.10; 13 trials, 893 participants; moderate-certainty evidence). They may also increase rates of depression remission at the end of treatment (risk ratio (RR) 1.84, 95% CI 1.18 to 2.88; 2 studies, with one study contributing 2 independent comparisons, 146 participants; low-certainty evidence). We were very uncertain about the effect of cognitive behavioural therapies on anxiety at the end of treatment (SMD -0.03, 95% CI -0.36 to 0.30; 3 trials, 143 participants; very low-certainty evidence). Cognitive behavioural therapies probably improve patient quality of life (SMD 0.31, 95% CI 0.13 to 0.50; 7 trials, 459 participants; moderate-certainty evidence) and activities of daily living at end of treatment compared to treatment as usual or active control (SMD -0.25, 95% CI -0.40 to -0.09; 7 trials, 680 participants; moderate-certainty evidence). Supportive and counselling interventions Meta-analysis showed that supportive and counselling interventions may have little or no effect on depressive symptoms in people with dementia compared to usual care at end of treatment (SMD -0.05, 95% CI -0.18 to 0.07; 9 trials, 994 participants; low-certainty evidence). We were very uncertain about the effects of these treatments on anxiety, which was assessed only in one small pilot study. Other interventions There were very few data and very low-certainty evidence on MBCT and interpersonal therapy, so we were unable to draw any conclusions about the effectiveness of these interventions.

AUTHORS' CONCLUSIONS

CBT-based treatments added to usual care probably slightly reduce symptoms of depression for people with dementia and MCI and may increase rates of remission of depression. There may be important effect modifiers (degree of baseline depression, cognitive diagnosis, or content of the intervention). CBT-based treatments probably also have a small positive effect on quality of life and activities of daily living. Supportive and counselling interventions may not improve symptoms of depression in people with dementia. Effects of both types of treatment on anxiety symptoms are very uncertain. We are also uncertain about the effects of other types of psychological treatments, and about persistence of effects over time. To inform clinical guidelines, future studies should assess detailed components of these interventions and their implementation in different patient populations and in different settings.

Mechanism of METTL3-mediated m6A modification in depression-induced cognitive deficits

Depressive disorder (DD) is associated with N6-methyladenosine (m6A) hypermethylation. This study sought to explore the molecular mechanism of Methyltransferase-like 3 (METTL3) in cognitive deficits of chronic unpredictable mild stress (CUMS)-treated rats and provide novel targets for DD treatment. A DD rat model was established via CUMS treatment. Cognitive deficits were assessed via body weighing and behavioral tests. METTL3, microRNA (miR)-221-3p, pri-miR-221, GRB2-associated binding protein 1 (Gab1) expressions in hippocampal tissues were detected via RT-qPCR and Western blotting. m6A, DiGeorge syndrome critical region gene 8 (DGCR8)-bound pri-miR-221 and pri-miR-221 m6A levels were measured. The binding relationship between miR-221-3p and Gab1 was testified by dual-luciferase and RNA pull-down assays. Rescue experiments were designed to confirm the role of miR-221-3p and Gab1. METTL3 was highly expressed in CUMS rats, and silencing METTL3 attenuated cognitive deficits of CUMS rats. METTL3-mediated m6A modification facilitated processing and maturation of pri-miR-221 via DGCR8 to upregulate miR-221-3p. miR-221-3p targeted Gab1. miR-221-3p overexpression or Gab1 downregulation reversed the role of silencing METTL3 in CUMS rats. Overall, METTL3-mediated m6A modification facilitated processing and maturation of pri-miR-221 to upregulate miR-221-3p and then inhibit Gab1, thereby aggravating cognitive deficits of CUMS rats.

Locus of Control and Its Associations with Depressive Symptoms amongst People with Dementia

INTRODUCTION

Depression is common amongst people with dementia. This study examines whether locus of control (LoC), a perceived control construct influential in the coping process, is related to depressive symptoms in this population.

METHODS

In this prospective observational study, 257 community-dwelling older adults with a confirmed dementia diagnosis were included. At baseline, measures of depressive symptoms, LoC, cognition, independent functional ability, general health, dementia severity, and dementia disease insight were collected. At follow-up, measures of depressive symptoms and cognition were collected. Multiple linear regression using degree of depressive symptoms as measured with Montgomery-Asberg Depression Rating Scale as a dependent variable was applied to assess whether LoC was associated with depressive symptoms at baseline and follow-up while controlling for covariates.

RESULTS

LoC (p < 0.001), general health (p = 0.003), and insight (p = 0.010) were associated with severity of depressive symptoms at baseline, accounting for 28% of the variance. LoC (p = 0.025) and depressive symptoms (p < 0.001) at baseline were associated with severity of depressive symptoms at follow-up, accounting for 56.3% of the variance.

CONCLUSION

LoC was significantly associated with severity of depressive symptoms in people with dementia at baseline and at follow-up. Attention to LoC may be valuable for our understanding of depression in people with dementia, and interventions targeting depression could benefit from including a focus on internalizing perceived control. However, these findings are novel, and more research is needed.

Quercetin-Conjugated Superparamagnetic Iron Oxide Nanoparticles Protect AlCl3-Induced Neurotoxicity in a Rat Model of Alzheimer's Disease via Antioxidant Genes, APP Gene, and miRNA-101

Alzheimer's disease (AD) is a neurodegenerative disease with cognitive impairment. Oxidative stress in neurons is considered as a reason for development of AD. Antioxidant agents such as quercetin slow down AD progression, but the usage of this flavonoid has limitations because of its low bioavailability. We hypothesized that quercetin-conjugated superparamagnetic iron oxide nanoparticles (QT-SPIONs) have a better neuroprotective effect on AD than free quercetin and regulates the antioxidant, apoptotic, and APP gene, and miRNA-101. In this study, male Wistar rats were subjected to AlCl3, AlCl3 + QT, AlCl3 + SPION, and AlCl3 + QT-SPION for 42 consecutive days. Behavioral tests and qPCR were used to evaluate the efficiency of treatments. Results of behavioral tests revealed that the intensity of cognitive impairment was decelerated at both the middle and end of the treatment period. The effect of QT-SPIONs on learning and memory deficits were closely similar to the control group. The increase in expression levels of APP gene and the decrease in mir101 led to the development of AD symptoms in rats treated with AlCl3 while these results were reversed in the AlCl3 + QT-SPIONs group. This group showed similar results with the control group. QT-SPION also decreased the expression levels of antioxidant enzymes along with increases in expression levels of anti-apoptotic genes. Accordingly, the antioxidant effect of QT-SPION inhibited progression of cognitive impairment via sustaining the balance of antioxidant enzymes in the hippocampus of AD model rats.

Depression in Alzheimer's Disease: A Delphi Consensus on Etiology, Risk Factors, and Clinical Management

Background: Alzheimer's disease (AD) and other forms of dementia are among the most common causes of disability in the elderly. Dementia is often accompanied by depression, but specific diagnostic criteria and treatment approaches are still lacking. This study aimed to gather expert opinions on dementia and depressed patient management to reduce heterogeneity in everyday practice. Methods: Prospective, multicenter, 2-round Modified Delphi survey with 53 questions regarding risk factors (11), signs and symptoms (7), diagnosis (8), and treatment (27) of depression in dementia, with a particular focus on AD. The questionnaire was completed by a panel of 37 expert physicians in neurodegenerative diseases (19 neurologists, 17 psychiatrists, and 1 geriatrician). Results: Consensus was achieved in 40 (75.5%) of the items: agreement in 33 (62.3%) and disagreement in 7 (13.2%) of them. Among the most relevant findings, depression in the elderly was considered an early sign (prodromal) and/or a dementia risk factor, so routine cognitive check-ups in depressed patients should be adopted, aided by clinical scales and information from relatives. Careful interpretation of neuropsychological assessment must be carried out in patients with depression as it can undermine cognitive outcomes. As agreed, depression in early AD is characterized by somatic symptoms and can be differentiated from apathy by the presence of sadness, depressive thoughts and early-morning awakening. In later-phases, symptoms of depression would include sleep-wake cycle reversal, aggressive behavior, and agitation. Regardless of the stage of dementia, depression would accelerate its course, whereas antidepressants would have the opposite effect. Those that improve cognitive function and/or have a dual or multimodal mode of action were preferred: Duloxetine, venlafaxine/desvenlafaxine, vortioxetine, tianeptine, and mirtazapine. Although antidepressants may be less effective than in cognitively healthy patients, neither dosage nor treatment duration should differ. Anti-dementia cholinesterase inhibitors may have a synergistic effect with antidepressants. Exercise and psychological interventions should not be applied alone before any pharmacological treatment, yet they do play a part in improving depressive symptoms in demented patients. Conclusions: This study sheds light on several unresolved clinical challenges regarding depression in dementia patients. Further studies and specific recommendations for this comorbid patient population are still needed.

Adult Hippocampal Neurogenesis in Major Depressive Disorder and Alzheimer's Disease

Depression and dementia are major public health problems. Major depressive disorder (MDD) and Alzheimer's disease (AD) reciprocally elevate the risk for one another. No effective drug is available to treat AD and about one-third of depressive patients show treatment resistance. The biological connection between MDD and AD is still unclear. Uncovering this link might open novel ways of treatment and prevention to improve patient healthcare. Here, we discuss recent studies specifically on the role of human adult hippocampal neurogenesis (AHN) in MDD and AD. We compare diverse approaches to analyse the effect of MDD and AD on human AHN and analyse different studies implicating the role of human AHN as a potential converging mechanism in MDD and AD.

Agmatine ameliorates manifestation of depression-like behavior and hippocampal neuroinflammation in mouse model of Alzheimer's disease

Extensive clinical and experimental studies established that depression and mood disorders are highly prevalent neuropsychiatric conditions in Alzheimer's disease (AD). However, its neurochemical basis is not clearly understood. Thus, understanding the neural mechanisms involved in mediating the co-morbidity of depression and AD may be crucial in exploring new pharmacological treatments for this condition. The present study investigated the role of the agmatinergic system in β-amyloid (Aβ_β1-42) peptide-induced depression using forced swim test (FST) in mice. Following the 28th days of its administration, Aβ_1-42 peptide produced depression-like behavior in mice as evidenced by increased immobility time in FST and increased expression of pro-inflammatory cytokines like IL-6 and TNF-α compared to the control animals. The Aβ_1-42 peptide-induced depression and neuroinflammatory markers were significantly inhibited by agmatine -, moxonidine, 2-BFI and l-arginine by once-daily administration during day 8-27 of the protocol. The antidepressant-like effect of agmatine in Aβ_1-42 peptide in mice was potentiated by imidazoline receptor I₁ agonist, moxonidine and imidazoline receptor I₂ agonist 2-BFI at their sub-effective doses. On the other hand, it was completely blocked by imidazoline receptor I₁ antagonist, efaroxan and imidazoline receptor I₂ antagonist, idazoxan Also, agmatine levels were significantly reduced in brain samples of β-amyloid injected mice as compared to the control animals. In conclusion, the present study suggests the importance of endogenous agmatinergic system and imidazoline receptors system in β-amyloid induced a depressive-like behavior in mice. The data projects agmatine as a potential therapeutic target for the AD-associated depression and comorbidities.

Minor and subthreshold depressive disorders in Alzheimer's disease: A systematic review and meta-analysis of prevalence studies

BACKGROUND

Depressive symptoms are common in Alzheimer's disease (AD) and negatively impact patient well-being. The main aim of the present study was to establish summary estimates for the prevalence of minor depressive disorder (MinD) and subthreshold depression in AD and synthesise evidence on prognosis and management of these symptoms in order to inform clinical guidelines.

METHODS

Systematic review and meta-analysis of cross-sectional and longitudinal studies of prevalence, prognosis, and treatments for minor and subthreshold depression in AD. We searched MEDLINE, Embase, PsycINFO and CINAHL. We included studies that reported prevalence of subthreshold depressive disorders and those reporting data on validity of diagnostic criteria, mechanisms, or randomised controlled clinical trials (RCTs) testing effectiveness of interventions. Estimates of prevalence were pooled using random-effects meta-analyses. Two authors screened articles and independently extracted data on study characteristics.

RESULTS

We reviewed 5671 abstracts, retrieved 621 full text articles and included a total of 15 studies. Pooling data from 10 studies showed that prevalence for MinD in AD was 22.0% (95% CI 16.0 to 28.0). Prevalence for a clinical diagnosis of MinD (DSM-III-R and DSM-IV) was 26.0% (95% CI 20.0 to 32.0; 6 studies). People with MinD experienced higher levels of neuropsychiatric symptoms, functional and cognitive decline, although studies remain cross-sectional. Neither sertraline nor a carer intervention were effective in reducing symptoms.

CONCLUSION

This review finds that MinD is prevalent in people with a diagnosis of AD and requires clinical attention. Research is warranted to develop effective interventions to treat and prevent these symptoms.

Personality disorders characterized by anxiety predict Alzheimer's disease in women: A case-control studies

This research is geared toward the evaluation of current and pre-morbid personality psychopathology in Alzheimer's disease (AD). The study was conducted with four groups who were administered the Personality Diagnostic Questionnaire-4+, mainly in the form of individual interviews. Current measurement: AD Group, 44 female participants (M = 81.36 years); Control Group, 80 female participants from the population at large (M = 75.84 years). Pre-morbid measurement: AD Group Informants (n = 40); Control Group Informants (n = 42). The incidence of all clusters in clinical state are significant, and Cluster B incidence in pre-morbidity is evidenced. Cluster C is highlighted throughout the life course as a predictor. Logistic regression analyses showed that schizotypical, narcissistic, avoidant, obsessive-compulsive, pre-morbid schizotypical, pre-morbid histrionic, and pre-morbid obsessive-compulsive personality disorders, predicted the presence of AD diagnosis, accounting for 49% of the variance. These findings are relevant to research relating personality and psychopathology in Alzheimer's disease.

Curcumin-Loaded Nanocapsules Reverses the Depressant-Like Behavior and Oxidative Stress Induced by β-Amyloid in Mice

Alzheimer's disease (AD) is a neurodegenerative disorder classically characterized by cognitive functions impairment. However, its symptomatology is complex and the depression is one of the most frequent behavioral changes in AD. AD pathology includes neuroinflammation and oxidative stress resulting in the Aβ protein accumulation. Curcumin is a natural phenolic compound that shows antioxidant and anti-inflammatory properties. Nevertheless, therapeutic use of curcumin is limited due to its low bioavailability and biodistribution. In this context, the use of curcumin-loaded nanocapsules (NLC C) emerges to overcome its limitations. Thus, the present study investigated the effects of NLC C on the depressant-like behavior and oxidative stress induced by an animal model of AD. For this, Swiss male mice were divided into five groups. The Aβ, Aβ + NLC C and Aβ + Curcumin groups received Aβ_25-35 aggregate (3 nmol/3 μL, i.c.v.). Control and NLC C groups received only vehicle. The NLC C were administered via gavage at a dose of 10 mg/kg in alternate days for 12 days. Our results demonstrated that Aβ infusion induced a depressantant-like behavior observed in the tail suspension and forced swimming tests, which was reversed by NLC C treatment. No change was observed in mice locomotion. Furthermore, NLC C reduced the Aβ-generated oxidative stress in the prefrontal cortex, evidenced by the increase in the reactive species levels, superoxide dismutase and catalase activities. Importantly, NLC C were more effective than the free curcumin. Thus, we demonstrated the antidepressant-like and antioxidant effects of NLC C in a mouse model of AD, suggesting its therapeutic potential for this disorder.

Mind the gaps: What we don't know about cognitive impairment in essential tremor

INTRODUCTION

Although the hallmark feature of essential tremor (ET) is tremor, there is growing appreciation that cognitive impairment also occurs, including increased prevalence of mild cognitive impairment (MCI) and increased prevalence and incidence of dementia. With emerging knowledge of ET-cognitive impairment, come fundamental questions regarding its course, bases, predictors and clinical outcomes. Studies in the general population and in Parkinson's disease (PD), a related movement disorder, offer a starting point from which to begin filling these clinically important knowledge gaps.

METHODS

A PubMed search (June 2018) identified articles for this review.

RESULTS

Much of our knowledge of cognitive impairment in ET is of the static condition (e.g., prevalence of cognitive impairment in ET), with nearly no information on its bases, predictors and dynamics (i.e., course, and clinical outcomes). In PD, where such data have been published, rates of cognitive decline and conversion to MCI/dementia are higher than in the general population. Predictors of cognitive change in PD and the general population have also been identified, yet they only partially overlap one another.

CONCLUSION

The predictors and dynamics of cognitive impairment have been investigated fairly extensively in the general population, to a somewhat lesser extent in PD, and are emerging only now in ET. We suggest that longitudinal studies specific to ET are needed, and we outline variables to be considered in these investigations. Increased knowledge of ET-cognitive impairment will facilitate meaningful counseling of patients and their families.