Depressive symptoms, sex, and risk for Alzheimer's disease

Psychiatric symptoms, associated pharmacological treatments and cognitive function: A population-based study of men

BACKGROUND

Psychiatric symptomatology and medications used in their treatment may be modifiable risk factors associated with cognitive function, although findings from population-based studies spanning the full adult age range are lacking. This study aimed to investigate associations between psychiatric symptomatology, psychotropic medication use and cognitive function in a population-based sample of men.

METHODS

Data for 537 men were drawn from the Geelong Osteoporosis Study. Cognitive function (psychomotor function, attention, working memory and visual learning) was determined using the Cog-State Brief Battery. Current depressive and anxiety symptomatology was determined using the Hospital Anxiety and Depression Scale, and psychotropic medication use was self-reported. Linear regression models were developed to determine associations between psychiatric symptomatology and psychotropic medication use with each cognitive measure.

RESULTS

Depressive symptomatology was associated with lower overall cognitive function (b-0.037 ± 0.010, η2 = 0.025, p < 0.001), psychomotor function (b 0.006 ± 0.002, η2 = 0.028 p < 0.001) and attention (b 0.004 ± 0.001, η2 = 0.021, p < 0.001), whereas psychotropic use was associated with lower overall cognitive function (b - 0.174 ± 0.075, η2 = 0.010, p = 0.021), attention (b 0.017 ± 0.008, η2 = 0.008, p = 0.038 and working memory (b 0.031 ± 0.012, η2 = 0.010, p = 0.010). Anticonvulsant use was associated with lower overall cognitive function (b - 0.723 ± 0.172, η2 = 0.032, p < 0.001), attention (b 0.065 ± 0.018, η2 = 0.029, p < 0.001) and working memory (b 0.088 ± 0.026, η2 = 0.022, p < 0.001). All relationships were found to have a small effect. There were no significant associations between anxiety symptomatology and antidepressant and anxiolytic use with any of the cognitive domains.

CONCLUSION

Depressive symptomatology and anticonvulsant use were associated with lower cognitive function. Understanding the underlying mechanisms involved in these relationships can advance knowledge on the heterogeneity in cognitive ageing and aid in prevention initiatives.

Traumatic brain injury alters the effects of class II invariant peptide (CLIP) antagonism on chronic meningeal CLIP + B cells, neuropathology, and neurobehavioral impairment in 5xFAD mice

BACKGROUND

Traumatic brain injury (TBI) is a significant risk factor for Alzheimer's disease (AD), and accumulating evidence supports a role for adaptive immune B and T cells in both TBI and AD pathogenesis. We previously identified B cell and major histocompatibility complex class II (MHCII)-associated invariant chain peptide (CLIP)-positive B cell expansion after TBI. We also showed that antagonizing CLIP binding to the antigen presenting groove of MHCII after TBI acutely reduced CLIP + splenic B cells and was neuroprotective. The current study investigated the chronic effects of antagonizing CLIP in the 5xFAD Alzheimer's mouse model, with and without TBI.

METHODS

12-week-old male wild type (WT) and 5xFAD mice were administered either CLIP antagonist peptide (CAP) or vehicle, once at 30 min after either sham or a lateral fluid percussion injury (FPI). Analyses included flow cytometric analysis of immune cells in dural meninges and spleen, histopathological analysis of the brain, magnetic resonance diffusion tensor imaging, cerebrovascular analysis, and assessment of motor and neurobehavioral function over the ensuing 6 months.

RESULTS

9-month-old 5xFAD mice had significantly more CLIP + B cells in the meninges compared to age-matched WT mice. A one-time treatment with CAP significantly reduced this population in 5xFAD mice. Importantly, CAP also improved some of the immune, histopathological, and neurobehavioral impairments in 5xFAD mice over the ensuing six months. Although FPI did not further elevate meningeal CLIP + B cells, it did negate the ability of CAP to reduce meningeal CLIP + B cells in the 5xFAD mice. FPI at 3 months of age exacerbated some aspects of AD pathology in 5xFAD mice, including further reducing hippocampal neurogenesis, increasing plaque deposition in CA3, altering microgliosis, and disrupting the cerebrovascular structure. CAP treatment after injury ameliorated some but not all of these FPI effects.

Elucidating the Link Between Anxiety/Depression and Alzheimer's Dementia in the Australian Imaging Biomarkers and Lifestyle (AIBL) Study

BACKGROUND

The associations between mood disorders (anxiety and depression) and mild cognitive impairment (MCI) or Alzheimer's dementia (AD) remain unclear.

METHODS

Data from the Australian Imaging, Biomarker & Lifestyle (AIBL) study were subjected to logistic regression to determine both cross-sectional and longitudinal associations between anxiety/depression and MCI/AD. Effect modification by selected covariates was analysed using the likelihood ratio test.

RESULTS

Cross-sectional analysis was performed to explore the association between anxiety/depression and MCI/AD among 2,209 participants with a mean [SD] age of 72.3 [7.4] years, of whom 55.4% were female. After adjusting for confounding variables, we found a significant increase in the odds of AD among participants with two mood disorders (anxiety: OR 1.65 [95% CI 1.04-2.60]; depression: OR 1.73 [1.12-2.69]). Longitudinal analysis was conducted to explore the target associations among 1,379 participants with a mean age of 71.2 [6.6] years, of whom 56.3% were female. During a mean follow-up of 5.0 [4.2] years, 163 participants who developed MCI/AD (refer to as PRO) were identified. Only anxiety was associated with higher odds of PRO after adjusting for covariates (OR 1.56 [1.03-2.39]). However, after additional adjustment for depression, the association became insignificant. Additionally, age, sex, and marital status were identified as effect modifiers for the target associations.

CONCLUSION

Our study provides supportive evidence that anxiety and depression impact on the evolution of MCI/AD, which provides valuable epidemiological insights that can inform clinical practice, guiding clinicians in offering targeted dementia prevention and surveillance programs to the at-risk populations.

Sex differences in the relationship between depression and Alzheimer's disease-mechanisms, genetics, and therapeutic opportunities

Depression and Alzheimer's disease (AD) are prevalent neuropsychiatric disorders with intriguing epidemiological overlaps. Their interrelation has recently garnered widespread attention. Empirical evidence indicates that depressive disorders significantly contribute to AD risk, and approximately a quarter of AD patients have comorbid major depressive disorder, which underscores the bidirectional link between AD and depression. A growing body of evidence substantiates pervasive sex differences in both AD and depression: both conditions exhibit a higher incidence among women than among men. However, the available literature on this topic is somewhat fragmented, with no comprehensive review that delineates sex disparities in the depression-AD correlation. In this review, we bridge these gaps by summarizing recent progress in understanding sex-based differences in mechanisms, genetics, and therapeutic prospects for depression and AD. Additionally, we outline key challenges in the field, holding potential for improving treatment precision and efficacy tailored to male and female patients' distinct needs.

Cluster analysis dissecting cognitive deficits in older adults with major depressive disorder and the association with neurofilament light chain

BACKGROUND

Cognitive impairment is a growing problem with increasing burden in global aging. Older adults with major depressive disorder (MDD) have higher risk of dementia. Neurofilament light chain (NfL) has been proven as a potential biomarker in neurodegenerative disease, including dementia. We aimed to investigate the association between cognitive deficits and NfL levels in older adults with MDD.

METHODS

In this cross-sectional study, we enrolled 39 MDD patients and 15 individuals with mild neurocognitive disorder or major neurocognitive disorder, Alzheimer's type, as controls, from a tertiary psychiatric hospital. Both groups were over age 65 and with matched Mini-Mental State Examination (MMSE) score. Demographic data, clinical variables, and plasma NfL levels were obtained. We used cluster analysis according to their cognitive profile and estimated the correlation between plasma NfL levels and each cognitive domain.

RESULTS

In the MDD group, participants had higher rate of family psychiatry history and current alcohol use habit compared with controls. Control group of neurocognitive disorders showed significantly lower score in total MMSE and higher plasma NfL levels. Part of the MDD patients presented cognitive deficits clustered with that of neurocognitive disorders (cluster A). In cluster A, the total MMSE score (r=-0.58277, p=0.0287) and the comprehension domain (r=-0.71717, p=0.0039) were negatively correlated to NfL levels after adjusting for age, while the associations had not been observed in the other cluster.

CONCLUSIONS

We noted the negative correlation between NfL levels and cognition in MDD patients clustered with neurodegenerative disorder, Alzheimer's type. NfL could be a promising candidate as a biomarker to predict subtype of patients in MDD to develop cognitive decline. Further longitudinal studies and within MDD cluster analysis are required to validate our findings for clinical implications.

Exploring the occurrence and the risk factors of the desire for hastened death and depression in people with early-stage dementia in Greece

OBJECTIVES

To assess the factors associated with desire for hastened death and depression in early-stage dementia as well as the association between them. Also, to explore the mediator and moderator role of age in the relationship between depression and desire for hasten death.

METHODS

A prospective cross-sectional study including 100 patients diagnosed with early-stage dementia from a rehabilitation center between December 2018 and July 2019. Measurement tools used were the Mini-Mental State Examination, the Greek Montreal Cognitive Assessment, the Greek Schedule of Attitudes toward Hastened Death, and the Geriatric Depression Scale-15 item. Patients diagnosed with dementia as a result of Stroke history were excluded.

RESULTS

Factors of multifactorial analysis significantly associated with desire for hastened death were as follows: age (p = 0.009), marital status (p = 0.001), and depression (p < 0.001). The factor significantly associated with depression was age (p = 0.001). Also, a mediation/moderation analysis has shown that depression and age are significant predictors of desire for hasten death.

SIGNIFICANCE OF RESULTS

The desire for hastened death and depression in people diagnosed with early-stage dementia includes many components. Younger patients, men, higher educated patients, single, childless, and those with higher depression scores had higher desire for hastened death, while men and older patients had higher scores of desire for depression. Our study provides important information about the desire for hastened death and depression in early-stage dementia, their risk factors, and their association.

Bidirectional association between major depressive disorder and dementia: Two population-based cohort studies in Taiwan

BACKGROUND

Major depressive disorder (MDD) and dementia are both major contributors to the global burden of disease. Despite existing literature on the association between MDD and dementia, there is a lack of a nationwide longitudinal cohort study that considers the competing risk of death. Therefore, this study assessed the bidirectional associations between MDD and dementia over an 11-year period in population-based settings, accounting for death as a competing risk.

METHODS

We conducted two population-based retrospective cohort studies in Taiwan. We identified 80,742 patients diagnosed with MDD in 2009-2010 and matched them with patients without MDD by sex, age, and year of diagnosis to assess the relative risk of dementia. We also identified 80,108 patients diagnosed with dementia in 2009-2010 and matched them with patients without dementia by sex, age, and year of diagnosis to assess the relative risk of MDD. All patients were followed until they received a diagnosis of new onset MDD or new onset dementia, their death, or the end of 2019. Cause-specific hazards models were used to estimate adjusted hazard ratios (aHRs).

RESULTS

The incidence density (ID) of dementia was higher in patients with MDD than in patients without MDD (7.63 vs. 2.99 per 1000 person-years), with an aHR of 2.71 (95% confidence interval [CI]: 2.55-2.88). The ID of MDD was higher in patients with dementia than in patients without dementia (12.77 vs. 4.69 per 1000 person-years), with an aHR of 2.47 (95% CI: 2.35-2.59).

CONCLUSIONS

This population-based study found a bidirectional association between MDD and dementia. Our findings suggest the need to identify dementia in patients with MDD and vice versa.

Bidirectional association between depressive symptoms and mild cognitive impairment over 20 years: Evidence from the Health and Retirement Study in the United States

BACKGROUND

Research examining the association between depressive symptoms and mild cognitive impairment (MCI) has yielded conflicting results. This study aimed to examine the bidirectional association between depressive symptoms and MCI, and the extent to which this bidirectional association is moderated by gender and education.

METHODS

Data come from the US Health and Retirement Study over a 20-year period (older adults aged ≥50 years). Competing-risks regression is employed to examine the association between baseline high-risk depressive symptoms and subsequent MCI (N = 9317), and baseline MCI and subsequent high-risk depressive symptoms (N = 9428). Interactions of baseline exposures with gender and education are tested.

RESULTS

After full adjustment, baseline high-risk depressive symptoms were significantly associated with subsequent MCI (SHR = 1.20, 95%CI 1.08-1.34). Participants with baseline MCI are more likely to develop subsequent high-risk depressive symptoms than those without baseline MCI (SHR = 1.16, 95%CI 1.01-1.33). Although gender and education are risk factors for subsequent depression and MCI, neither moderates the bidirectional association.

LIMITATIONS

Items used to construct the composite cognitive measure are limited; selection bias due to missing data; and residual confounding.

CONCLUSIONS

Our study found a bidirectional association between depressive symptoms and MCI. High-risk depressive symptoms are related to a higher risk of subsequent MCI; and MCI predicts subsequent high-risk depression. Though neither gender nor education moderated the bidirectional association, public health interventions crafted to reduce the risk of depression and MCI should pivot attention to older women and those with less formal education.

Societal Adaptation to Aging and Prevalence of Depression Among Older Adults: Evidence From 20 Countries

Policy Points Countries have adopted different strategies to support aging populations, which are broadly reflected in social, economic, and contextual environments. Referred to as "societal adaptation to aging," these factors affect countries' capacity to support older adults. Results from our study show that countries with more robust societal adaptation to aging had lower depression prevalence. Reductions in depression prevalence occurred among every investigated sociodemographic group and were most pronounced among the old-old. Findings suggest that societal factors have an underacknowledged role in shaping depression risk. Policies that improve societal approaches to aging may reduce depression prevalence among older adults.

CONTEXT

Countries have adopted various formal and informal approaches to support older adults, which are broadly reflected in different policies, programs, and social environments. These contextual environments, broadly referred to as "societal adaptation to aging," may affect population health.

METHODS

We used a new theory-based measure that captured societal adaptation to aging, the Aging Society Index (ASI), which we linked with harmonized individual-level data from 89,111 older adults from 20 countries. Using multi-levels models that accounted for differences in the population composition across countries, we estimated the association between country-level ASI scores and depression prevalence. We also tested if associations were stronger among the old-old and among sociodemographic groups that experience more disadvantage (i.e., women, those with lower educational attainment, unmarried adults).

FINDINGS

We found that countries with higher ASI scores, indicating more comprehensive approaches to supporting older adults, had lower depression prevalence. We found especially strong reductions in depression prevalence among the oldest adults in our sample. However, we did not find stronger reductions among sociodemographic groups who may experience more disadvantage.

CONCLUSIONS

Country-level strategies to support older adults may affect depression prevalence. Such strategies may become increasingly important as adults grow older. These results offer promising evidence that improvements in societal adaptation to aging-such as through adoption of more comprehensive policies and programs targeting older adults-may be one avenue to improve population mental health. Future research could investigate observed associations using longitudinal and quasi-experimental study designs, offering additional information regarding a potential causal relationship.

Sex Differences in Alzheimer's Disease

Reviewing the research presented in this article, it is evident that from an epidemiological perspective, it is important to evaluate the extent to which findings of sex and gender differences in Alzheimer's dementia (AD) are due to differences in longevity, survival bias, and comorbidities. Medical, genetic, psychosocial, and behavioral factors, in addition to hormonal factors, can differentially affect the risk and progression of AD in women versus men. Further, evaluation of sex differences in AD progression and the trajectory of change in cognitive function, neuroimaging, cerebrospinal fluid (CSF), and blood-based biomarkers of AD is needed. Finally, identifying sex differences in AD biomarkers and change across the lifespan is critical for the planning of prevention trials to reduce the risk of developing AD.

Is there a casual relation between air pollution and dementia?

Dementia has been cited as a critical public health risk in the contemporary world, while few empirical researchers try to reveal the casual relationship between air pollutant concentrations (APCs) and dementia, especially given the increasing prevalence of air pollution on a global scale. Accordingly, this paper tries to infer the causal relationship between APCs and dementia. The 59,605 valid data was compiled through a combination of the statistic from the China Family Panel Study, China Environmental Statistics Yearbook, World Meteorological Association and China National Bureau of Statistics. The RD design of this study utilizes the discontinuous variation in APCs and dementia as one crosses the Huai River boundary, which is an arbitrary heating policy that causes the significant difference in APCs between the north and south of China. We used stata17.0 to analyze the data. The results of the RD regression indicated that a 100 μ g/m³ rise in APCs led to an increase of 42.4% in the hazard ratio of suffering dementia (Coeff=-0.58, SD= 0.23, P < 0.05). Meanwhile, heterogeneous models revealed that the hazard ratio of suffering dementia by APCs was more significant in the older compared to younger (coeff= 1.35 vs coeff= 1.55, P < 0.05), male compared to female (coeff= 1.62 vs coeff= 0.71, P < 0.05), smoking compared to non-smoke (coeff= 2.12 vs coeff= 0.93, P < 0.05), and thin groups compared to medium and obesity (coeff= 2.05 vs coeff= 1.22, coeff= 1.28, P < 0.05). In addition, the O3 and SO2 were the air pollutants with the highest (coeff= 1.54, P < 0.05) and lowest effects (coeff= 0.81, P < 0.05) on the hazard ratio of suffering dementia among the five APCs, respectively. And the robustness of the results was ensured by changing the RD bandwidth, polynomial order. The results indicated that APCs significantly induced the hazard ratio of suffering dementia of Chinese residents, which provides empirical evidence in supporting the Chinese government to invest more in combating air pollution and ensure the public health of Chinese residents.

Blood pressure and Alzheimer's disease: A review of meta-analysis

Background

Alzheimer's disease (AD) is a neurological disorder of unknown cause, resulting in the death of brain cells. Identifying some of the modifiable risk factors for AD could be crucial for primary prevention and could lead to a reduction in the incidence of AD.

Objective

This study aimed to perform a meta-meta-analysis of studies in order to assess the effect of blood pressure (BP) on the diagnosis of AD.

Method

The search was restricted to meta-analyses assessing high systolic BP (SBP) and diastolic BP (DBP) and AD. We applied the PRISMA guidelines.

Results

A total of 214 studies were identified from major databases. Finally, five meta-analyses (52 studies) were analyzed in this review. Results confirm that high SBP is associated with AD. The exploration of parameters (sex, age, study design, region, and BP measurements) shows that only region significantly moderates the relationship between BP and AD. Asian people are those whose SBP levels >140 mmHg are associated with AD. BP is associated with AD in both people aged ≤65 years and those aged ≥65 years and in cross-sectional and longitudinal studies. In the case of DBP, only women are at a higher risk of AD, particularly when its levels are >90.

Conclusion

SBP is associated with both cerebrovascular disease and AD. Therefore, future studies should use other uncontrolled factors, such as cardiovascular diseases, diabetes, and stroke, to explain the relationship between SBP and AD.

Hormone therapy and the decreased risk of dementia in women with depression: a population-based cohort study

Background

The literature has shown depression to be associated with an increased risk of dementia. In addition, hormone therapy can be a responsive treatment option for a certain type of depression. In this study, we examined the association between hormone therapy, including lifetime oral contraceptive (OC) use, and hormone replacement therapy (HRT) after menopause with the occurrence of dementia among female patients with depression.

Methods

The South Korean national claims data from January 1, 2005, to December 31, 2018, was used. Female subjects aged 40 years or older with depression were included in the analyses. Information on hormone therapy was identified from health examination data and followed up for the occurrence of dementia during the average follow-up period of 7.72 years.

Results

Among 209,588 subjects, 23,555 were diagnosed with Alzheimer’s disease (AD) and 3023 with vascular dementia (VD). Lifetime OC usage was associated with a decreased risk of AD (OC use for < 1 year: HR, 0.92 [95% CI, 0.88–0.97]; OC use for ≥ 1 year: HR, 0.89 [95% CI, 0.84–0.94]), and HRT after menopause was associated with a decreased risk of AD (HRT for < 2 years: HR, 0.84 [95% CI, 0.79–0.89]; HRT for 2–5 years: HR, 0.80 [95% CI, 0.74–0.88]; and HRT for ≥ 5 years : HR, 0.78 [95% CI, 0.71–0.85]) and VD (HRT < 2 years: HR, 0.82 [95% CI, 0.71–0.96]; HRT for 2–5 years: HR, 0.81 [95% CI, 0.64–1.02]; and HRT for ≥ 5 years: HR, 0.61 [95% CI, 0.47–0.79]).

Conclusions

In this nationwide cohort study, lifetime OC use was associated with a decreased risk of AD, and HRT after menopause was associated with a decreased risk of AD and VD among female patients with depression. However, further studies are needed to establish causality.

Dementia Prevention in Clinical Practice

Over 55 million people globally are living with dementia and, by 2050, this number is projected to increase to 131 million. This poses immeasurable challenges for patients and their families and a significant threat to domestic and global economies. Given this public health crisis and disappointing results from disease-modifying trials, there has been a recent shift in focus toward primary and secondary prevention strategies. Approximately 40% of Alzheimer's disease (AD) cases, which is the most common form of dementia, may be prevented or at least delayed. Success of risk reduction studies through addressing modifiable risk factors, in addition to the failure of most drug trials, lends support for personalized multidomain interventions rather than a "one-size-fits-all" approach. Evolving evidence supports early intervention in at-risk patients using individualized interventions directed at modifiable risk factors. Comprehensive risk stratification can be informed by emerging principals of precision medicine, and include expanded clinical and family history, anthropometric measurements, blood biomarkers, neurocognitive evaluation, and genetic information. Risk stratification is key in differentiating subtypes of dementia and identifies targetable areas for intervention. This article reviews a clinical approach toward dementia risk stratification and evidence-based prevention strategies, with a primary focus on AD.

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

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

Depressive Symptoms and Cognitive Decline Among Chinese Rural Elderly Individuals: A Longitudinal Study With 2-Year Follow-Up

Background

Depressive symptoms and mild cognitive impairment (MCI) are highly prevalent in rural China. The study aimed to investigate the longitudinal associations between changes in depressive symptoms and cognitive decline and MCI incidence among Chinese rural elderly individuals.

Methods

A 2-year follow-up study was conducted among 1,477 participants from the Anhui Healthy Longevity Survey (AHLS). Depressive symptoms were assessed by the 9-item Patient Health Questionnaire (PHQ-9), and cognitive status was evaluated by the Mini Mental State Examination (MMSE). Multivariable linear regression and logistic regression were employed.

Results

Every 1-unit PHQ-9 score increase was significantly associated with more cognitive decline (β = 0.157, 95% CI: 0.092, 0.221, p &lt; 0.001) and a higher risk of MCI incidence (OR = 1.063, 95% CI: 1.025, 1.103, p = 0.001). The participants who experienced worsening of depression symptoms had a larger decline in the 2-year MMSE score (β = 0.650, 95% CI: 0.039, 1.261, p = 0.037) and elevated risks of incident MCI (OR = 1.573, 95% CI: 1.113, 2.223, p = 0.010).

Limitations

Screening tools rather than standard diagnostic procedures were used in the study. Moreover, the long-term associations still need further exploration since the follow-up time was short.

Conclusions

Increased depressive symptoms were associated with more cognitive decline and higher risks of incident MCI among Chinese rural residents.

Depression and bone loss as risk factors for cognitive decline: A systematic review and meta-analysis

BACKGROUND

Depression is linked to Alzheimer's disease (AD) but it is unclear whether depression is also associated with cognitive decline in the preclinical phase and mild cognitive impairment (MCI). Previous meta-analyses have only investigated AD as an outcome without accounting for individuals showing cognitive decline that does not meet the diagnostic criteria for AD. Other potentially modifiable risk factors such as bone loss have also been less explored and there remains uncertainty around their temporal relationship with cognitive decline.

AIMS

To conduct a systematic review and meta-analysis investigating depression and bone loss as risk factors for subsequent cognitive decline.

METHODS

A comprehensive search strategy was developed and applied using four databases; MEDLINE Complete, Embase, PsycINFO and CINAHL Complete. The pooled summary effects were estimated as odds ratios with 95% confidence intervals using a random-effects model. The study protocol was registered with PROSPERO (ID: CRD42020159369).

RESULTS

A total of 75 longitudinal cohort studies were identified for meta-analysis, of which 70 examined the impact of depression on cognitive decline and five examined the impact of bone loss. Prior exposure to depression was found to be associated with cognitive score reduction (OR 1.33 95% CI 1.17, 1.51), MCI incidence (OR 1.52 95% CI 1.28, 1.79) and AD incidence (OR 1.79 95% CI 1.46, 2.2). Bone loss was also associated with the incidence of AD (OR=1.81 95% CI 1.28, 2.55).

CONCLUSIONS

Overall, the results support the hypothesis that depression is associated with subsequent cognitive decline. Bone loss was also found to be associated with AD incidence; however, due to the small number of studies, the results should be viewed with caution.

Age and gender disparities in depression and subjective cognitive decline-related outcomes

OBJECTIVES

Determine the association between depression and SCD-related outcomes by age and gender.

METHODS

Using 2018 Behavioral Risk Factor Surveillance System survey data, crude and multivariable logistic regression models were used to determine the associations between depression and SCD-related outcomes by age and gender.

RESULTS

Among respondents 45 to 69, depression was associated with SCD [adjusted OR (aOR): 4.36; 95% CI: 3.24-5.86]; needing assistance with activities due to confusion/memory loss (aOR: 2.38; 95% CI: 1.26 - 4.51); needing help with activities and the help is not available (aOR: 4.46; 95% CI: 1.31 - 15.2); and having discussed confusion/memory loss with a health care professional (aOR: 1.87; 95% CI: 1.09 - 3.23). However, among respondents 70 and older, depression was associated with SCD (aOR): 3.52; 95% CI: 2.06-6.02); needing help with activities and the help is not available (aOR: 0.09; 95% CI: 0.01-0.56); confusion/memory loss interfering with work/social activities (aOR: 2.44; 95% CI: 1.03-5.79); and having discussed confusion/memory loss with a health care professional (aOR): 2.99; 95% CI: 1.20-7.40). Depression was positively associated with SCD among men (aOR): 3.68; 95% CI: 2.52-5.38) and women (aOR): 4.76; 95% CI: 3.29-6.87; and was positively associated with all SCD-related outcomes among men except for confusion/memory loss interfering with work/social activities and given up chores. Depression was positively associated with the latter among women (aOR): 2.10; 95% CI: 1.09-4.06).

DISCUSSION

SCD interventions should include assessment of and intervention for depression, and consider age and gender differences.

Female specific risk factors for the development of Alzheimer's disease neuropathology and cognitive impairment: Call for a precision medicine approach

Alzheimer's disease (AD) includes a long asymptomatic stage, which precedes the formal diagnosis of dementia. AD biomarker models provide a framework for precision medicine approaches during this stage. However, such approaches have ignored the possible influence of sex on cognition and brain health, despite female sex noted as a major risk factor. Since AD-related changes may emerge in midlife, intervention efforts are being redirected around this period. Midlife coincides with several endocrinological changes, such as the menopausal transition experienced by women. In this narrative review, we discuss evidence for sex-differences in AD neuropathological burden and outline key endocrinological mechanisms for both sexes, focussing on hormonal events throughout the lifespan that may influence female susceptibility to AD neuropathology and dementia onset. We further consider common non-modifiable (genetic) and modifiable (lifestyle and health) risk factors, highlighting possible sex-dependent differential effects for the AD disease course. Finally, we evaluate the studies selected for this review demonstrating sex-differences in cognitive, pathological and health factors, summarising the state of sex differences in AD risk factors. We further provide recommendations for targeted research on female-specific risk factors, to inform personalised strategies for AD-prevention and the promotion of female brain health.

Depression and Increased Risk of Alzheimer's Dementia: Longitudinal Analyses of Modifiable Risk and Sex-Related Factors

OBJECTIVE

Our understanding of why older adults with depression are at increased risk of Alzheimer's disease (AD) remains incomplete. Most adults living with AD are women, and women have a near twofold lifetime risk of depression. We examined the risk of depression upon incident AD, and how sex influences this risk.

METHODS

Using the National Alzheimer's Coordinating Center database, older adults (age 50+) with normal cognition, who visited memory clinics across the United States between September 2005 and December 2019, were followed until first diagnosis of AD or loss to follow up. Multivariable survival analyses were performed to determine if recent and/or remote depression were independent risk factors for AD, if this depression-related risk exists for each sex or was moderated by sex.

RESULTS

Six hundred and fifty-two of 10,739 enrolled participants developed AD over a median follow-up of 55.3 months. Recent depression (active within the last 2 years) was independently associated with increased risk of AD (hazard ratio [HR] = 2.0; 95%CI, 1.5-2.6) while a remote history of depression was not (HR = 1.0; 95%CI, 0.7-1.5). After stratification by sex, recent depression was an independent predictor in females (HR = 2.3; 95%CI, 1.7-3.1) but not in males (HR = 1.4; 95%CI, 0.8-2.6). No interaction between recent depression and sex was observed.

CONCLUSION

Only a recent history of depression was associated with higher risk of AD. This association was significant among women only, but was not moderated by sex. Future analyses should determine if these findings extend to other populations and may be explained by variable distribution of neurobiological or other modifiable risk factors between the sexes.

Association between lifetime depression history, hippocampal volume and memory in non-amnestic mild cognitive impairment

Hippocampal subfield volume loss in older adults with amnestic mild cognitive impairment (aMCI) and depression history are associated with amyloid beta and tau pathology, thereby increasing the risk for Alzheimer's disease (AD). However, no studies have exclusively examined distinct alterations in hippocampal subfields in non-amnestic MCI (naMCI) in relation to depression history. Here, we used both longitudinal and transverse hippocampal segmentation methods using the automated FreeSurfer software to examine whether a lifetime depression history is associated with differences in hippocampal head/body/tail (H/B/T) and key subfield volumes (CA1, subiculum, dentate gyrus) in older adults with naMCI. Further, we explored whether differences in hippocampal H/B/T and subfield volumes were associated with structured and unstructured verbal encoding and retention, comparing those with and without a depression history. The naMCI with a depression history group demonstrated larger or relatively preserved right CA1 volumes, which were associated with better unstructured verbal encoding and as well as structured verbal memory retention. This association between memory encoding and hippocampal CA1 and total head volume was significantly different to those with no depression history. The relationship between right CA1 volume and memory retention was also moderated by depression history status F (5,143) = 7.84, p < 0.001, R²  = 0.22. Those participants taking antidepressants had significantly larger hippocampal subiculum (p = 0.008), and right hippocampal body (p = 0.004) and better performance on structured encoding (p = 0.011) and unstructured memory retention (p = 0.009). These findings highlight the importance of lifetime depression history and antidepressant use on the hippocampus and encoding and memory retention in naMCI.

Gender Differences of Dementia in Response to Intensive Self-Administered Transcranial and Intraocular Near-Infrared Stimulation

Background

Transcranial near-infrared (tNIR) stimulation was proven to be a safe, reliable, and effective treatment for cognitive and behavioral symptoms of dementia. Dementia patients of different genders differ in terms of gross anatomy, biochemistry, genetic profile, clinical presentations, and socio-psychological status. Studies of the tNIR effect on dementia have thus far been gender-neutral, with dementia subjects being grouped based on diagnoses or dementia severity. This trial hereby investigated how dementia subjects of different sex respond to tNIR treatment.

Methods

A total of 60 patient-caregiver dyads were enrolled and randomized to this double-blind, sham-controlled clinical trial. The tNIR light has a wavelength of 1,060 nm to 1,080 nm and was delivered via a photobiomodulation (PBM) unit. The active PBM unit emits near-infrared (NIR) light while the sham unit does not. The treatment consists of a six-minute tNIR light stimulation session twice daily for eight weeks. Neuropsychological assessments conducted at baseline (week 0) and endline (week 8) were compared within the female and male group and between different sex, respectively.

Results

Over the course of treatment, active-arm female subjects had a 20.2% improvement in Mini‐Mental State Exam (MMSE) (mean 4.8 points increase, p < 0.001) and active-arm male cohort had 19.3% improvement (p < 0.001). Control-arm female subjects had a 6.5% improvement in MMSE (mean 1.5 points increase, p < 0.03) and control-arm male subjects had 5.9% improvement (p = 0.35) with no significant differences in the mean MMSE between female and male subjects in both arms respectively. Other comparison of assessments including Clock Copying and Drawing Test, Logical Memory Test - immediate and delayed recall yielded nominal but not statistically significant differences. No significant differences were observed in the mean MMSE between female and male subjects in both arms respectively before treatment implementation (active arm, p = 0.12; control arm, p = 0.50) at week 0, or after treatment completion (active arm, p = 0.11; control arm, p = 0.74) at week 8.

Conclusion

Despite differences between female and male dementia subjects, the response to tNIR light stimulation does not demonstrate gender-based differences. Further studies are warranted to refine the tNIR treatment protocol for subjects suffering from dementia or dementia-related symptoms.

Sex-Specific Associations Between Depressive Symptoms and Risk for Subsequent Dementia

BACKGROUND

An association between depression and an increased risk for subsequent dementia is well-established. Sexspecific associations are understudied yet.

OBJECTIVE

We aimed to investigate sex-specific associations between depressive symptoms and dementia risk.

METHODS

Longitudinal analyses were conducted in a pooled data set (n = 4,255, mean age = 80 years) of two prospective cohort studies (LEILA 75+, AgeCoDe). Depressive symptoms were harmonized by dichotomized scores of two different depression screening scales using established cutoffs. Transition to dementia was used as outcome in Cox proportional hazards models.

RESULTS

Depressive symptoms at baseline were associated with an increased risk for subsequent dementia, and this association was more pronounced in males (interaction of depressive symptoms × sex: HR = 1.64, 95% CI: 1.02-2.64, p = 0.042) in a model adjusted for study, age, and education. After additional adjustment for subjective and objective cognition, depressive symptoms and their interaction with sex (HR = 1.38, 95% CI: 0.85-2.23, p = 0.188) were no longer significantly associated with the risk for subsequent dementia. Sex-stratified analyses showed stronger and significant associations between depressive symptoms and subsequent dementia in men (e.g., HR= 2.10, 95% CI: 1.36-3.23, p = 0.001, compared to HR= 1.28, 95% CI: 1.04-1.58, p = 0.020, in women).

CONCLUSIONS

Overall, we provide evidence for a stronger association between depression and dementia in men compared to women. Depressive symptoms should be diagnosed, monitored, and treated, not only due to depression, but also with respect to the risk for subsequent dementia, especially in elderly men.

Depression as a Risk Factor for Alzheimer's Disease: A Systematic Review of Longitudinal Meta-Analyses

Alzheimer’s disease (AD) is the most frequent cause of dementia, linked to morbidity and mortality among elderly patients. Recently, several clinical studies suggested that depression is a potential risk factor for cognitive decline and AD. A review of meta-analyses was performed, calculating pooled odds ratios to estimate the risk of AD in people with a prior diagnosis (or clinically significant symptoms) of depression. A total of six meta-analyses which represented 28 individual studies were analyzed. A significant association between depression and AD was found (OR = 1.54, 95% CI [1.02–2.31]; p = 0.038). The results showed that heterogeneity across studies was substantial. We found a significant positive effect size for clinical measures of depression, but not for symptomatic rating scales, in the association of depression with risk of AD. The type of rating scale used to assess depression and the cut-off criteria selected also moderated the relationship between depression and AD risk. We found that studies that used clinically significant criteria for diagnosis of depression had more consistent and significant results than studies that used symptomatic scales.

Infiltrating Hematogenous Macrophages Aggregate Around β-Amyloid Plaques in an Age- and Sex-Dependent Manner in a Mouse Model of Alzheimer Disease

β-Amyloid (Aβ) plaques can trigger chronic inflammation in the cellular environment that recruits infiltrating macrophages during the course of Alzheimer disease (AD). Activated macrophages release pro-inflammatory cytokines that increase neurotoxicity associated with AD. A major impediment to investigating neuroinflammation involving macrophage activity is the inability to discriminate resident microglial macrophages (mMϕ) from hematogenous macrophages (hMϕ), as they are morphologically and phenotypically similar when activated. To distinguish between mMϕ and hMϕ and to determine their respective roles in chronic inflammation associated with the progression of amyloidosis, we used lys-EGFP-ki transgenic mice that express enhanced green fluorescent protein in hMϕ, but not in mMϕ. These mice were crossed with 5XFAD mice. The offspring demonstrated robust AD pathology and enabled visual discrimination of mMϕ from hMϕ. Mutant mice demonstrated robust increases in Aβ1-42, area of Aβ plaques, gliosis and deficits in spatial learning by age 5 months. The time-course of Aβ accumulation, paralleled by the accumulation of hMϕ around Aβ plaques, was more robust in female compared with male mice and preceded behavioral changes. Thus, the accumulation of infiltrating hMϕ around Aβ plaques was age- and sex-dependent and preceded cognitive impairment.

Evidence-based prevention of Alzheimer's disease: systematic review and meta-analysis of 243 observational prospective studies and 153 randomised controlled trials

BACKGROUND

Evidence on preventing Alzheimer's disease (AD) is challenging to interpret due to varying study designs with heterogeneous endpoints and credibility. We completed a systematic review and meta-analysis of current evidence with prospective designs to propose evidence-based suggestions on AD prevention.

METHODS

Electronic databases and relevant websites were searched from inception to 1 March 2019. Both observational prospective studies (OPSs) and randomised controlled trials (RCTs) were included. The multivariable-adjusted effect estimates were pooled by random-effects models, with credibility assessment according to its risk of bias, inconsistency and imprecision. Levels of evidence and classes of suggestions were summarised.

RESULTS

A total of 44 676 reports were identified, and 243 OPSs and 153 RCTs were eligible for analysis after exclusion based on pre-decided criteria, from which 104 modifiable factors and 11 interventions were included in the meta-analyses. Twenty-one suggestions are proposed based on the consolidated evidence, with Class I suggestions targeting 19 factors: 10 with Level A strong evidence (education, cognitive activity, high body mass index in latelife, hyperhomocysteinaemia, depression, stress, diabetes, head trauma, hypertension in midlife and orthostatic hypotension) and 9 with Level B weaker evidence (obesity in midlife, weight loss in late life, physical exercise, smoking, sleep, cerebrovascular disease, frailty, atrial fibrillation and vitamin C). In contrast, two interventions are not recommended: oestrogen replacement therapy (Level A2) and acetylcholinesterase inhibitors (Level B).

INTERPRETATION

Evidence-based suggestions are proposed, offering clinicians and stakeholders current guidance for the prevention of AD.

The temporal association between incident late-life depression and incident dementia

OBJECTIVE

There is an established association between depression and subsequent dementia. The present study examined temporal associations between incident late-life depression and subsequent dementia, also considering age and sex.

METHODS

We used longitudinal health claims data from the largest German health insurance provider ('Allgemeine Ortskrankenkasse') considering up to 9 follow-up years in piecewise exponential models. ICD-10 codes were used to define incident depression and dementia in individuals ≥65 years (n = 97 110).

RESULTS

Incident depression was associated with a higher risk of subsequent dementia (incidence rate ratios (IRR) adjusted for age and sex: IRR = 1.58, 95% CI = 1.51-1.64). The strongest association was found for the shortest interval of 1 quarter (IRR = 2.04, 95% CI = 1.88-2.21), with significant associations up to an interval of roughly 3 years. The association was more pronounced and lasted for more quarters in the younger portion of this study group (ages from 65-74: IRR = 2.00, 95% CI = 1.83-2.18; 75-84: IRR = 1.64, 95% CI = 1.55-1.73; ≥85: IRR = 1.19, 95% CI = 1.08-1.31). It was stronger among men than women (men: IRR = 1.98, 95% CI = 1.84-2.14; women: IRR = 1.44, 95% CI = 1.37-1.51) with no sex-specific temporal association.

CONCLUSION

This large claims data study confirmed that incident late-life depression is associated with a higher risk of dementia within the 3 years following diagnosis. Hence, incident late-life depression should prompt further cognitive examinations and referrals to specialists. This might apply especially to younger seniors and men.

Cognitive symptoms domain in major depressive disorder-revisited

Cognitive dysfunction in MDD is more of an endophenotype rather than an epiphenomenon. This sorely remains un face cachee of MDD and largely unimpacted by currently available pharmacological and non-pharmacological interventions. These deficits have been considerably tied to symptoms residua, increased risk of relapse, functional impairment, and, reduced quality of life. Accordingly, targeting cognitive symptoms domain in MDD is unmet clinical desideratum in the journey to functional recovery.

Risk of Dementia in persons who have previously experienced clinically-significant Depression, Anxiety, or PTSD: A Systematic Review and Meta-Analysis

BACKGROUND

Depression, anxiety and PTSD appear to be linked to dementia, but it is unclear whether they are risk factors (causal or prodromal) for, comorbid with, or sequelae to (secondary effect of) dementia. Existing meta-analyses have examined depression or anxiety in all-cause dementia, Alzheimer's disease (AD) and vascular dementia (VaD), but have not considered post-traumatic stress disorder (PTSD), dementia with Lewy bodies (DLB), or frontotemporal dementia (FTD). The current meta-analysis examined the risk of developing dementia (AD, VaD, DLB, FTD, all-cause) in people with and without a history of clinically-significant depression, anxiety or PTSD in order to better understand the link between mental illness and dementia (PROSPERO number: CRD42018099872).

METHODS

PubMed, EMBASE, PsycINFO and CINAHL searches identified 36 eligible studies.

RESULTS

There is a higher risk of developing all-cause dementia and AD in people with previous depression, and a higher risk of all-cause dementia in people with prior anxiety, than in persons without this history. Prior PTSD was not associated with a higher risk of later being diagnosed with dementia.

LIMITATIONS

The data for anxiety, PTSD, DLB and FTD were limited.

CONCLUSIONS

Depression and anxiety appear to be risk factors for dementia, but longitudinal studies across adulthood (young adult/mid-life/older adult) are needed to evaluate the likely causal or prodromal nature of this risk. The link between PTSD and dementia remains unclear. Regular screening for new onset mental illness and for cognitive changes in older adults with a history of mental illness may assist with earlier identification of dementia.

Adverse life events and late-life cognitive decline in a Chinese cohort: The Shanghai Aging Study

OBJECTIVE

This study aimed to demonstrate the association between adverse life events (ALEs) and the risk of late-life cognitive decline in older community-dwelling individuals in China.

METHODS

We prospectively followed up 1657 dementia-free participants with ALE data at baseline in the Shanghai Aging Study. The cohort was categorized into four subgroups (depression with ALEs, depression without ALEs, no depression with ALEs, and no depression without ALEs). Cox regressions were conducted to estimate the hazard ratio (HR) for incident dementia stratified by all participants and depressed and nondepressed participants.

RESULTS

We identified 168 incident dementia cases over a mean period of 5.2 years. The cumulative dementia incidence in nondepressed participants with ALEs was the lowest among the four subgroups. Nondepressed participants with ALEs had a lower risk of incident dementia (HR [95% CI]: 0.50 [0.27-0.92], P = .0267) than those without ALEs, adjusted for age, sex, education, apolipoprotein E ε4 (APOE ε4), body mass index, cigarette smoking, heart disease, hypertension, diabetes, stroke, Mini-Mental State Examination (MMSE) at baseline, and anxiety.

CONCLUSIONS

This study explored a significant inverse association between ALEs and the risk of incident cognitive decline among older adults without depression in China. Interventions for depression prevention immediately after ALEs may reduce the risk of cognitive decline later in life.

Pathways Connecting Late-Life Depression and Dementia

Late-life depression is associated with significant cognitive impairment. Meta-analyses showed that depression is associated with an increased risk for Alzheimer’s disease (AD) and it might be an etiological factor for AD. Since late-life depression is often connected with cognitive impairment and dementia is usually associated with depressive symptoms, a simple diagnostic approach to distinguish between the disorders is challenging. Several overlapping pathophysiological substrates might explain the comorbidity of both syndromes. Firstly, a stress syndrome, i.e., elevated cortisol levels, has been observed in up to 70% of depressed patients and also in AD pathology. Stress conditions can cause hippocampal neuronal damage as well as cognitive impairment. Secondly, the development of a depression and dementia after the onset of vascular diseases, the profile of cerebrovascular risk factors in both disorders and the impairments depending on the location of cerebrovascular lesions, speak in favor of a vascular hypothesis as a common factor for both disorders. Thirdly, neuroinflammatory processes play a key role in the etiology of depression as well as in dementia. Increased activation of microglia, changes in Transforming-Growth-Factor beta1 (TGF-beta1) signaling, production of pro-inflammatory cytokines as well as reduction of anti-inflammatory molecules are examples of common pathways impaired in dementia and depression. Fourthly, the neurotrophin BDNF is highly expressed in the central nervous system, especially in the hippocampus, where it plays a key role in the proliferation, differentiation and the maintenance of neuronal integrity throughout lifespan. It has been associated not only with antidepressant properties but also a reduction of cognitive impairment and therefore could be involved also in AD. Another etiologic factor is amyloid accumulation, as plasma amyloid beta-42 independently predicts both late-onset depression and AD. Higher plasma amyloid beta-42 predicts the development of late onset depression and conversion to possible AD. However, clinical trials with antibodies against beta amyloid recently failed, i.e., Solanezumab, Aducanumab, and Crenezumab. An overproduction of amyloid-beta might simply reflect a form of synaptic plasticity to compensate for neuronal dysfunction in different kind of neurological and psychiatric diseases of multiple etiologies. The tau hypothesis, sex/gender specific differences, epigenetics and the gut microbiota-brain axis imply other potential common pathways connecting late-life depression and dementia. In conclusion, different potential pathophysiological links between dementia and depression highlight several specific synergistic and multifaceted treatment possibilities, depending on the individual risk profile of the patient.

Late life depressive symptoms and cognitive function among older Mexican adults: the past and the present

Objective: To evaluate associations between depression and individual cognitive domains and how changes in depressive symptoms relate to cognition three years later in the context of Mexico, a developing country experiencing rapid aging.Method: Data comes from the 2012 and 2015 waves of the Mexican Health and Aging Study (n = 12,898, age 50+). Depression is ascertained using a modified Center for Epidemiologic Studies - Depression Scale. Cognition is assessed using verbal learning, verbal memory, visual scanning, verbal fluency, visuospatial ability, visual memory, and orientation tasks. Depressive symptoms and cognitive functioning were both measured in 2012 and 2015. Scores across cognitive domains are modeled using ordinary least squares regression, adjusting for demographic, health, and economic covariates.Results: When depression and cognition were measured concurrently in 2015, depression exhibited associations with all cognitive domains. When considering a respondent's history of depression, individuals who had elevated depressive symptoms in 2012 and recovered by 2015 continued to exhibit poorer cognitive function in 2015 in verbal learning, verbal memory, visual scanning, and verbal fluency tasks compared to individuals who were neither depressed in 2012 nor 2015.Conclusions: Depression was associated with cognition across cognitive domains among older Mexican adults. Despite improvements in depressive symptomatology, formerly depressed respondents continued to perform worse than their counterparts without a history of depression on several cognitive tasks. In addition to current mental health status, researchers should consider an individual's history of depression when assessing the cognitive functioning of older adults.

Depressive Symptoms in the Elderly-An Early Symptom of Dementia? A Systematic Review

Background

Depression and dementia are common incapacitating diseases in old age. The exact nature of the relationship between these conditions remains unclear, and multiple explanations have been suggested: depressive symptoms may be a risk factor for, a prodromal symptom of, or a coincidental finding in dementia. They may even be unrelated or only connected through common risk factors. Multiple studies so far have provided conflicting results.

Objectives

To determine whether a systematic literature review can clarify the nature of the relation between depressive symptoms and dementia.

Methods

Using the Patient/Problem/Population, Intervention, Comparator, Outcome or PICO paradigm, a known framework for framing healthcare and evidence questions, we formulated the question “whether depressive symptoms in cognitively intact older adults are associated with a diagnosis of dementia later in life.” We performed a systematic literature review of MEDLINE and PsycINFO in November 2018, looking for prospective cohort studies examining the aforementioned question.

Results

We critically analyzed and listed 31 relevant papers out of 1,656 and grouped them according to the main hypothesis they support: depressive symptoms as a risk factor, not a risk factor, a prodromal symptom, both, or some specific other hypothesis. All but three studies used clinical diagnostic criteria for dementia alone (i.e., no biomarkers or autopsy confirmation). Several studies contain solid arguments for the hypotheses they support, yet they do not formally contradict other findings or suggested explanations and are heterogeneous.

Conclusions

The exact nature of the relationship between depressive symptoms and dementia in the elderly remains inconclusive, with multiple studies supporting both the risk factor and prodromal hypotheses. Some provide arguments for common risk factors. It seems unlikely that there is no connection at all. We conclude that at least in a significant part of the patients, depressive symptoms and dementia are related. This may be due to common risk factors and/or depressive symptoms being a prodromal symptom of dementia and/or depression being a risk factor for dementia. These causal associations possibly overlap in some patients. Further research is warranted to develop predictive biomarkers and to develop interventions that may attenuate the risk of “conversion” from depressive symptoms to dementia in the elderly.

Trajectories of neuropsychiatric symptoms over time in healthy volunteers and risk of MCI and dementia

OBJECTIVES

To identify subtypes of neuropsychiatric symptom (NPS) course among cognitively normal individuals and to assess the association between these subtypes and hazard of later mild cognitive impairment (MCI) or dementia diagnosis.

METHODS

We modeled neuropsychiatric inventory questionnaire (NPI-Q) scores from 4184 volunteers over approximately 4 years using growth mixture models, generating latent classes of trajectory. We then fit Cox proportional hazard models to determine if membership in trajectory classes was associated with increased hazard of diagnosis of MCI or dementia.

RESULTS

We identified four trajectory classes: the majority of the sample (65%) would be expected to belong to a class with consistently low or zero NPS. The next most prevalent class, (16%) showed a decrease over time in NPI-Q total score but, compared with the majority class had an almost threefold increase in hazard of MCI or dementia (HR: 2.92; 95% CI: 1.82-4.68). Another class (14%) showed an increase in NPS over time and was also associated with greater hazard of MCI or dementia (HR: 3.96; CI: 2.61-6.03). The smallest class (5%) had high and fluctuating NPI-Q total scores and had the greatest hazard (HR: 4.57; CI: 2.72-7.63).

CONCLUSION

We have demonstrated that it is possible to identify meaningful groups of NPS trajectories and that trajectory of NPS can convey information beyond a single cross-sectional measure. While even those whose NPS improved were at increased hazard of MCI or dementia, hazard increased as a function of the severity of the NPS trajectory.

Sex-specific depressive symptoms as markers of pre-Alzheimer dementia: findings from the Three-City cohort study

Late-life depression, as a potential marker of pre-dementia, has seldom been explored by symptom dimension and sex, despite sexual dimorphic differences. This study aimed to examine whether specific depressive dimensions were associated with pre-Alzheimer's disease dementia (pre-AD), separately for women and men. Data were drawn from 5617 (58% women) community-dwellers aged 65+ recruited in 1999-2000 and followed at 2-year intervals for 12 years. We used Cox proportional hazard models to study associations between time-dependent Centre for Epidemiologic Studies-Depression Scale (CES-D) symptom dimensions (namely somatic, depressed, positive affect, and interpersonal challenge) and pre-AD, defined retrospectively from validated diagnoses established 3.5 (IQR: 3.2-4.0) years onwards. Analyses were performed according to overall depressive symptomatology (DS+: CES-D score ≥ 16) and antidepressant/anxiolytic medication use (AA). Results indicated that in DS+ women only, all four dimensions were significantly associated with pre-AD in the AA- group, in particular somatic item 'Mind' and depressed affect items 'Depressed' and 'Blues'. The most depression-specific dimension, depressed affect, was also significantly associated with pre-AD in the DS- AA- women (HR:1.28, 95%CI: 1.12;1.47). In both sexes, in the DS- groups somatic affect was the most robust pre-AD marker, irrespective of treatment (women: HR = 1.22, 95%CI: 1.08;1.38; men: HR = 1.30, 95%CI: 1.14;1.48). Our findings highlight sex-specific associations between depressive symptom dimensions and pre-AD, modulated by depressive symptomatology and treatment. Assessment of specific symptom dimensions taking into account overall symptomatology and treatment could help identify and target high-risk AD-dementia profiles for interventions.

An Investigation of Limbs Exercise as a Treatment in Improving the Psychomotor Speed in Older Adults with Mild Cognitive Impairment

Objectives: This study investigated the effects of therapeutic structured limb exercises intended to improve psychomotor speed in older adults with mild cognitive impairment (MCI). Methods: Forty-four patients with mild cognitive impairment who met the inclusion criteria were selected and assigned randomly to either an experimental group (22 patients) or a control group (22 patients). The numbers of participants were selected based on the calculated sample effect size (N = 38). The study involved a 10-week intervention, in which participants completed structured limb exercises during 60-min training sessions delivered three times per week. Forty-one subjects completed the experimental programme. Scores in the Finger Tapping Test (FTT), Purdue Pegboard Test (PPT) and Montreal Cognitive Assessment (MoCA), along with electroencephalography (EEG) data, were collected before, during and after the intervention. The experimental and control groups were compared using repeated measures analysis of variance. Results: The patients with MCI in the experimental group achieved significantly improved scores in the FTT, the PPT and all dimensions of the MoCA. Moreover, these patients exhibited significant increases in the alpha and beta EEG wave power values in all brain areas of MCI patients, indicating that limb exercise training positively influenced their brain functions. Conclusions: The results conclude that a structured therapeutic limb exercise intervention can effectively improve psychomotor speed in patients with MCI and mitigate declines in cognitive function. This training intervention appears to be effective as a treatment for community-dwelling patients with MCI.

Sex Differences in Vulnerability and Resilience to Stress Across the Life Span

Susceptibility and resilience to stress depend on 1) the timing of the exposure with respect to development, 2) the time across the life span at which effects are measured, and 3) the behavioral or biological phenotype under consideration. This translational review examines preclinical stress models that provide clues to causal mechanisms and their relationship to the more complex phenomenon of stress-related psychiatric and cognitive disorders in humans. We examine how genetic sex and epigenetic regulation of hormones contribute to the proximal and distal effects of stress at different epochs of life. Stress during the prenatal period and early postnatal life puts male offspring at risk of developing diseases involving socialization, such as autism spectrum disorder, and attention and cognition, such as attention-deficit/hyperactivity disorder. While female offspring show resilience to some of the proximal effects of prenatal and early postnatal stress, there is evidence that risk associated with developmental insults is unmasked in female offspring following periods of hormonal activation and flux, including puberty, pregnancy, and perimenopause. Likewise, stress exposures during puberty have stronger proximal effects on girls, including an increased risk of developing mood-related and stress-related illnesses, such as depression, anxiety, and posttraumatic stress disorder. Hormonal changes during menopause and andropause impact the processes of memory and emotion in women and men, though women are preferentially at risk for dementia, and childhood adversity further impacts estradiol effects on neural function. We propose that studies to determine mechanisms for stress risk and resilience across the life span must consider the nature and timing of stress exposures as well as the sex of the organism under investigation.

Gender, mental health and ageing

This article presents a broad narrative review of the epidemiological evidence on how and why the mental health of older adults varies by gender. We draw upon international research literatures spanning gerontology and population mental health, as well as major reports from global health agencies. Compared with older men, older women are more likely to experience common mental disorders such as depression and anxiety, although the gender gap is smaller than it is at younger ages. In contrast, the mortality-related impacts of poor mental health, including suicide, are more severe for older men. These gendered patterns vary by country and other social contexts. Factors proposed to account for these findings include cultural and social norms, differentiation of gender roles, disadvantage and (dis)empowerment across the life course, and the coping styles of older men. However, little research has explicitly tested these explanations. Research to date has overwhelmingly focused on identifying differences in the mental health of older men and women. Notably, most studies have been restricted to binary comparisons, lacking the data to disentangle sex and gender dynamics, and few studies have examined the mental health of minority gendered adults in later life. Finally, there remains a need for high-quality population-based research into the mental health of those aged over 80 that includes coverage of people living in residential aged care settings.

Anhedonia and Dysphoria Are Differentially Associated with the Risk of Dementia in the Cognitively Normal Elderly Individuals: A Prospective Cohort Study

OBJECTIVE

We investigated the impact of depressed mood (dysphoria) and loss of interest or pleasure (anhedonia)on the risk of dementia in cognitively-normal elderly individuals.

METHODS

This study included 2,685 cognitively-normal elderly individuals who completed the baseline and 4-year follow-up assessments of the Korean Longitudinal Study on Cognitive Aging and Dementia. We ascertained the presence of dysphoria and anhedonia using the Mini International Neuropsychiatric Inventory. We defined subjective cognitive decline as the presence of subjective cognitive complaints without objective cognitive impairments. We analyzed the association of dysphoria and anhedonia with the risk of cognitive disorders using multinomial logistic regression analysis adjusted for age, sex, education, Cumulative Illness Rating Scale score, Apolipoprotein E genotype, and neuropsychological test performance.

RESULTS

During the 4-year follow-up period, anhedonia was associated with an approximately twofold higher risk of mild cognitive impairment (OR=2.09, 95% CI=1.20-3.64, p=0.008) and fivefold higher risk of dementia (OR=5.07, 95% CI=1.44-17.92, p=0.012) but was not associated with the risk of subjective cognitive decline. In contrast, dysphoria was associated with an approximately twofold higher risk of subjective cognitive decline (OR=2.06, 95% CI=1.33-3.19, p=0.001) and 1.7-fold higher risk of mild cognitive impairment (OR=1.75, 95% CI=1.00-3.05, p=0.048) but was not associated with the risk of dementia.

CONCLUSION

Anhedonia, but not dysphoria, is a risk factor of dementia in cognitively-normal elderly individuals.

Dementia in Women

Despite the progress made in the understanding of the etiology, neuropathophysiology, and treatment of different types of dementia, such disorders continue to pose huge health problems worldwide. The differential effect of the burden of disease on women is just being realized. These effects range from direct effects of the disease processes themselves, the way women experience the disease, and the caregiver burden. This article provides a brief overview of the available information on this topic.

Sex Differences in Depression as a Risk Factor for Alzheimer's Disease: A Systematic Review

Background and Objectives

Depression is an important risk factor for Alzheimer’s disease (AD) but little is known about the mechanisms of this association. Given sex differences in both AD and depression, we sought to conduct a systematic review and meta-analysis to examine whether there are sex differences in their association, as this may improve understanding of underlying mechanisms.

Research Design and Methods

MEDLINE, PsycINFO, and Cochrane Reviews were searched for observational studies including both sexes and examining the association between history of depression and AD.

Results

Forty studies, including 62,729 women and 47,342 men, were identified. Meta-analysis was not possible because only 3 studies provided sufficient data. Seven studies provided information about the influence of sex for a qualitative synthesis. Two found an association in men only, 2 in women only, and 3 reported no sex differences. The 2 studies finding an association in women only were unique in that they had the shortest follow-up periods, and were the only clinic-based studies.

Discussion and Implications

The findings of our systematic review show that there are important methodological differences among the few studies providing data on the influence of sex on depression as a risk factor for AD. Had all 40 studies provided sex-segregated data, these methodological differences and their impact on sex effects could have been examined quantitatively. We encourage researchers to report these data, as well as potential moderating factors, so that the role of sex differences can be better understood.

Sex differences in Alzheimer's disease: Understanding the molecular impact

Alzheimer's disease (AD) is a common neurodegenerative disorder that presents with cognitive impairment and behavioral disturbance. Approximately 5.5 million people in the United States live with AD, most of whom are over the age of 65 with two-thirds being woman. There have been major advancements over the last decade or so in the understanding of AD neuropathological changes and genetic involvement. However, studies of sex impact in AD have not been adequately integrated into the investigation of disease development and progression. It becomes indispensable to acknowledge in both basic science and clinical research studies the importance of understanding sex-specific differences in AD pathophysiology and pathogenesis, which could guide future effort in the discovery of novel targets for AD. Here, we review the latest and most relevant literature on this topic, highlighting the importance of understanding sex dimorphism from a molecular perspective and its association to clinical trial design and development in AD research field.

Depressive symptoms in relation to clinical symptom onset of mild cognitive impairment

ABSTRACTObjective:There is increasing evidence of an association between depressive symptoms and mild cognitive impairment (MCI) in cross-sectional studies, but the longitudinal association between depressive symptoms and risk of MCI onset is less clear. The authors investigated whether baseline symptom severity of depression was predictive of time to onset of symptoms of MCI.

METHOD

These analyses included 300 participants from the BIOCARD study, a cohort of individuals who were cognitively normal at baseline (mean age = 57.4 years) and followed for up to 20 years (mean follow-up = 2.5 years). Depression symptom severity was measured using the Hamilton Depression Scale (HAM-D). The authors assessed the association between dichotomous and continuous HAM-D and time to onset of MCI within 7 years versus after 7 years from baseline (reflecting the mean time from baseline to onset of clinical symptoms in the cohort) using Cox regression models adjusted for gender, age, and education.

RESULTS

At baseline, subjects had a mean HAM-D score of 2.2 (SD = 2.8). Higher baseline HAM-D scores were associated with an increased risk of progression from normal cognition to clinical symptom onset ≤ 7 years from baseline (p = 0.043), but not with progression > 7 years from baseline (p = 0.194). These findings remained significant after adjustment for baseline cognition.

CONCLUSIONS

These results suggest that low levels of depressive symptoms may be predictive of clinical symptom onset within approximately 7 years among cognitively normal individuals and may be useful in identifying persons at risk for MCI due to Alzheimer's disease.

Meta-Analysis of Personality Traits in Alzheimer's Disease: A Comparison with Healthy Subjects

BACKGROUND

The role of specific personality traits as factor risks of Alzheimer's disease (AD) has been consistently found, whereas personality traits specifically related to AD (after the diagnosis) have not been outlined yet.

OBJECTIVE

A meta-analysis of published studies was performed to determine whether AD patients have a distinctive personality trait profile compared to healthy subjects (HC), similar to or different from a premorbid personality profile consistently reported in previous studies.

METHODS

A systematic literature search was performed using PsycInfo (PROQUEST), PubMed, and Scopus. The meta-analysis pooled results from primary studies using Hedges' g unbiased approach.

RESULTS

The meta-analysis included 10 primary studies and revealed that, when the personality was evaluated by informant-rated measures, AD patients had significantly higher levels of Neuroticism, lower levels of Openness, Agreeableness, Conscientiousness, and Extraversion than HCs. When the personality was evaluated by self-rated measures, the results obtained from informants were confirmed for Neuroticism, Openness, and Extraversion but not for Agreeableness and Conscientiousness where AD patients and HCs achieved similar scores.

CONCLUSIONS

The meta-analysis revealed that high Neuroticism and low Openness and Extraversion are distinctive personality traits significantly associated with a diagnosis of AD when evaluated both self-rated and informant-rated measures. This personality trait profile is similar to premorbid one, which contributes to development of AD over time. Therefore, our findings indirectly support the idea of specific premorbid personality traits as harbingers of AD.

The moderating effect of subjective age on the association between depressive symptoms and cognitive functioning in Korean older adults

OBJECTIVES

Depressive symptoms are greatly associated with cognitive impairment in older adults. Recent growing body of literature has reported that the subjective perception of one's own age (subjective age) predicts both cognitive performance and mental well-being in old age. This study aims to examine whether subjective age moderates the association between depressive symptoms and cognitive functioning in a representative sample of Korean older adults. To address this research question, we employed the Stereotype-Embodiment Theory as a theoretical guide.

METHOD

Data are from the 2016 Dementia Literacy Survey collected by Kyung Hee University, and 526 community-dwelling Korean older adults (ages 60-79) completed the questionnaire about depressive symptoms, cognitive functioning, and subjective age.

RESULTS

According to the hierarchical regression analysis, both higher levels of depressive symptoms and older subjective age were associated with poorer cognitive functioning. Further analyses showed that subjective age attenuated the effect of depressive symptoms on cognitive functioning: when older adults have a higher level of depression, those with younger subjective age reported a higher level of cognitive functioning than those with older subjective age.

CONCLUSION

Based on the findings from this study, both theoretical and practical implications were discussed.

Understanding the impact of sex and gender in Alzheimer's disease: A call to action

INTRODUCTION

Precision medicine methodologies and approaches have advanced our understanding of the clinical presentation, development, progression, and management of Alzheimer's disease (AD) dementia. However, sex and gender have not yet been adequately integrated into many of these approaches.

METHODS

The Society for Women's Health Research Interdisciplinary Network on AD, comprised of an expert panel of scientists and clinicians, reviewed ongoing and published research related to sex and gender differences in AD.

RESULTS

The current review is a result of this Network's efforts and aims to: (1) highlight the current state-of-the-science in the AD field on sex and gender differences; (2) address knowledge gaps in assessing sex and gender differences; and (3) discuss 12 priority areas that merit further research.

DISCUSSION

The exclusion of sex and gender has impeded faster advancement in the detection, treatment, and care of AD across the clinical spectrum. Greater attention to these differences will improve outcomes for both sexes.

Current advances of pharmacological properties of 7-chloro-4-(phenylselanyl) quinoline: Prevention of cognitive deficit and anxiety in Alzheimer's disease model

This study investigated the effect of 7-chloro-4-(phenylselanyl) quinoline (4-PSQ) at a dose of 1 mg/kg in memory impairment and anxiety in an Alzheimer's disease (AD) model induced by amyloid β-peptide (Aβ) (fragment 25-35) in mice. The involvement of acetylcholinesterase (AChE) activity and lipid peroxidation in hippocampus and cerebral cortex was evaluated. Male Swiss mice were pretreated with 4-PSQ (1 mg/kg, intragastrically (i.g.), daily) for fourteen days. Thirty minutes after the first treatment with 4-PSQ, the animals received a single injection of Aβ (3 nmol/3 μl/per site, intracerebroventricular (i.c.v.)). Mice were submitted to the behavioral tasks (open-field, elevated plus maze, Barnes maze, object recognition and location, and step-down inhibitory avoidance tests) from the fifth day onwards. On the fifteenth day, blood was removed for analysis of biochemical markers (glucose, triglycerides, urea, aspartate (AST) and alanine (ALT) aminotrasferases), and cerebral cortex and hippocampus for determination of AChE activity and thiobarbituric acid reactive species (TBARS) levels. Aβ caused memory impairment, anxiogenic behavior, increased AChE activity in the cerebral structures and TBARS levels in the cerebral cortex. 4-PSQ was effective to protect against behavioral changes, AChE activity and TBARS levels. In conclusion, 4-PSQ protected against learning and memory impairment and anxiety in a mouse model of AD induced by Aβ, and anticholinesterase and antioxidant actions are involved in the pharmacological effect of the compound.

Hippocampal volume and integrity as predictors of cognitive decline in intact elderly

The risk of Alzheimer's disease can be predicted by volumetric analyses of MRI data in the medial temporal lobe. The present study compared a volumetric measurement of the hippocampus with a novel measure of hippocampal integrity (HI) derived from the ratio of parenchyma volume over total volume. Participants were cognitively intact and aged 60 years or older at baseline, and were tested twice, roughly 3 years apart. Participants had been recruited for a study on late-life major depression (LLMD) and were evenly split between depressed patients and controls. Linear regression models were applied to the data with a cognitive composite score as the outcome, and HI and volume, together or separately, as predictors. Subsequent cognitive performance was predicted well by models that included an interaction between HI and LLMD status, such that lower HI scores predicted more cognitive decline in depressed patients. More research is needed, but tentative results from this study appear to suggest that the newly introduced measure HI is an effective tool for the purpose of predicting future changes in general cognitive ability, and especially so in individuals with LLMD.

Integrating sex and gender into neurodegeneration research: A six-component strategy

Introduction

Despite important sex differences, there remains a paucity of studies examining sex and gender differences in neurodegeneration. The Canadian Consortium on Neurodegeneration in Aging (CCNA), a national network of researchers, provides an ideal platform to incorporate sex and gender.

Methods

CCNA's Women, Gender, Sex and Dementia program developed and implemented a six-component strategy involving executive oversight, training, research collaboration, progress report assessment, results dissemination, and ongoing manuscript review. The inclusion of sex and gender in current and planned CCNA projects was examined in two progress reporting periods in 2016.

Results

Sex and gender research productivity increased substantially for both preclinical (36%–45%) and human (56%–60%) cohorts. The main barrier was lack of funding.

Discussion

The Women, Gender, Sex and Dementia strategy resulted in a major increase of sex and gender into research on neurodegenerative disorders. This best practice model could be utilized by a wide variety of large multidisciplinary groups.

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There is a paucity of research on sex and gender in neurodegenerative disorders.

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A six-component strategy to integrate sex and gender into research was developed.

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Strategy implemented in national network of researchers studying neurodegeneration.

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Sex and gender research productivity increased for preclinical and human research.

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Strategy could be adapted and utilized across various multidisciplinary groups.