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

Body mass index changes and trajectories from midlife to late-life: association with subjective cognitive complaints in a 30-year Women's cohort study

BACKGROUND

The relationship between body mass index (BMI) changes across the lifespan and cognitive health in later life remains unclear. This study evaluated the association between BMI changes from midlife to late-life and subsequent subjective cognitive complaints (SCCs) in women.

METHODS

We analysed data from 5160 women in the New York University Women's Health Study, a prospective cohort with over 30 years of follow-up. BMI was calculated using self-reported height and weight at baseline and follow-up. SCCs were assessed using a validated questionnaire in 2018-2020. Odds ratios (ORs) for reporting ≥2 SCCs were estimated using unconditional logistic regression.

RESULTS

BMI at specific life stages was not significantly associated with SCC risk. BMI changes from midlife to late-life were associated with SCC risk. Compared to women with stable BMI (≤5% change), moderate BMI loss (5.1-10% decrease) was associated with higher odds of ≥2 SCCs (OR: 1.23, 95% CI: 1.02-1.48), large BMI gain (>10% increase) was associated with lower odds of ≥2 SCCs (OR: 0.81, 95% CI: 0.67-0.97). These findings were consistent across sensitivity analyses, including varying age cut-offs and excluding BMI changes occurring 5-10 years before late-life.

CONCLUSIONS

Our findings emphasize the importance of considering lifelong weight changes in assessing cognitive health risks. In particular, significant weight loss from midlife to late-life may serve as a potential indicator of cognitive decline in older adults. Further research is needed to elucidate the underlying mechanisms of this association and to explore effective interventions for mitigating cognitive health risks.

Biological brain age and resilience in cognitively unimpaired 70-year-old individuals

INTRODUCTION

This study investigated the associations of brain age gap (BAG)-a biological marker of brain resilience-with life exposures, neuroimaging measures, biological processes, and cognitive function.

METHODS

We derived BAG by subtracting predicted brain age from chronological age in 739 septuagenarians without dementia or neurological disorders. Robust linear regression models assessed BAG associations with life exposures, plasma inflammatory and metabolic biomarkers, magnetic resonance imaging, and cerebrospinal fluid biomarkers of neurodegeneration and vascular brain injury, and cognitive performance.

RESULTS

Greater BAG (older-looking brains) was associated with physical inactivity, diabetes, and stroke, while prediabetes was related to lower BAG, that is, younger-looking brains. Physical activity mitigated the link between obesity and BAG. Greater BAG was associated with greater small vessel disease burden, white-matter alterations, inflammation, high glucose, poorer vascular-related cognitive domains. Sex-specific associations were identified.

DISCUSSION

Vascular-related lifestyles and health shape brain appearance. Inflammation and insulin-related processes may be keys to understanding vascular cognitive disorders.

HIGHLIGHTS

BAG, reflecting deviations from CA, can indicate resilience. Diabetes, stroke, and low physical activity link to "older" brains (greater BAG). Physical activity yielded to "younger" brains in septuagenarians with obesity. High cerebrovascular burden, inflammation, and glucose associate with "older" brains. Sex differences were detected in all BAG-associated factors.

Female Brain and Endocrinological Research-Veteran (FemBER-Vet) study: A study protocol for identifying endocrinological, lifestyle and psychosocial determinants of brain health outcomes in female veterans for future intervention success

BACKGROUND

Recent studies have demonstrated a greater risk of dementia in female veterans compared to civilians; with the highest prevalence noted for former service women with a diagnosis of psychiatric (trauma, alcoholism, depression), and/or a physical health condition (brain injury, insomnia, diabetes). Such findings highlight the need for increased and early screening of medical and psychiatric conditions, and indeed dementia, in the female veteran population. Further, they call for a better understanding of the underlying biopsychosocial mechanisms that might confer heightened risk for female veterans, to tailor preventative and interventional strategies that support brain health across the lifespan.

METHODS

The Female Brain and Endocrinological Research-Veteran (FemBER-Vet) Study will create a highly-phenotyped readiness cohort of ex-service persons as well as non-veterans to assess the impacts of, and risks associated with, military service on brain health, using state-of-the-art non-invasive cognitive, physiological and biomarker capture techniques. FEMBER-Vet will include 90 participants across three study groups (30 female veterans, 30 male veterans, 30 female civilians) to delineate the precise biological, socio-demographic, health, lifestyle, military-related, and life-course determinants of brain health outcomes (psychosocial, cognitive, neurophysiological, and other biomarkers).

DISCUSSION

This work addresses the poorly understood biopsychosocial outcomes that female veterans experience compared to their male counterparts and the general female population. Ultimately, it will provide evidence to support the development of tailored interventions for an emerging health priority that currently lacks sufficient evidence for screening and therapeutic intervention.

Hormone replacement therapy, menopausal age and lifestyle variables are associated with better cognitive performance at follow-up but not cognition over time in older-adult women irrespective of APOE4 carrier status and co-morbidities

Introduction

The impact of Hormone Replacement Therapy (HRT) on cognitive function in postmenopausal women remains a topic of considerable debate. Although estrogen's neuroprotective effects suggest potential cognitive benefits, empirical findings are mixed.

Methods

This study uses data from the Cognitive Function and Ageing Study Wales (CFAS Wales) cohort to explore the relationships between HRT use, age at menopause, APOE4 carrier status, lifestyle factors, comorbidities, and cognitive outcomes in older adult women. Two regression models were employed: one analyzing cognitive performance at follow-up and another examining changes in cognitive scores over time.

Results

Results indicate that while age, education, HRT use, age at menopause, alcohol consumption, and diet were associated with cognitive function at a single later time point, only age remained a significant predictor when modeling cognition over time.

Discussion

These findings suggest that while HRT, menopausal age and lifestyle factors may support cognitive stability, they do not necessarily predict cognitive decline in post-menopausal older women. A major limitation of the current work is the lack of detail regarding HRT use, such as formulation, timing and duration; caveats that future studies should address. The study underscores the need for longer follow-up periods, consideration of other female-specific risk factors, and more comprehensive lifestyle and health assessments to clarify the complex interplay between HRT use, reproductive history, lifestyle, comorbidities and cognitive aging in women.

Blood biomarkers in Down syndrome: Facilitating Alzheimer's disease detection and monitoring

Blood-based biomarkers continue to be explored for disease detection, monitoring of progression, and therapeutic outcomes as the diagnostic determination of Alzheimer's Disease in Down Syndrome (DS-AD) remains challenging in clinical settings. This perspective highlights the current status of this effort. Overall, amyloid (A), tau (T), and neurodegeneration (AT[N]) blood-based biomarkers have been shown to increase with disease pathology for individuals with DS. Phosphorylated tau biomarkers (p-tau217, p-tau181) have been consistently shown to track disease progression for DS-AD and are likely good candidates for use in clinical settings. Biomarkers of inflammation (glial fibrillary acidic protein) also show promise; however, additional work is needed. Findings from stability work of blood-based biomarkers conducted among non-DS also support the potential longitudinal utility of biomarkers such as neurofilament light chain and p-tau181 in DS. Gaps in our knowledge are highlighted, and a potential role for sex differences in biomarker outcomes is noted, along with recommendations for determining the appropriate context of use when translating biomarkers into clinical applications. HIGHLIGHTS: An overview of blood-based biomarkers for Alzheimer's disease (AD) was provided for consideration of their utility among individuals with Down syndrome when looking toward potential clinical applications. Longitudinal stability of many blood biomarkers and improvement in detection sensitivity make blood such as plasma a viable source for exploring AD pathology. Variability in reviewed findings regarding the application of blood biomarkers highlights the importance of understanding and defining the appropriate context of use, particularly when translating them into clinical practice.

Perspectives on the Dementia Public Health Exposome

Dementia is a public health concern in the aging population with an estimated 55 million people impacted globally. Public health initiatives that focus on minimizing dementia risk factors may support efforts to reduce the incidence of dementia in at-risk populations. Exposomics considers both modifiable and non-modifiable risk factors for disease, including genetic changes with age and lifetime exposures to environmental, social, and behavioral risk factors. Dementia precursors may remain undetected for up to 20 years. An understanding and application of the dementia exposome may promote healthy brain interventions, screening, and risk mitigation. The proposed dementia public health exposome (DPHE) provides a framework for understanding and addressing the complex interactions between genetics, health behavior, and environment (natural, built, and social) linked to modifiable and non-modifiable risk factors for dementia. The DPHE may be used to inform public health strategies and advancements in healthy brain initiatives.

Cardiovascular risk of dementia is associated with brain-behaviour changes in cognitively healthy, middle-aged individuals

Alzheimer's Disease (AD) neuropathology start decades before clinical manifestations, but whether risk factors are associated with early cognitive and brain changes in midlife remains poorly understood. We examined whether AD risk factors were associated with cognition and functional connectivity (FC) between the Locus Coeruleus (LC) and hippocampus - two key brain structures in AD neuropathology - cross-sectionally and longitudinally in cognitively healthy midlife individuals. Neuropsychological assessments and functional Magnetic Resonance Imaging were obtained at baseline (N=210), and two-years follow-up (N=188). Associations of cognition and FC with apolipoprotein ε4 (APOE ε4) genotype, family history of dementia, and the Cardiovascular Risk Factors, Aging, and Incidence of Dementia (CAIDE) score were investigated. Cross-sectionally, higher CAIDE scores were associated with worse cognition. Menopausal status interacted with the CAIDE risk on cognition. Furthermore, the CAIDE score significantly moderated the relationship between cognition and LC-Hippocampus FC. Longitudinally, the LC-Hippocampus FC decreased significantly over 2 years. These results suggest that cardiovascular risk of dementia is associated with brain-behaviour changes in cognitively healthy, middle-aged individuals.

Chronic obstructive pulmonary disease as a risk factor for cognitive impairment: a systematic review and meta-analysis

BACKGROUND

Cognitive impairment is affecting plenty of patients with chronic obstructive pulmonary disease (COPD), and it is the main leading cause of quality of life to varying degrees. However, there are still wide discrepancies in these prevalence rates can be attributed to the diversity in study designs, participant age ranges, inclusion criteria and the methodologies used for assessment. Previous studies revealed the association between COPD and cognitive impairment, but the conclusions remain controversial.

OBJECTIVES

The current systematic review aimed to investigate whether COPD is an independent risk factor for cognitive impairment.

STUDY DESIGN

A systematic review and meta-analysis.

DATA SOURCES

PubMed, Cochrane Library, MEDLINE, Embase, Web of Science, China Knowledge Resource Integrated Database, Wanfang Database, Chinese Biomedical Database and Weipu Database were searched from inception to 1 December 2022.

ELIGIBILITY CRITERIA

The inclusion criteria involved studies that reported cognitive impairment in COPD. We just included cohort designs, published in English or Chinese language.

DATA EXTRACTION AND SYNTHESIS

Two reviewers independently extracted and assessed the quality of data using Newcastle-Ottawa Quality Assessment Scale. The outcomes were assessed with random-effects model and reported as the HR with 95% CI using the Review Manager software.

RESULTS

12 studies from 10 articles reporting on 625 644 people were included. The findings indicated that compared with those without COPD at baseline, patients with COPD were associated with an increased risk of cognitive impairment. Subgroup analysis showed the association was not significantly different in sex and age, and the subgroup supports that COPD has a higher risk of non-amnestic mild cognitive impairment (na-MCI) than amnestic MCI.

CONCLUSIONS

Patients with COPD have a higher risk of developing cognitive impairment and are more likely to cause na-MCI compared with those without COPD, and this risk is not affected by gender or age. Therefore, continuous monitoring of cognitive function in COPD is critical.

PROSPERO REGISTRATION NUMBER

CRD42021285913.

Comparative Study of Injected Alzheimer's Disease Models in Rats: Insights from Experimental Research

BACKGROUND/OBJECTIVES

Alzheimer's disease (AD) remains incurable, highlighting the need for new and diverse animal models to better understand its complex mechanisms. This study compares various injected animal models of AD, focusing on the main theories that explain the disease; Methods: Female Wistar rats (10-months old) were administered intracebroventricularly by artificial cerebrospinal fluid (aCSF) (Control), beta amyloid Aβ1-42 (BA), okadaic acid (OKA), lipopolysaccharides (LPS), buthionine sulfoximine (BSO) or by a mixture of these different molecules (MLG). Cognitive performance was assessed one week or one month after stereotaxic surgery; Results: Our results, show that only the Aβ and the MLG induced a persistence and progressive deficits in the working memory, recognition memory and spatial memory in rats. As the hippocampus (HIP) and the prefrontal cortex (PFC) are particularly involved in memory behavior, we analyzed long-term neuroadaptations in these brain subregions using spectrophotometric and histological methods to assess oxidative stress changes and neuronal loss, respectively. We found that the behavioral impairments in memory and learning were accompanied by irreversible oxidative stress changes and neurodegenerescence, particularly in the HIP; Conclusions: This study provides promising data on the modeling of AD in order to develop an effective therapeutic approach.

Age of menopause and dementia risk in 10,832 women from the Swedish Twin Registry

INTRODUCTION

An earlier age of menopause (AOM) is hypothesized to increase vulnerability to the neuropathological processes of dementia which begin in midlife.

METHODS

We tested this hypothesis in a sample of 10,832 women from the Swedish Twin Registry, stratified by menopause etiology. Survival models showed that a U-shaped association was present for women whose menopause occurred spontaneously. Sensitivity analyses conducted in hormone naïve, APOE ε4+ and AOM restricted subsamples showed largely analogous patterns of results.

DISCUSSION

Supporting conclusions from basic research, our results suggest that estrogens (proxied here by AOM) interact with several biological pathways mediating dementia disease processes. In line with trends in hormone research across the past century, our findings challenge the oversimplified 'more-is-better' perspective on hormone exposure. Specifically, the non-linear association we observed between AOM and dementia risk points to the involvement of distinct and interacting biological mechanisms beyond just estrogen levels.

Associations between sex and lifestyle activities with cognitive reserve in mid-life adults with genetic risk for Alzheimer's disease

BACKGROUND

Females have a higher age-adjusted incidence of Alzheimer's Disease (AD) than males, even when accounting for longer lifespan and, therefore, stand to benefit the most from dementia prevention efforts. As exposure to many modifiable risk factors for dementia begins in mid-life, interventions must be implemented from middle-age. Building cognitive reserve, particularly through stimulating avocational activities and occupational attainment presents a crucial, underexplored, dementia prevention approach for mid-life. It is currently unknown, however, whether modifiable lifestyle factors can protect against AD processes, from mid-life, differentially for females and males who carry inherited risk for late-life dementia. To address this gap, this study investigated the impact of biological sex and APOE4 carrier status on the relationship between stimulating activities, occupational attainment, and cognition in mid-life.

METHODS

We leveraged the PREVENT-Dementia program, the world's largest study investigating the origins and early diagnosis of dementia in mid-life at-risk individuals (N = 700; 40-59 years). Cognitive performance was measured using the Cognito Battery and the Visual Short Term Memory Binding task. Mid-life specific reserve contributors were assessed via the Lifetime of Experiences Questionnaire.

RESULTS

Females had significantly better episodic and relational memory (p < 0.001), and lower occupational attainment than males (p < 0.001). Engagement in stimulating activities was positively associated with episodic and relational memory, regardless of sex and APOE4 status (β = 0.05, CI 0.03-0.07, p < 0.001). APOE4 carriers showed significant sex differences in the association between occupational attainment and episodic and relational memory (β = 0.38, CI 0.12-0.63, p = 0.003). APOE4 carrier females with higher occupational attainment showed better cognition (β = 0.16, CI -0.002-0.32, p = 0.053), whereas APOE4 carrier males showed the opposite effect (β = -0.20, CI -0.40 - -0.001, p = 0.049).

CONCLUSION

Our findings suggest that occupational attainment in mid-life contributes to cognitive reserve against inherited risk of dementia in females, but not males. They highlight the need for high precision approaches that consider biological sex and APOE4 carrier status to inform Alzheimer's disease prevention strategies and clinical trials.

Emerging paradigms in Alzheimer's therapy

Alzheimer's disease is a neurodegenerative disorder that affects elderly, and its incidence is continuously increasing across the globe. Unfortunately, despite decades of research, a complete cure for Alzheimer's disease continues to elude us. The current medications are mainly symptomatic and slow the disease progression but do not result in reversal of all disease pathologies. The growing body of knowledge on the factors responsible for the onset and progression of the disease has resulted in the identification of new targets that could be targeted for treatment of Alzheimer's disease. This has opened new vistas for treatment of Alzheimer's disease that have moved away from chemotherapeutic agents modulating a single target to biologics and combinations that acted on multiple targets thereby offering better therapeutic outcomes. This review discusses the emerging directions in therapeutic interventions against Alzheimer's disease highlighting their merits that promise to change the treatment paradigm and challenges that limit their clinical translation.

Bibliometric analysis of research trends on factors affecting older adults with mild cognitive impairment

Background

In recent years, the problem of cognitive impairment in the elderly has become increasingly prominent. Understanding the research trend of influencing factors of mild cognitive impairment, and provide reference for medical staff to early screening of the elderly with mild cognitive impairment.

Objective

Through the visual analysis of the influence factors of the elderly with mild cognitive impairment, the current research status was discussed.

Methods

The relevant literature in the field of influencing factors of mild cognitive impairment in the elderly included in the Web of Science core collection database from 2013 to 2022 was searched. Using software such as Cite Space and VOS viewer to visually analyze literature citations, country, keywords, and development trends.

Results

A total of 547 relevant literatures were included, and the number of publications showed an increasing trend in the past ten years. The United States ranked first in both the number of published papers (157) and centrality (0.34), and the United States and China had a greater influence on the influencing factors of mild cognitive impairment. Alzheimer's disease, cognitive decline, the elderly, risk factors, are the research hotspot in this field.

Conclusion

Cognitive decline will affect the autonomy of the elderly. Cognitive frailty, MRI is the forefront of MCI research, to understand the research hotspots and frontiers in this field, to conduct early screening and intervention guidance for people with mild cognitive impairment, so as to delay the occurrence of Alzheimer's disease, and reduce the pressure on family caregivers and society.

Integration of sex/gender and utilization of ecological Momentary assessment of cognition in clinical populations: A scoping review

Objectives: We aimed to describe the methods of smartphone-based cognitive ecological momentary assessment designs in clinical populations, with an intention to evaluate how the role of sex and/or gender has been considered in the design and analyses, particularly including female-specific physiology. Methods: This scoping review was conducted based on JBI scoping review methodology. On March 2nd, 2023, we searched for literature across four databases. Screening of the results and data extraction were conducted in duplicate according to the a priori methods in the pre-registered protocol. Results: 31 articles were included in this review. Participants ranged in age from 15-85 years old with various clinical disorders. Prompts were given between 1-7 times per day for 7-84 days. Executive function was the most frequently assessed cognitive domain. Over half the studies (n = 17, 55%) did not investigate the effects of sex and/or gender, and only one study considered the impact of hormonal therapy. Many studies (n = 14, 45%) used sex and gender interchangeably or incorrectly. Conclusions: Studies varied in design, with heterogeneity in the reporting of methodological information. The lack of attention to sex/gender on neuropsychological outcomes can lead to confusion and contradiction regarding its potential impact on cognition in clinical populations. This may hinder the identification of effective interventions for those assigned female at birth who have been overlooked or considered indistinguishable from their male counterparts. Given the well-documented impact of sex/gender on cognition, it is essential that future neuropsychological research, especially EMA-based studies, prioritize investigating sex/gender to ensure better outcomes for all.

Alzheimer's disease as a women's health challenge: a call for action on integrative precision medicine approaches

Alzheimer's Disease (AD) is marked by pronounced sex differences in pathophysiology and progression. However, the field has yet to fully recognize AD as a women's health issue, delaying the development of targeted preventative strategies and treatments. This perspective explores the elements impacting AD in women, identifying sex specificity in risk factors, highlighting new diagnostic approaches with electronic health records, and reviewing key molecular studies to underscore the need for integrative precision medicine approaches. Established AD risk factors such as advancing age, the apolipoprotein E4 allele, and poorer cardiovascular health affect women differently. We also shed light on sociocultural risk factors, focusing on the gender disparities that may play a role in AD development. From a biological perspective, sex differences in AD are apparent in biomarkers and transcriptomics, further emphasizing the need for targeted diagnostics and treatments. The convergence of novel multiomics data and cutting-edge computational tools provides a unique opportunity to study the molecular underpinnings behind sex dimorphism in AD. Thus, precision medicine emerges as a promising framework for understanding AD pathogenesis through the integration of genetics, sex, environment, and lifestyle. By characterizing AD as a women's health challenge, we can catalyze a transformative shift in AD research and care, marked by improved diagnostic accuracy, targeted interventions, and ultimately, enhanced clinical outcomes.

The killifish germline regulates longevity and somatic repair in a sex-specific manner

Classical evolutionary theories propose tradeoffs between reproduction, damage repair, and lifespan. However, the specific role of the germline in shaping vertebrate aging remains largely unknown. Here, we use the turquoise killifish ( N. furzeri ) to genetically arrest germline development at discrete stages, and examine how different modes of infertility impact life-history. We first construct a comprehensive single-cell gonadal atlas, providing cell-type-specific markers for downstream phenotypic analysis. Next, we show that germline depletion - but not arresting germline differentiation - enhances damage repair in female killifish. Conversely, germline-depleted males instead showed an extension in lifespan and rejuvenated metabolic functions. Through further transcriptomic analysis, we highlight enrichment of pro-longevity pathways and genes in germline-depleted male killifish and demonstrate functional conservation of how these factors may regulate longevity in germline-depleted C. elegans . Our results therefore demonstrate that different germline manipulation paradigms can yield pronounced sexually dimorphic phenotypes, implying alternative responses to classical evolutionary tradeoffs.

Sex differences in Alzheimer's disease blood biomarkers in a Caribbean population of African ancestry: The Tobago Health Study

INTRODUCTION

Alzheimer's disease (AD) is increasing in the Caribbean, especially for persons of African ancestry (PAA) and women. However, studies have mostly utilized surveys without AD biomarkers.

METHODS

In the Tobago Health Study (n = 309; 109 women, mean age 70.3 ± 6.6), we assessed sex differences and risk factors for serum levels of phosphorylated tau-181 (p-tau181), amyloid-beta (Aβ)42/40 ratio, glial fibrillary acidic protein (GFAP), and neurofilament light chain (NfL). Blood samples were from 2010 to 2013 for men and from 2019 to 2023 for women.

RESULTS

Women were more obese, hypertensive, and sedentary but reported less smoking and alcohol use than men (age-adjusted p < 0.04). Compared to men, women had worse levels of AD biomarkers, with higher p-tau181 and lower Aβ42/40, independent of covariates (p < 0.001). In sex-stratified analyses, higher p-tau181 was associated with older age in women and with hypertension in men. GFAP and NfL did not differ by sex.

DISCUSSION

Women had worse AD biomarkers than men, unexplained by age, cardiometabolic diseases, or lifestyle. Studying risk factors for AD in PAA is warranted, especially for women earlier in life.

The role of gender in cognitive outcomes from stroke

OBJECTIVE

Stroke can cause cognitive impairment, which can lead to challenges returning to day-to-day activities. Knowing what factors are associated with cognitive impairment post-stroke can be useful for predicting outcomes and guiding rehabilitation. One such factor is gender: previous studies are inconclusive as to whether gender influences cognitive outcomes post-stroke. Accounting for key variables, we examined whether there are gender differences in cognitive outcomes after stroke.

METHOD

We analyzed data from neuropsychological assessments of 237 individuals tested in the chronic epoch (≥ 3 months) following ischemic stroke. Using ANCOVA and linear mixed modeling, we examined gender as a predictor of cognition as measured by general cognitive ability (g), Full-Scale IQ, and 18 cognitive tests, controlling for age at stroke onset, education, premorbid intelligence, and lesion volume.

RESULTS

There were no significant gender differences in overall cognitive outcomes as measured by g (p = .887) or Full-Scale IQ (p = .801). There were some significant gender differences on specific cognitive tests, with women outperforming men on scores from the Rey Auditory Verbal Learning Test (ps < .01) and men outperforming women on the Wechsler Adult Intelligence Scale Arithmetic and Information subtests (ps < .01).

CONCLUSIONS

Our findings indicate that men and women have similar overall cognitive outcomes after stroke, when demographic and lesion factors are accounted for. Although men and women differed in their performance on some individual cognitive tests, neither gender performed systematically better or worse. However, for learning, working memory, and verbal knowledge/comprehension, gender may be an important predictor of outcome post-stroke.

Sex-specific differences in neuropsychological profiles of mild cognitive impairment in a hospital-based clinical sample

OBJECTIVE

Mild cognitive impairment (MCI) is an etiologically nonspecific diagnosis including a broad spectrum of cognitive decline between normal aging and dementia. Several large-scale cohort studies have found sex effects on neuropsychological test performance in MCI. The primary aim of the current project was to examine sex differences in neuropsychological profiles in a clinically diagnosed MCI sample using clinical and research diagnostic criteria.

METHOD

The current study includes archival data from 349 patients (age M = 74.7; SD = 7.7) who underwent an outpatient neuropsychological evaluation and were diagnosed with MCI. Raw scores were converted to z-scores using normative datasets. Sex differences in neurocognitive profiles including severity, domain-specific composites (memory, executive functioning/information processing speed, and language), and modality-specific learning curves (verbal, visual) were examined using Analysis of Variance, Chi-square analyses, and linear mixed models. Post hoc analyses examined whether sex effects were uniform across age and education brackets.

RESULTS

Females exhibit worse non-memory domain and test-specific cognitive performances compared to males with otherwise comparable categorical MCI criteria and global cognition measured via screening and composite scores. Analysis of learning curves showed additional sex-specific advantages (visual Males>Females; verbal Females >Males) not captured by MCI subtypes.

CONCLUSIONS

Our results highlight sex differences in a clinical sample with MCI. The emphasis of verbal memory in the diagnosis of MCI may result in diagnosis at more advanced stages for females. Additional investigation is needed to determine whether these profiles confer greater risk for progressing to dementia or are confounded by other factors (e.g., delayed referral, medical comorbidities).

Cortical cerebrovascular and metabolic perturbations in the 5xFAD mouse model of Alzheimer's disease

Introduction

The 5xFAD mouse is a popular model of familial Alzheimer's disease (AD) that is characterized by early beta-amyloid (Aβ) deposition and cognitive decrements. Despite numerous studies, the 5xFAD mouse has not been comprehensively phenotyped for vascular and metabolic perturbations over its lifespan.

Methods

Male and female 5xFAD and wild type (WT) littermates underwent in vivo 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) imaging at 4, 6, and 12 months of age to assess regional glucose metabolism. A separate cohort of mice (4, 8, 12 months) underwent "vessel painting" which labels all cerebral vessels and were analyzed for vascular characteristics such as vessel density, junction density, vessel length, network complexity, number of collaterals, and vessel diameter.

Results

With increasing age, vessels on the cortical surface in both 5xFAD and WT mice showed increased vessel length, vessel and junction densities. The number of collateral vessels between the middle cerebral artery (MCA) and the anterior and posterior cerebral arteries decreased with age but collateral diameters were significantly increased only in 5xFAD mice. MCA total vessel length and junction density were decreased in 5xFAD mice compared to WT at 4 months. Analysis of 18F-FDG cortical uptake revealed significant differences between WT and 5xFAD mice spanning 4-12 months. Broadly, 5xFAD males had significantly increased 18F-FDG uptake at 12 months compared to WT mice. In most cortical regions, female 5xFAD mice had reduced 18F-FDG uptake compared to WT across their lifespan.

Discussion

While the 5xFAD mouse exhibits AD-like cognitive deficits as early as 4 months of age that are associated with increasing Aβ deposition, we only found significant differences in cortical vascular features in males, not in females. Interestingly, 5xFAD male and female mice exhibited opposite effects in 18F-FDG uptake. The MCA supplies blood to large portions of the somatosensory cortex and portions of motor and visual cortex and increased vessel length alongside decreased collaterals which coincided with higher metabolic rates in 5xFAD mice. Thus, a potential mismatch between metabolic demand and vascular delivery of nutrients in the face of increasing Aβ deposition could contribute to the progressive cognitive deficits seen in the 5xFAD mouse model.

Regional contributions of D-serine to Alzheimer's disease pathology in male AppNL-G-F/NL-G-F mice

Background

Neurodegenerative processes in Alzheimer's disease (AD) are associated with excitotoxicity mediated by the N-methyl-D-aspartate receptor (NMDAR). D-Serine is an endogenous co-agonist necessary for NMDAR-mediated excitotoxicity. In the mammalian brain, it is produced by serine racemase (SRR) from L-serine, suggesting that dysregulation of L-serine, D-serine, or SRR may contribute to AD pathogenesis.

Objective and methods

We examined the contributions of D-serine to AD pathology in the App^{NL-G-F/NL-G-F} gene knock-in (APPKI) mouse model of AD. We first examined brain SRR expression levels and neuropathology in APPKI mice and then assessed the effects of long-term D-serine supplementation in drinking water on neurodegeneration. To further confirm the involvement of endogenous D-serine in AD progression, we generated Srr gene-deleted APPKI (APPKI-SRRKO) mice. Finally, to examine the levels of brain amino acids, we conducted liquid chromatography-tandem mass spectrometry.

Results

Expression of SRR was markedly reduced in the retrosplenial cortex (RSC) of APPKI mice at 12 months of age compared with age-matched wild-type mice. Neuronal density was decreased in the hippocampal CA1 region but not altered significantly in the RSC. D-Serine supplementation exacerbated neuronal loss in the hippocampal CA1 of APPKI mice, while APPKI-SRRKO mice exhibited attenuated astrogliosis and reduced neuronal death in the hippocampal CA1 compared with APPKI mice. Furthermore, APPKI mice demonstrated marked abnormalities in the cortical amino acid levels that were partially reversed in APPKI-SRRKO mice.

Conclusion

These findings suggest that D-serine participates in the regional neurodegenerative process in the hippocampal CA1 during the amyloid pathology of AD and that reducing brain D-serine can partially attenuate neuronal loss and reactive astrogliosis. Therefore, regulating SRR could be an effective strategy to mitigate NMDAR-dependent neurodegeneration during AD progression.

The association between sex hormones and the change in brain-predicted age difference in older women

OBJECTIVE

The role of circulating sex hormones on structural brain ageing is yet to be established. This study explored whether concentrations of circulating sex hormones in older women are associated with the baseline and longitudinal changes in structural brain ageing, defined by the brain-predicted age difference (brain-PAD).

DESIGN

Prospective cohort study using data from NEURO and Sex Hormones in Older Women; substudies of the ASPirin in Reducing Events in the Elderly clinical trial.

PATIENTS

Community-dwelling older women (aged 70+ years).

MEASUREMENTS

Oestrone, testosterone, dehydroepiandrosterone (DHEA), and sex-hormone binding globulin (SHBG) were quantified from plasma samples collected at baseline. T1-weighted magnetic resonance imaging was performed at baseline, 1 and 3 years. Brain age was derived from whole brain volume using a validated algorithm.

RESULTS

The sample comprised of 207 women not taking medications known to influence sex hormone concentrations. A statistically higher baseline brain-PAD (older brain age relative to chronological age) was seen for women in the highest DHEA tertile compared with the lowest in the unadjusted analysis (p = .04). This was not significant when adjusted for chronological age, and potential confounding health and behavioural factors. Oestrone, testosterone and SHBG were not associated with brain-PAD cross-sectionally, nor were any of the examined sex hormones or SHBG associated with brain-PAD longitudinally.

CONCLUSION

No strong evidence of an association between circulating sex hormones and brain-PAD. Given there is prior evidence to suggests sex hormones may be important for brain ageing, further studies of circulating sex hormones and brain health in postmenopausal women are warranted.

Sex and gender considerations in dementia: a call for global research

Studies have identified sex and/or gender differences in Alzheimer’s disease, but few have examined other dementias. We highlight sex and gender differences in other dementias, discuss sociocultural factors and provide a framework for future global studies.

Beyond sex differences: short- and long-term effects of pregnancy on the brain

Growing attention has been directed to the inclusion of females in neuroscience studies, and to the importance of studying sex as a biological variable. However, how female-specific factors such as menopause and pregnancy, affect the brain remains understudied. In this review, we use pregnancy as a case in point of a female-unique experience that can alter neuroplasticity, neuroinflammation, and cognition. We examine studies in both humans and rodents indicating that pregnancy can modify neural function in the short term, as well as alter the trajectory of brain aging. Furthermore, we discuss the influence of maternal age, fetal sex, number of pregnancies, and presence of pregnancy complications on brain health outcomes. We conclude by encouraging the scientific community to prioritize researching female health by recognizing and including factors such as pregnancy history in research.

Exploring the aging process of cognitively healthy adults by analyzing cerebrospinal fluid metabolomics using liquid chromatography-tandem mass spectrometry

BACKGROUND

During biological aging, significant metabolic dysregulation in the central nervous system may lead to cognitive decline and neurodegeneration. However, the metabolomics of the aging process in cerebrospinal fluid (CSF) has not been thoroughly explored.

METHODS

In this cohort study of CSF metabolomics using liquid chromatography-mass spectrometry (LC-MS), fasting CSF samples collected from 92 cognitively unimpaired adults aged 20-87 years without obesity or diabetes were analyzed.

RESULTS

We identified 37 metabolites in these CSF samples with significant positive correlations with aging, including cysteine, pantothenic acid, 5-hydroxyindoleacetic acid (5-HIAA), aspartic acid, and glutamate; and two metabolites with negative correlations, asparagine and glycerophosphocholine. The combined alterations of asparagine, cysteine, glycerophosphocholine, pantothenic acid, sucrose, and 5-HIAA showed a superior correlation with aging (AUC = 0.982). These age-correlated changes in CSF metabolites might reflect blood-brain barrier breakdown, neuroinflammation, and mitochondrial dysfunction in the aging brain. We also found sex differences in CSF metabolites with higher levels of taurine and 5-HIAA in women using propensity-matched comparison.

CONCLUSIONS

Our LC-MS metabolomics of the aging process in a Taiwanese population revealed several significantly altered CSF metabolites during aging and between the sexes. These metabolic alterations in CSF might provide clues for healthy brain aging and deserve further exploration.

Leading mediators of sex differences in the incidence of dementia in community-dwelling adults in the UK Biobank: a retrospective cohort study

BACKGROUND

Little is known regarding whether sex assigned at birth modifies the association between several predictive factors for dementia and the risk of dementia itself.

METHODS

Our retrospective cohort study included 214,670 men and 214,670 women matched by age at baseline from the UK Biobank. Baseline data were collected between 2006 and 2010, and incident dementia was ascertained using hospital inpatient or death records until January 2021. Mediation analysis was tested for 133 individual factors.

RESULTS

Over 5,117,381 person-years of follow-up, 5928 cases of incident all-cause dementia (452 cases of young-onset dementia, 5476 cases of late-onset dementia) were documented. Hazard ratios (95% CI) for all-cause, young-onset, and late-onset dementias associated with the male sex (female as reference) were 1.23 (1.17-1.29), 1.42 (1.18-1.71), and 1.21 (1.15-1.28), respectively. Out of 133 individual factors, the strongest mediators for the association between sex and incident dementia were multimorbidity risk score (percentage explained (95% CI): 62.1% (45.2-76.6%)), apolipoprotein A in the blood (25.5% (15.2-39.4%)), creatinine in urine (24.9% (16.1-36.5%)), low-density lipoprotein cholesterol in the blood (23.2% (16.2-32.1%)), and blood lymphocyte percentage (21.1% (14.5-29.5%)). Health-related conditions (percentage (95% CI) explained: 74.4% (51.3-88.9%)) and biomarkers (83.0% (37.5-97.5%)), but not lifestyle factors combined (30.1% (20.7-41.6%)), fully mediated sex differences in incident dementia. Health-related conditions combined were a stronger mediator for late-onset (75.4% (48.6-90.8%)) than for young-onset dementia (52.3% (25.8-77.6%)), whilst lifestyle factors combined were a stronger mediator for young-onset (42.3% (19.4-69.0%)) than for late-onset dementia (26.7% (17.1-39.2%)).

CONCLUSIONS

Our analysis matched by age has demonstrated that men had a higher risk of all-cause, young-onset, and late-onset dementias than women. This association was fully mediated by health-related conditions or blood/urinary biomarkers and largely mediated by lifestyle factors. Our findings are important for understanding potential mechanisms of sex in dementia risk.

Sex differences in coronary artery bypass grafting-related morbidity and mortality

BACKGROUND

Coronary artery bypass grafting (CABG) is associated with both cardiovascular disease (CVD) and non-CVD traits. In addition, women's prognosis after coronary events and revascularizations is worse than in men. As the course of CVD in women differs from that of men, we performed a phenome-wide analysis on the sex differences in CABG -related morbidity and mortality.

MATERIALS AND METHODS

We performed an untargeted analysis on the sex differences in predictors and outcomes of CABG. We studied a sample of 176,680 FinnGen participants, including 5,950 individuals who underwent CABG (4,988 men and 962 women) and were followed between 1998 and 2019. Over 1,100 different traits were analyzed for both sexes and the results were adjusted with age, smoking status and BMI. Cox proportional hazards models with sex-trait interactions were used to estimate the associations between (1) traits and incident CABG; and (2) CABG and incident traits.

RESULTS

In women, CABG was more strongly related to greater increases in risk of diseases such as hypertension, Alzheimer's, aortic aneurysms, gout, and chronic kidney disease compared to risk increases observed in men (all interaction p-values < 0.03). After CABG, men had 2.5-fold (p = 3.1E-15) and women 6.3-fold (p = 9.4E-08) greater risk of cardiac death compared to same-sex individuals who did not undergo CABG (p for interaction 8.2E-4). Moreover, the risk of death in women remained higher even 12 years after CABG, whereas the long-term risk of death in men was not increased, compared to same-sex individuals who did not undergo CABG.

CONCLUSION

The adverse outcomes after CABG, both quantity and quality, also appear to differ between men and women. In women, CABG is related to greater long-term increases in risk of cardiac death and several other disease states than in men. Consideration should therefore be given to whether women receive adequate long-term post-operative therapy and follow-up as CABG is not associated with equally improved cardiovascular disease prognosis in women than in men.

X-linked ubiquitin-specific peptidase 11 increases tauopathy vulnerability in women

Although women experience significantly higher tau burden and increased risk for Alzheimer's disease (AD) than men, the underlying mechanism for this vulnerability has not been explained. Here, we demonstrate through in vitro and in vivo models, as well as human AD brain tissue, that X-linked ubiquitin specific peptidase 11 (USP11) augments pathological tau aggregation via tau deubiquitination initiated at lysine-281. Removal of ubiquitin provides access for enzymatic tau acetylation at lysines 281 and 274. USP11 escapes complete X-inactivation, and female mice and people both exhibit higher USP11 levels than males. Genetic elimination of usp11 in a tauopathy mouse model preferentially protects females from acetylated tau accumulation, tau pathology, and cognitive impairment. USP11 levels also strongly associate positively with tau pathology in females but not males. Thus, inhibiting USP11-mediated tau deubiquitination may provide an effective therapeutic opportunity to protect women from increased vulnerability to AD and other tauopathies.

What is there to know about the effects of progestins on the human brain and cognition?

Progestins are an important component of hormonal contraceptives (HCs) and hormone replacement therapies (HRTs). Despite an increasing number of studies elucidating the effects of HCs and HRTs, little is known about the effects of different types of progestins included in these medications on the brain. Animal studies suggest that various progestins interact differently with sex steroid, mineralocorticoid and glucocorticoid receptors and have specific modulatory effects on neurotransmitter systems and on the expression of neuropeptides, suggesting differential impacts on cognition and behavior. This review focuses on the currently available knowledge from human behavioral and neuroimaging studies pooled with evidence from animal research regarding the effects of progestins on the brain. The reviewed information is highly relevant for improving women's mental health and making informed choices regarding specific types of contraception or treatment.

B-cell-specific ablation of β-1,4-galactosyltransferase 1 prevents aging-related IgG glycans changes and improves aging phenotype in mice

IgG N-glycans levels change with advancing age, making it a potential biomarker of aging. β-1,4-galactosyltransferase (B4GALT) gene expression levels also increase with aging. Ultra performance liquid chromatography (UPLC) was used to examine changes inserum IgG N-glycans at six time points during the aging process. Most serum IgG N-glycans changed with aging in WT but not in CD19-cre B4GALT1 floxed mice. The relative abundance of fucosylated biantennary glycans with or without Neu5Gc structures changed with aging in heterozygous B4GALT1 floxed mice but not in homozygous B4GALT1 floxed mice. Additionally, the aging phenotype was more apparent in WT mice than in B4GALT1 floxed mice. These results demonstrate that fucosylated biantennary glycans and fucosylated biantennary glycans containing N-glycolylneuraminic acid (Neu5Gc)-linked N-acetyllactosamine (LacNAc) were highly associated with aging and were affected by the B4GALT1 floxed mouse genotype. The changing levels of fucosylated monoantennary glycans observed with aging in WT mice was reversed in B4GALT1 floxed mice and was not sex specific. In summary, B-cell-specific ablation of B4GALT1 from a glycoproteomic perspective prevented age-related changes in IgG N-glycans in mice. SIGNIFICANCE: In this study, serum IgG glycoproteomic data in wild-type (WT) and B-cell-specific ablation of β-1,4-galactosyltransferase 1 mice (B4GALT) were analyzed. Results showed that fucosylated biantennary glycans with or without N-glycolylneuraminic acid (Neu5Gc)-linked N-acetyllactosamine (LacNAc) were highly associated with aging and were also affected by the B4GALT1 floxed mouse genotype. In terms of gender-specific information, the trend towards elevated fucosylated monoantennary glycans in WT mice was not seen in CD19-cre B4GALT1 floxed mice in either sex. B-cell-specific ablation of B4GALT1 plays an important role in age-related glycan changes; its specific functions and mechanisms are worthy of in-depth study. Our data suggest that investigating the relationship between galactosylation and aging may help advance the field of glycoproteomics and aging research.

Sex Differences in Metabolic Indices and Chronic Neuroinflammation in Response to Prolonged High-Fat Diet in ApoE4 Knock-In Mice

Late-onset Alzheimer’s disease (LOAD) likely results from combinations of risk factors that include both genetic predisposition and modifiable lifestyle factors. The E4 allele of apolipoprotein E (ApoE) is the most significant genetic risk factor for LOAD. A Western-pattern diet (WD) has been shown to strongly increase the risk of cardiovascular disease and diabetes, conditions which have been strongly linked to an increased risk for developing AD. Little is known about how the WD may contribute to, or enhance, the increased risk presented by possession of the ApoE4 allele. To model this interaction over the course of a lifetime, we exposed male and female homozygote ApoE4 knock-in mice and wild-type controls to nine months of a high-fat WD or standard chow diet. At eleven months of age, the mice were tested for glucose tolerance and then for general activity and spatial learning and memory. Postmortem analysis of liver function and neuroinflammation in the brain was also assessed. Our results suggest that behavior impairments resulted from the convergence of interacting metabolic alterations, made worse in a male ApoE4 mice group who also showed liver dysfunction, leading to a higher level of inflammatory cytokines in the brain. Interestingly, female ApoE4 mice on a WD revealed impairments in spatial learning and memory without the observed liver dysfunction or increase in inflammatory markers in the brain. These results suggest multiple direct and indirect pathways through which ApoE and diet-related factors interact. The striking sex difference in markers of chronic neuroinflammation in male ApoE4 mice fed the high-fat WD suggests a specific mechanism of interaction conferring significant enhanced LOAD risk for humans with the ApoE4 allele, which may differ between sexes. Additionally, our results suggest researchers exercise caution when designing and interpreting results of experiments employing a WD, being careful not to assume a WD impacts both sexes by the same mechanisms.

Lights and Shadows of Cerebrospinal Fluid Biomarkers in the Current Alzheimer's Disease Framework

BACKGROUND

The most significant biomarkers that are included in the Alzheimer's disease (AD) research framework are amyloid-β plaques deposition, p-tau, t-tau, and neurodegeneration.Although cerebrospinal fluid (CSF) biomarkers are included in the most recent AD research criteria, their use is increasing in the routine clinical practice and is applied also to the preclinical phases of AD, including mild cognitive impairment. The role of these biomarkers is still unclear concerning the preclinical stage of AD diagnosis, the CSF methodology, and the costs-benefits of the biomarkers' tests. The controversies regarding the use of biomarkers in the clinical practice are related to the concepts of analytical validity, clinical validity, and clinical utility and to the question of whether they are able to diagnose AD without the support of AD clinical phenotypes.

OBJECTIVE

The objective of the present work is to expose the strengths and weaknesses of the use of CSF biomarkers in the diagnosis of AD in a clinical context.

METHODS

We used PubMed as main source for articles published and the final reference list was generated on the basis of relevance to the topics covered in this work.

RESULTS

The use of CSF biomarkers for AD diagnosis is certainly important but its indication in routine clinical practice, especially for prodromal conditions, needs to be regulated and also contextualized considering the variety of possible clinical AD phenotypes.

CONCLUSION

We suggest that the diagnosis of AD should be understood both as clinical and pathological.

Learning From Human Responses to Deconditioning Environments: Improved Understanding of the "Use It or Lose It" Principle

Physical activity, mobility or patterned mobility (i.e., exercise) is intrinsic to the functioning of Homo sapiens, and required for maintenance of health. Thus, systems such as the musculoskeletal and cardiovascular systems appear to require constant reinforcement or conditioning to maintain integrity. Loss of conditioning or development of chronic deconditioning can have multiple consequences. The study of different types of deconditioning and their prevention or reversal can offer a number of clues to the regulation of these systems and point to how deconditioning poses risk for disease development and progression. From the study of deconditioning associated with spaceflight, a condition not predicted by evolution, prolonged bedrest, protracted sedentary behavior, as well as menopause and obesity and their consequences, provide a background to better understand human heterogeneity and how physical fitness may impact the risks for chronic conditions subsequent to the deconditioning. The effectiveness of optimized physical activity and exercise protocols likely depend on the nature of the deconditioning, the sex and genetics of the individual, whether one is addressing prevention of deconditioning-associated disease or disease-associated progression, and whether it is focused on acute or chronic deconditioning associated with different forms of deconditioning. While considerable research effort has gone into preventing deconditioning, the study of the process of deconditioning and its endpoints can provide clues to the regulation of the affected systems and their contributions to human heterogeneity that have been framed by the boundary conditions of Earth during evolution and the "use it or lose it" principle of regulation. Such information regarding heterogeneity that is elaborated by the study of deconditioning environments could enhance the effectiveness of individualized interventions to prevent deconditions or rescue those who have become deconditioned.

The close link between brain vascular pathological conditions and neurodegenerative diseases: Focus on some examples and potential treatments

A close relationship is emerging among the age-related neurodegenerative decline, and the age-related typical alterations, dysfunctions, and related diseases of the cerobro-and/or cardiovascular system, which contributes in a significative manner to the triggering and progressing of neurodegenerative diseases (NeuroDegD). Specifically, macroinfarcts, microinfarcts, micro-hemorrhages (and particularly their number), atherosclerosis, arteriolosclerosis and cerebral amyloid angiopathy have been documented to be significantly associated with the onset of the cognitive impairment. In addition, vascular alterations and dysfunctions resulting in a reduced cerebral blood flow, and anomalies in the brain blood barrier (BBB), have been also demonstrated to contribute to NeuroDegD pathophysiologic processes. At the same time, such vascular alterations are also observed in cognitively unimpaired subjects. Here, some of these aspects are described with a particular focus on some NeuroDegD, as well as potential strategies for delaying or stopping their onset and progression.