Sex differences in cognitive impairment in Alzheimer’s disease

Menopausal hormone therapy and the female brain: Leveraging neuroimaging and prescription registry data from the UK Biobank cohort

Background

Menopausal hormone therapy (MHT) is generally thought to be neuroprotective, yet results have been inconsistent. Here, we present a comprehensive study of MHT use and brain characteristics in females from the UK Biobank.

Methods

19,846 females with magnetic resonance imaging data were included. Detailed MHT prescription data from primary care records was available for 538. We tested for associations between the brain measures (i.e. gray/white matter brain age, hippocampal volumes, white matter hyperintensity volumes) and MHT user status, age at first and last use, duration of use, formulation, route of administration, dosage, type, and active ingredient. We further tested for the effects of a history of hysterectomy ± bilateral oophorectomy among MHT users and examined associations by APOE ε4 status.

Results

Current MHT users, not past users, showed older gray and white matter brain age, with a difference of up to 9 mo, and smaller hippocampal volumes compared to never-users. Longer duration of use and older age at last use post-menopause was associated with older gray and white matter brain age, larger white matter hyperintensity volume, and smaller hippocampal volumes. MHT users with a history of hysterectomy ± bilateral oophorectomy showed younger gray matter brain age relative to MHT users without such history. We found no associations by APOE ε4 status and with other MHT variables.

Conclusions

Our results indicate that population-level associations between MHT use and female brain health might vary depending on duration of use and past surgical history.

Funding

The authors received funding from the Research Council of Norway (LTW: 223273, 249795, 273345, 298646, 300768), the South-Eastern Norway Regional Health Authority (CB: 2023037, 2022103; LTW: 2018076, 2019101), the European Research Council under the European Union's Horizon 2020 research and innovation program (LTW: 802998), the Swiss National Science Foundation (AMGdL: PZ00P3_193658), the Canadian Institutes for Health Research (LAMG: PJT-173554), the Treliving Family Chair in Women's Mental Health at the Centre for Addiction and Mental Health (LAMG), womenmind at the Centre for Addiction and Mental Health (LAMG, BHL), the Ann S. Bowers Women's Brain Health Initiative (EGJ), and the National Institutes of Health (EGJ: AG063843).

Promotion of neuroinflammation in select hippocampal regions in a mouse model of perimenopausal Alzheimer's disease

Introduction

Alzheimer's disease, the most common form of dementia, is characterized by age-dependent amyloid beta (Ab) aggregation and accumulation, neuroinflammation, and cognitive deficits. Significantly, there are prominent sex differences in the risk, onset, progression, and severity of AD, as well as response to therapies, with disease burden disproportionately affecting women. Although menopause onset (i.e., perimenopause) may be a critical transition stage for AD susceptibility in women, the role of early ovarian decline in initial disease pathology, particularly key neuroinflammatory processes, is not well understood.

Methods

To study this, we developed a unique mouse model of perimenopausal AD by combining an accelerated ovarian failure (AOF) model of menopause induced by 4-vinylcyclohexene diepoxide (VCD) with the 5xFAD transgenic AD mouse model. To target early stages of disease progression, 5xFAD females were studied at a young age (∼4 months) and at the beginning stage of ovarian failure analogous to human perimenopause (termed "peri-AOF"), and compared to age-matched males. Assessment of neuropathology was performed by immunohistochemical labeling of Ab as well as markers of astrocyte and microglia activity in the hippocampus, a brain region involved in learning and memory that is deleteriously impacted during AD.

Results

Our results show that genotype, AOF, and sex contributed to AD-like pathology. Aggregation of Ab was heightened in female 5xFAD mice and further increased at peri-AOF, with hippocampal subregion specificity. Further, select increases in glial activation also paralleled Ab pathology in distinct hippocampal subregions. However, cognitive function was not affected by peri-AOF.

Discussion

These findings align with the hypothesis that perimenopause constitutes a period of susceptibility for AD pathogenesis in women.

A systematic analysis for disease burden, risk factors, and trend projection of Alzheimer's disease and other dementias in China and globally

BACKGROUND

This study aims to provide improvement directions for aging societies by analyzing the disease burden, risk factors and trend forecasts of AD and other dementias (ADD) in China and globally from 1990 to 2021.

METHODS

Data sourced from Global Burden of Disease 2021. We extracted indicators of disease burden and risk factors for ADD in people aged 40 years and older, including incidence, prevalence, deaths, disability-adjusted life years, years lived with disability and years of life lost. The annual percent change and average annual percent change over the past 32 years were analyzed by Joinpoint regression. Decomposition analysis was used to clarify the contribution of aging, population and epidemiological change. The directions of deaths and incidence in China and globally were predicted using ARIMA model for the next 15 years.

RESULTS

The disease burden of ADD in China is heavier than in most countries and regions. By 2021, China's disease burden has increased by three times, while the global disease burden has doubled. Females bear more burden but face lower mortality. Population growth is the main reason for the burden. Smoking, high fasting plasma glucose and high body-mass index are the three major risk factors, among which high fasting plasma glucose occupies a dominant position.

CONCLUSION

The disease burden of ADD in China and globally is increasing daily and will remain high in the future. It is urgent to introduce some effective intervention measures to prevent such diseases as early as possible.

No sex differences in the association between regional brain structure abnormalities and cognitive functioning in a geriatric memory clinic population

Differences between men and women in cognitive impairment and neurodegeneration are not yet well understood. Although sex differences in brain structure abnormalities, including white matter hyperintensities (WMH) and grey matter (GM) atrophy, have been associated with cognitive decline in the ageing population, the evidence is limited and inconclusive. Therefore, we explored sex differences in brain structure abnormalities and in the association between brain structure abnormalities and cognitive functioning. We analyzed global and regional volumetric measures of WMH and GM of 475 patients visiting an academic geriatric memory clinic in the Netherlands with multiple linear regression analyses. For both global and regional WMH and GM, we found no sex differences in brain structure abnormalities. We also found no interaction of sex on the association between brain structure abnormalities and cognitive functioning. We reflect on using a binary classification of men and women based on sex in this study, which might overlook individual differences and does not elucidate gender-related factors that influence health and risk of pathology. Future studies should focus on exploring the relationship between sex and gender on brain structure and cognitive functioning beyond this binary model, by including more data on social context, more diverse populations and using intersectional approaches.

Unraveling sex differences in Alzheimer's disease and related endophenotypes with brain proteomes

INTRODUCTION

Sex differences exist in Alzheimer's disease (AD), but the underlying mechanisms remain unclear.

METHODS

We examined brain proteomes profiled from the dorsolateral prefrontal cortex of 770 donors (66.2% female).

RESULTS

Proteome-wide differential expression analysis in males and females jointly identified many significant proteins for AD dementia (n = 1228), amyloid beta (n = 1183), tangles (n = 1309), and global cognitive trajectory (n = 2325) at a false discovery rate of <0.05. Sex-stratified analyses also identified many proteins associated with AD or its endophenotypes. Finally, we found 10 proteins with significant sex-by-trait interactions, including one in AD clinical diagnosis (MARCKS), seven in cognitive trajectories (TOGARAM1, PLCD3, SLC22A5, MTFR1L, DCUN1D5, S100A12, and TRIM46), and two in cerebral pathologies (PANK4 and SOS1).

DISCUSSION

The 10 proteins with sex interaction in AD cover a range of functions likely relevant for AD pathogenesis, including estrogen response, inflammation, and mitochondrial biology, and their specific roles in AD ought to be studied. Future work should test their potential as sex-specific AD biomarkers.

HIGHLIGHTS

At the phenotypic level, we found sex differences in baseline cognitive performance, cognitive trajectories, and AD hallmark pathologies. Proteome-wide differential expression analyses identified many brain proteins associated with AD and its endophenotypes in either sex alone or when considered together. We found 10 brain proteins with significant sex interactions in AD and its endophenotypes, which could be investigated as potential sex-specific biomarkers of AD.

Gene-dose-dependent reduction of Fshr expression improves spatial memory deficits in Alzheimer's mice

High post-menopausal levels of the pituitary gonadotropin follicle-stimulating hormone (FSH) are strongly associated with the onset of Alzheimer's disease (AD). We have shown recently that FSH directly activates the hippocampal FSH receptors (FSHRs) to drive AD-like pathology and memory loss in mice. To unequivocally establish a role for FSH in memory loss, we depleted the Fshr on a 3xTg background and utilized Morris Water Maze to study deficits in spatial memory. 3xTg;Fshr+/+ mice displayed impaired spatial memory at 5 months of age. The loss of memory acquisition and retrieval were both rescued in 3xTg;Fshr-/- mice and, to a lesser extent, in 3xTg;Fshr+/- mice-documenting clear gene-dose-dependent prevention of spatial memory loss. Furthermore, at 5 and 8 months, sham-operated 3xTg;Fshr-/- mice showed better memory performance during the learning and/or retrieval phases, further suggesting that Fshr deletion prevents age-related progression of memory deficits. This prevention was not seen when mice were ovariectomized, except in the 8-month-old 3xTg;Fshr-/- mice. There was also a gene-dose-dependent reduction mainly in the amyloid β40 isoform in whole brain extracts. Finally, serum FSH levels <8 ng/mL in 16-month-old APP/PS1 mice were associated with better retrieval of spatial memory. Collectively, the data provide compelling genetic evidence for a protective effect of inhibiting FSH signaling on the progression of spatial memory deficits in mice and lay a firm foundation for the use of an FSH-blocking agent for the early prevention of memory loss in post-menopausal women.

Dietary patterns derived using reduced rank regression in postmenopausal women and risk of mortality: A population-based study

OBJECTIVES

The menopause transition increases the risk of chronic conditions in women. Given the crucial role of diet in health, we identified dietary patterns that explain variations in factors related to major health concerns in postmenopausal women. Also, we explored their association with all-cause and cardiovascular mortality.

STUDY DESIGN

This study was conducted on 1814 postmenopausal women from the population-based Rotterdam Study.

MAIN OUTCOME MEASURES

Dietary patterns were identified using reduced rank regression. Response variables included bone mineral density, body composition parameters, lipid profile markers, insulin resistance, systolic blood pressure, cognitive function, depression, and sleep quality. The associations with risk of mortality were assessed using Cox proportional hazard models.

RESULTS

The first dietary pattern, characterized by higher intake of vegetables, whole grains, legumes, nuts, coffee, tea, alcoholic beverages, and cheese, explained 2.95 % of the variation in responses, accounted for 12.11 % of the variation in general cognitive function captured by G-factor, 5.62 % in systolic blood pressure, and 4.13 % in bone mineral density, and was correlated with less adiposity, lower blood pressure, lipid markers, and insulin resistance. The second dietary pattern, characterized by higher intakes of processed meat, unprocessed red meat, poultry, eggs, and coffee, and lower intakes of sweets and tea, explained 1.54 % of the variation in responses, accounted for 5.45 % of variation in fat mass percentage, 3.47 % in lean mass index, and 3.29 % in bone mineral density, and was correlated with higher adiposity, insulin resistance, and lipid markers. No associations with mortality risk were identified after adjusting for confounders such as demographics, socioeconomic status, lifestyle, disease history, and medication use.

CONCLUSIONS

We identified dietary patterns explaining a range of variation in health factors related to postmenopausal health. While these dietary patterns explained a large variation in some of the individual factors, their combined explained variation across multiple risk factors simultaneously was limited and no significant association with mortality risk was observed. This study provides a foundation for future research aimed at identifying optimal dietary patterns, integrating diverse health aspects, to improve health in postmenopausal populations.

Sexual dimorphisms in innate immune activation markers in predementia Alzheimer's disease

Females have an increased risk of developing Alzheimer's disease (AD). The innate immune system plays a key role in AD pathology, and sex differences in innate immune responses may contribute to differences in disease risk and progression. This study investigated sex differences in innate immune responses among participants without cerebrospinal fluid (CSF) determined amyloid pathology [A-; cognitively normal (CN), n = 83] and those with amyloid pathology (A+, n = 202), further stratified into preclinical (CN with A+, n = 72) and mild cognitive impairment (MCI with A+, n = 130). Participants were drawn from the Norwegian Dementia Disease Initiation cohort (n = 285). We measured plasma glial fibrillary acidic protein (GFAP) and CSF concentrations of nine innate immune markers: soluble triggering receptor expressed on myeloid cells 2 (sTREM2), monocyte chemoattractant protein 1 (MCP-1), fractalkine, chitinase 3-like 1 (YKL-40), clusterin, interferon gamma (IFN-γ), interleukin-6 (IL-6), IL-10, and IL-18. Linear regression was used, adjusted for multiple comparisons using the false discovery rate. In A+ cases (n = 202, females = 105), females had lower MCP-1 (P  < 0.01), IL-6 and IL-18 (both P  < 0.05) than males, while no sex differences were observed in A- cases (n = 83, females = 39). Among A+ participants, no sex differences were observed in CN cases (n = 72, females = 37), but females (n = 68) with MCI had lower MCP-1 and IL-6 (both P  < 0.05) than males (n = 62) with MCI. Moreover, A+ females exhibited stronger positive associations between sTREM2 and clusterin with CSF total tau (P < 0.001; P < 0.05) and Neurofilament light chain (P < 0.01; P < 0.01) than males. These findings suggest sex-specific differences in innate immune responses, which may contribute to disease progression in amyloid-positive individuals.

Perimenopause promotes neuroinflammation in select hippocampal regions in a mouse model of Alzheimer's disease

Alzheimer's disease (AD) is the most common neurodegenerative disorder characterized by age-dependent amyloid beta (Aβ) aggregation and accumulation, neuroinflammation, and cognitive deficits. Significantly, there are prominent sex differences in the risk, onset, progression, and severity of AD, as well as response to therapies, with disease burden disproportionally affecting women. Although menopause onset (i.e., perimenopause) may be a critical transition stage for AD susceptibility in women, the role of early ovarian decline in initial disease pathology, particularly key neuroinflammatory processes, is not well understood. To study this, we developed a unique mouse model of perimenopausal AD by combining an accelerated ovarian failure (AOF) model of menopause induced by 4-vinylcyclohexene diepoxide (VCD) with the 5xFAD transgenic AD mouse model. To target early stages of disease progression, 5xFAD females were studied at a young age (∼4 months) and at the beginning stage of ovarian failure analogous to human perimenopause (termed "peri-AOF"), and compared to age-matched males. Assessment of neuropathology was performed by immunohistochemical labeling of Aβ as well as markers of astrocyte and microglia activity in the hippocampus, a brain region involved in learning and memory that is deleteriously impacted during AD. Our results show that genotype, AOF, and sex contributed to AD-like pathology. Aggregation of Aβ was heightened in female 5xFAD mice and further increased at peri-AOF, with hippocampal subregion specificity. Further, select increases in glial activation also paralleled Aβ pathology in distinct hippocampal subregions. However, cognitive function was not affected by peri-AOF. These findings align with the hypothesis that perimenopause constitutes a period of susceptibility for AD pathogenesis in women.

Sex differences in age-associated neurological diseases-A roadmap for reliable and high-yield research

Once taken into consideration, sex differences in neurological diseases emerge in abundance: (i) Stroke severity is significantly higher in females than in males, (ii) Alzheimer's disease (AD) pathology is more pronounced in females, and (iii) conspicuous links with hormonal cycles led to female-specific diagnoses, such as catamenial migraines and epilepsy. While these differences receive increasing attention in isolation, they likely link to similar processes in the brain. Hence, this review aims to present an overview of the influences of sex chromosomes, hormones, and aging on male and female brains across health and disease, with a particular focus on AD and stroke. The focus here on advancements across several fields holds promise to fuel future research and to lead to an enriched understanding of the brain and more effective personalized neurologic care for all.

Acute effects of high-intensity interval exercise plus whole-body vibration on bone turnover markers, BDNF, irisin, and neurocognitive performance in postmenopausal women

The acute effects of exercise can elucidate the molecular and psychophysiological mechanisms underlying exercise's benefits in several systems (e.g., the brain, muscle, and bone). In this study, a single 30-minute session of high-intensity interval aerobic exercise (HIIAE) administered in conjunction with isometric resistance exercise on a whole-body vibration (WBV) platform (HIIAE+WBV) was compared with HIIAE alone in their effects on molecular and neurocognitive indices among 63 sedentary, healthy postmenopausal women who were randomly assigned to HIIAE (n = 20), HIIAE+WBV (n = 20), and Control (n = 23) groups. The assessed molecular indices were serum levels of osteocalcin (OC), uncarboxylated OC (ucOC), carboxylated OC (cOC), brain-derived neurotrophic factor (BDNF), and irisin, and the assessed neurocognitive indices were the accuracy rate (AR), reaction time (RT), and electroencephalography event-related potentials (ERPs) of P2 and P3 components in a visuospatial working memory task. Data on these indices before versus after an acute bout of HIIAE or HIIAE+WBV or after a resting session were compared. An HIIAE or HIIAE+WBV intervention yielded no significant change in ERP P2 latency/amplitude and P3 latency but yielded significantly higher ARs, shorter RTs, larger ERP P3 amplitudes, and higher OC, cOC, BDNF, and irisin levels in the postmenopausal women. HIIAE+WBV outperformed HIIAE alone in AR, ucOC, and BDNF. However, the changes in these molecular and neurocognitive indices induced by the two exercise modes did not show any significant correlations in the present study. The present findings suggest that HIIAE and HIIAE+WBV have the potential to acutely influence markers of bone and brain health, with HIIAE+WBV showing greater effectiveness than HIIAE alone. These interventions should be further investigated in future randomized controlled trials involving postmenopausal women.

Sex-Specific Adaptations in Alzheimer's Disease and Ischemic Stroke: A Longitudinal Study in Male and Female APPswe/PS1dE9 Mice

The long-term impact of stroke on Alzheimer's disease (AD) progression, particularly regarding sex-specific differences, remains unknown. Using a longitudinal study design, we investigated transient middle cerebral artery occlusion in 3.5-month-old APPswe/PS1dE9 (APP/PS1) and wild-type mice. In vivo, we assessed behavior, cerebral blood flow (CBF), and structural integrity by neuroimaging, as well as post-mortem myelin integrity (polarized light imaging, PLI), neuroinflammation, and amyloid beta (Aβ) deposition. APP/PS1 mice exhibited cognitive decline, white matter degeneration (reduced fractional anisotropy (FA) via diffusion tensor imaging (DTI)), and decreased myelin density via PLI. Despite early hypertension, APP/PS1 mice showed only sporadic hypoperfusion. Cortical thickening and hippocampal hypertrophy likely resulted from Aβ accumulation and neuroinflammation. Stroke-operated mice retained cognition despite cortical thinning and hippocampal atrophy due to cerebrovascular adaptation, including increased CBF in the hippocampus and thalamus. Stroke did not worsen AD pathology, nor did AD exacerbate stroke outcomes. Sex differences were found: female APP/PS1 mice had more severe Aβ deposition, hyperactivity, lower body weight, and reduced CBF but less neuroinflammation, suggesting potential neuroprotection. These findings highlight white matter degeneration and Aβ pathology as key drivers of cognitive decline in AD, with stroke-related deficits mitigated by (cerebro)vascular adaptation. Sex-specific therapies are crucial for AD and stroke.

Sex differences in the neuroinflammatory signaling pathway: effect of miRNAs on fatty acid synthesis in microglia

BACKGROUND

Significant sex differences exist in the prevalence and incidence of Alzheimer's disease (AD). Notably, testosterone has been reported to regulate cognitive functions in the brain, with low serum testosterone levels correlating with increased AD risk. However, the specific mechanisms underlying this relationship remain unclear. Recent studies have demonstrated that microglia, the primary innate immune cells in the brain, play a crucial role in AD development. Therefore, this study aimed to explore sex differences in microglial function, specifically focusing on the role of testosterone in miRNA-mediated regulation of microglial gene expression.

METHODS

Microglia were isolated from pooled hippocampal tissue of five 8-month-old male and female mice. Total RNA was extracted and subjected to miRNA microarray analysis. The mouse microglial cell line MG6 was used for in vitro experiments. Following testosterone treatment, miRNA, gene, and protein expression levels were investigated. An inflammatory response was induced using lipopolysaccharide (LPS) stimulation, and subsequent p65 phosphorylation was assessed.

RESULTS

Sex-dependent differences were observed in miRNA-mediated biological processes, with males exhibiting greater changes. Male-enriched miRNAs were associated with fatty acid synthesis and metabolism pathways. In MG6 cells, testosterone treatment upregulated the expression of several miRNAs enriched in male microglia, particularly those targeting genes related to fatty acid synthesis. Additionally, testosterone significantly reduced the gene expression of fatty acid synthase (FASN). This testosterone-induced inhibition of FASN expression attenuated NF-κB/p65 phosphorylation. Consequently, the suppression of FASN expression led to reduced expression and secretion of tumor necrosis factor-alpha following LPS stimulation in MG6 cells.

CONCLUSIONS

These findings suggest that testosterone modulates inflammation in male microglia by regulating fatty acid synthesis, potentially contributing to the observed sex differences in AD pathogenesis.

Hippocampal neuroinflammation induced by lipopolysaccharide causes sex-specific disruptions in action selection, food approach memories, and neuronal activation

Hippocampal neuroinflammation is present in multiple diseases and disorders that impact motivated behaviour in a sex-specific manner, but whether neuroinflammation alone is sufficient to disrupt this behaviour is unknown. We investigated this question here using mice. First, the application of an endotoxin to primary cultures containing only hippocampal neurons did not affect their activation. However, when the same endotoxin was applied to mixed neuronal/glial cultures it did increase neuronal activation, providing initial indications of how it might be able to effect behavioural change. We next showed neuroinflammatory effects on behaviour directly, demonstrating that intra-hippocampal administration of the same endotoxin increased locomotor activity and accelerated goal-directed learning in both male and female mice. In contrast, lipopolysaccharide-induced hippocampal neuroinflammation caused sex-specific disruptions to the acquisition of instrumental actions and to Pavlovian food-approach memories. Finally, we showed that LPS-induced hippocampal neuroinflammation had a sexually dimorphic effect on neuronal activation: increasing it in females and decreasing it in males.

Resting-state neural dynamics changes in older adults with post-COVID syndrome and the modulatory effect of cognitive training and sex

Post-COVID syndrome manifests with numerous neurological and cognitive symptoms, the precise origins of which are still not fully understood. As females and older adults are more susceptible to developing this condition, our study aimed to investigate how post-COVID syndrome alters intrinsic brain dynamics in older adults and whether biological sex and cognitive training might modulate these effects, with a specific focus on older females. The participants, aged between 60 and 75 years, were divided into three experimental groups: healthy old female, post-COVID old female and post-COVID old male. They underwent an adaptive task-switching training protocol. We analysed multiscale entropy and spectral power density of resting-state EEG data collected before and after the training to assess neural signal complexity and oscillatory power, respectively. We found no difference between post-COVID females and males before training, indicating that post-COVID similarly affected both sexes. However, cognitive training was effective only in post-COVID females and not in males, by modulating local neural processing capacity. This improvement was further evidenced by comparing healthy and post-COVID females, wherein the latter group showed increased finer timescale entropy (1-30 ms) and higher frequency band power (11-40 Hz) before training, but these differences disappeared following cognitive training. Our results suggest that in older adults with post-COVID syndrome, there is a pronounced shift from more global to local neural processing, potentially contributing to accelerated neural aging in this condition. However, cognitive training seems to offer a promising intervention method for modulating these changes in brain dynamics, especially among females.

Sex and APOE genotype modulate neuropsychological profile and depression in temporal lobe epilepsy

Introduction

Temporal lobe epilepsy is the most common form of focal epilepsy, often associated with cognitive impairments, particularly in memory functions, and depression. Sex and APOE ε4 genotype play a crucial role in modulating cognitive outcomes and depression in various neurological conditions like Alzheimer's disease. However, the combined effects of APOE genotype and sex on cognitive performance and depression in temporal lobe epilepsy have not been previously investigated.

Objective

This study aims to (i) identify impaired cognitive performance and clinically relevant depression; (ii) explore the interaction between sex and APOE ε4 genotype on cognitive performance and depression in individuals with temporal lobe epilepsy.

Methods

We used a comprehensive battery of neuropsychological tests to assess domains such as learning and memory, attention, executive functions, language, and visuo-spatial constructional skills and the Hamilton Depression Rating Scale. We also performed APOE genotyping to assess its role in the study. The final sample was composed by fifty-four patients (53.7% female). Cognitive performance and depression were analyzed using normative cut-off scores. To examine the main effects and interactions of sex and APOE ε4 carrier status on neuropsychological test scores and the Hamilton Depression Rating Scale, we also conducted a two-way Analysis of Variance (ANOVA).

Results

Female APOE ε4 carriers compared to normative cut-offs, exhibited poor performance on multiple test scores, including the MMSE, The Rey Auditory Verbal Learning Test (immediate and delayed recall), The Corsi Block-Tapping Task, The Verbal Fluency Test, The Raven's Standard Progressive Matrices and The Pentagon-copying Test. Males showed impairment only in visuo-spatial short-term memory. ANOVA analysis revealed significant main effects of APOE ε4 status and sex on the MMSE, The Rey Auditory Verbal Learning Test, The Verbal Fluency, The Raven's Standard Progressive Matrices and The Pentagon-copying Test scores. Specifically, female APOE ε4 carriers performed consistently worse than other groups on many tasks. For depression, only an effect of sex emerged. Females scored higher besides APOE genotype.

Conclusions

These findings underscore the importance of considering both sex and APOE genotype when assessing cognitive performance in patients with temporal lobe epilepsy. The significant cognitive deficits we observed among females carrying the APOE ε4 allele highlight previously unexplored genetic and sex-related influences on cognition. This has potential implications for personalized therapeutic strategies, emphasizing the need for targeted assessment and intervention.

Menopausal hormone therapy and the female brain: leveraging neuroimaging and prescription registry data from the UK Biobank cohort

Background and Objectives

Menopausal hormone therapy (MHT) is generally thought to be neuroprotective, yet results have been inconsistent. Here, we present a comprehensive study of MHT use and brain characteristics in middle- to older aged females from the UK Biobank, assessing detailed MHT data, APOE ε4 genotype, and tissue-specific gray (GM) and white matter (WM) brain age gap (BAG), as well as hippocampal and white matter hyperintensity (WMH) volumes.

Methods

A total of 19,846 females with magnetic resonance imaging data were included (current-users = 1,153, 60.1 ± 6.8 years; past-users = 6,681, 67.5 ± 6.2 years; never-users = 12,012, mean age 61.6 ± 7.1 years). For a sub-sample (n = 538), MHT prescription data was extracted from primary care records. Brain measures were derived from T1-, T2- and diffusion-weighted images. We fitted regression models to test for associations between the brain measures and MHT variables including user status, age at initiation, dosage and duration, formulation, route of administration, and type (i.e., bioidentical vs synthetic), as well as active ingredient (e.g., estradiol hemihydrate). We further tested for differences in brain measures among MHT users with and without a history of hysterectomy ± bilateral oophorectomy and examined associations by APOE ε4 status.

Results

We found significantly higher GM and WM BAG (i.e., older brain age relative to chronological age) as well as smaller left and right hippocampus volumes in current MHT users, not past users, compared to never-users. Effects were modest, with the largest effect size indicating a group difference of 0.77 years (~9 months) for GM BAG. Among MHT users, we found no significant associations between age at MHT initiation and brain measures. Longer duration of use and older age at last use post menopause was associated with higher GM and WM BAG, larger WMH volume, and smaller left and right hippocampal volumes. MHT users with a history of hysterectomy ± bilateral oophorectomy showed lower GM BAG relative to MHT users without such history. Although we found smaller hippocampus volumes in carriers of two APOE ε4 alleles compared to non-carriers, we found no interactions with MHT variables. In the sub-sample with prescription data, we found no significant associations between detailed MHT variables and brain measures after adjusting for multiple comparisons.

Discussion

Our results indicate that population-level associations between MHT use, and female brain health might vary depending on duration of use and past surgical history. Future research is crucial to establish causality, dissect interactions between menopause-related neurological changes and MHT use, and determine individual-level implications to advance precision medicine in female health care.

Exploring the Role of Sex and Gender in the Adoption of Assistive Technology in Dementia Care: A Scoping Review

Given that women are disproportionately affected by dementia on several levels and assistive technology (AT) is increasingly used to manage the care of the growing number of people with dementia (PwD), there is an urgent need to understand the role of sex and gender regarding adoption of AT in dementia care. We conducted a scoping review following the framework of Arksey and O'Malley. All identified topics of sex and gender analysis (compatibility, attitude, usage, acceptance, access, usefulness, and well-being) were related to AT adoption, where the majority revealed sex and gender differences. Relevance of topics is discussed in relation to generation, culture, and mental health, including a switch of perspective to the gender of the technology. Even though we demonstrated sex and gender differences in AT adoption, their practical implications need to be further elaborated on in future research.

Is there something sexual in the ventral midline thalamus?

This mini-review explores sexual dimorphism in the ventral midline thalamus, focusing on the reuniens nucleus and its role in behavioral functions. Traditionally linked to tasks such as working memory, cognitive flexibility, fear generalization, and memory consolidation, most studies have been conducted in male rodents. Research comparing the effects of ventral midline thalamus manipulations between female and male rodents is limited. Emerging evidence suggests sex-specific differences, particularly in response to stress, pharmacological manipulations, and memory processes. Studies reveal distinct c-Fos expression patterns in the reuniens nucleus between females and males, especially under stress, with females often showing different neural activation. Additionally, females exhibit different recruitment of the reuniens nucleus in object recognition tasks, indicating possible sex-dependent cognitive strategies. While evidence suggests functional differences between sexes in the reuniens nucleus, current data are limited. Further research is needed to understand how sex influences brain function and cognition, particularly in the ventral midline thalamus, which is crucial for various cognitive processes.

Sex-Specific Entorhinal Cortex Functional Connectivity in Cognitively Normal Older Adults with Amyloid-β Pathology

Sex and apolipoprotein E (APOE) genotype have been shown to influence the risk and progression of Alzheimer's disease (AD). However, the impact of these factors on the functional connectivity of the entorhinal cortex (ERC) in clinically unpaired older adults (CUOA) with amyloid-β (Aβ +) pathology remains unclear. A total of 1022 cognitively normal older adults with Aβ + (603 females and 586 APOE ε4 +) from the Anti-Amyloid Treatment in Asymptomatic Alzheimer's (A4) study were included in this study. The 2 × 2 (gender, 2 APOE genotypes) analysis of covariance was performed to compare the demographic information, cognitive performance, and volumetric MRI data among these groups. Voxel-wise comparisons of bilateral ERC functional connectivity (FC) were conducted, and partial correlation analyses were used to explore the associations between cognitive performance and ERC-FC strength. We found that the APOE genotype influenced ERC functional connectivity mainly in the sensorimotor network (SMN). Males exhibited higher ERC-FC in the salience network (SN), while females displayed higher ERC-FC in the default mode network (DMN), executive control network (ECN), and reward network. The interplay of sex and APOE genotype on ERC-FC was observed in the SMN and cerebellar lobe. The ERC-FC was associated with executive function and memory performance in individuals with CUOA-Aβ + . Our findings provide evidence of sex-specific ERC functional connectivity compensation mechanism in cognitively normal older adults with Aβ + pathology. This study may contribute to a better understanding of the mechanisms underlying the early stages of AD and may help develop personalized interventions in preclinical AD.

Establishing group-level brain structural connectivity incorporating anatomical knowledge under latent space modeling

Brain structural connectivity, capturing the white matter fiber tracts among brain regions inferred by diffusion MRI (dMRI), provides a unique characterization of brain anatomical organization. One fundamental question to address with structural connectivity is how to properly summarize and perform statistical inference for a group-level connectivity architecture, for instance, under different sex groups, or disease cohorts. Existing analyses commonly summarize group-level brain connectivity by a simple entry-wise sample mean or median across individual brain connectivity matrices. However, such a heuristic approach fully ignores the associations among structural connections and the topological properties of brain networks. In this project, we propose a latent space-based generative network model to estimate group-level brain connectivity. Within our modeling framework, we incorporate the anatomical information of brain regions as the attributes of nodes to enhance the plausibility of our estimation and improve biological interpretation. We name our method the attributes-informed brain connectivity (ABC) model, which compared with existing group-level connectivity estimations, (1) offers an interpretable latent space representation of the group-level connectivity, (2) incorporates the anatomical knowledge of nodes and tests its co-varying relationship with connectivity and (3) quantifies the uncertainty and evaluates the likelihood of the estimated group-level effects against chance. We devise a novel Bayesian MCMC algorithm to estimate the model. We evaluate the performance of our model through extensive simulations. By applying the ABC model to study brain structural connectivity stratified by sex among Alzheimer's Disease (AD) subjects and healthy controls incorporating the anatomical attributes (volume, thickness and area) on nodes, our method shows superior predictive power on out-of-sample structural connectivity and identifies meaningful sex-specific network neuromarkers for AD.

Sex Disparities in Cognitive Impairment Research: A Scoping Review in Informatics Literature

Rationale

A scoping review was conducted to investigate knowledge gaps in the informatics research literature regarding sex differences in cognitive decline, identifying existing studies and areas where further studies are needed.

Materials and Methods

We searched Ovid and other databases for studies on sex differences and cognitive decline, focusing on publications in peer-reviewed informatics journals and conference proceedings from 2000 to 2023. The selected manuscripts were analyzed and summarized through discussion among three reviewers.

Results

A total of 13 articles were selected and examined for metadata and attributes analysis. Most studies are conducted in United States (n=5) and European Union (n=4), about a half are published after 2020 (n=6), and most studies are published in Springer and Elsevier. Our attributes-based analysis highlights the different aspects of reported studies such as task, method, dataset and its size, and sex-specific inferences.

Discussion

Sex-specific disparities in cognitive decline remain a critical issue in healthcare, yet most informatics research has primarily concentrated on identifying basic sex differences, such as tracking the progression of cognitive decline in men and women. While these studies are valuable, they fall short of addressing the more complex underlying causes of these sex-specific disparities in progression of cognitive decline.

Conclusion

There is a significant gap using informatics in understanding how biological, social, and behavioral factors contribute to sex-specific disparities. This limited focus restricts the development of effective intervention strategies for mitigating sex-specific differences in cognitive health outcomes, underscoring the need for more comprehensive research that goes beyond mere identification to find the root cause of these disparities in healthcare.

Biological mechanism of sex differences in mental rotation: Evidence from multimodal MRI, transcriptomic and receptor/transporter data

Sex differences in mental rotation are a well-documented phenomenon in cognitive research, with implications for the differing prevalence of neuropsychiatric disorders such as autism spectrum disorder (ASD), Alzheimer's disease (AD) and major depressive disorder (MDD) between the sexes. Despite extensive documentation, the biological mechanism underpinning these differences remain elusive. This study aimed to elucidate neural, genetic, and molecular bases of these disparities in mental rotation by integrating data from multimodal magnetic resonance imaging (MRI), transcriptomic and receptor/transporter. We first calculated the dynamic regional homogeneity (dReHo), gray matter volume (GMV) and fractional anisotropy (FA) in voxel-wise manner and parceled them into 246 brain regions based on Brainnetome Atlas. Subsequent analyses involved Pearson Correlations to examine the association between mental rotation performance and dReHo/GMV/FA and two-sample t-tests to delineate gender differences in these indices. Based on the above results, further mediation analysis was conducted to explore the relationship between sex, brain biomarkers and mental rotation. In addition, transcriptome-neuroimaging association analysis and correlation analysis between brain biomarkers and neurotransmitter receptor/transporter distribution were also performed to uncover genetic and molecular mechanisms contributing to the observed sex differences in mental rotation. We found correlations between mental rotation performance and dReHo, GMV and FA of the inferior parietal lobule (IPL) and superior temporal gyrus (STG) and sex effects on these brain biomarkers. Notably, the dReHo of the left IPL mediated the relationship between sex and mental rotation. Further correlation analysis revealed that the proton-coupled oligopeptide transporter PEPT2 (SLC15A2) and interleukin 17 receptor D (IL17RD) were associated with sex-related t-statistic maps and mental rotation-related r-statistic maps of dReHo. Moreover, γ-aminobutyric acid subtype A (GABAA) receptor availability was correlated with the r-statistic of dReHo, while norepinephrine transporter (NET) availability was correlated with its t-statistic. Serial mediation models revealed the indirect effect of these genes on the r-statistic maps through the transporter/receptor and t-statistic maps. Our findings provide novel insights into the biological mechanism underlying sex differences in mental rotation, identifying potential biomarkers for cognitive impairment and explaining variations in prevalence of certain mental disorders between the sexes. These results highlight the necessity of considering sex in research on mental health disorders.

Neuroendocrinology of bone

The past decade has witnessed significant advances in our understanding of skeletal homeostasis and the mechanisms that mediate the loss of bone in primary and secondary osteoporosis. Recent breakthroughs have primarily emerged from identifying disease-causing mutations and phenocopying human bone disease in rodents. Notably, using genetically-modified rodent models, disrupting the reciprocal relationship with tropic pituitary hormone and effector hormones, we have learned that pituitary hormones have independent roles in skeletal physiology, beyond their effects exerted through target endocrine glands. The rise of follicle-stimulating hormone (FSH) in the late perimenopause may account, at least in part, for the rapid bone loss when estrogen is normal, while low thyroid-stimulating hormone (TSH) levels may contribute to the bone loss in thyrotoxicosis. Admittedly speculative, suppressed levels of adrenocorticotropic hormone (ACTH) may directly exacerbate bone loss in the setting of glucocorticoid-induced osteoporosis. Furthermore, beyond their established roles in reproduction and lactation, oxytocin and prolactin may affect intergenerational calcium transfer and therefore fetal skeletal mineralization, whereas elevated vasopressin levels in chronic hyponatremic states may increase the risk of bone loss.. Here, we discuss the interaction of each pituitary hormone in relation to its role in bone physiology and pathophysiology.

Sexual dimorphism, altered hippocampal glutamatergic neurotransmission, and cognitive impairment in APP knock-in mice

BACKGROUND

It is well established that glutamatergic neurotransmission plays an essential role in learning and memory. Previous studies indicate that glutamate dynamics shift with Alzheimer's disease (AD) progression, contributing to negative cognitive outcomes.

OBJECTIVE

In this study, we characterized hippocampal glutamatergic signaling with age and disease progression in a knock-in mouse model of AD (APPNL-F/NL--F).

METHODS

At 2-4 and 18+ months old, male and female APPNL/NL, APPNL-F/NL-F, and C57BL/6 mice underwent cognitive assessment using Morris water maze (MWM) and Novel Object Recognition (NOR). Then, basal and 70 mM KCl stimulus-evoked glutamate release was measured in the dentate gyrus (DG), CA3, and CA1 regions of the hippocampus using a glutamate-selective microelectrode in anesthetized mice.

RESULTS

Glutamate recordings support elevated stimulus-evoked glutamate release in the DG and CA3 of young APPNL-F/NL-F male mice that declined with age compared to age-matched control mice. Young female APPNL-F/NL-F mice exhibited increased glutamate clearance in the CA1 that slowed with age compared to age-matched control mice. Male and female APPNL-F/NL-F mice exhibited decreased CA1 basal glutamate levels, while males also showed depletion in the CA3. Cognitive assessment demonstrated impaired spatial cognition in aged male and female APPNL-F/NL-F mice, but only aged females displayed recognition memory deficits compared to age-matched control mice.

CONCLUSIONS

These findings confirm a sex-dependent hyper-to-hypoactivation glutamatergic paradigm in APPNL-F/NL-F mice. Further, data illustrate a sexually dimorphic biological aging process resulting in a more severe cognitive phenotype for female APPNL-F/NL-F mice than their male counterparts. Research outcomes mirror that of human AD pathology and provide further evidence of divergent AD pathogenesis between sexes.

Neurobehavioral dysfunction in a mouse model of Down syndrome: upregulation of cystathionine β-synthase, H2S overproduction, altered protein persulfidation, synaptic dysfunction, endoplasmic reticulum stress, and autophagy

Down syndrome (DS) is a genetic condition where the person is born with an extra chromosome 21. DS is associated with accelerated aging; people with DS are prone to age-related neurological conditions including an early-onset Alzheimer's disease. Using the Dp(17)3Yey/ + mice, which overexpresses a portion of mouse chromosome 17, which encodes for the transsulfuration enzyme cystathionine β-synthase (CBS), we investigated the functional role of the CBS/hydrogen sulfide (H2S) pathway in the pathogenesis of neurobehavioral dysfunction in DS. The data demonstrate that CBS is higher in the brain of the DS mice than in the brain of wild-type mice, with primary localization in astrocytes. DS mice exhibited impaired recognition memory and spatial learning, loss of synaptosomal function, endoplasmic reticulum stress, and autophagy. Treatment of mice with aminooxyacetate, a prototypical CBS inhibitor, improved neurobehavioral function, reduced the degree of reactive gliosis in the DS brain, increased the ability of the synaptosomes to generate ATP, and reduced endoplasmic reticulum stress. H2S levels in the brain of DS mice were higher than in wild-type mice, but, unexpectedly, protein persulfidation was decreased. Many of the above alterations were more pronounced in the female DS mice. There was a significant dysregulation of metabolism in the brain of DS mice, which affected amino acid, carbohydrate, lipid, endocannabinoid, and nucleotide metabolites; some of these alterations were reversed by treatment of the mice with the CBS inhibitor. Thus, the CBS/H2S pathway contributes to the pathogenesis of neurological dysfunction in DS in the current animal model.

Clinical and demographic factors modify the association between plasma phosphorylated tau-181 and cognition

INTRODUCTION

Plasma phosphorylated tau-181 (p-tau181) associations with global cognition and memory are clear, but the link between p-tau181 with other cognitive domains and subjective cognitive decline (SCD) across the clinical spectrum of Alzheimer's disease (AD) and how this association changes based on genetic and demographic factors is poorly understood.

METHODS

Participants were drawn from the Alzheimer's Disease Neuroimaging Initiative (ADNI) and included 1185 adults >55 years of age with plasma p-tau181 and neuropsychological test data. Linear regression models related plasma p-tau181 to neuropsychological composite and SCD scores with follow-up models examining plasma p-tau181 interactions with cognitive diagnosis, apolipoprotein E (APOE) ε4 carrier status, age, and sex on cognitive outcomes.

RESULTS

Higher plasma p-tau181 level was associated with worse memory, executive functioning, and language abilities, and greater informant-reported SCD. Visuospatial abilities and self-report SCD were not associated with plasma p-tau181. Associations were generally stronger in mild cognitive impairment (MCI) or dementia, APOE ε4 carriers, women, and younger participants.

DISCUSSION

Higher levels of plasma p-tau181 are associated with worse neuropsychological test performance across multiple cognitive domains; however, these associations vary based on disease stage, genetic risk status, age, and sex.

Highlights

Greater plasma p-tau181 was associated with lower cognition across most domains.Associations between p-tau181 and cognition were modified by age and sex.Level of p-tau181 was more strongly associated with cognition in people with mild cognitive impairment (MCI) and apolipoprotein E (APOE) ε4.

Common and unique brain aging patterns between females and males quantified by large-scale deep learning

There has been extensive evidence that aging affects human brain function. However, there is no complete picture of what brain functional changes are mostly related to normal aging and how aging affects brain function similarly and differently between males and females. Based on resting-state brain functional connectivity (FC) of 25,582 healthy participants (13,373 females) aged 49-76 years from the UK Biobank project, we employ deep learning with explainable AI to discover primary FCs related to progressive aging and reveal similarity and difference between females and males in brain aging. Using a nested cross-validation scheme, we conduct 4200 deep learning models to classify all paired age groups on the main data for females and males separately and then extract gender-common and gender-specific aging-related FCs. Next, we validate those FCs using additional 21,000 classifiers on the independent data. Our results support that aging results in reduced brain functional interactions for both females and males, primarily relating to the positive connectivity within the same functional domain and the negative connectivity between different functional domains. Regions linked to cognitive control show the most significant age-related changes in both genders. Unique aging effects in males and females mainly involve the interaction between cognitive control and the default mode, vision, auditory, and frontoparietal domains. Results also indicate females exhibit faster brain functional changes than males. Overall, our study provides new evidence about common and unique patterns of brain aging in females and males.

Microglial Drivers of Alzheimer's Disease Pathology: An Evolution of Diverse Participating States

Microglia, the resident immune-competent cells of the brain, become dysfunctional in Alzheimer's disease (AD), and their aberrant immune responses contribute to the accumulation of pathological proteins and neuronal injury. Genetic studies implicate microglia in the development of AD, prompting interest in developing immunomodulatory therapies to prevent or ameliorate disease. However, microglia take on diverse functional states in disease, playing both protective and detrimental roles in AD, which largely overlap and may shift over the disease course, complicating the identification of effective therapeutic targets. Extensive evidence gathered using transgenic mouse models supports an active role of microglia in pathology progression, though results vary and can be contradictory between different types of models and the degree of pathology at the time of study. Here, we review microglial immune signaling and responses that contribute to the accumulation and spread of pathological proteins or directly affect neuronal health. We additionally explore the use of induced pluripotent stem cell (iPSC)-derived models to study living human microglia and how they have contributed to our knowledge of AD and may begin to fill in the gaps left by mouse models. Ultimately, mouse and iPSC-derived models have their own limitations, and a comprehensive understanding of microglial dysfunction in AD will only be established by an integrated view across models and an appreciation for their complementary viewpoints and limitations.

Association between formal social participation and cognitive function in middle-aged and older adults: a longitudinal study using SHARE data

Formal social participation significantly impacts health and well-being, potentially mitigating cognitive decline, although not consistently across all studies. Existing research often focuses solely on baseline participation levels, and age-related differences have primarily been explored among the Asian population. Therefore, this longitudinal study aims to assess the association between formal social participation and cognition across different age groups in individuals aged 50+ living in Europe and Israel, while capturing the dynamic nature of formal social participation. We use data from three waves (four, six, and eight) of the Survey of Health, Ageing, and Retirement in Europe (SHARE), comprising 85,601 respondents. Linear mixed-effects models were applied. The results show that participation in formal social activities mitigates cognitive decline in middle-aged and older adults, especially among those aged 70 to 79 and 80+. These findings support the need for social policies promoting formal social activities, for lasting cognitive health benefits.

Increased expression of SLC25A18 is associated with Alzheimer's disease and is involved in Aβ42-induced mitochondrial dysfunction and apoptosis in neuronal cells

Alzheimer's disease (AD) is currently one of the most serious public health concerns in the world. However, the best approach to treat AD has yet to be discovered, implying that we must continue to work hard to find new AD target genes. In this study, we further analysed Gene Expression Omnibus (GEO) data and discovered that the expression of the Mitochondria glutamate carrier SLC25A18 is associated with AD by screening the differentially expressed genes in different regions of the brains of Alzheimer's disease patients. To verify the expression of SLC25A18 during Alzheimer's disease development, we analysed animal models (5×FAD transgenic AD animal model, chemically induced AD animal model, natural ageing animal model), and the results showed that the expression of SLC25A18 was increased in animal models of AD. Further investigation of the different regions found that SLC25A18 expression was elevated in the EC, TeA, and CA3, and expressed in neurons. Next, We found that Aβ42 treatment elevated SLC25A18 expression in Neuro 2A cells. Reducing SLC25A18 expression attenuated mitochondrial dysfunction and neuronal apoptosis caused by Aβ42. Overexpression of SLC25A18 increased ATP and intracellular superoxide anions but decreased mitochondrial membrane potential. The results indicate that SLC25A18 affects mitochondrial function and neuronal apoptosis, and is related to AD, which makes it a potential target for treating brain dysfunction.

Exploring the parity paradox: Differential effects on neuroplasticity and inflammation by APOEe4 genotype at middle age

Female sex and Apolipoprotein E (APOE) ε4 genotype are top non-modifiable risk factors for Alzheimer's disease (AD). Although female-unique experiences like parity (pregnancy and motherhood) have positive effects on neuroplasticity at middle age, previous pregnancy may also contribute to AD risk. To explore these seemingly paradoxical long-term effects of parity, we investigated the impact of parity with APOEε4 genotype by examining behavioural and neural biomarkers of brain health in middle-aged female rats. Our findings show that primiparous (parous one time) hAPOEε4 rats display increased use of a non-spatial cognitive strategy and exhibit decreased number and recruitment of new-born neurons in the ventral dentate gyrus of the hippocampus in response to spatial working memory retrieval. Furthermore, primiparity and hAPOEε4 genotype synergistically modulate inflammatory markers in the ventral hippocampus. Collectively, these findings demonstrate that previous parity in hAPOEε4 rats confers an added risk to present with reduced activity and engagement of the hippocampus as well as elevated pro-inflammatory signaling, and underscore the importance of considering female-specific factors and genotype in health research.

Sex and gender differences in cognitive resilience to aging and Alzheimer's disease

Sex and gender-biological and social constructs-significantly impact the prevalence of protective and risk factors, influencing the burden of Alzheimer's disease (AD; amyloid beta and tau) and other pathologies (e.g., cerebrovascular disease) which ultimately shape cognitive trajectories. Understanding the interplay of these factors is central to understanding resilience and resistance mechanisms explaining maintained cognitive function and reduced pathology accumulation in aging and AD. In this narrative review, the ADDRESS! Special Interest Group (Alzheimer's Association) adopted a multidisciplinary approach to provide the foundations and recommendations for future research into sex- and gender-specific drivers of resilience, including a sex/gender-oriented review of risk factors, genetics, AD and non-AD pathologies, brain structure and function, and animal research. We urge the field to adopt a sex/gender-aware approach to resilience to advance our understanding of the intricate interplay of biological and social determinants and consider sex/gender-specific resilience throughout disease stages. HIGHLIGHTS: Sex differences in resilience to cognitive decline vary by age and cognitive status. Initial evidence supports sex-specific distinctions in brain pathology. Findings suggest sex differences in the impact of pathology on cognition. There is a sex-specific change in resilience in the transition to clinical stages. Gender and sex factors warrant study: modifiable, immune, inflammatory, and vascular.

Early spatial recognition memory deficits in 5XFAD female mice are associated with disruption of prefrontal parvalbumin neurons

Women have a two-fold increased risk of developing Alzheimer's disease (AD) than men, yet the underlying mechanisms of this sex-specific vulnerability remain unknown. Here, we aimed at determining in the 5XFAD mouse model whether deficits in prefrontal-dependent cognitive functions, which are impacted in the preclinical stages of AD, appear earlier in females, and whether these cognitive deficits are associated with alterations in the activity of prefrontal parvalbumin (PV)-neurons that regulate prefrontal circuits activity. We observed that 3.5-month-old 5XFAD females, but not males, display impairments in spatial short-term recognition memory, a function that relies on the integrity of the prefrontal cortex. Hippocampal-dependent cognitive functions were intact in both sexes. We then observed that 5XFAD females have more prefrontal PV neurons expressing the marker of chronic activity FosB; this was inversely correlated with prefrontal-dependent cognitive performances. Our findings show for the first time sex-specific, early deregulation of prefrontal PV neurons activity, which is associated with early appearance of prefrontal-dependent cognitive functions in 5XFAD females providing a potential novel mechanism to the increased risk to AD in females.

Overcoming Pandemic-Related Challenges in Recruitment and Screening: Strategies and Representation of Older Women With Cardiovascular Disease for a Multidomain Lifestyle Trial to Prevent Cognitive Decline

BACKGROUND

Recruiting participants with cardiovascular disease into research during the COVID-19 pandemic was challenging, particularly those at risk of health disparities.

OBJECTIVE

During the pandemic, 12 cohorts of older women with cardiovascular disease were recruited from cardiology clinics into a lifestyle intervention trial to prevent cognitive decline. Objectives were to ( a ) describe the results of modified recruitment/screening strategies to overcome pandemic-related challenges and ( b ) evaluate differences in age, race, and ethnicity between patients recruited/randomized, recruited/not randomized (entered recruitment but not randomized because of being ineligible or not interested), and not recruited (clinic patients who met preliminary criteria but did not enter recruitment).

METHODS

This was a cross-sectional descriptive analysis. In-person study strategies proposed before the COVID-19 pandemic were modified before study onset (September 2020). Women 65 years or older with cardiovascular disease were recruited from cardiology clinics by clinicians, posted flyers, and letters mailed to patients randomly selected from electronic health record data extractions. Patients were classified as recruited/randomized, recruited/not randomized, and not recruited.

RESULTS

Of 5719 patients potentially eligible, 1689 patients entered recruitment via referral (49.1%), posted flyers (0.5%), or mailed letters (50.3%), and 253 patients were successfully recruited/randomized. Recruited/randomized participants were, on average, 72.4 years old (range, 65-90 years old), non-Hispanic White (54.2%), non-Hispanic Black (38.3%), Hispanic/Latinx (1.6%), and other/not reported (5.1%). The recruited/randomized group was significantly younger with fewer patients of Hispanic/Latinx ethnicity compared with those not recruited.

CONCLUSIONS

During the pandemic, all recruitment/screening goals were met using modified strategies. Differences in sociodemographic representation indicate a need for tailored strategies.

Cognitive performance trends among European older adults: exploring variations across cohorts, gender, and educational levels (2007-2017)

BACKGROUND

This study explores recent cohort trends in cognitive performance among older Europeans from 2007 to 2017, addressing three key questions: (1) Did cognitive performance improve universally and across the performance distribution during this period? (2) Did these improvements occur across educational levels and for both men and women? (3) Can established risk factors explain these performance gains?

METHODS

Using data from the Survey of Health, Ageing and Retirement in Europe (SHARE) across 12 European countries, we assessed immediate recall, delayed recall, and verbal fluency in individuals aged 60 to 94 in both 2007 and 2017 (n = 32 773). Differences between the two time points were estimated with linear mixed effects regression models and quantile regression.

RESULTS

Cognitive performance improved in all age groups, across educational levels, and for both men and women between 2007 and 2017. Notably, improvements were more pronounced at the upper end of the performance distribution for delayed recall and verbal fluency. Education explained approximately 20% of the observed improvements. Risk factors did not explain the observed improvements.

CONCLUSIONS

European cohorts of both younger-old and older adults continue to exhibit improvements in cognitive performance. Variation in the size of the cohort improvements across the performance distributions in delayed recall and in verbal fluency may contribute to growing inequalities in cognitive outcomes. Future research should further investigate the potential heterogeneity in cognitive performance gains.

TRIAL REGISTRATION

Not applicable.

Sexual Dimorphism, Altered Hippocampal Glutamatergic Neurotransmission and Cognitive Impairment in APP Knock-In Mice

Background

It is well established that glutamatergic neurotransmission plays an essential role in learning and memory. Previous studies indicate that glutamate dynamics shift with Alzheimer's disease (AD) progression, contributing to negative cognitive outcomes.

Objective

In this study, we characterized hippocampal glutamatergic signaling with age and disease progression in a knock-in mouse model of AD (APPNL-F/NL-F).

Methods

At 2-4 and 18+ months old, male and female APPNL/NL, APPNL-F/NL-F, and C57BL/6 mice underwent cognitive assessment using Morris water maze (MWM) and Novel Object Recognition (NOR). Then, basal and 70 mM KCl stimulus-evoked glutamate release was measured in the dentate gyrus (DG), CA3, and CA1 regions of the hippocampus using a glutamate-selective microelectrode in anesthetized mice.

Results

Glutamate recordings support elevated stimulus-evoked glutamate release in the DG and CA3 of young APPNL-F/NL-F male mice that declined with age compared to age-matched control mice. Young female APPNL-F/NL-F mice exhibited increased glutamate clearance in the CA1 that slowed with age compared to age-matched control mice. Male and female APPNL-F/NL-F mice exhibited decreased CA1 basal glutamate levels, while males also showed depletion in the CA3. Cognitive assessment demonstrated impaired spatial cognition in aged male and female APPNL-F/NL-F mice, but only aged females displayed recognition memory deficits compared to age-matched control mice. Conclusions: These findings confirm a sex-dependent hyper-to-hypoactivation glutamatergic paradigm in APPNL-F/NL-F mice. Further, data illustrate a sexually dimorphic biological aging process resulting in a more severe cognitive phenotype for female APPNL-F/NL-F mice than their male counterparts. Research outcomes mirror that of human AD pathology and provide further evidence of divergent AD pathogenesis between sexes.

Assessment of Cognitive Function in European Adults Aged 50+in Relation to Their Handgrip Strength and Physical Inactivity: The SHARE Study During 2019-2020

BACKGROUND

Cognitive function is crucial during aging. This study assessed the cognitive function of European adults aged 50 and over in relation to handgrip strength and physical inactivity. Study Design: This was a cross-sectional survey.

METHODS

Data were collected from 41,395 adults from 27 European countries participating in the Survey of Health, Ageing, and Retirement in Europe (SHARE) during 2019-2020. Cognitive function was assessed based on five tests, and cognitive impairment was defined using 3+tests. Handgrip strength and physical inactivity were also correlated through the analysis of covariance using a complex study design.

RESULTS

The majority of participants were female (56.6%), with a mean age of 70.9 years, and 22.6% presented multimorbidity. Furthermore, 51.1% had a normal cognitive function, while 13.3% had cognitive impairment (The estimated population was 21,944,722). Moreover, cognitive impairment was more prevalent in females than in males (14.4% vs. 12.0%, P<0.001) in patients with no years of education (P<0.001) and origin from southern European countries (P<0.001). Additionally, participants with cognitive impairment had lower mean handgrip strength compared to those with cognitive impairment in 1-2 criteria or with normal cognitive function (29.3 vs. 33.4 and 35.1 kg, respectively, P<0.001). Physically inactive participants had higher odds ratio (OR) of cognitive impairment than those engaging in moderate/vigorous physical activity, both in 1-2 tests (OR:1.73, 95% confidence interval (CI): 1.32-2.26) and in 3+tests (OR: 3.36, 95% CI: 2.57-4.40).

CONCLUSION

Cognitive impairment presented low prevalence and was associated with low levels of handgrip strength and physical inactivity. These specific factors may play a special role in early detection, diagnosis, and treatment or may slow down the progression of cognitive impairment.

Transcriptomic analysis reveals sex-specific patterns in the hippocampus in Alzheimer's disease

Background

The hippocampus, vital for memory and learning, is among the first brain regions affected in Alzheimer's Disease (AD) and exhibits adult neurogenesis. Women face twice the risk of developing AD compare to men, making it crucial to understand sex differences in hippocampal function for comprehending AD susceptibility.

Methods

We conducted a comprehensive analysis of bulk mRNA postmortem samples from the whole hippocampus (GSE48350, GSE5281) and its CA1 and CA3 subfields (GSE29378). Our aim was to perform a comparative molecular signatures analysis, investigating sex-specific differences and similarities in the hippocampus and its subfields in AD. This involved comparing the gene expression profiles among: (a) male controls (M-controls) vs. female controls (F-controls), (b) females with AD (F-AD) vs. F-controls, (c) males with AD (M-AD) vs. M-controls, and (d) M-AD vs. F-AD. Furthermore, we identified AD susceptibility genes interacting with key targets of menopause hormone replacement drugs, specifically the ESR1 and ESR2 genes, along with GPER1.

Results

The hippocampal analysis revealed contrasting patterns between M-AD vs. M-controls and F-AD vs. F-controls, as well as M-controls vs. F-controls. Notably, BACE1, a key enzyme linked to amyloid-beta production in AD pathology, was found to be upregulated in M-controls compared to F-controls in both CA1 and CA3 hippocampal subfields. In M-AD vs. M-controls, the GABAergic synapse was downregulated, and the Estrogen signaling pathway was upregulated in both subfields, unlike in F-AD vs. F-controls. Analysis of the whole hippocampus also revealed upregulation of the GABAergic synapse in F-AD vs. F-controls. While direct comparison of M-AD vs. F-AD, revealed a small upregulation of the ESR1 gene in the CA1 subfield of males. Conversely, F-AD vs. F-controls exhibited downregulation of the Dopaminergic synapse in both subfields, while the Calcium signaling pathway showed mixed regulation, being upregulated in CA1 but downregulated in CA3, unlike in M-AD vs. M-controls. The upregulated Estrogen signaling pathway in M-AD, suggests a compensatory response to neurodegenerative specifically in males with AD. Our results also identified potential susceptibility genes interacting with ESR1 and ESR2, including MAPK1, IGF1, AKT1, TP53 and CD44.

Conclusion

These findings underscore the importance of sex-specific disease mechanisms in AD pathogenesis. Region-specific analysis offers a more detailed examination of localized changes in the hippocampus, enabling to capture sex-specific molecular patterns in AD susceptibility and progression.

Exploring the link between comorbidities and Alzheimer's dementia in the Australian Imaging, Biomarker & Lifestyle (AIBL) study

INTRODUCTION

Mounting evidence suggests that certain comorbidities may influence the clinical evolution of Alzheimer's dementia (AD).

METHODS

We conducted logistic regression analyses on the medical history and cognitive health diagnoses of participants in the Australian Imaging, Biomarker & Lifestyle study (n = 2443) to investigate cross-sectional associations between various comorbidities and mild cognitive impairment (MCI)/AD.

RESULTS

A mixture of associations were observed. Higher comorbidity of anxiety and other neurological disorders was associated with higher odds of AD, while arthritis, cancer, gastric complaints, high cholesterol, joint replacement, visual defect, kidney and liver disease were associated with lower odds of AD.

DISCUSSION

This study underscores the links between specific comorbidities and MCI/AD. Further research is needed to elucidate the longitudinal comorbidity-MCI/AD associations and underlying mechanisms of these associations.

Highlights

Comorbidities that significantly increased AD odds included anxiety and other neurological disorders.Arthritis, cancer, gastric complaints, high cholesterol, joint replacement, visual defect, kidney and liver disease were associated with lower odds of AD.Alcohol consumption had the most significant confounding effect in the study.Visual-AD association was modified by age, sex, and APOE ε4 allele status.Anxiety-AD and depression-AD associations were modified by sex.

Differential predictability of cognitive profiles from brain structure in older males and females

Structural brain imaging parameters may successfully predict cognitive performance in neurodegenerative diseases but mostly fail to predict cognitive abilities in healthy older adults. One important aspect contributing to this might be sex differences. Behaviorally, older males and females have been found to differ in terms of cognitive profiles, which cannot be captured by examining them as one homogenous group. In the current study, we examined whether the prediction of cognitive performance from brain structure, i.e. region-wise grey matter volume (GMV), would benefit from the investigation of sex-specific cognitive profiles in a large sample of older adults (1000BRAINS; N = 634; age range 55-85 years). Prediction performance was assessed using a machine learning (ML) approach. Targets represented a) a whole-sample cognitive component solution extracted from males and females, and b) sex-specific cognitive components. Results revealed a generally low predictability of cognitive profiles from region-wise GMV. In males, low predictability was observed across both, the whole sample as well as sex-specific cognitive components. In females, however, predictability differences across sex-specific cognitive components were observed, i.e. visual working memory (WM) and executive functions showed higher predictability than fluency and verbal WM. Hence, results accentuated that addressing sex-specific cognitive profiles allowed a more fine-grained investigation of predictability differences, which may not be observable in the prediction of the whole-sample solution. The current findings not only emphasize the need to further investigate the predictive power of each cognitive component, but they also emphasize the importance of sex-specific analyses in older adults.

Does Sex Matter? High Semantic Autobiographical Retrieval in Women and Men With Alzheimer's Disease

The decline of autobiographical memory in Alzheimer's disease (AD) is mainly characterized by overgenerality. While there is a large body of research on autobiographical overgenerality in AD, this research has mainly assessed retrieval with a dichotomy between specific vs. general retrieval. To go beyond this dichotomy, we assessed several degrees of autobiographical specificity in patients with AD, namely, we assessed specific vs. categoric vs. extended vs. semantic retrieval. We also assessed sex differences regarding these degrees of autobiographical specificity. We invited patients with mild AD and control participants to complete sentences (e. g., "When I think back to/of…") with autobiographical memories. Memories were categorized into specific, categoric, extended, or semantic memories. Results demonstrated more semantic than specific, categoric or extended memories in men and women with AD. In control participants, analysis demonstrated more specific than categoric, extended, and semantic memories in men and women. Also, no significant differences were observed between women and men with AD, or between control women and men, regarding specific, categoric, extended, and semantic memoires. This study offers not only a nuanced analysis of autobiographical specificity in patients with mild AD, but also an original analysis regarding this specificity by sex.

A cross-sectional study of the major risk factor at different levels of cognitive performance within Chinese-origin middle-aged and elderly individuals

OBJECTIVE

Senior citizens suffering from cognitive impairment (CI) are on the East Asia rise. Multiple variables could lead to inter-/intra-individual cognition effectiveness variations, though previous research efforts did not consider weighting issues.

METHODS

This study scrutinized 5639 participants meeting required inclusion criteria by the CHARLS. Cognitive capacity was evaluated through Mini-Mental State Examination (MMSE). Considering that MMSE scorings were not following normal distribution, a non-parametric test and multiple linear regression were performed to screen candidate variables linked to cognitive capacity. Such applicability of candidate factors in the cumulative effect and the weighting of the impact on cognitive performance were evaluated by random forest (RF) algorithm.

RESULTS

Age, gender, education, marital status, residence, the type of residence, exercise, socialization level and drinking were correlated to MMSE scorings (p < 0.05). Among them, age, education, gender and sociality were correlated to individual MMSE items (p < 0.05). Regardless of MMSE scores and several MMSE items, age is always a prime factor. However, in the attention and computation item, education is better than age and ranks first.

CONCLUSIONS

This preliminary study prompted age, education, gender, and sociality with varying weightings to be linked to cognitive capacity within a Chinese cohort by differing cognitive aspects. At different levels of cognitive performance, the main risk factors are basically similar, but there are still some differences.

Behavioral and Neurophysiological Implications of Pathological Human Tau Expression in Serotonin Neurons

Alzheimer's disease (AD) is a progressive degenerative disorder that results in a severe loss of brain cells and irreversible cognitive decline. Memory problems are the most recognized symptoms of AD. However, approximately 90% of patients diagnosed with AD suffer from behavioral symptoms, including mood changes and social impairment years before cognitive dysfunction. Recent evidence indicates that the dorsal raphe nucleus (DRN) is among the initial regions that show tau pathology, which is a hallmark feature of AD. The DRN harbors serotonin (5-HT) neurons, which are critically involved in mood, social, and cognitive regulation. Serotonergic impairment early in the disease process may contribute to behavioral symptoms in AD. However, the mechanisms underlying vulnerability and contribution of the 5-HT system to AD progression remain unknown. Here, we performed behavioral and electrophysiological characterizations in mice expressing a phosphorylation-prone form of human tau (hTauP301L) in 5-HT neurons. We found that pathological tau expression in 5-HT neurons induces anxiety-like behavior and alterations in stress-coping strategies in female and male mice. Female mice also exhibited social disinhibition and mild cognitive impairment in response to 5-HT neuron-specific hTauP301L expression. Behavioral alterations were accompanied by disrupted 5-HT neuron physiology in female and male hTauP301L expressing mice with exacerbated excitability disruption in females only. These data provide mechanistic insights into the brain systems and symptoms impaired early in AD progression, which is critical for disease intervention.

Sex differences in fetal brain functional network topology

The fetal period is a critical stage in brain development, and understanding the characteristics of the fetal brain is crucial. Although some studies have explored aspects of fetal brain functional networks, few have specifically focused on sex differences in brain network characteristics. We adopted the graph theory method to calculate brain network functional connectivity and topology properties (including global and nodal properties), and further compared the differences in these parameters between male and female fetuses. We found that male fetuses showed an increased clustering coefficient and local efficiency than female fetuses, but no significant group differences concerning other graph parameters and the functional connectivity matrix. Our study suggests the existence of sex-related distinctions in the topological properties of the brain network at the fetal stage of development and demonstrates an increase in brain network separation in male fetuses compared with female fetuses.

Gene-Dose-Dependent Reduction Fshr Expression Improves Spatial Memory Deficits in Alzheimer's Mice

Alzheimer's disease (AD) is a major progressive neurodegenerative disorder of the aging population. High post-menopausal levels of the pituitary gonadotropin follicle-stimulating hormone (FSH) are strongly associated with the onset of AD, and we have shown recently that FSH directly activates the hippocampal Fshr to drive AD-like pathology and memory loss in mice. To establish a role for FSH in memory loss, we used female 3xTg;Fshr+/+, 3xTg;Fshr+/- and 3xTg;Fshr-/- mice that were either left unoperated or underwent sham surgery or ovariectomy at 8 weeks of age. Unoperated and sham-operated 3xTg;Fshr-/- mice were implanted with 17β-estradiol pellets to normalize estradiol levels. Morris Water Maze and Novel Object Recognition behavioral tests were performed to study deficits in spatial and recognition memory, respectively, and to examine the effects of Fshr depletion. 3xTg;Fshr+/+ mice displayed impaired spatial memory at 5 months of age; both the acquisition and retrieval of the memory were ameliorated in 3xTg;Fshr-/- mice and, to a lesser extent, in 3xTg;Fshr+/- mice- -thus documenting a clear gene-dose-dependent prevention of hippocampal-dependent spatial memory impairment. At 5 and 10 months, sham-operated 3xTg;Fshr-/- mice showed better memory performance during the acquasition and/or retrieval phases, suggesting that Fshr deletion prevented the progression of spatial memory deficits with age. However, this prevention was not seen when mice were ovariectomized, except in the 10-month-old 3xTg;Fshr-/- mice. In the Novel Object Recognition test performed at 10 months, all groups of mice, except ovariectomized 3xTg;Fshr-/- mice showed a loss of recognition memory. Consistent with the neurobehavioral data, there was a gene-dose-dependent reduction mainly in the amyloid β40 isoform in whole brain extracts. Finally, serum FSH levels < 8 ng/mL in 16-month-old APP/PS1 mice were associated with better retrieval of spatial memory. Collectively, the data provide compelling genetic evidence for a protective effect of inhibiting FSH signaling on the progression of spatial and recognition memory deficits in mice, and lay a firm foundation for the use of an FSH-blocking agent for the early prevention of cognitive decline in postmenopausal women.

Maximizing utility of neuropsychological measures in sex-specific predictive models of incident Alzheimer's disease in the Framingham Heart Study

INTRODUCTION

Sex differences in neuropsychological (NP) test performance might have important implications for the diagnosis of Alzheimer's disease (AD). This study investigates sex differences in neuropsychological performance among individuals without dementia at baseline.

METHODS

Neuropsychological assessment data, both standard test scores and process coded responses, from Framingham Heart Study participants were analyzed for sex differences using regression model and Cox proportional hazards model. Optimal NP profiles were identified by machine learning methods for men and women.

RESULTS

Sex differences were observed in both summary scores and composite process scores of NP tests in terms of adjusted means and their associations with AD incidence. The optimal NP profiles for men and women have 10 and 8 measures, respectively, and achieve 0.76 mean area under the curve for AD prediction.

DISCUSSION

These results suggest that NP tests can be leveraged for developing more sensitive, sex-specific indices for the diagnosis of AD.

Associations between sex, body mass index and the individual microglial response in Alzheimer's disease

BACKGROUND AND OBJECTIVES

18-kDa translocator protein position-emission-tomography (TSPO-PET) imaging emerged for in vivo assessment of neuroinflammation in Alzheimer's disease (AD) research. Sex and obesity effects on TSPO-PET binding have been reported for cognitively normal humans (CN), but such effects have not yet been systematically evaluated in patients with AD. Thus, we aimed to investigate the impact of sex and obesity on the relationship between β-amyloid-accumulation and microglial activation in AD.

METHODS

49 patients with AD (29 females, all Aβ-positive) and 15 Aβ-negative CN (8 female) underwent TSPO-PET ([18F]GE-180) and β-amyloid-PET ([18F]flutemetamol) imaging. In 24 patients with AD (14 females), tau-PET ([18F]PI-2620) was additionally available. The brain was parcellated into 218 cortical regions and standardized-uptake-value-ratios (SUVr, cerebellar reference) were calculated. Per region and tracer, the regional increase of PET SUVr (z-score) was calculated for AD against CN. The regression derived linear effect of regional Aβ-PET on TSPO-PET was used to determine the Aβ-plaque-dependent microglial response (slope) and the Aβ-plaque-independent microglial response (intercept) at the individual patient level. All read-outs were compared between sexes and tested for a moderation effect of sex on associations with body mass index (BMI).

RESULTS

In AD, females showed higher mean cortical TSPO-PET z-scores (0.91 ± 0.49; males 0.30 ± 0.75; p = 0.002), while Aβ-PET z-scores were similar. The Aβ-plaque-independent microglial response was stronger in females with AD (+ 0.37 ± 0.38; males with AD - 0.33 ± 0.87; p = 0.006), pronounced at the prodromal stage. On the contrary, the Aβ-plaque-dependent microglial response was not different between sexes. The Aβ-plaque-independent microglial response was significantly associated with tau-PET in females (Braak-II regions: r = 0.757, p = 0.003), but not in males. BMI and the Aβ-plaque-independent microglial response were significantly associated in females (r = 0.44, p = 0.018) but not in males (BMI*sex interaction: F(3,52) = 3.077, p = 0.005).

CONCLUSION

While microglia response to fibrillar Aβ is similar between sexes, women with AD show a stronger Aβ-plaque-independent microglia response. This sex difference in Aβ-independent microglial activation may be associated with tau accumulation. BMI is positively associated with the Aβ-plaque-independent microglia response in females with AD but not in males, indicating that sex and obesity need to be considered when studying neuroinflammation in AD.

Investigation of sex differences in mutation carriers of the Dominantly Inherited Alzheimer Network

INTRODUCTION

Studies suggest distinct differences in the development, presentation, progression, and response to treatment of Alzheimer's disease (AD) between females and males. We investigated sex differences in cognition, neuroimaging, and fluid biomarkers in dominantly inherited AD (DIAD).

METHODS

Three hundred twenty-five mutation carriers (55% female) and one hundred eighty-six non-carriers (58% female) of the Dominantly Inherited Alzheimer Network Observational Study were analyzed. Linear mixed models and Spearman's correlation explored cross-sectional sex differences in cognition, cerebrospinal fluid (CSF) biomarkers, Pittsburgh compound B positron emission tomography (11 C-PiB PET) and structural magnetic resonance imaging (MRI).

RESULTS

Female carriers performed better than males on delayed recall and processing speed despite similar hippocampal volumes. As the disease progressed, symptomatic females revealed higher increases in MRI markers of neurodegeneration and memory impairment. PiB PET and established CSF AD markers revealed no sex differences.

DISCUSSION

Our findings suggest an initial cognitive reserve in female carriers followed by a pronounced increase in neurodegeneration coupled with worse performance on delayed recall at later stages of DIAD.

Assessing the Global, Regional, and National Impact of High Body Mass Index on Alzheimer's Disease and Other Dementias Between 1990 and 2019

BACKGROUND

Obesity significantly increases Alzheimer's disease (AD) and dementia risk. Understanding the link between a high body mass index (BMI) and these conditions is crucial for effective management and prevention.

OBJECTIVE

We aimed to estimate the burden of AD and other dementias attributed to high BMI from 1990 to 2019 based on sex, age, and socio-demographic indicators (SDI) at global, regional, and national levels.

METHODS

We collected data on deaths, disability-adjusted life years (DALYs), age-standardized mortality rates (ASMR), and age-standardized DALY rates (ASDR) from the 2019 Global Burden of Disease study for AD and dementia attributed to high BMI. We explored the correlation between SDI levels and ASDR.

RESULTS

In 2019, there were 198,476.2 deaths (95% UI: 32,695.4-593,366.4) and 3,159,912.4 DALYs (848,330.5-8,042,531) attributed to high BMI. Numbers of deaths, DALYs, ASMR, and ASDR increased since 1990. Females had higher deaths, ASMR, and ASDR than males. Mortality and DALYs rates increased with age. ASMR and ASDR increased across five SDI levels, with the highest rise in Low-middle SDI. High-income North America had the most deaths [30,993.9 (5,101.7-89,912.9)], while North Africa and the Middle East had the highest ASMR [4.61 (0.79-13.64)] and ASDR [72.56 (20.98-181.16)] in 2019.

CONCLUSIONS

The burden of AD and other dementias attributed to high BMI increased since 1990 globally and is still heaviest in developed regions. Females accounted predominantly for the burden than males. Timely measures are needed to against high BMI.