Estrogen plus progestin and the incidence of dementia and mild cognitive impairment in postmenopausal women: the Women's Health Initiative Memory Study: a randomized controlled trial

Modulation of neural gene networks by estradiol in old rhesus macaque females

The postmenopausal decrease in circulating estradiol (E2) levels has been shown to contribute to several adverse physiological and psychiatric effects. To elucidate the molecular effects of E2 on the brain, we examined differential gene expression and DNA methylation (DNAm) patterns in the nonhuman primate brain following ovariectomy (Ov) and subsequent subcutaneous bioidentical E2 chronic treatment. We identified several dysregulated molecular networks, including MAPK signaling and dopaminergic synapse response, that are associated with ovariectomy and shared across two different brain areas, the occipital cortex (OC) and prefrontal cortex (PFC). The finding that hypomethylation (p = 1.6 × 10-51) and upregulation (p = 3.8 × 10-3) of UBE2M across both brain regions provide strong evidence for molecular differences in the brain induced by E2 depletion. Additionally, differential expression (p = 1.9 × 10-4; interaction p = 3.5 × 10-2) of LTBR in the PFC provides further support for the role E2 plays in the brain, by demonstrating that the regulation of some genes that are altered by ovariectomy may also be modulated by Ov followed by hormone replacement therapy (HRT). These results present real opportunities to understand the specific biological mechanisms that are altered with depleted E2. Given E2's potential role in cognitive decline and neuroinflammation, our findings could lead to the discovery of novel therapeutics to slow cognitive decline. Together, this work represents a major step toward understanding molecular changes in the brain that are caused by ovariectomy and how E2 treatment may revert or protect against the negative neuro-related consequences caused by a depletion in estrogen as women approach menopause.

Severe menopausal symptoms linked to cognitive impairment: an exploratory study

OBJECTIVE

To evaluate the association between menopausal symptoms and cognitive decline in postmenopausal women.

METHODS

This was a subanalysis of a cross-sectional, observational study conducted among women attending gynecological consultations across nine Latin American countries. The survey involved late postmenopausal women who were asked to complete a general questionnaire and the Menopause Rating Scale (MRS) to assess menopausal symptoms, with the Montreal Cognitive Assessment used to evaluate cognitive function as an outcome. A Montreal Cognitive Assessment score of less than 21 was used to define women with mild cognitive impairment (MCI).

RESULTS

The study included 1,287 postmenopausal women with a mean age of 55.5 years and a mean body mass index of 26.3 kg/m 2 . On average, participants had 13.8 years of education and 2.3 ± 1.8 children, with 72.8% reporting having a partner. Additionally, 36.7% ever used menopausal hormone therapy. Regarding lifestyle factors, 50.3% engaged in a sedentary lifestyle, whereas 70.5% had never smoked. 15.3% of women had MCI exhibited significantly more intense menopausal symptoms compared with those without MCI (MRS total score 15.24 ± 12.58 vs 10.53 ± 8.84, respectively, P < 0.001). Logistic regression analysis revealed a significant association between severe menopausal symptoms (MRS total score ≥14 points) and MCI (odds ratio [OR], 1.74; 95% CI, 1.25-2.42). Conversely, a lower body mass index (OR, 0.96; 95% CI, 0.95-0.98), sexual activity (OR, 0.70; 95% CI, 0.51-0.96), physical exercise (OR, 0.55; 95% CI, 0.39-0.76), menopausal hormone therapy use (OR, 0.36; 95% CI, 0.24-0.55), and higher educational level (OR, 0.31; 95% CI, 0.21-0.46) were associated with lower odds for MCI.

CONCLUSION

Severe menopausal symptoms in postmenopausal women were associated with cognitive impairment. This study highlights the intricate interplay between hormonal, lifestyle, and sociodemographic factors and cognitive health.

Society for endocrinology guideline for understanding, diagnosing and treating female hypogonadism

Female hypogonadism (FH) is a relatively common endocrine disorder in women of premenopausal age, but there are significant uncertainties and wide variation in its management. Most current guidelines are monospecialty and only address premature ovarian insufficiency (POI); some allude to management in very brief and general terms, and most rely upon the extrapolation of evidence from the studies relating to physiological estrogen deficiency in postmenopausal women. The Society for Endocrinology commissioned new guidance to provide all care providers with a multidisciplinary perspective on managing patients with all forms of FH. It has been compiled using expertise from Endocrinology, Primary Care, Gynaecology and Reproductive Health practices, with contributions from expert patients and a patient support group, to help clinicians best manage FH resulting from both POI and hypothalamo-pituitary disorders, whether organic or functional.

Breast and endometrial safety of micronised progesterone versus norethisterone acetate in menopausal hormone therapy (PROBES): study protocol of a double-blind randomised controlled trial

INTRODUCTION

Data suggest that micronised progesterone (mP) in menopausal hormone therapy is safer for the breast than synthetic progestins, while protection of the endometrium appears to be less effective. However, comparative randomised trial data are lacking. The objective of the Progesterone Breast Endometrial Safety Study is to investigate breast and endometrial safety of mP versus norethisterone acetate (NETA) in continuous combination with oral oestrogen.

METHODS AND ANALYSIS

This multicentre trial, conducted at three University Hospitals in Stockholm and Uppsala, Sweden, consists of two phases: part 1 focuses on breast safety and is designed as a double-blind, randomised controlled trial. 260 postmenopausal women will be randomised to 100 mg mP or 0.5 mg NETA per day in continuous combination with 1 mg oestradiol. The primary objective is to compare the treatments with respect to percentage change in mammographic breast density after 12-month treatment. Secondary outcomes are breast proliferation, endometrial histology and proliferation, bleeding pattern, gut and vaginal microbiome, hormone levels and coagulation and metabolic factors, mood, and health-related quality of life. Part 2 features an open, single-arm design to study endometrial safety of 1-year treatment with mP in continuous combination with oestradiol on endometrial pathology (hyperplasia and cancer). We will treat 260 additional women with 100 mg mP/1 mg oestradiol resulting in an endometrial safety population of 390 women. The total number of participants in part 1 and part 2 will be 520.

ETHICS AND DISSEMINATION

The study protocol was approved by the Swedish Ethical Review Authority (2021-03033) on 29 June 2021 with amendment (2023-01480-02, protocol version 3.1) on 14 March 2023. Results of the study will be published in peer-reviewed journals and presented at scientific meetings.

TRIAL REGISTRATION NUMBER

NCT05586724.

Is it time to revisit the recommendations for initiation of menopausal hormone therapy?

Findings from the Women's Health Initiative studies led to menopausal hormone therapy (MHT) guidelines generally recommending the initiation of MHT be limited to women within 10 years of their menopause or before the age of 60 years. This recommendation has led to women who experience troublesome menopausal symptoms and who have not commenced MHT within these limits often being denied this type of therapy. Similarly, the majority of women who might benefit from the protective effects of MHT against bone loss and fracture are not offered this treatment option if they do not fit with these criteria. Based on review of the evidence that led to the conditional initiation of MHT, and subsequent studies, we propose that the recommendations regarding the initiation of MHT need to change to be more inclusive of women outside these chronological limits.

Administration of Young Coconut (Cocos nucifera L.) Juice Ameliorates Memory Impairment in a Menopausal Rat Model

BACKGROUND/OBJECTIVES

In Southeast Asia, the traditional use of young coconut (Cocos nucifera L.) juice (YCJ) by women to alleviate postmenopausal symptoms suggests potential estrogenic properties. However, few studies explore the impact of YCJ on pathologies associated with estrogen deficiency in postmenopausal animal models. This study examines the impact of YCJ supplementation on memory impairment and depression-like behavior in ovariectomized (Ovx) rats.

METHODS

Ten-week-old female rats underwent either a sham operation (Sham) or bilateral Ovx. The rats in the Ovx + YCJ group received 5×-concentrated YCJ by gavage at a dose of 15 mL/kg body weight. Twelve weeks later, the Morris water maze and forced swim tests were used to evaluate hippocampus-dependent spatial memory and depression-like behavior, respectively.

RESULTS

The Ovx rats displayed significant memory impairment (p < 0.05) and depression-like behaviors (p < 0.05), while the memory performance in the rats in the Ovx + YCJ group resembled that of the Sham rats. However, the administration of YCJ did not result in the improvement of depression-like behavior.

CONCLUSIONS

These findings suggest that YCJ consumption may help ameliorate memory impairment in postmenopausal women.

Therapeutic Effects Of Combined and Chronic Treatment of Tat-GluA23y and D-Serine on Cognitive Dysfunction in Postmenopausal Rats

BACKGROUND

The incidence of Alzheimer's disease (AD) in female gender compared with male has been addressed as a health concern, particularly in menopausal age. We here hypothesized that co-administration of NMDARs agonist (D-serine) and AMPARs endocytosis inhibitor (Tat-GluA23y) might be a potential target for alleviating memory impairment in sporadic Alzheimer model of rats.

METHODS

Forty-eight female Wistar rats weighing 200-220 randomly divided into six groups. One month later, ovariectomized rats underwent stereotaxic surgery and were cannulated into the brain lateral ventricles. Streptozotocin was injected (3 mg/kg), then animals received the related treatments until the day 51, which experienced acquisition of spatial memory in Morris Water Maze test. Finally, the level of phosphorylated cAMP response element binding protein (CREB) in the hippocampus was measured by Western blotting.

RESULTS

Co-administration of D-serine and GluA23y significantly enhanced the acquisition and retrieval of impaired spatial memory in ovariectomized rats with AD (p < .001). Compared to Glu-A 23, D-serine caused more improvement in the mentioned parameters above, however, these values for both groups were still significantly different from the control group (P < .05).

CONCLUSION

Simultaneous treatment with D-serine and GluA23y synergistically improved STZ induced spatial memory impairment in OVX rat, probably partly via increase in phosphorylated CREB protein.

Menopausal symptoms and utilization of menopausal hormone therapy among women aged 40-60 years in Addis Ababa, Ethiopia: a cross-sectional study

BACKGROUND

The onset of menopause leads to diminished estrogen exposure, resulting in a high morbidity burden related to menopausal symptoms. Menopausal hormonal therapy is an effective therapy that offers more advantages than disadvantages for women aged less than 60 years or who have had menopause for less than 10 years.

OBJECTIVE

This study aimed to assess the prevalence of menopausal symptoms, identify factors associated with menopausal symptoms, and assess the use of menopausal hormone therapy among women aged 40-60 who visited the gynecological clinics of three hospitals in Addis Ababa, Ethiopia.

METHODS

A facility-based cross-sectional study was conducted from January 2022 to June 2022 at Gandhi Memorial Hospital, Tikur Anbessa Hospital, and Zewditu Memorial Hospital on 296 middle-aged women. Data were collected using an interviewer-administered structured questionnaire and analyzed for sociodemographic factors, utilization of menopausal hormone therapy, and prevalence of menopausal symptoms using the menopause rating scale. Data were analyzed using SPSS version 25. Bivariate and multivariate logistic regression analyses were performed to identify independent predictors of each subscale of menopausal symptoms. The strength of the association was measured using odds ratios with 95% confidence intervals, and statistical significance was set at a value of P < 0.05.

RESULT

The prevalence of menopausal symptoms was 89.9%. According to the menopausal rating scale, the frequency of reported symptoms was hot flushes (54.7%), muscle and joint pain (32.1%) on the somatic subscale; physical and mental exhaustion (55.1%), irritability (48.6%) on psychological subscale; and sexual problems (41.3%), bladder problems (39.2%) on urogenital subscale. This study also showed that the age of women [aOR: 0.317, 95%CI (0.102, 0.990)], and monthly family income [aOR = 0.182, 95% CI (0.041, 0.912)] were significantly associated with somatic menopausal symptoms. There was no utilization of menopausal hormonal therapy to treat menopausal symptoms and to prevent complications.

CONCLUSION

The prevalence of menopausal symptoms is high; however, the utilization of individualized administration of menopausal hormone therapy according to symptoms is negligible. It appears essential for these institutions to work on service availability and delivery of menopausal hormone therapy for those in need of wider benefits for their clients.

Female Reproductive Endocrine Disorders

This article is a summary of normal menstrual bleeding and how to recognize abnormalities based on patient's symptoms as well as identify possible causes in order to direct treatment. This article discusses abnormal uterine bleeding including the definition, etiology, evaluation, and treatment. It also discusses primary ovarian insufficiency, transgender medicine, and menopause.

Influence of the Onset of Menopause on the Risk of Developing Alzheimer's Disease

Menopause is a natural phase marked by the permanent cessation of menstrual cycles, occurring when the production of reproductive hormones from the ovaries stops for at least 12 consecutive months. Studies have suggested a potential connection between menopause and a heightened risk of developing Alzheimer's disease (AD), underscoring the significant role of reduced estrogen levels in the development of AD. Estrogen plays a crucial role in brain metabolism, influencing energy metabolism, synaptic plasticity, and cognitive functions. The cognitive benefits associated with hormone replacement therapy (HRT) are believed to be linked to estrogen's neuroprotective effects, either through direct action on the brain or indirectly by improving cardiovascular health. Extensive literature supports the positive impact of estrogen on brain cells. While the physiological effects of estrogen on the brain have not been consistently replicated in clinical trials, further research is crucial to provide more definitive recommendations to menopausal patients regarding the influence of HRT on AD. This review aims to comprehensively explore the interplay between menopause and AD, as well as the potential of HRT to mitigate cognitive decline in post-menopausal individuals.

Sex and Gender Differences in Alzheimer's Disease: Genetic, Hormonal, and Inflammation Impacts

Two-thirds of Americans with Alzheimer's disease are women, indicating a profound variance between the sexes. Variances exist between the sexes in the age and intensity of the presentation, cognitive deficits, neuroinflammatory factors, structural and functional brain changes, as well as psychosocial and cultural circumstances. Herein, we summarize the existing evidence for sexual dimorphism and present the available evidence for these distinctions. Understanding these complexities is critical to developing personalized interventions for the prevention, care, and treatment of Alzheimer's disease.

The effects of estrogens on spatial learning and memory in female rodents - A systematic review and meta-analysis

Estrogens have inconsistent effects on learning and memory in both the clinical and preclinical literature. Preclinical literature has the advantage of investigating an array of potentially important factors contributing to the varied effects of estrogens on learning and memory, with stringently controlled studies. This study set out to identify specific factors in the animal literature that influence the effects of estrogens on cognition, for possible translation back to clinical practice. The literature was screened and studies meeting strict inclusion criteria were included in the analysis. Eligible studies included female ovariectomized rodents with an adequate vehicle for the estrogen treatment, with an outcome of spatial learning and memory in the Morris water maze. Training days of the Morris water maze were used to assess acquisition of spatial learning, and the probe trial was used to evaluate spatial memory recall. Continuous outcomes were pooled using a random effects inverse variance method and reported as standardized mean differences with 95 % confidence intervals. Subgroup analyses were developed a priori to assess important factors. The overall analysis favoured treatment for the later stages of training and for the probe trial. Factors including the type of estrogen, route, schedule of administration, age of animals, timing relative to ovariectomy, and duration of treatment were all found to be important. The subgroup analyses showed that chronic treatment with 17β-estradiol, either cyclically or continuously, to young animals improved spatial recall. These results, observed in animals, can inform and guide further clinical research on hormone replacement therapy for cognitive benefits.

Hormone Therapy and Biological Aging in Postmenopausal Women

Importance

Menopause is associated with biological aging, and hormone therapy (HT) is associated with health outcomes in postmenopausal women.

Objective

To evaluate the association between HT use and discrepancies between chronological and biological age in postmenopausal women as well as the potential modifying role of socioeconomic status (SES).

Design, Setting, and Participants

This population-based, retrospective cohort study included postmenopausal women registered in the UK Biobank. A baseline survey on HT use and biological aging biomarkers was conducted from March 2006 to October 2010. Data analyses were conducted in December 2023.

Exposures

Information regarding HT use, the age at starting HT, and HT duration was collected via a touchscreen questionnaire. SES was evaluated by education, family income, occupation, and the Townsend Deprivation Index.

Main Outcomes and Measures

Biological aging discrepancy was evaluated using validated phenotypic age, which was calculated using chronological age and 9 biomarkers measured at baseline. All-cause and cause-specific mortality were also assessed.

Results

Among the 117 763 postmenopausal women (mean [SD] age, 60.2 [5.4] years), 47 461 (40.3%) ever used HT. The mean phenotypic age was 52.1 (7.9) years. Ever use of HT was associated with a smaller biological aging discrepancy than never use of HT (β, -0.17 years; 95% CI, -0.23 to -0.10 years). This smaller aging discrepancy was more evident in those who started HT at age 55 years or older (β, -0.32 years; 95% CI, -0.48 to -0.15 years) and in those who used HT for 4 to 8 years (β, -0.25 years; 95% CI, -0.35 to -0.15 years). The association between HT and a smaller aging discrepancy was more evident in women with low SES, with a significant interaction observed for education (higher education: β, -0.08 years [95% CI, -0.17 to 0.01]; other education: β, -0.23 [95% CI, -0.32 to -0.14] years; P for interaction = .02). Phenotypic aging discrepancy mediated 12.7% (95% CI, 6.3% to 23.9%) of the association between HT and all-cause mortality and cause-specific mortality.

Conclusions and Relevance

In this study, postmenopausal women with historical HT use were biologically younger than those not receiving HT, with a more evident association observed in those with low SES. The biological aging discrepancy mediated the association between HT and decreased mortality. Promoting HT in postmenopausal women could be important for healthy aging.

Hormone therapy is associated with lower Alzheimer's disease tau biomarkers in post-menopausal females -evidence from two independent cohorts

BACKGROUND

Females represent approximately 70% of the Alzheimer's disease (AD) cases and the literature has proposed a connection between the decreased estrogen levels during menopause and an increased AD risk. Previous investigations have predominantly focused on assessing how hormone therapy (HT) affects the likelihood of AD development and cognitive deterioration. However, as the research framework has shifted toward a biomarker-defined AD and alterations in specific biomarkers could take place years before cognitive decline becomes discernible, it is crucial to examine how HT influences AD biomarkers. The main goal of this study was to evaluate the impact of HT on AD biomarker-informed pathophysiology in both cognitively unimpaired (CU) and cognitively impaired (CI) post-menopausal females across the aging and AD spectrum.

METHODS

This cross-sectional study included post-menopausal females without HT history (HT-) and with HT (HT+) at the time of PET imaging assessment from two cohorts: the Translational Biomarkers in Aging and Dementia (TRIAD) cohort, and the Alzheimer's Disease Neuroimaging Initiative (ADNI). Participants underwent magnetic resonance imaging (MRI), positron emission tomography (PET) and biofluid collection. Voxel-based t-tests were performed to assess the differences in amyloid-β (Aβ) and tau neurofibrillary tangles (NFTs) loads between HT- and HT + females. Linear regression models with interaction terms were also conducted to examine the interactive effects of HT and Aβ-PET on regional tau-PET.

RESULTS

HT + females demonstrated significantly lower tau-PET standardized uptake value ratio (SUVR) in Braak I-II ROIs (P < 0.05, Hedges' g = 0.73), Braak III-IV ROIs (P < 0.0001, Hedges' g = 0.74) and Braak V-VI ROIs (P < 0.0001, Hedges' g = 0.69) compared to HT- females. HT + females also showed significantly lower CSF p-tau181 (P < 0.001) and plasma p-tau181 (P < 0.0001) concentrations. Additionally, results from multivariate linear regression models indicated that HT interacts with cortical Aβ and is associated with lower regional NFT load.

CONCLUSIONS

Overall, findings from this observational study suggest that HT is associated with lower tau neuroimaging and fluid biomarkers in postmenopausal females. Due to the close link between tau and cognition, this study highlights the need for large randomized controlled trials designed to systemically study the influences of HT on AD biomarkers and disease progression.

Alzheimer Disease and Related Dementia Following Hormone-Modulating Therapy in Patients With Breast Cancer

Importance

Hormone-modulating therapy (HMT) is a widely accepted treatment for hormone receptor-positive breast cancer, although its cognitive effects, including a potential link to Alzheimer disease and related dementias (ADRD), remain understudied.

Objective

To investigate the association between HMT for breast cancer treatment and risk of developing ADRD in women aged 65 years or older.

Design, Setting, and Participants

This cohort study used a comprehensive dataset from the Surveillance, Epidemiology, and End Results (SEER)-Medicare linked database to identify patients who did and did not receive HMT treatment within 3 years after the initial diagnosis of breast cancer and assessed their risk of developing ADRD in later life. Individuals with a preexisting diagnosis of ADRD or receiving HMT before the diagnosis of breast cancer were excluded. This study was performed from June 2022 through January 2024.

Exposure

Receipt of HMT.

Main Outcomes and Measures

Risk of ADRD associated with HMT; associations of risk with age, self-identified race, and HMT type. Risk was measured using hazard ratios (HRs) with 95% CIs and adjusted for potential confounders such as demographic, sociocultural, and clinical variables.

Results

Among 18 808 women aged 65 years and older diagnosed with breast cancer between 2007 and 2009 (1266 Black [6.7%], 16 526 White [87.9%], 1016 other [5.4%]), 12 356 (65.7%) received HMT within 3 years after diagnosis, while 6452 (34.3%) did not. The most common age group in both samples was the 75 to 79 years age group (HMT, 2721 women [22.0%]; no HMT, 1469 women [22.8%]), and the majority of women in both groups self-identified as White (HMT, 10 904 women [88.3%]; no HMT, 5622 women [87.1%]). During an average of 12 years of follow-up, 2926 (23.7%) of HMT users and 1802 (27.9%) of non-HMT users developed ADRD. HMT was associated with a 7% lower relative risk of ADRD overall (HR, 0.93; 95% CI, 0.88-0.98; P = .005). The association decreased with age and varied by race. The reduction in ADRD risk associated with HMT was greatest for women aged 65 to 74 years who self-identified as Black (HR, 0.76; 95% CI, 0.62-0.92). This association decreased among women aged 75 years or older (HR, 0.81; 95% CI, 0.67-0.98). Women aged 65 to 74 years who self-identified as White had an 11% relative risk reduction (HR, 0.89; 95% CI, 0.81-0.97), but the association disappeared for women aged 75 years or older (HR, 0.96; 95% CI, 0.90-1.02). Other races showed no significant association between HMT and ADRD. Age- and race-based associations also varied by HMT type.

Conclusions and Relevance

In this retrospective cohort study, hormone therapy was associated with protection against ADRD in women aged 65 years or older with newly diagnosed breast cancer; the decrease in risk was relatively greater for Black women and women under age 75 years, while the protective effect of HMT diminished with age and varied by race in women. When deciding to use HMT for breast cancer in women aged 65 years or more, clinicians should consider age, self-identified race, and HMT type in treatment decisions.

Longitudinal associations of reproductive factors and exogeneous estrogens with neuroimaging biomarkers of Alzheimer's disease and cerebrovascular disease

INTRODUCTION

Female-specific reproductive factors and exogeneous estrogen use are associated with cognition in later life. However, the underlying mechanisms are not understood. The present study aimed to investigate the effect of reproductive factors on neuroimaging biomarkers of Alzheimer's disease (AD) and cerebrovascular pathologies.

METHODS

We evaluated 389 females (median age of 71.7 years) enrolled in the Mayo Clinic Study of Aging with reproductive history data and longitudinal magnetic resonance imaging (MRI) scans. We used linear mixed effect models to examine the associations between reproductive factors and changes in neuroimaging measures.

RESULTS

Ever hormonal contraception (HC) use was longitudinally associated with higher fractional anisotropy across the corpus callosum, lower white matter hyperintensity (WMH) volume, and greater cortical thickness in an AD meta-region of interest (ROI). The initiation of menopausal hormone therapy (MHT) > 5 years post menopause was associated with higher WMH volume.

DISCUSSION

HC use and initiation of MHT >5 years post menopause were generally associated with neuroimaging biomarkers of cerebrovascular pathologies.

HIGHLIGHTS

Hormonal contraception use was associated with better brain white matter (WM) integrity. Initiation of menopausal hormone therapy >5 years post menopause was associated with worsening brain WM integrity. Hormonal contraception use was associated with greater cortical thickness. Ages at menarche and menopause and number of pregnancies were not associated with imaging measures. There were few associations between reproductive factors or exogenous estrogens and amyloid or tau PET.

Estrogen signalling and Alzheimer's disease: Decoding molecular mechanisms for therapeutic breakthrough

In females, Alzheimer's disease (AD) incidences increases as compared to males due to estrogen deficiency after menopause. Estrogen therapy is the mainstay therapy for menopause and associated complications. Estrogen, a hormone with multifaceted physiological functions, has been implicated in AD pathophysiology. Estrogen plays a crucial role in amyloid precursor protein (APP) processing and overall neuronal health by regulating various factors such as brain-derived neurotrophic factor (BDNF), intracellular calcium signalling, death domain-associated protein (Daxx) translocation, glutamatergic excitotoxicity, Voltage-Dependent Anion Channel, Insulin-Like Growth Factor 1 Receptor, estrogen-metabolising enzymes and apolipoprotein E (ApoE) protein polymorphisms. All these factors impact the physiology of postmenopausal women. Estrogen replacement therapies play an important treatment strategy to prevent AD after menopause. However, use of these therapies may lead to increased risks of breast cancer, venous thromboembolism and cardiovascular disease. Various therapeutic approaches have been used to mitigate the effects of estrogen on AD. These include hormone replacement therapy, Selective Estrogen Receptor Modulators (SERMs), Estrogen Receptor Beta (ERβ)-Selective Agonists, Transdermal Estrogen Delivery, Localised Estrogen Delivery, Combination Therapies, Estrogen Metabolism Modulation and Alternative Estrogenic Compounds like genistein from soy, a notable phytoestrogen from plant sources. However, mechanism via which these approaches modulate AD in postmenopausal women has not been explained earlier thoroughly. Present review will enlighten all the molecular mechanisms of estrogen and estrogen replacement therapies in AD. Along-with this, the association between estrogen, estrogen-metabolising enzymes and ApoE protein polymorphisms will also be discussed in postmenopausal AD.

Postmenopausal hormone therapy and cognition in twins

OBJECTIVE

Mild cognitive impairment may be caused by pathophysiological changes occurring decades prior to symptom development. It has been hypothesised that oestrogen can prevent such changes. We aimed to investigate the association between postmenopausal hormone therapy and cognition in Danish female twins and to examine differences in this association before and after publication of the findings from the Women's Health Initiative study in 2002.

STUDY DESIGN

This study includes cognitive assessment of 4510 twins aged 50+ years. Information on hormone therapy was obtained through Danish health registries. The association between current hormone therapy use and cognition was analysed in twins aged 50+ using both cross-sectional, intrapair and longitudinal analysis, adjusting for age, education, social class, and unobserved familial confounding.

RESULTS

Cross-sectionally, systemic HT users aged 70+ had a significantly lower cognitive function than non-users, whereas systemic HT users aged 50-69 did not differ from non-users before 2002. Longitudinal data in younger twins aged 50-69 showed a significantly lower cognitive function in systemic HT users after 2002 compared to non-users. Systemic HT users aged 70+ showed that the lower cognitive function was most explicit before 2002, whereas after 2002 the cognitive function was closer to non-users. Twins aged 50-69 who changed from systemic HT to local HT after 2002, or dropped it altogether, performed cognitively better.

CONCLUSIONS

Our findings cautiously indicate a change in the association between cognition and hormone therapy use after 2002, which suggests an alteration in the hormone therapy user profile in the wake of the 2002 WHI publication.

Comparing Cancer Risks and Mortality between Phytopharmaceuticals and Estrogen-Progestogen Medications for Menopausal Women: A Population-Based Cohort Study

We evaluated the long-term risks of overall cancer and all-cause mortality associated with five types of phytopharmaceuticals and the most commonly used estrogen-progestogen medications for the treatment of postmenopausal syndrome in women. Using data from Taiwan's National Health Insurance Research Database (NHIRD) from 1 January 2000 to 31 December 2018, we conducted a 1:2 matched cohort study with 12,087 eligible patients. We compared phytopharmaceuticals -only users (n = 4029, phytopharmaceuticals group) with HRT-only users (n = 8058, HRT group) with a washout period of ≥6 months. The phytopharmaceuticals group had significantly lower risks of overall cancer and all-cause mortality than the HRT group (adjusted hazard ratio [95% confidence interval]: 0.60 [0.40-0.9] and 0.40 [0.16-0.99], respectively) after over 180 days of use. Bupleurum and Peony Formula were associated with lower risks of overall cancer and all-cause mortality (aHR: 0.57 [0.36-0.92] and 0.33 [0.11-1.05], respectively). In conclusion, phytopharmaceuticals may serve as an alternative therapy to HRT for alleviating menopausal symptoms and reducing health risks, leading to more favorable long-term health outcomes. Further randomized control trials are necessary to validate the findings of this study.

Risks and benefits of hormone therapy after menopause for cognitive decline and dementia: A conceptual review

OBJECTIVE

The effects on the brain of hormone therapy after the onset of menopause remain uncertain. The effects may be beneficial, neutral, or harmful. We provide a conceptual review of the evidence.

METHODS

We 1) provide a brief history of the evidence, 2) discuss some of the interpretations of the evidence, 3) discuss the importance of age at menopause, type of menopause, and presence of vasomotor symptoms, and 4) provide some clinical recommendations.

RESULTS

The evidence and the beliefs about hormone therapy and dementia have changed over the last 30 years or more. Five recent observation studies suggested that hormone therapy is associated with an increased risk of dementia, and the association appears not to change with the timing of initiation of therapy. These harmful associations may be explained by a causal effect of hormone therapy on the brain or by several confounding mechanisms. We suggest that the use of hormone therapy should be customized for different subgroups of women. It may be important to subgroup women based on age at onset of menopause, type of menopause, and presence or absence of vasomotor symptoms. In addition, the effects may vary by type, dose, route, and duration of administration of estrogens and by the concurrent use of progestogens.

DISCUSSION

The relation of hormone therapy with the risk of dementia is complex. Hormone therapy may have beneficial, neutral, or harmful effects on the brain. Hormone therapy should be guided by the clinical characteristics of the women being treated.

Sex differences in luteinizing hormone aggravates Aβ deposition in APP/PS1 and Aβ1-42-induced mouse models of Alzheimer's disease

Alzheimer's disease (AD) exhibits a higher incidence rate among older women, and dysregulation of the hypothalamic-pituitary-gonadal (HPG) axis during aging is associated with cognitive impairments and the development of dementia. luteinizing hormone (LH) has an important role in CNS function, such as mediating neuronal pregnenolone production, and modulating neuronal plasticity and cognition. The sex differences in LH and its impact on Aβ deposition in AD individuals remain unclear, with no reported specific mechanisms. Here, we show through data mining that LH-related pathways are significantly enriched in female AD patients. Additionally, LH levels are elevated in female AD patients and exhibit a negative correlation with cognitive levels but a positive correlation with AD pathology levels, and females exhibit a greater extent of AD pathology, such as Aβ deposition. In vivo, we observed that the exogenous injection of LH exacerbated behavioral impairments induced by Aβ1-42 in mice. LH injection resulted in worsened neuronal damage and increased Aβ deposition. In SH-SY5Y cells, co-administration of LH with Aβ further exacerbated Aβ-induced neuronal damage. Furthermore, LH can dose-dependently decrease the levels of NEP and LHR proteins while increasing the expression of GFAP and IBA1 in vivo and in vitro. Taken together, these results indicate that LH can exacerbate cognitive impairment and neuronal damage in mice by increasing Aβ deposition. The potential mechanism may involve the reduction of NEP and LHR expression, along with the exacerbation of Aβ-induced inflammation.

Associations Between Age at Menopause, Vascular Risk, and 3-Year Cognitive Change in the Canadian Longitudinal Study on Aging

BACKGROUND AND OBJECTIVES

Mounting evidence supports sex differences in Alzheimer disease (AD) risk. Vascular and hormonal factors may together contribute to AD risk in female adults. We investigated whether age at menopause, vascular risk, and history of hormone therapy (HT) containing estrogens together influence cognition over a 3-year follow-up period. We hypothesized that earlier menopause and elevated vascular risk would have a synergistic association with lower cognitive scores at follow-up and that HT containing estrogens would attenuate this synergistic association to preserve cognition.

METHODS

We used data from postmenopausal female participants and age-matched male participants in the Canadian Longitudinal Study on Aging. Vascular risk was calculated using a summary score of elevated blood pressure, antihypertensive medications, elevated low-density lipoprotein cholesterol, diabetes, smoking, and obesity. Cognition was measured with a global cognitive composite at baseline and 3-year follow-up. Linear models tested independent and interactive associations of age at menopause, vascular risk, and HT history with cognition at 3-year follow-up, adjusting for baseline cognition, baseline age, years of education, and test language (English/French).

RESULTS

We included 8,360 postmenopausal female participants (mean age at baseline = 65.0 ± 8.53 years, mean age at menopause = 50.1 ± 4.62 years) and 8,360 age-matched male participants for comparison. There was an interaction between age at menopause and vascular risk, such that earlier menopause and higher vascular risk were synergistically associated with lower cognitive scores at follow-up (β = 0.013, 95% CI 0.001-0.025, p = 0.03). In stratified analyses, vascular risk was associated with lower cognitive scores in female participants with earlier menopause (menopausal ages 35-48 years; β = -0.044, 95% CI -0.066 to -0.022, p < 0.001), but not average (ages 49-52 years; β = -0.007, 95% CI -0.027 to 0.012, p = 0.46) or later menopause (ages 53-65 years; β = 0.003, 95% CI -0.020 to 0.025, p = 0.82). The negative association of vascular risk with cognition in female participants with earlier menopause was stronger than the equivalent association in age-matched male participants. HT history did not further modify the synergistic association of age at menopause and vascular risk with follow-up cognition (β = -0.005, 95% CI -0.032 to 0.021, p = 0.69).

DISCUSSION

Endocrine and vascular processes may synergistically contribute to increased risk of cognitive decline in female adults. These findings have implications for the development of sex-specific dementia prevention strategies.

Plasma oxysterols are associated with serum lipids and dementia risk in older women

INTRODUCTION

Apolipoprotein E4 (APOE4) carriers' tendency toward hypercholesterolemia may contribute to Alzheimer's disease (AD) risk through oxysterols, which traverse the blood-brain barrier.

METHODS

Relationships between baseline plasma oxysterols, APOE status, serum lipids, and cognitive impairment risk were examined in 328 postmenopausal women from the Women's Health Initiative Memory Study. Women were followed for 25 years or until incident dementia or cognitive impairment.

RESULTS

Levels of 24(S)-hydroxycholesterol (24-OHC), 27-hydroxycholesterol (27-OHC), and 24-OHC/27-OHC ratio did not differ by APOE status (p's > 0.05). Higher 24-OHC and 27-OHC were associated with higher total, low density lipoprotein (LDL), non-high density lipoprotein (HDL), remnant, LDL/HDL, and total/HDL cholesterol and triglycerides (p's < 0.05). Higher 24-OHC/27-OHC was associated with greater dementia risk (hazard ratio = 1.51, 95% confidence interval:1.02-2.22), which interaction analyses revealed as significant for APOE3 and APOE4+, but not APOE2+ carriers.

DISCUSSION

Less favorable lipid profiles were associated with higher oxysterol levels. A higher ratio of 24-OHC/27-OHC may contribute to dementia risk in APOE3 and APOE4+ carriers.

Mechanisms of sex differences in Alzheimer's disease

Alzheimer's disease (AD) and the mechanisms underlying its etiology and progression are complex and multifactorial. The higher AD risk in women may serve as a clue to better understand these complicated processes. In this review, we examine aspects of AD that demonstrate sex-dependent effects and delve into the potential biological mechanisms responsible, compiling findings from advanced technologies such as single-cell RNA sequencing, metabolomics, and multi-omics analyses. We review evidence that sex hormones and sex chromosomes interact with various disease mechanisms during aging, encompassing inflammation, metabolism, and autophagy, leading to unique characteristics in disease progression between men and women.

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 Impacts of Age at Menarche on Cognitive Aging in Late Adulthood: Evidence from a Mendelian Randomization Study on the Taiwanese Population

INTRODUCTION

The potential influence of age at menarche (AM) on cognitive aging remains inadequate, partly because of the difficulties presented by multiple confounders. To address this issue, Mendelian randomization (MR) analysis was used to explore the causal impacts of AM on cognitive aging.

METHODS

Using the publicly accessible Taiwan Biobank, we identified single nucleotide polymorphisms (SNPs) significantly associated with AM as instrumental variables to estimate the effects of instruments on cognitive function assessed with the Mini-Mental State Examination (MMSE). We employed several MR methods, including two-stage least squares, inverse variance weighting (IVW), MR-Egger, weighted median, weighted mode, and constrained maximum likelihood (cML) MR methods, to ensure the stability and reliability of the results.

RESULTS

MR analyses indicated no significant causal relationship between genetically determined AMs and total and subdomain MMSE scores, except the G5 subdomain (βIVW = 0.156, 95% confidence interval [CI]: 0.005, 0.307; βcML = 0.161, 95% CI: 0.014, 0.309). However, in a leave-one-out sensitivity analysis, we found a significant relationship between AM and cognitive aging after eliminating rs157863 and rs6758290, thus demonstrating the potential pleiotropic effects of these two SNPs. After these two SNPs were eliminated, we found a significant causal relationship between AM and overall MMSE scores (βIVW = 0.425, 95% CI: 0.011, 0.839), though.

CONCLUSION

Evidence from the present MR study did not fully support a causal relationship between AM and cognitive function decline in later life. Potential pleiotropic effects of the genes underlying these two traits are worthy of further investigation.

Optimising health after early menopause

The typical age at menopause is 50-51 years in high-income countries. However, early menopause is common, with around 8% of women in high-income countries and 12% of women globally experiencing menopause between the ages of 40 years and 44 years. Menopause before age 40 years (premature ovarian insufficiency) affects an additional 2-4% of women. Both early menopause and premature ovarian insufficiency can herald an increased risk of chronic disease, including osteoporosis and cardiovascular disease. People who enter menopause at younger ages might also experience distress and feel less supported than those who reach menopause at the average age. Clinical practice guidelines are available for the diagnosis and management of premature ovarian insufficiency, but there is a gap in clinical guidance for early menopause. We argue that instead of distinct age thresholds being applied, early menopause should be seen on a spectrum between premature ovarian insufficiency and menopause at the average age. This Series paper presents evidence for the short-term and long-term consequences of early menopause. We offer a practical framework for clinicians to guide diagnosis and management of early menopause, which considers the nature and severity of symptoms, age and medical history, and the individual's wishes and priorities to optimise their quality of life and short-term and long-term health. We conclude with recommendations for future research to address key gaps in the current evidence.

Systematic review and meta-analysis of the effects of menopause hormone therapy on cognition

Introduction

Despite evidence from preclinical studies suggesting estrogen's neuroprotective effects, the use of menopausal hormone therapy (MHT) to support cognitive function remains controversial.

Methods

We used random-effect meta-analysis and multi-level meta-regression to derive pooled standardized mean difference (SMD) and 95% confidence intervals (C.I.) from 34 randomized controlled trials, including 14,914 treated and 12,679 placebo participants.

Results

Associations between MHT and cognitive function in some domains and tests of interest varied by formulation and treatment timing. While MHT had no overall effects on cognitive domain scores, treatment for surgical menopause, mostly estrogen-only therapy, improved global cognition (SMD=1.575, 95% CI 0.228, 2.921; P=0.043) compared to placebo. When initiated specifically in midlife or close to menopause onset, estrogen therapy was associated with improved verbal memory (SMD=0.394, 95% CI 0.014, 0.774; P=0.046), while late-life initiation had no effects. Overall, estrogen-progestogen therapy for spontaneous menopause was associated with a decline in Mini Mental State Exam (MMSE) scores as compared to placebo, with most studies administering treatment in a late-life population (SMD=-1.853, 95% CI -2.974, -0.733; P = 0.030). In analysis of timing of initiation, estrogen-progestogen therapy had no significant effects in midlife but was associated with improved verbal memory in late-life (P = 0.049). Duration of treatment >1 year was associated with worsening in visual memory as compared to shorter duration. Analysis of individual cognitive tests yielded more variable results of positive and negative effects associated with MHT.

Discussion

These findings suggest time-dependent effects of MHT on certain aspects of cognition, with variations based on formulation and timing of initiation, underscoring the need for further research with larger samples and more homogeneous study designs.

Menopausal hormone therapy and risk for dementia in women with CKD: A nationwide observational cohort study

AIM

The risk for dementia is increased in postmenopausal women. The incidences of premature menopause and dementia have increased in patients with chronic kidney disease (CKD). The potential benefits of hormone replacement therapy (HRT) on cognitive function may be a more critical issue for patients with CKD.

METHODS

Women aged >40 years with or without HRT were identified using the 2009 National Health Screening Questionnaire. Women who were newly diagnosed with CKD between 2009 and 2013 were enrolled. HRT was used as an exposure variable, and participants were followed from the day CKD was diagnosed to December 2019. The hazard ratio (HR) for dementia was evaluated using Cox proportional hazards regression analysis.

RESULTS

We included 755 426 postmenopausal women with CKD. The median follow-up period was 7.3 (IQR, 5.8-8.7) years. All-cause dementia, Alzheimer's disease, and vascular dementia occurred in 107 848 (14.3%), 87 833 (11.6%), and 10 245 (1.4%) women, respectively. HRT was significantly associated with a lower risk for dementia in the adjusted Cox regression model (all-cause dementia: HR 0.80; 95% confidence interval [CI] 0.78-0.82; p < 0.001; Alzheimer's disease: HR 0.80; 95% CI 0.77-0.82; p < 0.001; vascular dementia: HR 0.80; 95% CI 0.74-0.87; p < 0.001).

CONCLUSIONS

HRT was significantly associated with a lower risk for CKD-related cognitive dysfunction in postmenopausal women. Prospective studies are needed to determine whether HRT lowers the risk for dementia in menopausal women with CKD.

Estradiol enhanced neuronal plasticity and ameliorated astrogliosis in human iPSC-derived neural models

Introduction

17β-Estradiol (E2) is a sex hormone that has been previously demonstrated to have neurotherapeutic effects on animal models of Alzheimer's disease (AD). However, clinical trials on E2 replacement therapy for preventing AD onset yielded inconsistent results. Therefore, it is imperative to clarify the therapeutic effects of E2 on human cells. In this study, we utilized induced pluripotent stem cells (iPSCs) derived from multiple AD donors to explore the therapeutic effects of E2 on the in vitro model of human cells.

Methods

We conducted a systematic review and meta-analysis using a random-effects model of the previously reported AD clinical trials to summarize the effects of E2 replacement therapy on AD prevention. Subsequently, we induced iPSCs from the donors of the healthy control (1210B2 line (female) and 201B7 line (female)), the familial AD (APP V717L line (female) and APP KM670/671NL line (female)), and the sporadic AD (UCSD-SAD3.7 line (APOE ε3/ε3) (male), UCSD-SAD7D line (APOE ε3/ε4) (male), and TMGH-1 line (APOE ε3/ε3) (female)), then differentiated to neurons. In addition to the mono-culture model of the neurons, we also examined the effects of E2 on the co-culture model of neurons and astrocytes.

Results

The meta-analysis of the clinical trials concluded that E2 replacement therapy reduced the risk of AD onset (OR, 0.69; 95 % confidence interval [CI], 0.53-0.91; I2 = 82 %). Neural models from the iPSCs of AD donors showed an increase in secreted amyloid-beta (Aβ) levels in the mono-culture model and an astrogliosis-like phenotype in the co-culture model. E2 treatment to the neuronal models derived from the iPSCs enhanced neuronal activity and increased neurite complexity. Furthermore, E2 treatment of the co-culture model ameliorated the astrogliosis-like phenotype. However, in contrast to the previous reports using mouse models, E2 treatment did not change AD pathogenesis, including Aβ secretion and phosphorylated tau (pTau) accumulation.

Conclusion

E2 treatment of the human cellular model did not impact Aβ secretion and pTau accumulation, but promoted neuronal plasticity and alleviated the astrogliosis-like phenotype. The limited effects of E2 may give a clue for the mixed results of E2 clinical trials.

Sex- and region-specific cortical and hippocampal whole genome transcriptome profiles from control and APP/PS1 Alzheimer's disease mice

A variety of Alzheimer's disease (AD) mouse models has been established and characterized within the last decades. To get an integrative view of the sophisticated etiopathogenesis of AD, whole genome transcriptome studies turned out to be indispensable. Here we carried out microarray data collection based on RNA extracted from the retrosplenial cortex and hippocampus of age-matched, eight months old male and female APP/PS1 AD mice and control animals to perform sex- and brain region specific analysis of transcriptome profiles. The results of our studies reveal novel, detailed insight into differentially expressed signature genes and related fold changes in the individual APP/PS1 subgroups. Gene ontology and Venn analysis unmasked that intersectional, upregulated genes were predominantly involved in, e.g., activation of microglial, astrocytic and neutrophilic cells, innate immune response/immune effector response, neuroinflammation, phagosome/proteasome activation, and synaptic transmission. The number of (intersectional) downregulated genes was substantially less in the different subgroups and related GO categories included, e.g., the synaptic vesicle docking/fusion machinery, synaptic transmission, rRNA processing, ubiquitination, proteasome degradation, histone modification and cellular senescence. Importantly, this is the first study to systematically unravel sex- and brain region-specific transcriptome fingerprints/signature genes in APP/PS1 mice. The latter will be of central relevance in future preclinical and clinical AD related studies, biomarker characterization and personalized medicinal approaches.

Dual decline in subjective gait speed and domain-specific cognition is associated with higher risk of incident dementia in older Japanese adults: A 15-year age-specific cohort study

OBJECTIVES

Dual decline in gait speed and cognition has been found to have higher dementia risk than no decline or pure decline. However, evidence from the Asian population is lacking. Therefore, we aimed to investigate the association of dual decline from age 65 to 70 years with late-life dementia in older Japanese adults with different personal characteristics.

METHODS

Data were collected from an age-specific cohort study conducted in 482 Japanese 65-year-old adults. We investigated participant demographics, medical histories, lifestyles, subjective gait speed, and cognition at both 64/65 and 70/71 years old, and confirmed dementia until age of 85 years. Cox proportion hazard models were used to estimate the risk of dementia, with adjustments for covariates, and death was treated as a competing risk.

RESULTS

After a mean follow-up period of 12.5-years, 111 participants developed dementia. Older adults with dual decline are more likely to have hyperlipidemia, diabetes, and smoking habits. And we found that dual decline in gait speed and domain-specific cognition was associated with a higher risk of dementia compared with no decline in most cognitive tests, with the highest risk observed for gait speed combined with memory (sub-distribution hazard ratio:3.89, 95 %, confidence intervals: [1.68-9.01]). However, significant differences only existed in men after stratification by sex.

CONCLUSIONS

A dual decline in subjective gait speed and cognition may serve as a robust predictor of dementia over a decade prior to its onset, particularly in men. These findings highlighted the importance of screening for dual decline at an early age.

Estrogen genotoxicity causes preferential development of Fuchs endothelial corneal dystrophy in females

Fuchs endothelial corneal dystrophy (FECD) is a genetically complex, age-related, female-predominant disorder characterized by loss of post-mitotic corneal endothelial cells (CEnCs). Ultraviolet-A (UVA) light has been shown to recapitulate the morphological and molecular changes seen in FECD to a greater extent in females than males, by triggering CYP1B1 upregulation in females. Herein, we investigated the mechanism of greater CEnC susceptibility to UVA in females by studying estrogen metabolism in response to UVA in the cornea. Loss of NAD(P)H quinone oxidoreductase 1 (NQO1) resulted in increased production of estrogen metabolites and mitochondrial-DNA adducts, with a higher CEnC loss in Nqo1-/- female compared to wild-type male and female mice. The CYP1B1 inhibitors, trans-2,3',4,5'-tetramethoxystilbene (TMS) and berberine, rescued CEnC loss. Injection of wild-type male mice with estrogen (E2; 17β-estradiol) increased CEnC loss, followed by increased production of estrogen metabolites and mitochondrial DNA (mtDNA) damage, not seen in E2-treated Cyp1b1-/-male mice. This study demonstrates that the endo-degenerative phenotype is driven by estrogen metabolite-dependent CEnC loss that is exacerbated in the absence of NQO1; thus, explaining the mechanism accounting for the higher incidence of FECD in females. The mitigation of estrogen-adduct production by CYP1B1 inhibitors could serve as a novel therapeutic strategy for FECD.

Clinical and Treatment Considerations for the Pediatric and Aging Patients with Multiple Sclerosis

Chronologic aging is associated with multiple pathologic and immunologic changes that impact the clinical course of multiple sclerosis (MS). Clinical phenotypes evolve across the lifespan, from a highly inflammatory course in the very young to a predominantly neurodegenerative phenotype in older patients. Thus, unique clinical considerations arise for the diagnosis and management of the two age extremes of pediatric and geriatric MS populations. This review covers epidemiology, diagnosis, and treatment strategies for these populations with nuanced discussions on therapeutic approaches to effectively care for patients living with MS at critical transition points during their lifespan.

Investigating the synergistic effects of hormone replacement therapy, apolipoprotein E and age on brain health in the UK Biobank

Global prevalence of Alzheimer's Disease has a strong sex bias, with women representing approximately two-thirds of the patients. Yet, the role of sex-specific risk factors during midlife, including hormone replacement therapy (HRT) and their interaction with other major risk factors for Alzheimer's Disease, such as apolipoprotein E (APOE)-e4 genotype and age, on brain health remains unclear. We investigated the relationship between HRT (i.e., use, age of initiation and duration of use) and brain health (i.e., cognition and regional brain volumes). We then consider the multiplicative effects of HRT and APOE status (i.e., e2/e2, e2/e3, e3/e3, e3/e4 and e4/e4) via a two-way interaction and subsequently age of participants via a three-way interaction. Women from the UK Biobank with no self-reported neurological conditions were included (N = 207,595 women, mean age = 56.25 years, standard deviation = 8.01 years). Generalised linear regression models were computed to quantify the cross-sectional association between HRT and brain health, while controlling for APOE status, age, time since attending centre for completing brain health measure, surgical menopause status, smoking history, body mass index, education, physical activity, alcohol use, ethnicity, socioeconomic status, vascular/heart problems and diabetes diagnosed by doctor. Analyses of structural brain regions further controlled for scanner site. All brain volumes were normalised for head size. Two-way interactions between HRT and APOE status were modelled, in addition to three-way interactions including age. Results showed that women with the e4/e4 genotype who have used HRT had 1.82% lower hippocampal, 2.4% lower parahippocampal and 1.24% lower thalamus volumes than those with the e3/e3 genotype who had never used HRT. However, this interaction was not detected for measures of cognition. No clinically meaningful three-way interaction between APOE, HRT and age was detected when interpreted relative to the scales of the cognitive measures used and normative models of ageing for brain volumes in this sample. Differences in hippocampal volume between women with the e4/e4 genotype who have used HRT and those with the e3/e3 genotype who had never used HRT are equivalent to approximately 1-2 years of hippocampal atrophy observed in typical health ageing trajectories in midlife (i.e., 0.98%-1.41% per year). Effect sizes were consistent within APOE e4/e4 group post hoc sensitivity analyses, suggesting observed effects were not solely driven by APOE status and may, in part, be attributed to HRT use. Although, the design of this study means we cannot exclude the possibility that women who have used HRT may have a predisposition for poorer brain health.

Effect of hormone replacement therapy on amyloid beta (Aβ) plaque density in the rhesus macaque amygdala

Background

Amyloid beta (Aβ) plaque density was examined in the amygdala of rhesus macaques, to elucidate the influence of age, diet and hormonal environment.

Methods

Luminex technology was used to measure cerebrospinal fluid (CSF) concentrations of Aβ40 and Aβ42 across three decades, while immunohistochemistry was used to examine Aβ plaque density in the amygdala.

Results

Aβ40 was found to be the predominant isoform of Aβ in the CSF, but neither Aβ40 or Aβ42 concentrations showed an age-related change, and the ratio of Aβ42 to Aβ40 showed only a marginal increase. Significantly fewer Aβ plaques were detected in the amygdala of old ovariectomized animals if they received estradiol HRT (p < 0.001); similar results were obtained regardless of whether they had been maintained on a regular monkey chow for ∼48 months or on a high-fat, high-sugar, Western-style diet for ∼30 months.

Conclusion

The results demonstrate that HRT involving estrogen can reduce Aβ plaque load in a cognitive brain region of aged non-human primates. The results from this translational animal model may therefore have clinical relevance to the treatment of AD in post-menopausal women, whether used alone, or as a supplement to current pharmacological and monoclonal antibody-based interventions.

Targets, trials and tribulations in Alzheimer therapeutics

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by abnormal accumulation of extracellular amyloid beta senile plaques and intracellular neurofibrillary tangles in the parts of the brain responsible for cognition. The therapeutic burden for the management of AD relies solely on cholinesterase inhibitors that provide only symptomatic relief. The urgent need for disease-modifying drugs has resulted in intensive research in this domain, which has led to better understanding of the disease pathology and identification of a plethora of new pathological targets. Currently, there are over a hundred and seventy clinical trials exploring disease modification, cognitive enhancement, and reduction of neuro-psychiatric complications. However, the path to developing safe and efficacious AD therapeutics has not been without challenges. Several clinical trials have been terminated in advanced stages due to lack of therapeutic translation or increased incidence of adverse events. This review presents an in-depth look at the various therapeutic targets of AD and the lessons learnt during their clinical assessment. Comprehensive understanding of the implication of modulating various aspects of Alzheimer brain pathology is crucial for development of drugs with potential to halt disease progression in Alzheimer therapeutics.

Women and the risk of Alzheimer's disease

Purpose of the review

This review will elucidate reasons to explain why women may be at greater risk for Alzheimer's disease.

Recent findings

Potential mechanisms to explain sex and gender differences in Alzheimer dementia include: differences in risk associated with the apolipoprotein E 4 allele; telomere shortening- which is linked with neurodegeneration, higher incidence of depression and insomnia in women as psychiatric co-morbidities which are linked with an increased Alzheimer disease risk, disorders of pregnancy including gestational hypertension and preeclampsia and psychosocial factors such as educational level which may contribute to differences in cognitive reserve.

Summary

The sex and gender differences in Alzheimer's disease can be explained by biological and psychosocial factors.

Hormone Replacement Therapy and Alzheimer's Disease: Current State of Knowledge and Implications for Clinical Use

Alzheimer's disease (AD) is a progressive neurodegenerative disorder responsible for over half of dementia cases, with two-thirds being women. Growing evidence from preclinical and clinical studies underscores the significance of sex-specific biological mechanisms in shaping AD risk. While older age is the greatest risk factor for AD, other distinct biological mechanisms increase the risk and progression of AD in women including sex hormones, brain structural differences, genetic background, immunomodulation and vascular disorders. Research indicates a correlation between declining estrogen levels during menopause and an increased risk of developing AD, highlighting a possible link with AD pathogenesis. The neuroprotective effects of estrogen vary with the age of treatment initiation, menopause stage, and type. This review assesses clinical and observational studies conducted in women, examining the influence of estrogen on cognitive function or addressing the ongoing question regarding the potential use of hormone replacement therapy (HRT) as a preventive or therapeutic option for AD. This review covers recent literature and discusses the working hypothesis, current use, controversies and challenges regarding HRT in preventing and treating age-related cognitive decline and AD. The available evidence indicates that estrogen plays a significant role in influencing dementia risk, with studies demonstrating both beneficial and detrimental effects of HRT. Recommendations regarding HRT usage should carefully consider the age when the hormonal supplementation is initiated, baseline characteristics such as genotype and cardiovascular health, and treatment duration until this approach can be more thoroughly investigated or progress in the development of alternative treatments can be made.

Alzheimer's Disease and (Phyto) Estrogen Treatment: Modification of Effects by Age, Type of Treatment, and Duration of Use

Background

There is a continued debate on whether menopausal hormone therapy (MHT) protects women against Alzheimer's disease (AD). It is also unclear whether phytoestrogen could be an alternative treatment for AD.

Objective

To investigate whether mixed study findings may be due to differences in age at initiation of MHT and duration of prescription of different types of MHT using meta-analyses.

Methods

After a systematic literature search, meta-analyses were carried out using Cochrane Revman 5.4.1.software including data from large nationwide studies of registered medically diagnosed AD and prescribed MHT. These analyses were stratified for duration and type of treatment, by age at start of prescription of therapy. Insufficient quality data were available for phytoestrogen treatment and AD meta-analyses.

Results

A total of 912,157 women were included from five registries, of whom 278,495 had developed AD during follow-up. Meta-analyses suggested a small increased AD risk after 5-10 years prescription of combination MHT regardless of age, and over 10 years only in women younger than 60 years of age. No association was seen for estrogen alone for women younger than 60 years of age, but AD risk did increase for women over 60 years of age for up to 5 years of MHT prescriptions.

Conclusions

Combination MHT should probably be prescribed for less than 5 years after menopause to reduce risk for AD, while estrogen alone should not be prescribed to women over 60. For phytoestrogen, small treatment trials suggested some benefit of tempeh (fermented soy), which should be investigated further.

Modulation of neural gene networks by estradiol in old rhesus macaque females

The postmenopausal decrease in circulating estradiol (E2) levels has been shown to contribute to several adverse physiological and psychiatric effects. To elucidate the molecular effects of E2 on the brain, we examined differential gene expression and DNA methylation (DNAm) patterns in the nonhuman primate brain following ovariectomy (Ov) and subsequent E2 treatment. We identified several dysregulated molecular networks, including MAPK signaling and dopaminergic synapse response, that are associated with ovariectomy and shared across two different brain areas, the occipital cortex (OC) and prefrontal cortex (PFC). The finding that hypomethylation (p=1.6×10-51) and upregulation (p=3.8×10-3) of UBE2M across both brain regions, provide strong evidence for molecular differences in the brain induced by E2 depletion. Additionally, differential expression (p=1.9×10-4; interaction p=3.5×10-2) of LTBR in the PFC, provides further support for the role E2 plays in the brain, by demonstrating that the regulation of some genes that are altered by ovariectomy may also be modulated by Ov followed by hormone replacement therapy (HRT). These results present real opportunities to understand the specific biological mechanisms that are altered with depleted E2. Given E2's potential role in cognitive decline and neuroinflammation, our findings could lead to the discovery of novel therapeutics to slow cognitive decline. Together, this work represents a major step towards understanding molecular changes in the brain that are caused by ovariectomy and how E2 treatment may revert or protect against the negative neuro-related consequences caused by a depletion in estrogen as women approach menopause.

Associations of dietary cholesterol and fat, blood lipids, and risk for dementia in older women vary by APOE genotype

INTRODUCTION

Whether apolipoprotein E's (APOE's) involvement in lipid metabolism contributes to Alzheimer's disease (AD) risk remains unknown.

METHODS

Incident probable dementia and cognitive impairment (probable dementia+mild cognitive impairment) were analyzed in relation to baseline serum lipids (total, low-density lipoprotein [LDL], high-density lipoprotein [HDL], non-HDL cholesterol, total-to-HDL, LDL-to-HDL, remnant cholesterol, and triglycerides) using Mendelian randomization in 5358 postmenopausal women from the Women's Health Initiative Memory Study. We also examined associations of baseline dietary cholesterol and fat with lipids based on APOE status.

RESULTS

After an average of 11.13 years, less favorable lipid levels related to greater dementia and cognitive impairment risk. Dementia (odds ratio [OR] = 3.13; 95% confidence interval [CI]: 2.31 to 4.24) and cognitive impairment (OR = 2.38; 95% CI: 1.85 to 3.06) risk were greatest in relation to higher remnant cholesterol levels. Greater cholesterol consumption related to poorer lipids in APOE4+ compared to APOE3 carriers.

DISCUSSION

APOE4+ carriers consuming more cholesterol had less favorable lipids, which were associated with greater dementia and cognitive impairment risk.

HIGHLIGHTS

Less favorable serum lipids were associated with higher dementia incidence. Mendelian randomization findings suggest causality between lipids and dementia. Lipid levels in older women may be clinical indicators of dementia risk. APOE4 carriers had poorest lipid profiles in relation to cholesterol consumption. APOE risk for dementia may be modifiable through lipid management.

Sex steroids and the female brain across the lifespan: insights into risk of depression and Alzheimer's disease

Despite widespread sex differences in prevalence and presentation of numerous illnesses affecting the human brain, there has been little focus on the effect of endocrine ageing. Most preclinical studies have focused on males only, and clinical studies often analyse data by covarying for sex, ignoring relevant differences between the sexes. This sex- (and gender)-neutral approach is biased and contributes to the absence of targeted treatments and services for all sexes (and genders). Female health has been historically understudied, with grave consequences for their wellbeing and health equity. In this Review, we spotlight female brain health across the lifespan by informing on the role of sex steroids, particularly oestradiol, on the female brain and on risk for diseases more prevalent in females, such as depression and Alzheimer's disease.

Systematic review and meta-analysis of the effects of menopause hormone therapy on risk of Alzheimer's disease and dementia

Introduction

Despite a large preclinical literature demonstrating neuroprotective effects of estrogen, use of menopausal hormone therapy (HT) for Alzheimer's disease (AD) risk reduction has been controversial. Herein, we conducted a systematic review and meta-analysis of HT effects on AD and dementia risk.

Methods

Our systematic search yielded 6 RCT reports (21,065 treated and 20,997 placebo participants) and 45 observational reports (768,866 patient cases and 5.5 million controls). We used fixed and random effect meta-analysis to derive pooled relative risk (RR) and 95% confidence intervals (C.I.) from these studies.

Results

Randomized controlled trials conducted in postmenopausal women ages 65 and older show an increased risk of dementia with HT use compared with placebo [RR = 1.38, 95% C.I. 1.16-1.64, p < 0.001], driven by estrogen-plus-progestogen therapy (EPT) [RR = 1.64, 95% C.I. 1.20-2.25, p = 0.002] and no significant effects of estrogen-only therapy (ET) [RR = 1.19, 95% C.I. 0.92-1.54, p = 0.18]. Conversely, observational studies indicate a reduced risk of AD [RR = 0.78, 95% C.I. 0.64-0.95, p = 0.013] and all-cause dementia [RR = .81, 95% C.I. 0.70-0.94, p = 0.007] with HT use, with protective effects noted with ET [RR = 0.86, 95% C.I. 0.77-0.95, p = 0.002] but not with EPT [RR = 0.910, 95% C.I. 0.775-1.069, p = 0.251]. Stratified analysis of pooled estimates indicates a 32% reduced risk of dementia with midlife ET [RR = 0.685, 95% C.I. 0.513-0.915, p = 0.010] and non-significant reductions with midlife EPT [RR = 0.775, 95% C.I. 0.474-1.266, p = 0.309]. Late-life HT use was associated with increased risk, albeit not significant [EPT: RR = 1.323, 95% C.I. 0.979-1.789, p = 0.069; ET: RR = 1.066, 95% C.I. 0.996-1.140, p = 0.066].

Discussion

These findings support renewed research interest in evaluating midlife estrogen therapy for AD risk reduction.

New Horizons: Gonadotropin-Releasing Hormone and Cognition

Pulsatile secretion of gonadotropin-releasing hormone (GnRH) is essential for activating and maintaining the function of the hypothalamic-pituitary-gonadal axis, which controls the onset of puberty and fertility. Two recent studies suggest that, in addition to controlling reproduction, the neurons in the brain that produce GnRH are also involved in the control of postnatal brain maturation, odor discrimination, and adult cognition. This review will summarize the development and establishment of the GnRH system, with particular attention to the importance of its first postnatal activation, a phenomenon known as minipuberty, for later reproductive and nonreproductive functions. In addition, we will discuss the beneficial effects of restoring physiological (ie, pulsatile) GnRH levels on olfactory and cognitive alterations in preclinical Down syndrome and Alzheimer disease models, as well as the potential risks associated with long-term continuous (ie, nonphysiological) GnRH administration in certain disorders. Finally, this review addresses the intriguing possibility that pulsatile GnRH therapy may hold therapeutic potential for the management of some neurodevelopmental cognitive disorders and pathological aging in elderly people.

The role of oestrogen therapy in reducing risk of Alzheimer's disease: systematic review

BACKGROUND

Studies have shown a relationship between oestrogen and Alzheimer's disease. However, there is neither clear nor strong evidence on the use of oestrogen-only therapy in reducing the risk of Alzheimer's disease.

AIMS

To assess the effects of oestrogen-only therapy on reducing the risk of Alzheimer's disease.

METHOD

Inclusion criteria was determined with the PICO framework. Outcome was cognitive function measured by neuropsychological tests and strict protocols. Exclusion criteria included non-Alzheimer's dementia, progesterone-only therapy and pre-menopausal women. Searches were conducted in nine electronic healthcare databases, last searched in July 2022. Quality assessments conducted on randomised controlled trials (RCTs) were performed with the GRADE assessment, and cohort studies and case-control studies were assessed with the Newcastle-Ottawa Scale. Extracted data were used to analyse participants, interventions and outcomes.

RESULTS

Twenty-four studies satisfied the search criteria (four RCTs, nine cohort studies, 11 case-control studies). Fifteen studies showed positive associations for oestrogen-only therapy reducing the risk of Alzheimer's disease, and the remaining nine found no evidence of association.

CONCLUSIONS

Fifteen studies showed that oestrogen-only therapy effectively reduced the risk of Alzheimer's disease, whereas nine showed no correlation. Studies also investigated oestrogen-related variables such as length of oestrogen exposure, being an apolipoprotein E ε4 carrier and concomitant use of non-steroidal anti-inflammatory drugs, and their role in neuroprotection. This review was limited by the limited ranges of duration of oestrogen treatment and type of oestrogen-only therapy used. In conclusion, oestrogen-only therapy has potential for use in preventing Alzheimer's disease, although current evidence is inconclusive and requires further study.

Early menopause and premature ovarian insufficiency are associated with increased risk of dementia: A systematic review and meta-analysis of observational studies

BACKGROUND/AIMS

Among other risk factors, the decline in estrogen concentrations during menopause may compromise cognitive function. Whether early menopause (EM) is associated with an increased risk of dementia remains unclear. The purpose of this study was to systematically review and meta-analyze current evidence regarding the association between EM or premature ovarian insufficiency (POI) and the risk of dementia of any type.

MATERIALS AND METHODS

A comprehensive literature search was conducted through the PubMed, Scopus and CENTRAL databases up to August 2022. Study quality was assessed using the Newcastle-Ottawa scale. Associations were calculated as odds ratio (OR) with 95 % confidence interval (CI). The I2 index was employed for heterogeneity.

RESULTS

Eleven studies (nine assessed as of good and two as of fair quality) were included in the meta-analysis (n = 4,716,862). Women with EM demonstrated a greater risk of dementia of any type than women of normal age at menopause (OR 1.37, 95 % CI 1.22-1.54; I2 93%). However, after excluding a large retrospective cohort study, the results were altered (OR 1.07, 95 % CI 0.78-1.48; I2 94%). Increased risk of dementia was also found in women with POI (OR 1.18, 95 % CI 1.15-1.21; I2 0%). Subgroup analysis showed that this risk was mostly evident in cohort studies, and those which included women with natural menopause.

CONCLUSIONS

Women with EM or POI may be at increased risk of dementia compared with women of normal age at menopause, but further research investigating that hypothesis is warranted.