Female reproductive factors and the risk of dementia: a nationwide cohort study

The Heterogeneity of Post-Menopausal Disease Risk: Could the Basis for Why Only Subsets of Females Are Affected Be Due to a Reversible Epigenetic Modification System Associated with Puberty, Menstrual Cycles, Pregnancy and Lactation, and, Ultimately, Menopause?

For much of human evolution, the average lifespan was <40 years, due in part to disease, infant mortality, predators, food insecurity, and, for females, complications of childbirth. Thus, for much of evolution, many females did not reach the age of menopause (45-50 years of age) and it is mainly in the past several hundred years that the lifespan has been extended to >75 years, primarily due to public health advances, medical interventions, antibiotics, and nutrition. Therefore, the underlying biological mechanisms responsible for disease risk following menopause must have evolved during the complex processes leading to Homo sapiens to serve functions in the pre-menopausal state. Furthermore, as a primary function for the survival of the species is effective reproduction, it is likely that most of the advantages of having such post-menopausal risks relate to reproduction and the ability to address environmental stresses. This opinion/perspective will be discussed in the context of how such post-menopausal risks could enhance reproduction, with improved survival of offspring, and perhaps why such risks are preserved. Not all post-menopausal females exhibit risk for this set of diseases, and those who do develop such diseases do not have all of the conditions. The diseases of the post-menopausal state do not operate as a unified complex, but as independent variables, with the potential for some overlap. The how and why there would be such heterogeneity if the risk factors serve essential functions during the reproductive years is also discussed and the concept of sets of reversible epigenetic changes associated with puberty, pregnancy, and lactation is offered to explain the observations regarding the distribution of post-menopausal conditions and their potential roles in reproduction. While the involvement of an epigenetic system with a dynamic "modification-demodification-remodification" paradigm contributing to disease risk is a hypothesis at this point, validation of it could lead to a better understanding of post-menopausal disease risk in the context of reproduction with commonalities may also lead to future improved interventions to control such risk after menopause.

Altered pubertal timing in 7q11.23 copy number variations and associated genetic mechanisms

Pubertal timing, including age at menarche (AAM), is a heritable trait linked to lifetime health outcomes. Here, we investigate genetic mechanisms underlying AAM by combining genome-wide association study (GWAS) data with investigations of two rare genetic conditions clinically associated with altered AAM: Williams syndrome (WS), a 7q11.23 hemideletion characterized by early puberty; and duplication of the same genes (7q11.23 Duplication syndrome [Dup7]) characterized by delayed puberty. First, we confirm that AAM-derived polygenic scores in typically developing children (TD) explain a modest amount of variance in AAM (R2 = 0.09; p = 0.04). Next, we demonstrate that 7q11.23 copy number impacts AAM (WS < TD < Dup7; p = 1.2x10-8, η2 = 0.45) and pituitary volume (WS < TD < Dup7; p = 3x10-5, ηp2 = 0.2) with greater effect sizes. Finally, we relate an AAM-GWAS signal in 7q11.23 to altered expression in postmortem brains of STAG3L2 (p = 1.7x10-17), a gene we also find differentially expressed with 7q11.23 copy number (p = 0.03). Collectively, these data explicate the role of 7q11.23 in pubertal onset, with STAG3L2 and pituitary development as potential mediators.

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.

Connections between reproductive health and cognitive aging among women enrolled in the HCHS/SOL and SOL-INCA

INTRODUCTION

Reproductive health history may contribute to cognitive aging and risk for Alzheimer's disease, but this is understudied among Hispanic/Latina women.

METHODS

Participants included 2126 Hispanic/Latina postmenopausal women (44 to 75 years) from the Study of Latinos-Investigation of Neurocognitive Aging. Survey linear regressions separately modeled the associations between reproductive health measures (age at menarche, history of oral contraceptive use, number of pregnancies, number of live births, age at menopause, female hormone use at Visit 1, and reproductive span) with cognitive outcomes at Visit 2 (performance, 7-year change, and mild cognitive impairment [MCI] prevalence).

RESULTS

Younger age at menarche, oral contraceptive use, lower pregnancies, lower live births, and older age at menopause were associated with better cognitive performance. Older age at menarche was protective against cognitive change. Hormone use was linked to lower MCI prevalence.

DISCUSSION

Several aspects of reproductive health appear to impact cognitive aging among Hispanic/Latina women.

Male- and female-specific reproductive risk factors across the lifespan for dementia or cognitive decline: a systematic review and meta-analysis

BACKGROUND

Sex difference exists in the prevalence of dementia and cognitive decline. The impacts of sex-specific reproductive risk factors across the lifespan on the risk of dementia or cognitive decline are still unclear. Herein, we conducted this systemic review and meta-analysis to finely depict the longitudinal associations between sex-specific reproductive factors and dementia or cognitive decline.

METHODS

PubMed, EMBASE, and Cochrane Library were searched up to January 2023. Studies focused on the associations of female- and male-specific reproductive factors with dementia or cognitive decline were included. Multivariable-adjusted effects were pooled via the random effect models. Evidence credibility was scored by the GRADE system. The study protocol was pre-registered in PROSPERO and the registration number is CRD42021278732.

RESULTS

A total of 94 studies were identified for evidence synthesis, comprising 9,839,964 females and 3,436,520 males. Among the identified studies, 63 of them were included in the meta-analysis. According to the results, seven female-specific reproductive factors including late menarche (risk increase by 15%), nulliparous (11%), grand parity (32%), bilateral oophorectomy (8%), short reproductive period (14%), early menopause (22%), increased estradiol level (46%), and two male-specific reproductive factors, androgen deprivation therapy (18%), and serum sex hormone-binding globulin (22%) were associated with an elevated risk of dementia or cognitive decline.

CONCLUSIONS

These findings potentially reflect sex hormone-driven discrepancy in the occurrence of dementia and could help build sex-based precise strategies for preventing dementia.

Hormonal contraception and risk for cognitive impairment or Alzheimer's disease and related dementias in young women: a scoping review of the evidence

Introduction

Women are significantly more likely to develop Alzheimer's disease and related dementias (ADRD) than men. Suggestions to explain the sex differences in dementia incidence have included the influence of sex hormones with little attention paid to date as to the effect of hormonal contraception on brain health. The aim of this scoping review is to evaluate the current evidence base for associations between hormonal contraceptive use by women and non-binary people in early adulthood and brain health outcomes.

Methods

A literature search was conducted using EMBASE, Medline and Google Scholar, using the keywords "hormonal contraception" OR "contraception" OR "contraceptive" AND "Alzheimer*" OR "Brain Health" OR "Dementia".

Results

Eleven papers were identified for inclusion in the narrative synthesis. Studies recruited participants from the UK, USA, China, South Korea and Indonesia. Studies included data from women who were post-menopausal with retrospective data collection, with only one study contemporaneously collecting data from participants during the period of hormonal contraceptive use. Studies reported associations between hormonal contraceptive use and a lower risk of ADRD, particularly Alzheimer's disease (AD), better cognition and larger grey matter volume. Some studies reported stronger associations with longer duration of hormonal contraceptive use, however, results were inconsistent. Four studies reported no significant associations between hormonal contraceptive use and measures of brain health, including brain age on MRI scans and risk of AD diagnosis.

Discussion

Further research is needed on young adults taking hormonal contraceptives, on different types of hormonal contraceptives (other than oral) and to explore intersections between sex, gender, race and ethnicity.

Systematic Review Registration

https://doi.org/10.17605/OSF.IO/MVX63, identifier: OSF.io: 10.17605/OSF.IO/MVX63.

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.

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.

Parity and Risk of Dementia in Women: The Atherosclerosis Risk in Communities Study

Objective: Reproductive factors, including parity, may contribute to dementia risk, due to hormonal, physiological, social, and demographic factors. We hypothesized that higher parity would be associated with increased dementia risk. Materials and Methods: We utilized data from the Atherosclerosis Risk in Communities (ARIC) community-based cohort study. Participants were recruited in 1987-1989 and followed through 2017. Participants, all born between 1921 and 1945, were from four U.S. communities in Forsyth County, NC; Jackson, MS; Minneapolis, MN; and Washington County, MD. We included all female participants seen at ARIC visit three or five for whom parity and dementia outcomes were available (N = 7,921). The primary exposure was self-reported number of live births. Our primary outcome was dementia, diagnosed via neurocognitive assessments, informant interviews, and expert adjudication. We created Cox proportional hazards models to evaluate the association between parity and incident dementia, adjusting for demographic factors, education level, apolipoprotein E allele status, and vascular risk factors. We tested for interactions by race and birth cohort. Results: The adjusted hazard ratio was 0.82 (95% confidence intervals [CI] 0.69-0.99) for dementia in women with 0-1 births and 0.85 (95% CI 0.72-0.99) for women with 5+ births, compared to women with 2 births (reference group). This association was present in women born from 1924 to 1934, but not in women born in 1935 or later (p-interaction <0.001). Conclusion: We found an inverted U-shaped association of parity with dementia risk. This effect was modified by birth cohort, suggesting that the association may depend on demographic and sociocultural factors.

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.

Review of mendelian randomization studies on age at natural menopause

Menopause marks the end of the reproductive phase of life. Based on epidemiological studies, abnormal age at natural menopause (ANM) is thought to contribute to a number of adverse outcomes, such as osteoporosis, cardiovascular disease, and cancer. However, the causality of these associations remains unclear. A powerful epidemiological method known as Mendelian randomization (MR) can be used to clarify the causality between ANM and other diseases or traits. The present review describes MR studies that included ANM as an exposure, outcome and mediator. The findings of MR analyses on ANM have revealed that higher body mass index, poor educational level, early age at menarche, early age at first live birth, early age at first sexual intercourse, and autoimmune thyroid disease appear to be involved in early ANM etiology. The etiology of late ANM appears to be influenced by higher free thyroxine 4 and methylene tetrahydrofolate reductase gene mutations. Furthermore, early ANM has been found to be causally associated with an increased risk of osteoporosis, fracture, type 2 diabetes mellitus, glycosylated hemoglobin, and the homeostasis model of insulin resistance level. In addition, late ANM has been found to be causally associated with an increased systolic blood pressure, higher risk of breast cancer, endometrial cancer, endometrioid ovarian carcinoma, lung cancer, longevity, airflow obstruction, and lower risk of Parkinson's disease. ANM is also a mediator for breast cancer caused by birth weight and childhood body size. However, due to the different instrumental variables used, some results of studies are inconsistent. Future studies with more valid genetic variants are needed for traits with discrepancies between MRs or between MR and other types of epidemiological studies.

Age at menopause and all-cause and cause-specific dementia: a prospective analysis of the UK Biobank cohort

STUDY QUESTION

Are there associations between natural or surgical menopause and incident dementia by age at menopause?

SUMMARY ANSWER

Compared to age at menopause of 46-50 years, earlier natural menopause (≤40 and 41-45 years) was related to higher risk of all-cause dementia, while a U-shape relationship was observed between age at surgical menopause and risk of dementia.

WHAT IS KNOWN ALREADY

Menopause marks the end of female reproductive period. Age at menopause reflects the length of exposure to endogenous estrogen. Evidence on the association between age at natural, surgical menopause, and risk of dementia has been inconsistent.

STUDY DESIGN, SIZE, DURATION

A population-based cohort study involving 160 080 women who participated in the UK Biobank study.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Women with no dementia at baseline, and had no missing data on key exposure variables and covariates were included. Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% CIs on the association of categorical menopause age with incident all-cause dementia, Alzheimer's disease (AD) and vascular dementia (VD). Restricted cubic splines were used to model the non-linear relationship between continuous age at natural, surgical menopause, and risk of dementia. In addition, we analyzed the interaction effect of ever-used menopausal hormone therapy (MHT) at baseline, income level, leisure activities, and age at menopause on risk of dementia.

MAIN RESULTS AND THE ROLE OF CHANCE

Compared to women with age at menopause of 46-50 years, women with earlier natural menopause younger than 40 years (1.36, 1.01-1.83) and 41-45 years (1.19, 1.03-1.39) had a higher risk of all-cause dementia, while late natural menopause >55 years was linked to lower risk of dementia (0.83, 0.71-0.98). Compared to natural menopause, surgical menopause was associated with 10% higher risk of dementia (1.10, 0.98-1.24). A U-shape relationship was observed between surgical menopause and risk of dementia. Women with surgical menopause before age 40 years (1.94, 1.38-2.73) and after age 55 years (1.65, 1.21-2.24) were both linked to increased risk of all-cause dementia. Women with early natural menopause without ever taking MHT at baseline had an increased risk of AD. Also, in each categorized age at the menopause level, higher income level or higher number of leisure activities was linked to a lowers risk of dementia.

LIMITATIONS, REASONS FOR CAUTION

Menopausal age was based on women's self-report, which might cause recall bias.

WIDER IMPLICATION OF THE FINDINGS

Women who experienced natural menopause or had surgical menopause at an earlier age need close monitoring and engagement for preventive health measures to delay the development of dementia.

STUDY FUNDING/COMPETING INTERESTS

This work was supported by the Start-up Foundation for Scientific Research in Shandong University (202099000066), Science Fund Program for Excellent Young Scholars of Shandong Provence (Overseas) (2022HWYQ-030), and the National Natural Science Foundation of China (82273702). There are no competing interests.

TRIAL REGISTRATION NUMBER

N/A.

Association of earlier age at menopause with risk of incident dementia, brain structural indices and the potential mediators: a prospective community-based cohort study

Background

To date, there is no homogeneous evidence of whether earlier age at menopause is associated with incident dementia. In addition, the underlying mechanism and driven mediators are largely unknown. We aimed to fill these knowledge gaps.

Methods

This community-based cohort study included 154,549 postmenopausal women without dementia at enrolment (between 2006 and 2010) from the UK Biobank who were followed up until June 2021. We followed up until June 2021. Age at menopause was entered as a categorical variable (<40, 40-49, and ≥50 years) with ≥50 years taken as a reference. The primary outcome was all-cause dementia in a time-to-event analysis and the secondary outcomes included Alzheimer's disease, vascular dementia, and other types of dementia. In addition, we investigated the association between magnetic resonance (MR) brain structure indices with earlier menopause, and explored the potential underlying driven mediators on the relationship between earlier menopause and dementia.

Findings

2266 (1.47%) dementia cases were observed over a median follow-up period of 12.3 years. After adjusting for confounders, women with earlier menopause showed a higher risk of all-cause dementia compared with those ≥50 years (adjusted-HRs [95% CIs]: 1.21 [1.09-1.34] and 1.71 [1.38-2.11] in the 40-49 years and <40 years groups, respectively; P for trend <0.001). No significant interactions between earlier menopause and polygenic risk score, cardiometabolic factors, type of menopause, or hormone-replacement therapy strata were found. Earlier menopause was negatively associated with brain MR global and regional grey matter indices, and positively associated with white matter hyperintensity. The relationship between earlier menopause and dementia was partially mediated by menopause-related comorbidities including sleep disturbance, mental health disorder, frailty, chronic pain, and metabolic syndrome, with the proportion (95% CI) of mediation effect being 3.35% (2.18-5.40), 1.38% (1.05-3.20), 5.23% (3.12-7.83), 3.64% (2.88-5.62) and 3.01% (2.29-4.40), respectively. Multiple mediator analysis showed a combined effect being 13.21% (11.11-18.20).

Interpretation

Earlier age at menopause was associated with risk of incident dementia and deteriorating brain health. Further studies are warranted to clarify the underlying mechanisms by which earlier age at menopause is linked to an increased risk of dementia, and to determine public health strategies to attenuate this association.

Funding

National Natural Science Foundation of China, the Science and Technology Program of Guangzhou, the Key Area Research and Development Program of Guangdong Province, the China Postdoctoral Science Foundation, and the Guangdong Basic and Applied Basic Research Foundation.

Cognitive Decline in Early and Premature Menopause

Early and premature menopause, or premature ovarian insufficiency (POI), affects 1% of women under the age of 40 years. This paper reviews the main aspects of early and premature menopause and their impact on cognitive decline. Based on the literature, cognitive complaints are more common near menopause: a phase marked by a decrease in hormone levels, especially estrogen. A premature reduction in estrogen puts women at a higher risk for cardiovascular disease, parkinsonism, depression, osteoporosis, hypertension, weight gain, midlife diabetes, as well as cognitive disorders and dementia, such as Alzheimer's disease (AD). Experimental and epidemiological studies suggest that female sex hormones have long-lasting neuroprotective and anti-aging properties. Estrogens seem to prevent cognitive disorders arising from a cholinergic deficit in women and female animals in middle age premature menopause that affects the central nervous system (CNS) directly and indirectly, both transiently and in the long term, leads to cognitive impairment or even dementia, mainly due to the decrease in estrogen levels and comorbidity with cardiovascular risk factors, autoimmune diseases, and aging. Menopausal hormone therapy from menopause to the age of 60 years may provide a "window of opportunity" to reduce the risk of mild cognitive impairment (MCI) and AD in later life. Women with earlier menopause should be taken care of by various specialists such as gynecologists, endocrinologists, neurologists, and psychiatrists in order to maintain their mental health at the highest possible level.

Women's reproductive traits and cerebral small-vessel disease: A two-sample Mendelian randomization study

Background

Observational studies have suggested that women's reproductive factors (age at menarche (AAM), age at first birth (AFB), age at first sexual intercourse (AFS), age at natural menopause (ANM), and pregnancy loss) may influence the risk of cerebral small-vessel disease (CSVD) although the causality remains unclear.

Methods

We conducted two-sample univariable Mendelian randomization (UVMR) and multivariable MR (MVMR) to simultaneously investigate the causal relationships between five women's reproductive traits and CSVD clinical [intracerebral hemorrhage (ICH) by location or small-vessel ischemic stroke (SVS)] and subclinical measures [white matter hyperintensities (WMH), fractional anisotropy (FA), and mean diffusivity (MD)], utilizing data from large-scale genome-wide association studies of European ancestry. For both UVMR and MVMR, the inverse-variance-weighted (IVW) estimates were reported as the main results. The MR-Egger, weighted median, generalized summary-data-based MR (GSMR), and MR-pleiotropy residual sum and outlier (MR-PRESSO) methods for UVMR and MVMR-Egger, and the MVMR-robust methods for MVMR were used as sensitivity analyses. Sex-combined instruments for AFS and AFB were used to assess the impact of sex instrumental heterogeneity. Positive control analysis was implemented to measure the efficacy of selected genetic instruments.

Results

We found no evidence to support causal associations between genetic liability for women's reproductive factors and the risk of CSVD in UVMR (all P-values &gt; 0.05). Using MVMR, the results were consistent with the findings of UVMR after accounting for body mass index and educational attainment (all P-values &gt; 0.05). Sensitivity analyses also provided consistent results. The putative positive causality was observed between AAM, ANM, and ovarian cancer, ensuring the efficacy of selected genetic instruments.

Conclusion

Our findings do not convincingly support a causal effect of women's reproductive factors on CSVD. Future studies are warranted to investigate specific estrogen-related physiological changes in women, which may inform current researchers on the causal mechanisms involved in cerebral small-vessel disease progression.

Walking for Cognitive Health: Previous Parity Moderates the Relationship Between Self-Reported Walking and Cognition

BACKGROUND

Older females show greater cognitive gains from physical activity (PA) than males, which may be related to long-term consequences of female-specific reproductive events (eg, pregnancy) on cognitive health.

METHODS

To determine whether previous parity could moderate the relationship between PA and cognitive decline in older women, we conducted secondary analyses of data from the Health, Aging, and Body Composition Study. We tested whether the association between average PA over 10 years and cognition (Modified Mini-Mental State Examination [3MS]) and executive functioning (digit symbol substitution test [DSST]) over 10 years varied by previous parity (nulliparity, low parity, medium parity, and grand multiparity). An analysis of covariance was performed with cognition (average and change over 10 years) as the dependent variables, parity as a categorical predictor, average PA as a continuous predictor, and a set of relevant covariates.

RESULTS

Significant interactions were found between PA and parity group for all 4 comparisons: average 3MS (p = .014), average DSST (p = .032), change in 3MS (p = .016), and change in DSST (p = .017). Simple slope analyses indicated the positive relationship between PA and average 3MS and DSST was only significant in the nulliparity and grand multiparity groups, and the positive relationship between PA and change in 3MS and DSST was only significant in the grand multiparity group.

CONCLUSION

The findings suggest the relationship between self-reported walking and cognitive performance was strongest in the groups at risk for cognitive decline and dementia, the nulliparous and grand multiparous groups.

Associations of reproductive factors with incidence of myocardial infarction and ischemic stroke in postmenopausal women: a cohort study

BACKGROUND

To assess the association between the reproductive factors of age at menarche, age at menopause, and reproductive span and the incidence of myocardial infarction (MI) and ischemic stroke (IS).

METHODS

We used a population-based retrospective cohort study from the National Health Insurance Service database of Korea including a total of 1,224,547 postmenopausal women. Associations between age at menarche (≤ 12, 13-14 [reference], 15, 16, and ≥ 17 years), age at menopause (< 40, 40-45, 46-50, 51-54 [reference], and ≥ 55 years), and reproductive span (< 30, 30-33, 34-36, 37-40 [reference], and ≥ 41 years) and the incidence of MI and IS were assessed by Cox proportional hazard models with adjustment for traditional cardiovascular risk factors and various reproductive factors.

RESULTS

During a median follow-up of 8.4 years, 25,181 MI and 38,996 IS cases were identified. Late menarche (≥ 16 years), early menopause (≤ 50 years), and short reproductive span (≤ 36 years) were linearly associated with a 6%, 12-40%, and 12-32% higher risk of MI, respectively. Meanwhile, a U-shaped association between age at menarche and risk of IS was found, with a 16% higher risk in early menarche (≤ 12 years) and a 7-9% higher risk in late menarche (≥ 16 years). Short reproductive span was linearly associated with an increased risk of MI, whereas both shorter and longer reproductive spans were associated with an increased risk of IS.

CONCLUSIONS

This study demonstrated different patterns of association between age at menarche and incidence of MI and IS: a linear association for MI versus a U-shaped association for IS. Female reproductive factors in addition to traditional cardiovascular risk factors should be considered when assessing overall cardiovascular risk in postmenopausal women.

Is Hormone Replacement Therapy a Risk Factor or a Therapeutic Option for Alzheimer's Disease?

Alzheimer's disease (AD) is a progressive neurodegenerative disorder that accounts for more than half of all dementia cases in the elderly. Interestingly, the clinical manifestations of AD disproportionately affect women, comprising two thirds of all AD cases. Although the underlying mechanisms for these sex differences are not fully elucidated, evidence suggests a link between menopause and a higher risk of developing AD, highlighting the critical role of decreased estrogen levels in AD pathogenesis. The focus of this review is to evaluate clinical and observational studies in women, which have investigated the impact of estrogens on cognition or attempted to answer the prevailing question regarding the use of hormone replacement therapy (HRT) as a preventive or therapeutic option for AD. The articles were retrieved through a systematic review of the databases: OVID, SCOPUS, and PubMed (keywords "memory", "dementia," "cognition," "Alzheimer's disease", "estrogen", "estradiol", "hormone therapy" and "hormone replacement therapy" and by searching reference sections from identified studies and review articles). This review presents the relevant literature available on the topic and discusses the mechanisms, effects, and hypotheses that contribute to the conflicting findings of HRT in the prevention and treatment of age-related cognitive deficits and AD. The literature suggests that estrogens have a clear role in modulating dementia risk, with reliable evidence showing that HRT can have both a beneficial and a deleterious effect. Importantly, recommendation for the use of HRT should consider the age of initiation and baseline characteristics, such as genotype and cardiovascular health, as well as the dosage, formulation, and duration of treatment until the risk factors that modulate the effects of HRT can be more thoroughly investigated or progress in the development of alternative treatments can be made.

Cognitive decline and dementia in women after menopause: Prevention strategies

Worldwide, cognitive decline and dementia are becoming one of the biggest challenges for public health. The decline in cognition and the development of dementia may be caused by predisposing or trigger factors. There is no consensus over whether the drop in estrogen levels after menopause is a risk factor for cognitive decline and dementia. This article discusses the prevention of cognitive decline and dementia in women after menopause, both primary prevention (essentially pharmacological intervention) and secondary prevention (chiefly diet and weight reduction). Further study is required to clarify whether menopausal hormone therapy (MHT) has a role in dementia.

Mental rotation, episodic memory, and executive control: Possible effects of biological sex and oral contraceptive use

Oral contraceptives (OCs) are one of the most common forms of hormonal birth control. A small literature suggests that OC use may affect visuospatial ability, episodic memory, and executive control. However, previous studies have been criticized for small sample sizes and the use of different, single cognitive tests. We investigated the degree to which biological sex and OC use might affect individual mental rotation, episodic memory, and executive control in a large sample of healthy, young adults (N = 155, including 52 OC users, 53 naturally cycling females, and 50 males) tested individually over videoconference. To measure cognition, we used a set of neuropsychological tasks inspired by Glisky and colleagues' two-factor episodic memory and executive control battery, from which two composite scores (based on principal component analysis) were derived for each participant. Our pre-registered analysis revealed a clear female advantage in episodic memory, independent of OC use. In an exploratory analysis, gist memory was elevated in OC users. Interestingly, we found no significant sex-related differences nor effects of OC use on mental rotation or executive control. Duration of OC use was also not related to any of our cognitive measures. These results suggest that the use of combined, monophasic OCs does not lead to many significant changes in cognition in young adults, although young females overall may have better episodic memory than young males. Additional studies, including longitudinal designs and looking in more detail at the menstrual cycle and OC use history, will further clarify the effects of different types of OCs and their duration of use on different aspects of cognition.

Therapeutics of Alzheimer's Disease: Recent Developments

With increasing aging, dementia is a growing public health concern globally. Patients with dementia have multiple psychological and behavioral changes, including depression, anxiety, inappropriate behavior, paranoia, agitation, and hallucinations. The major types of dementia are Alzheimer's disease (AD), vascular dementia (VCID), Lewy body dementia (LBD), frontotemporal dementia (FTD), and mixed dementia (MiAD). Among these, AD is the most common form of dementia in the elderly population. In the last three decades, tremendous progress has been made in understanding AD's biology and disease progression, particularly its molecular basis, biomarker development, and drug discovery. Multiple cellular changes have been implicated in the progression of AD, including amyloid beta, phosphorylated tau, synaptic damage, mitochondrial dysfunction, deregulated microRNAs, inflammatory changes, hormonal deregulation, and others; based on these changes, therapeutic strategies have been developed, which are currently being tested in animal models and human clinical trials. The purpose of our article is to highlight recent therapeutic strategies' developments, critically discuss current strategies' failures, and propose new strategies to combat this devasting mental illness.

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

Background

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

Methods

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

Results

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

Conclusions

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

Dementia Prevention in Clinical Practice

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

Sex differences in the association between cardiovascular diseases and dementia subtypes: a prospective analysis of 464,616 UK Biobank participants

BACKGROUND

Whether the association of cardiovascular diseases (CVDs) with dementia differs by sex remains unclear, and the role of socioeconomic, lifestyle, genetic, and medical factors in their association is unknown.

METHODS

We used data from the UK Biobank, a population-based cohort study of 502,649 individuals. We used Cox proportional hazards models to estimate sex-specific hazard ratios (HRs) and 95% confidence intervals (CI), and women-to-men ratio of HRs (RHR) for the association between CVD (coronary heart diseases (CHD), stroke, and heart failure) and incident dementia (all-cause dementia, Alzheimer's Disease (AD), and vascular dementia (VD)). The moderator roles of socioeconomic (education, income), lifestyle (smoking, BMI, leisure activities, and physical activity), genetic factors (APOE allele status), and medical history were also analyzed.

RESULTS

Compared to people who did not experience a CVD event, the HRs (95%CI) between CVD and all-cause dementia were higher in women compared to men, with an RHR (Female/Male) of 1.20 (1.13, 1.28). Specifically, the HRs for AD were higher in women with CHD and heart failure compared to men, with an RHR (95%CI) of 1.63 (1.39, 1.91) and 1.32 (1.07, 1.62) respectively. The HRs for VD were higher in men with heart failure than women, with RHR (95%CI) of 0.73 (0.57, 0.93). An interaction effect was observed between socioeconomic, lifestyle, genetic factors, and medical history in the sex-specific association between CVD and dementia.

CONCLUSION

Women with CVD were 1.5 times more likely to experience AD than men, while had 15% lower risk of having VD than men.

Oophorectomy and rate of dementia: a prospective cohort study

OBJECTIVE

Globally, dementia disproportionally affects women, which is not fully explained by higher female longevity. Oophorectomy at any age leads to the permanent loss of ovarian sex steroids, potentially increasing the risk of dementia. We aimed to investigate the association between oophorectomy and dementia and whether this was conditional on age at oophorectomy, hysterectomy or use of hormone therapy (HT).

METHODS

A prospective study of 24,851 female nurses from the Danish Nurse Cohort. Nurses were followed from age 60 years or entry into the cohort, whichever came last, until date of dementia, death, emigration or end of follow-up (December 31, 2018), whichever came first. Poisson regression models with log-transformed person-years as offset were used to estimate the associations.

RESULTS

During 334,420 person-years of follow-up, 1,238 (5.0%) nurses developed dementia and 1,969 (7.9%)/ 1,016 (4.1%) contributed person-time after bilateral-/unilateral oophorectomy. In adjusted analyses, an 18% higher rate of dementia was observed following bilateral oophorectomy (aRR 1.18: 95% CI, 0.89-1.56) and 13% lower rate (aRR 0.87: 95% CI, 0.59-1.23) following unilateral oophorectomy compared to nurses who retained their ovaries. Similar effects were detected after stratification according to age at oophorectomy. No statistically significant modifying effects of hysterectomy or HT were detected (Pinteraction≥0.60).

CONCLUSIONS

Bilateral, but not unilateral, oophorectomy was associated with an increased rate of incident dementia. We were unable to establish whether this association was conditional on hysterectomy or HT use. Although an increase in dementia after bilateral oophorectomy is biologically plausible, limited statistical power hampers the precision of the estimates.

Prediction Models for Conversion From Mild Cognitive Impairment to Alzheimer’s Disease: A Systematic Review and Meta-Analysis

Background and Purpose

Alzheimer’s disease (AD) is a devastating neurodegenerative disorder with no cure, and available treatments are only able to postpone the progression of the disease. Mild cognitive impairment (MCI) is considered to be a transitional stage preceding AD. Therefore, prediction models for conversion from MCI to AD are desperately required. These will allow early treatment of patients with MCI before they develop AD. This study performed a systematic review and meta-analysis to summarize the reported risk prediction models and identify the most prevalent factors for conversion from MCI to AD.

Methods

We systematically reviewed the studies from the databases of PubMed, CINAHL Plus, Web of Science, Embase, and Cochrane Library, which were searched through September 2021. Two reviewers independently identified eligible articles and extracted the data. We used the Critical Appraisal and Data Extraction for Systematic Reviews of Prediction Modeling Studies (CHARMS) checklist for the risk of bias assessment.

Results

In total, 18 articles describing the prediction models for conversion from MCI to AD were identified. The dementia conversion rate of elderly patients with MCI ranged from 14.49 to 87%. Models in 12 studies were developed using the data from the Alzheimer’s Disease Neuroimaging Initiative (ADNI). C-index/area under the receiver operating characteristic curve (AUC) of development models were 0.67–0.98, and the validation models were 0.62–0.96. MRI, apolipoprotein E genotype 4 (APOE4), older age, Mini-Mental State Examination (MMSE) score, and Alzheimer’s Disease Assessment Scale cognitive (ADAS-cog) score were the most common and strongest predictors included in the models.

Conclusion

In this systematic review, many prediction models have been developed and have good predictive performance, but the lack of external validation of models limited the extensive application in the general population. In clinical practice, it is recommended that medical professionals adopt a comprehensive forecasting method rather than a single predictive factor to screen patients with a high risk of MCI. Future research should pay attention to the improvement, calibration, and validation of existing models while considering new variables, new methods, and differences in risk profiles across populations.

Reproductive factors and the risk of incident dementia: A cohort study of UK Biobank participants

BACKGROUND

Women's reproductive factors have been associated with the risk of dementia; however, these findings remain uncertain. This study aimed to examine the risk of incident all-cause dementia associated with reproductive factors in women and the number of children in both sexes and whether the associations vary by age, socioeconomic status (SES), smoking status, and body mass index (BMI) in the UK Biobank.

METHODS AND FINDINGS

A total of 273,240 women and 228,957 men without prevalent dementia from the UK Biobank were included in the analyses. Cox proportional hazard regressions estimated hazard ratios (HRs) for reproductive factors with incident all-cause dementia. Multiple adjusted models included age at study entry, SES, ethnicity, smoking status, systolic blood pressure, BMI, history of diabetes mellitus, total cholesterol, antihypertensive drugs, and lipid-lowering drugs. Over a median of 11.8 years follow-up, 1,866 dementia cases were recorded in women and 2,202 in men. Multiple adjusted HRs ((95% confidence intervals (CIs)), p-value) for dementia were 1.20 (1.08, 1.34) (p = 0.016) for menarche <12 years and 1.19 (1.07, 1.34) (p = 0.024) for menarche >14 years compared to 13 years; 0.85 (0.74, 0.98) (p = 0.026) for ever been pregnant; 1.43 (1.26, 1.62) (p < 0.001) for age at first live birth <21 compared to 25 to 26 years; 0.82 (0.71, 0.94) (p = 0.006) for each abortion; 1.32 (1.15, 1.51) (p = 0.008) for natural menopause at <47 compared to 50 years; 1.12 (1.01, 1.25) (p = 0.039) for hysterectomy; 2.35 (1.06, 5.23) (p = 0.037) for hysterectomy with previous oophorectomy; and 0.80 (0.72, 0.88) (p < 0.001) for oral contraceptive pills use. The U-shaped associations between the number of children and the risk of dementia were similar for both sexes: Compared with those with 2 children, for those without children, the multiple adjusted HR ((95% CIs), p-value) was 1.18 (1.04, 1.33) (p = 0.027) for women and 1.10 (0.98, 1.23) (p = 0.164) for men, and the women-to-men ratio of HRs was 1.09 (0.92, 1.28) (p = 0.403); for those with 4 or more children, the HR was 1.14 (0.98, 1.33) (p = 0.132) for women and 1.26 (1.10, 1.45) (p = 0.003) for men, and the women-to-men ratio of HRs was 0.93 (0.76, 1.14) (p = 0.530). There was evidence that hysterectomy (HR, 1.31 (1.09, 1.59), p = 0.013) and oophorectomy (HR, 1.39 (1.08, 1.78), p = 0.002) were associated with a higher risk of dementia among women of relatively lower SES only. Limitations of the study include potential residual confounding and self-reported measures of reproductive factors, as well as the limited representativeness of the UK Biobank population.

CONCLUSIONS

In this study, we observed that some reproductive events related to shorter cumulative endogenous estrogen exposure in women were associated with higher dementia risk, and there was a similar association between the number of children and dementia risk between women and men.

Association of reproductive factors with dementia: A systematic review and dose-response meta-analyses of observational studies

BACKGROUND

Associations between endogenous estrogen exposure indicators and risk of subtypes of dementia have been unclear.

METHODS

Databases (PubMed, EMBASE and Web of Science) were searched electronically on 1st July and updated regularly until 12nd November 2021. Observational studies of English language were selected if reported an effect estimate [e.g., odds ratio (OR), rate ratio (RR) or hazard ratio (HR)] and 95% CI for the association between any exposure (age of menarche, age at menopause, reproductive period, estradiol level) and any endpoint variable [all-cause dementia, Alzheimer's disease (AD), vascular dementia (VD), cognitive impairment (CI)]. Random-effects models and dose-response meta-analyses were used to calculate estimates and to show the linear/nonlinear relationship. PROSPERO CRD42021274827.

FINDINGS

We included 22 studies (475 9764 women) in this analysis. We found no clear relationship between late menarche (≥14 vs <14 years) and dementia, CI in categorical meta-analysis compared to a J-shape relationship in dose-response meta-analyses. Later menopause (≥45 vs <45 years) was consistently associated with a lower risk of all-cause dementia (pooled RR: 0.87, 95%CI: 0.78-0.97, I²=56.0%), AD (0.67, 0.44-0.99, I²=78.3%), VD (0.87, 0.80-0.94) and CI (0.82, 0.71-0.94, I²=19.3%) in categorical meta-analysis, showing similar results in dose-response meta-analyses. An inverse relationship between longer reproductive duration (≥35 vs <35 years) and dementia was observed in dose-response meta-analysis. In addition, estradiol levels after menopause were inversely correlated with the risk of AD and CI.

INTERPRETATION

In this study, later menopause and longer reproductive period were associated with a lower risk of dementia, while the relationship for menarchal age was J-shaped. There was an inverse relationship between higher postmenopausal estrogen levels and risk of AD and CI. Longitudinal study are needed to further explore the association between life-time estrogen exposure and risk of subtypes of dementia.

FUNDING

Start-up Foundation for Scientific Research in Shandong University.

Cognitive health after menopause: Does menopausal hormone therapy affect it?

Dementia is a pandemic chronic non-communicable disease. 10 in 100 women above age 65 will be diagnosed with dementia, primarily Alzheimer's disease (AD). Apart from age and hereditary risk factors, there are multiple acquired risk and protective factors. So far, Menopausal Hormone Therapy (MHT) is not recommended as preventive measure. A systematic literature search on MHT and dementia risk and MHT and cognitive performance in demented women, respectively, was performed. Two recent meta-analyses identified 18 and 16 studies analyzing the impact of MHT on dementia/AD risk. Our systematic literature search identified eight additional original articles. The majority of studies found a risk reducing impact of MHT by 11-33%. However, results may vary depending on MHT type, age at initiation and study design. For example, the Women's Health Initiative Memory Study (WHIMS) reported an approximately 2-fold increased risk of dementia/Alzheimer's disease if MHT comprising conjugated equine estrogens and medroxyprogesterone acetate was initiated in predominantly comorbid postmenopausal women above age 65. In general, MHT displays a beneficial effect on several dementia risk factors and also augments some protective factors. Accordingly, clinicians can be reassured that MHT can be safely prescribed in the context of cognition in women free of dementia. However, MHT is not indicated for cognitive improvement in demented women. International scientific guidelines on MHT and dementia should consider incorporating most recent data.

The effect of hormone replacement therapy on cognitive function in healthy postmenopausal women: a meta-analysis of 23 randomized controlled trials

To investigate how hormone replacement therapy (HRT) intervention affects cognitive function in randomized controlled trials of healthy postmenopausal women, the PubMed and Web of Science databases were searched for relevant publications up to 1 May 2020. Random-effects, subgroup analysis, sensitivity analysis and meta-regression analyses were conducted with 23 selected publications. HRT had a significant negative effect on global cognition (standardized mean difference (SMD): -0.04, 95% confidence interval (CI): -0.08 to -0.01). Via subgroup analysis, for those older than 60 years and with more than 6 months' intervention duration, HRT aggravated global cognition (SMD: -0.05, 95% CI: -0.08 to -0.01; SMD: -0.05, 95% CI: -0.08 to -0.01). The results of meta-regression demonstrated no significant association between HRT intervention and global cognition after adjusting for participants' age or intervention duration. In conclusion, HRT had a significant negative effect on global cognition, and this effect might be especially more visible for those aged more than 60 years and with more than 6 months' intervention. Further randomized controlled trials for postmenopausal women with a younger age and short-term HRT exposure are necessary to clarify the effects of HRT on global and domain-specific cognitive functions.

The relationship between fertility history and incident dementia in the US Health and Retirement Study

OBJECTIVES

An emerging literature suggests that fertility history, which includes measures of parity and birth timing, may influence cognitive health in older ages, especially among women given their differential exposure to pregnancy and sex hormones. Yet, few studies have examined associations between measures of fertility history and incident dementia in population-based samples.

METHODS

We examined the associations between parity, younger age at first birth, and older age at last birth with incident dementia over a 16-year period in a prospective sample of 15,361 men and women aged 51-100 years at baseline drawn from the Health and Retirement Study. We used Cox regression and the Fine and Gray model to obtain cause-specific (csHRs) and subdistribution hazard ratios (sdHRs) for incident dementia from gender-stratified models in which we accounted for the semi-competing risk of death.

RESULTS

During the follow-up period (median 13.0 years), the crude incidence rate for dementia was 16.6 and 19.9 per 1,000 person-years for men and women, respectively. In crude models estimating csHRs, higher parity (vs. parity 2) and younger age at first birth were associated with increased risk of dementia for both genders. These associations did not persist after full covariate adjustment. Across all models in which we estimated sdHRs, we observed a positive relationship between older age at last birth and incident dementia for women only.

DISCUSSION

In this population-based, multi-ethnic cohort, we observed limited evidence for an association between measures of fertility history and incident dementia among men and women after adjusting for potential confounders.

FEMALE REPRODUCTIVE FACTORS AND THE RISK OF EXUDATIVE AGE-RELATED MACULAR DEGENERATION: A Nationwide Cohort Study

PURPOSE

To evaluate the association between female reproductive factors and the incidence of exudative age-related macular degeneration (AMD).

METHODS

A total of 1,297,388 postmenopausal women over 50 years of age who participated in both national health screening and cancer screening in 2009 were identified using the Korea National Health Insurance System database. Data on female reproductive factors were collected using a self-administered questionnaire. Patients were followed up until 2018, and the incident cases of exudative AMD were identified. The hazard ratios and 95% confidence intervals for exudative AMD were estimated using the multivariable-adjusted Cox proportional hazard model.

RESULTS

During a mean follow-up of 7.27 years, 4,086 patients were newly diagnosed with exudative AMD. The hazard ratio (95% confidence intervals) for exudative AMD was 1.14 (1.01-1.31) for a reproductive period ≥40 years compared with a reproductive period <30 years, 1.72 (1.48-2.00) for patients with ≥5 years of hormone replacement therapy, and 1.29 (1.09-1.52) for those with 2 to 5 years of hormone replacement therapy compared with those who never underwent hormone replacement therapy.

CONCLUSION

Female reproductive factors were associated with the risk of exudative AMD. Greater lifetime exposure to endogenous and exogenous estrogen was associated with a higher incidence of exudative AMD.

Menopause and cognitive impairment: A narrative review of current knowledge

A severe impairment of cognitive function characterizes dementia. Mild cognitive impairment represents a transition between normal cognition and dementia. The frequency of cognitive changes is higher in women than in men. Based on this fact, hormonal factors likely contribute to cognitive decline. In this sense, cognitive complaints are more common near menopause, a phase marked by a decrease in hormone levels, especially estrogen. Additionally, a tendency toward worsened cognitive performance has been reported in women during menopause. Vasomotor symptoms (hot flashes, sweating, and dizziness), vaginal dryness, irritability and forgetfulness are common and associated with a progressive decrease in ovarian function and a subsequent reduction in the serum estrogen concentration. Hormone therapy (HT), based on estrogen with or without progestogen, is the treatment of choice to relieve menopausal symptoms. The studies conducted to date have reported conflicting results regarding the effects of HT on cognition. This article reviews the main aspects of menopause and cognition, including the neuroprotective role of estrogen and the relationship between menopausal symptoms and cognitive function. We present and discuss the findings of the central observational and interventional studies on HT and cognition.

The role of age at menarche and age at menopause in Alzheimer's disease: evidence from a bidirectional mendelian randomization study

The association between endogenous estrogen exposure and Alzheimer's disease (AD) remains inconclusive in previous observational studies, and few Mendelian randomization (MR) studies have focused on their causality thus far. We performed a bidirectional MR study to clarify the causality and causal direction of age at menarche and age at menopause, which are indicators of endogenous estrogen exposure, on AD risk. We obtained all genetic datasets for the MR analyses using publicly available summary statistics based on individuals of European ancestry from the IEU GWAS database. The MR analyses indicated no significant causal relationship between the genetically determined age at menarche (outlier-adjusted inverse variance weighted odds ratio [IVWOR] = 0.926; 95% confidence interval [CI], 0.803-1.066) or age at menopause (outlier-adjusted IVWOR = 0.981; 95% CI, 0.941-1.022) and AD risk. Similarly, AD did not show any causal association with age at menarche or age at menopause. The sensitivity analyses yielded similar results. In contrast, an inverse association was detected between age at menarche and body mass index (BMI, outlier-adjusted IVW β = -0.043; 95% CI, -0.077 to -0.009). Our bidirectional MR study provides no evidence for a causal relationship between the genetically determined age at menarche or age at menopause and AD susceptibility, or vice versa. However, earlier menarche might be associated with higher adult BMI.

A Lifecourse Perspective on Female Sex-Specific Risk Factors for Later Life Cognition

PURPOSE OF REVIEW

The prevalence of Alzheimer's disease and related dementias is greater in women compared to men. We provide a review of female sex-specific risk factors across the lifecourse for cognition in older adulthood, highlighting areas that need further study.

RECENT FINDINGS

Pregnancy may affect late-life cognition, with adverse pregnancy outcomes associated with an increased risk of cognitive decline but parity providing a protective effect. Cumulative estrogen exposure, influenced by age of menarche, menopause, and exogenous estrogen use, may modify a woman's risk for dementia. Menopause transition-associated symptoms may impact cognitive health at the time of the symptoms, but long-term effects remain unknown. As compared to natural menopause, surgical menopause seems to increase the risk for cognitive impairment. Studies that have assessed the association between women's reproductive health and cognition have produced conflicting results. Future studies that address these inconsistencies among diverse populations are needed to better care for women throughout their lives.

Reproductive period and preclinical cerebrospinal fluid markers for Alzheimer disease: a 25-year study

OBJECTIVE

The aim of the study was to examine the association between reproductive period, as an indicator of endogenous estrogen, and levels of cerebrospinal fluid (CSF) biomarkers for Alzheimer disease (AD).

METHODS

A population-based sample of women from Gothenburg, Sweden was followed from 1968 to 1994 (N = 75). All women had natural menopause and were free from dementia. Information on reproductive period (age at menarche to age at menopause) was obtained from interviews from 1968 to 1980. Lumbar puncture was performed from 1992 to 1994 and CSF levels of Aβ42, Aβ40, P-tau, and T-tau were measured with immunochemical methods. Linear regression models adjusted for potential confounders were used to analyze the relationship between reproductive period and CSF biomarkers for AD.

RESULTS

Longer reproductive period was associated with lower levels of Aβ42 (β = -19.2, P  = 0.01), higher levels of P-tau (β = 0.03, P  = 0.01), and lower ratio of Aβ42/Aβ40 (β = -0.02, P  = 0.01), while no association was observed for T-tau (β = 0.01, P  = 0.46). In separate analyses, examining the different components of reproductive period, earlier age at menarche was associated higher levels of P-tau (β = -0.07, P  = 0.031) and lower ratio of Aβ42/Aβ40 (β = 0.05, P  = 0.021), whereas no association was observed with Aβ42 (β = 31.1, P  = 0.11) and T-tau (β = -0.001, P  = 0.98). Furthermore, no association was observed between age at menopause and CSF biomarkers for AD.

CONCLUSIONS

Our findings suggest that longer exposure to endogenous estrogen may be associated with increased levels of AD biomarkers in the preclinical phase of AD. These findings, however, need to be confirmed in larger samples.

Reproductive risk factors of pterygium in postmenopausal women: a nationwide study in the Republic of Korea

This study is to elucidate the associations between female reproductive factors and pterygium. A total of 1,339,969 postmenopausal women in a retrospective cohort of Korean National Health Insurance Service data on ages 40 and above in 2009 was included. Cox proportional hazards regression was conducted to assess the hazard ratio (HR) for pterygium according to reproductive factors. Late menarche, early menopause, short reproductive period, increasing parity (≥ 2 children), breastfeeding (≥ 6 months), and no use of hormone replacement therapy (HRT) or oral contraceptive (OC) were significantly associated with risk of pterygium. In multivariate analysis, the HR for pterygium was 1.764 (95% confidence interval [CI], 1.529–2.035) for menarche age ≥ 17 years (reference: menarche age < 12 years). The HR of menopause age ≥ 55 years was 0.782 (95% CI, 0.724–0.845) (reference: menopause age < 40 years). The HR of parity ≥ 2 was 1.261 (95% CI, 1.148–1.385) (reference: nulliparity). The HR of breastfeeding ≥ 1 year was 1.663 (95% CI, 1.564–1.768) (reference: no breastfeeding). The HRs of HRT and OC use for any length of time were lower than those for the non-user groups (reference). Reproductive factors that increase estrogen exposure have protective effects against pterygium in females.

The Treatment of Complementary and Alternative Medicine on Premature Ovarian Failure

It has been confirmed by growing evidence that common hormone replacement therapy is associated with an increasing risk of causing cardiovascular disease and cancer, while complementary and alternative medicine (CAM) is gaining popularity and application in more and more patients with premature ovarian failure (POF). Although there is little data concerning the clinical safety and efficacy of CAM, the literature includes application studies on the phytoestrogen-rich herbal, acupuncture treatment and intervention therapy. This article reviews recent literature on CAM therapy for POF, aiming to provide theoretical support for clinical application.