Reproductive period, endogenous estrogen exposure and dementia incidence among women in Latin America and China; A 10/66 population-based cohort study

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.

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.

Associations of reproductive factors and exogenous estrogens with global and domain-specific cognition in later life

INTRODUCTION

Few studies have comprehensively examined the impact of reproductive factors (i.e., reproductive window, parity, hormonal contraception [HC], and menopausal hormone therapy [MHT]) on global and domain-specific cognition in later life.

METHODS

We studied a population-based sample of 2458 women (median age 74.2 years) residing in Olmsted County, Minnesota; participants underwent a clinical evaluation and comprehensive cognitive testing.

RESULTS

The length of a woman's reproductive window was not associated with cognition. Higher parity was associated with greater cognitive decline in all domains. Ever HC use was associated with less decline in all domains. Ever MHT use was associated with greater decline in global cognition and all domain-specific z-scores except visuospatial; results were driven by women who initiated MHT 5 or more years after menopause. Additional adjustments for APOE and vascular-related covariates did not attenuate the results.

DISCUSSION

Multiple reproductive risk factors are associated with cognitive decline in later life.

HIGHLIGHTS

The length of a woman's reproductive window was not associated with cognition longitudinally. Greater parity was associated with greater cognitive decline longitudinally. Ever HC use was associated with less decline in global cognition and all domain-specific z-scores longitudinally (all p < 0.01). Ever MHT use was associated with greater decline in global cognition and all domain-specific z-scores except visuospatial longitudinally (all p < 0.01). The greatest cognitive decline was among women who initiated MHT more than 5 years after menopause.

Number of children and cognitive function among Chinese menopausal women: The mediating role of depressive symptoms and social participation

OBJECTIVES

This study examined the association between number of children and cognitive function and its possible hormone and psychosocial pathways in Chinese menopausal women.

METHODS

We analyzed data from the China Health and Retirement Longitudinal Study (CHALRS), including 4803 menopausal women. Ordinary least squares (OLS) regression modeling and structural equation modeling (SEM) were applied to explore the association between number of children and cognitive function and the potential mechanisms.

RESULTS

Overall, the median number of biological children was three among participants. The cognitive function score decreased significantly with increasing numbers of children [β = -0.547, 95 % confidence interval (CI): -0.677, -0.416]. There was a significant interaction between number of children and residence (P = 0.003). Compared with older women with three or less children, women with more than three children had worse cognitive function (β = -0.798, 95 % CI: -1.081, -0.514). Mediation analysis verified that depressive symptoms and social participation partially mediate the associations between the number of children and cognitive function.

LIMITATIONS

First, because of the cross-sectional design, our study was unable to make causal inferences. Second, information about endogenous estrogen exposure was not collected in CHARLS. Third, recall bias may exist due to the use of self-reported data.

CONCLUSION

Our results indicated that a higher number of children is associated with an increased risk for cognitive impairment. We suggest paying special attention to mental and social health among women with multiple children (>3).

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.

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.

Possible cognition changes in women with polycystic ovary syndrome: a narrative review

Nowadays, polycystic ovary syndrome (PCOS) and cognitive dysfunction are major health problems among female. This narrative review aimed to investigate cognitive dysfunction in female with PCOS. English and Persian articles published in PubMed, Scopus, Web of Science, Google Scholar, PsycINFO, Scientific Information Database, and Cochrane Database of Systematic Reviews until May 2022 were searched. Sixteen studies involving 850 female with PCOS and 974 controls were assessed. In these studies, the association between biochemical factors and symptoms of PCOS and memory, attention, executive functioning, information processing speed, and visuospatial skills was evaluated. The literature review revealed the possible cognitive changes in female with PCOS. This study summarized the different aspects of cognitive function in female with PCOS due to medication, psychological problems (mood disorders caused by disease symptoms and complications), and biochemical markers, such as metabolic and sex hormone abnormalities. Considering the existing scientific gap regarding the possibility of cognitive complications in female with PCOS, further biological studies should be conducted to evaluate the potential mechanisms involved.

Reproductive period duration and cognitive function in postmenopausal Latina women in the Hispanic Community Health Study/Study of Latinos (HCHS/SOL)

OBJECTIVES

A shorter reproductive period, a marker of estrogen exposure, has been related to cognitive impairment among older (>65 years) non-Hispanic White women. We explored whether reproductive period duration, age at menarche, and age at menopause are related to cognitive function among postmenopausal Hispanic/Latina women.

METHODS

This cross-sectional analysis used baseline (Visit 1: 2008-2011) data from 3630 postmenopausal women in the Hispanic Community Health Study/Study of Latinos. Reproductive period duration, age at menarche, and age at menopause were assessed by self-report. Cognitive function variables included global cognition, verbal learning, memory, verbal fluency, and processing speed. Associations between each reproductive event and cognitive function were examined using multivariable linear and logistic regression analyses accounting for the complex survey design of the study and adjusting for socio-demographics, parity, and cardiovascular risk factors. We assessed whether associations differed by type of menopause (natural versus surgical) and hormone therapy use.

RESULTS

The study population was on average aged 59 years, with a mean reproductive period duration of 35 years. Older age at menopause and a longer reproductive period were related to higher verbal learning (β = 0.04, SE = 0.02; p < 0.05) and processing speed (ß = 0.16, SE = 0.04; p < 0.001); associations were more pronounced for women with natural menopause. Older age at menarche was associated with lower scores on the digit symbol substitution test (ß = -0.62, SE = 0.15; p < 0.0001). There were no associations with global cognition.

CONCLUSION

Among postmenopausal Hispanic/Latinas, a longer reproductive period was related to more favorable cognitive measures of verbal learning and processing speed. Our findings support the hypothesis that greater lifetime exposure to estrogens may be associated with higher cognitive performance.

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.

Age at menarche of adolescent girls and the neighbourhood socioeconomic status of their school area

PURPOSE

To assess the association between abnormal timing of menarche among adolescent girls and neighbourhood socioeconomic status of their school area.

MATERIALS AND METHODS

Our analysis included 187,024 girls aged 15-18 years from the Korea Youth Risk Behaviour Web-Based Survey (KYRBS) from 2007 to 2015. Early and late menarche were defined as menarche before 11 years and no menarche by age 14 years, respectively. The deprivation index values for the areas where the schools were located were used as an indicator of neighbourhood socioeconomic status based on the 2005 national census data. We calculated odds ratios (OR) for early and late menarche using a multinomial logistic regression model. Covariates included body mass index, parental education, single or stepparents, siblings, household wealth, year of birth, survey year, and urbanisation.

RESULTS

Mean age at menarche was 12 years. The overall proportions of early and late menarche were 11.3% and 3.3%, respectively. When divided into four quartile groups based on the socioeconomic deprivation index, 11.3% of girls in the most deprived quartile and 10.6% in the least deprived area showed early menarche. The prevalence of late menarche did not differ across the deprivation index quartiles of school area. Attendance at schools located in highly deprived areas was associated with up to 10% higher risk of early menarche. This positive association was not evident for late menarche.

CONCLUSION

Among contemporary Korean girls, socioeconomic deprivation of the school area was associated with earlier puberty. This finding highlights the potential role of the socioeconomic environment of schools in women's lifetime health.

Associations Between Parity and Cognition: Race/Ethnic Differences

BACKGROUND

Race/ethnicity is associated with differences in reproductive history and cognition individually, yet it remains an understudied factor in the relationship between parity and later-life cognition.

OBJECTIVE

To evaluate if the association between parity and cognition differs between racial/ethnic groups.

METHODS

Participants included 778 older, postmenopausal women from the Health and Nutrition Examination Survey (Latina: n = 178, Non-Latino Black [NLB]: n = 169, Non-Latino White [NLW]: n = 431) who self-reported at least one birth. Cognitive outcomes included working memory, learning memory, and verbal fluency. Covariates included age, education, cardiovascular and other reproductive health factors, adult socioeconomic status (SES) and depressive symptoms. We fit a series of linear models to examine a) whether parity was associated with cognitive functioning, b) if this association varied by race/ethnicity through parity by race/ethnicity interactions, and c) individual parity with cognition associations stratified by race/ethnicity.

RESULTS

In the full sample, parity was significantly negatively associated with Digit Symbol Substitution Test (DSST) performance (b = -0.70, p = 0.024) but not Animal Fluency or word-list learning and memory. Tests of race/ethnicity-by-parity interactions were not statistically significant (ps > 0.05). However, stratified analyses by race/ethnicity showed a differential effect of parity on DSST performance, such that parity was significantly negatively associated with DSST performance (b = -1.66, p = 0.007) among Latinas but not in NLWs (b = -0.16, p = 0.74) or NLBs (b = -0.81, p = 0.191).

CONCLUSION

Among Latina, but not NLB or NLW women, greater parity was associated with worse processing speed/executive functioning later in life. Further research is needed to understand the mechanisms driving racial/ethnic differences.

The mediating role of socioeconomic status on the relationship between pregnancy history and later-life cognition

OBJECTIVE

The association of pregnancy with later-life cognition is not well understood. We examined whether full-term and incomplete pregnancies were associated with cognition in a sample of postmenopausal women, and whether socioeconomic status (SES) factors mediated these relationships.

METHODS

A total of 1016 cognitively normal women from the National Health and Nutrition Examination Survey (NHANES) were examined. Cognitive measures included the Digit Symbol Substitution Test (DSST), Animal Fluency (AF) and the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) Word Learning (CERAD-WL) and Delayed Recall (CERAD-DR) tasks. Analyses examined the relationship between the number of term and incomplete pregnancies with cognitive performance, as well as the mediating effects of education and the federal income-to-poverty ratio (PIR).

RESULTS

A greater number of term pregnancies was associated with worse performance on the DSST (β = -0.09, 95% confidence interval [CI]: -0.12, -0.06), AF (β = -0.03, 95% CI: -0.07, 0.00) and CERAD-DR (β = -0.04, 95% CI: -0.08, -0.01). More incomplete pregnancies were associated with better CERAD-DR performance (β = 0.07, 95% CI: 0.01, 0.13), and 28% (95% CI: 0.17, 0.42) of the association of term pregnancies with the DSST was mediated by the PIR.

CONCLUSIONS

A higher number of term pregnancies was associated with worse cognitive performance, whereas a higher number of incomplete pregnancies was associated with better cognitive performance. Results indicate the necessity to consider SES factors when studying the relationship between pregnancy and cognition.

The Effect of Cumulative Lifetime Estrogen Exposure on Cognition in Depressed Versus Non-Depressed Older Women

OBJECTIVES

Two-thirds of individuals living with Alzheimer's disease are women. Declining estrogen levels influence mood and cognition. Cumulative lifetime estrogen exposure (CLEE) correlates with cognition later in life. We examined the relationship of CLEE to depression and cognition in older women with major depression compared to non-depressed women.

DESIGN

Older women (age ≥60 years) with depression were compared to non-depressed women using a lifetime estrogen exposure questionnaire. CLEE was defined as combined durations of reproductive span (age of menopause minus age of menarche) and any post-menopausal hormone replacement therapy use. Higher vs lower CLEE groups were based on a median of 474 months of estrogen exposure.

SETTING

University hospital outpatient research program.

PARTICIPANTS

135 women ≥60 years; 64 depressed and 71 non-depressed.

MEASURMENTS

Participants completed a comprehensive cognitive test battery. General linear models were used to examine the association between cognitive domain scores and CLEE in depressed and non-depressed women, controlling for age, education, and ethnicity.

RESULTS

Depressed and non-depressed groups had significantly different levels of CLEE, measured in months: mean 495.7 (SD 108.6) vs 456.4 (SD 66.0) months, F(1,130) = 5.01, p = .03. Within the non-depressed participants, higher CLEE was associated with improved delayed recall (F(1,59) = 5.94, p = .02, effect size = .61), while no such relationship was observed in the depressed group.

CONCLUSION

Higher CLEE was associated with improvement in delayed recall among non-depressed, but not among depressed participants. This suggests a protective role of estrogen on memory in non-depressed older postmenopausal women. Further research should examine the role of the CLEE in antidepressant response and cognitive decline.

Sex hormones, body mass index, and related comorbidities associated with developing Sjögren's disease: a nested case-control study

OBJECTIVE

Sjögren's disease (SjD), a highly female predominant systemic autoimmune disease, peaks in perimenopause. Prior studies lack details on timing or type of sex hormone exposure. We examined SjD risk using endogenous and exogenous hormone exposure and related comorbidities.

METHODS

We performed a retrospective case-control study of adult women, nested within a population cohort. Cases had SjD diagnosed by a rheumatology provider or two SjD diagnoses from a non-rheumatology provider with a positive anti-SSA antibody or salivary gland biopsy. Cases were age-matched to three SjD-free controls. We calculated modified composite estrogen scores (mCES) and collected demographics, comorbidities, and endogenous and exogenous hormone exposures. Risk ratios were adjusted for demographics.

RESULTS

Of 546 SjD cases and 1637 age-matched controls, mCES was not significantly associated with SjD in adjusted models. The top individual hormone exposures associated with SjD included estrogen replacement therapy (ERT; RR 1.78 [95% CI 1.47-2.14]), polycystic ovarian syndrome (1.65 [1.28-2.12]), and hysterectomy without bilateral oophorectomy (1.51 [1.13-2.03]). We identified comorbidities preceding SjD including fibromyalgia, pulmonary disease, diabetes, lymphoma, osteoporosis, peripheral vascular disease, and renal disease. Taking comorbidities into account, we developed a predictive model for SjD that included fibromyalgia (2.50 [1.93-3.25]), osteoporosis (1.84 [1.27-2.66]), hormone replacement therapy (HRT) (1.61 [1.22-2.12]), diabetes (0.27 [0.13-0.50]), and body mass index (BMI) (0.97 [0.95-0.99]).

CONCLUSIONS

We report a novel algorithm to improve identifying patients at risk for SjD and describe sex hormone association with SjD. Finally, we report new comorbidities associated with SjD decrease, BMI and diabetes, and increase, lymphoma and osteoporosis.. Key Points •Given female predominance and typical perimenopausal onset, sex hormones should be considered when studying comorbidities in Sjögren's disease. •The top exposures associated with developing Sjögren's disease included fibromyalgia, osteoporosis, and use of hormone replacement therapy. Possible protective factors included prior diabetes and higher body mass index. •We used our newly identified exposures to generate a predictive algorithm, which has potential to improve diagnosis and pathogenic insights into Sjögren's disease.

Ovarian steroid hormones: A long overlooked but critical contributor to brain aging and Alzheimer's disease

Ovarian hormones, particularly 17β-estradiol, are involved in numerous neurophysiological and neurochemical processes, including those subserving cognitive function. Estradiol plays a key role in the neurobiology of aging, in part due to extensive interconnectivity of the neural and endocrine system. This aspect of aging is fundamental for women's brains as all women experience a drop in circulating estradiol levels in midlife, after menopause. Given the importance of estradiol for brain function, it is not surprising that up to 80% of peri-menopausal and post-menopausal women report neurological symptoms including changes in thermoregulation (vasomotor symptoms), mood, sleep, and cognitive performance. Preclinical evidence for neuroprotective effects of 17β-estradiol also indicate associations between menopause, cognitive aging, and Alzheimer's disease (AD), the most common cause of dementia affecting nearly twice more women than men. Brain imaging studies demonstrated that middle-aged women exhibit increased indicators of AD endophenotype as compared to men of the same age, with onset in perimenopause. Herein, we take a translational approach to illustrate the contribution of ovarian hormones in maintaining cognition in women, with evidence implicating menopause-related declines in 17β-estradiol in cognitive aging and AD risk. We will review research focused on the role of endogenous and exogenous estrogen exposure as a key underlying mechanism to neuropathological aging in women, with a focus on whether brain structure, function and neurochemistry respond to hormone treatment. While still in development, this research area offers a new sex-based perspective on brain aging and risk of AD, while also highlighting an urgent need for better integration between neurology, psychiatry, and women's health practices.

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.

Endogenous and Exogenous Estrogen Exposures: How Women's Reproductive Health Can Drive Brain Aging and Inform Alzheimer's Prevention

After advanced age, female sex is the major risk factor for late-onset Alzheimer's disease (AD), the most common cause of dementia affecting over 24 million people worldwide. The prevalence of AD is higher in women than in men, with postmenopausal women accounting for over 60% of all those affected. While most research has focused on gender-combined risk, emerging data indicate sex and gender differences in AD pathophysiology, onset, and progression, which may help account for the higher prevalence in women. Notably, AD-related brain changes develop during a 10-20 year prodromal phase originating in midlife, thus proximate with the hormonal transitions of endocrine aging characteristic of the menopause transition in women. Preclinical evidence for neuroprotective effects of gonadal sex steroid hormones, especially 17β-estradiol, strongly argue for associations between female fertility, reproductive history, and AD risk. The level of gonadal hormones to which the female brain is exposed changes considerably across the lifespan, with relevance to AD risk. However, the neurobiological consequences of hormonal fluctuations, as well as that of hormone therapies, are yet to be fully understood. Epidemiological studies have yielded contrasting results of protective, deleterious and null effects of estrogen exposure on dementia risk. In contrast, brain imaging studies provide encouraging evidence for positive associations between greater cumulative lifetime estrogen exposure and lower AD risk in women, whereas estrogen deprivation is associated with negative consequences on brain structure, function, and biochemistry. Herein, we review the existing literature and evaluate the strength of observed associations between female-specific reproductive health factors and AD risk in women, with a focus on the role of endogenous and exogenous estrogen exposures as a key underlying mechanism. Chief among these variables are reproductive lifespan, menopause status, type of menopause (spontaneous vs. induced), number of pregnancies, and exposure to hormonal therapy, including hormonal contraceptives, hormonal therapy for menopause, and anti-estrogen treatment. As aging is the greatest risk factor for AD followed by female sex, understanding sex-specific biological pathways through which reproductive history modulates brain aging is crucial to inform preventative and therapeutic strategies for AD.

Effects of Reproductive Factors on Lauren Intestinal-Type Gastric Cancers in Females: A Multicenter Retrospective Study in South Korea

Background/Aims

Gastric cancers (GCs), particularly the Lauren intestinal type, show a male predominance. The aim of this study was to investigate the effects of reproductive factors on GCs in females, according to Lauren classification.

Methods

Medical records of 1,849 males and 424 females who underwent radical gastrectomy or endoscopic resection for GCs between 2010 and 2018 were reviewed. The incidences of intestinal-type GCs were compared between males and groups of females stratified according to postmenopausal period. Associations between reproductive factors in females and intestinaltype GCs were analyzed using multivariate models.

Results

The proportions of intestinal-type GCs were significantly lower in premenopausal (19%), less than 10 years postmenopausal (30.4%), and 10 to 19 years postmenopausal females (44.1%) than in males (61.0%) (p<0.05 for all). Females ≥20 years postmenopause had a proportion of intestinal-type GCs similar to that in males (60.6% vs 61.0%; p=0.948). Multivariate analysis revealed that age (odds ratio [OR], 1.075; 95% confidence interval [CI], 1.039 to 1.113; p<0.001) and parity ≥3 (OR, 1.775; 95% CI, 1.012 to 3.114; p=0.045) were positively associated with an increased risk of intestinal-type GCs in postmenopausal females, while long fertility duration (OR, 1.147; 95% CI, 1.043 to 1.261; p=0.005) was positively associated with an increased risk of intestinal-type GCs in premenopausal females.

Conclusions

There were no significant differences in the proportions of intestinal-type GCs between males and females ≥20 years postmenopause, suggesting that female reproductive factors play a role in the prevention of intestinal-type GC.

Reproductive factors and cognitive impairment in natural menopausal women: A cross-sectional study

INTRODUCTION

Little information on rural older women in northern China has been reported, apart from three studies in southern and eastern China in the past decade. This study aims to evaluate the relationships between reproductive factors and the risk of cognitive impairment, including mild cognitive impairment (MCI) and dementia, in Chinese women with natural menopause.

METHODS

The cross-sectional study was conducted in 112 community primary healthcare centers in rural northern China between April 2019 and January 2020. A total of 4,275 women aged ≥65 years who had natural menopause were included. Reproductive factors as well as the reproductive period (= age at menopause - age at menarche) were recorded. The relationships between reproductive factors and cognitive impairment were evaluated by correlation and logistic regression analysis.

RESULTS

Overall, 28.6% and 11.4% of women were diagnosed with MCI or dementia, respectively. In natural menopause women, the age at menopause (adjusted r = 0.070, p < 0.001), reproductive period (adjusted r = 0.053, p = 0.001), and number of pregnancies (adjusted r = -0.042, p = 0.007) and parities (adjusted r = -0.068, p < 0.001) were correlated with Mini-Mental State Examination (Chinese version) scores, and with similar findings concerning MCI and dementia with Lewy bodies (DLB). Greater age at menopause and a long reproductive period significantly decreased the risk of MCI and Alzheimer's disease (AD), and more parities significantly increased the risks of MCI (odds ratio (OR) = 1.111, 95% confidence interval (CI): 1.039-1.187, p = 0.002), dementia (OR = 1.162, 95% CI: 1.061-1.271, p = 0.001), particular AD (OR = 1.131, 95% CI: 1.010-1.266, p = 0.032), DLB (OR = 1.238, 95% CI: 1.003-1.528, p = 0.047), and vascular dementia (VaD) (OR = 1.288, 95% CI: 1.080-1.536, p = 0.005).

CONCLUSIONS

The prevalence rates of MCI and dementia were 28.6% and 11.4% in older women. Greater age at menarche, young age at menopause, shorter reproductive period, and larger numbers of pregnancies/parities were correlated with poor cognition and significantly increased the risks of MCI and dementia, particularly AD, DLB, and VaD.

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.

Sex is a defining feature of neuroimaging phenotypes in major brain disorders

Sex is a biological variable that contributes to individual variability in brain structure and behavior. Neuroimaging studies of population-based samples have identified normative differences in brain structure between males and females, many of which are exacerbated in psychiatric and neurological conditions. Still, sex differences in MRI outcomes are understudied, particularly in clinical samples with known sex differences in disease risk, prevalence, and expression of clinical symptoms. Here we review the existing literature on sex differences in adult brain structure in normative samples and in 14 distinct psychiatric and neurological disorders. We discuss commonalities and sources of variance in study designs, analysis procedures, disease subtype effects, and the impact of these factors on MRI interpretation. Lastly, we identify key problems in the neuroimaging literature on sex differences and offer potential recommendations to address current barriers and optimize rigor and reproducibility. In particular, we emphasize the importance of large-scale neuroimaging initiatives such as the Enhancing NeuroImaging Genetics through Meta-Analyses consortium, the UK Biobank, Human Connectome Project, and others to provide unprecedented power to evaluate sex-specific phenotypes in major brain diseases.

Association of Reproductive History With Brain MRI Biomarkers of Dementia Risk in Midlife

BACKGROUND AND OBJECTIVES

To examine associations between indicators of estrogen exposure from women's reproductive history and brain MRI biomarkers of Alzheimer disease (AD) in midlife.

METHODS

We evaluated 99 cognitively normal women 52 ± 6 years of age and 29 men 52 ± 7 years of age with reproductive history data, neuropsychological testing, and volumetric MRI scans. We used multiple regressions to examine associations among reproductive history indicators, voxel-wise gray matter volume (GMV), and memory and global cognition scores, adjusting for demographics and midlife health indicators. Exposure variables were menopause status, age at menarche, age at menopause, reproductive span, hysterectomy status, number of children and pregnancies, and use of menopause hormonal therapy (HT) and hormonal contraceptives (HC).

RESULTS

All menopausal groups exhibited lower GMV in AD-vulnerable regions compared to men, with perimenopausal and postmenopausal groups also exhibiting lower GMV in temporal cortex compared to the premenopausal group. Reproductive span, number of children and pregnancies, and use of HT and HC were positively associated with GMV, chiefly in temporal cortex, frontal cortex, and precuneus, independent of age, APOE ε4 status, and midlife health indicators. Although reproductive history indicators were not directly associated with cognitive measures, GMV in temporal regions was positively associated with memory and global cognition scores.

DISCUSSION

Reproductive history events signaling more estrogen exposure such as premenopausal status, longer reproductive span, higher number of children, and use of HT and HC were associated with larger GMV in women in midlife. Further studies are needed to elucidate sex-specific biological pathways through which reproductive history influences cognitive aging and AD risk.

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.

Association of the Reproductive Period with Decreased Estimated Glomerular Filtration Rate in Menopausal Women: A Study from the Shanghai Suburban Adult Cohort and Biobank (2016-2020)

In previous studies, it has been documented that a short reproductive period is associated with a higher risk of diabetes, cardiovascular disease, and chronic kidney disease. This study aims to investigate the association of the reproductive period length with decreased renal function. This study obtained data from “the Shanghai Suburban Adult Cohort and Biobank”. An estimated glomerular filtration rate (eGFR) below 60 mL/min/1.73 m² indicated decreased renal function during follow-up. Participants were grouped into quintiles by reproductive period. Logistic regression analysis was performed to examine the association between the reproductive period and decreased renal function. A total of 5503 menopausal women with baseline eGFR > 60 mL/min/1.73 m² were included. Age, eGFR, and metabolic equivalent of task (MET) at baseline were 61.0 (range, 36.0–74.0) years, 92.2 (range, 60.1–194.5) mL/min/1.73 m², and 1386 (range, 160–6678), respectively. A reproductive period of 37–45 years was associated with a lower risk of decreased eGFR (OR: 0.59, 95% CI: 0.35–1.00, p = 0.049) after adjusting for confounding variables. METs decreased the risk of decreased eGFR in women with a reproductive period of 37–45 years (OR: 0.43, 95% CI: 0.23–0.81, p = 0.010). Women with a longer reproductive period have a lower risk of decreased renal function. METs had an opposite influence on renal function in women with longer (decreased risk) or shorter (increased risk) reproductive periods.

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.

Female reproductive health and cognitive function

OBJECTIVE

The impact of sex hormones milieu on women's cognitive performance at different reproductive stages has caused increased caution. Our research aims to explore whether parity is negatively correlated with cognitive function.

METHODS

There were 1,093 postmenopausal participants recruited from the Health and Nutrition Examination Survey dataset. Cognitive functioning was evaluated by digit symbol substitution test (DSST). We performed log transformation to normalize the distributions of the DSST values.

RESULTS

Participants were categorized into tertile groups based on the number of pregnancies. Using the zero to one pregnancy group as the reference, there was a reduced DSST scores with β values of -0.13 (95% confidence interval [CI] -0.23 to -0.03; P = 0.008) in the ≥5 pregnancies group after adjusting for socioeconomic, medical disease, lifestyle, and reproductive components. Moreover, women who had their last pregnancy after 28 years old and education less than 12 years also was correlate with cognitive malfunction after adjusting relevant covariates (both P < 0.001).

CONCLUSIONS

Women with at least five pregnancies had poorer cognitive performance. Last pregnancy after 28 years old and education less than 12 years also was associated with poorer DSST scores. VIDEO SUMMARY:: http://links.lww.com/MENO/A634.

Fertility History and Cognitive Function in Late Life: The Case of Mexico

OBJECTIVES

Mexico is aging rapidly, which makes identification of life-course factors influencing cognition a public health priority. We evaluate how the number of children one has relates to cognition in Mexico, a rapidly aging country that experienced fertility declines across recent cohorts of older people.

METHOD

We analyze older adults (age 50+, n = 11,380) from the 2015 Mexican Health and Aging Study. Respondents were categorized by number of children ever born (0-1, 2-3, 4-5, 6+). Using ordinary least squares regression, we estimate independent associations between fertility history and cognition accounting for demographic, socioeconomic, health, and psychosocial factors.

RESULTS

We observed an inverse U-shaped relationship between number of children (peaking at 2-3 children) and cognitive function, regardless of gender. In regression analyses adjusted for confounding variables, having 0-1 (vs 2-3 children) was associated with poorer cognitive function only for females. Regardless of gender, having 6+ (vs 2-3 children) was associated with poorer cognitive function. These associations remained significant even after accounting for socioeconomic, health, employment, and psychosocial factors.

DISCUSSION

Our results suggest fertility history may play a role in late-life cognitive health and provide evidence that both low and high fertility may relate to poorer cognitive function. We discuss differences by gender.

Temporal dynamics, patterns and correlates of single and multimorbidity in India, 1994-2018

OBJECTIVE

As a consequence of the epidemiological transition, multimorbidity has been identified as a critical public health challenge in India. The majority of the studies in the domain are grounded on hospital-based data or are based on small sample size, findings from which can only be generalized to a specific sub-group. These studies recommend exploring multimorbidity holistically at a national level to ensure adequate healthcare management in the country. Therefore, the present study examines the pattern and correlates of single and multimorbidity over the past two decades in India.

METHODS

The study utilized data on 397901, 257519, and 399705 individuals from 52nd (1994-1995), 60th (2004-2005), and 75th (2018) rounds of cross-sectional data from the National Sample Survey (NSS). Univariate, bivariate, and multivariable statistical methods were applied to draw inferences from the data. The findings depict an increase in single and multimorbidity burden over individuals' age and NSS rounds.

RESULTS

Hypertension and diabetes were the fastest-growing morbidities over time. Higher education, urban residence, and belonging to an affluent class were significantly associated with both single and multimorbidity occurrence over time.

CONCLUSION

The burden of single and multimorbidity increases over time among India's older adults. Therefore, there is an urgent need to recuperate chronic disease management strategies for older adults in the Indian healthcare infrastructure.

Age, menstruation history, and the brain

OBJECTIVES

To investigate the cross-sectional association between measures of menstruation history (including menopausal status, age of menopause, age of menarche, and duration of reproductive stage) and brain volume.

METHODS

Women (aged 45 to 79 years) from the UK Biobank were included (n = 5,072) after excluding those who had (1) hysterectomy or bilateral oophorectomy, (2) ever used menopausal hormone therapy, (3) ever had a stroke, or (4) were perimenopausal. Multiple linear hierarchical regression models were computed to quantify the cross-sectional association between measures of menstruation history and brain volume. Sensitivity analysis based on propensity matching for age (and other demographic/health covariates) were applied to estimate differences in brain volumes between matched premenopausal and postmenopausal women.

RESULTS

Postmenopausal women had 1.06% (95% confidence interval [CI]; 1.05-1.06) and 2.17% (95% CI, 2.12-2.22) larger total brain volume (TBV) and hippocampal volumes (HV), respectively, than premenopausal women. Sensitivity analysis with age matched samples produced consistent results (TBV: 0.82%, 95% CI, 0.25-1.38; HV: 1.33%, 95% CI, 0.01-2.63). For every year increase in age above 45 years, postmenopausal women experienced 0.23% greater reduction in TBV than premenopausal women (95% CI, -0.60 to -0.14), which was not observed for HV. Moreover, every 1 year delayed onset of menopause after 45 was associated with 0.32% (95% CI, -0.35 to -0.28) and 0.31% (95% CI, -0.40 to -0.22) smaller TBV and HV, respectively. Every additional year in age of menarche was associated with 0.10% (95% CI, 0.04-0.16) larger TBV, which was not detected for HV. Similarly, every 1 year increase in duration of reproductive stage was associated with 0.09% smaller TBV (95% CI, -0.15 to -0.03), which was not detected for HV.

CONCLUSIONS

Menopause may contribute to brain volume beyond typical aging effects. Furthermore, early age of menarche, delayed age of menopause and increasing duration of reproductive stage were negatively associated with brain volume. Further research is required to determine whether the negative association between age of menopause and HV is potentially an indicator of future vulnerability for dementia.

Associations between Depression, Depressive Symptoms, and Incidence of Dementia in Latin America: A 10/66 Dementia Research Group Study

BACKGROUND

A growing body of evidence suggests that depression is related to dementia in older adults. Previous research has been done in high-income countries and there is a lack of studies in low- and middle income countries (LMICs).

OBJECTIVE

To examine the relationship between depressive symptoms and incidence of dementia in a population-based study of older adults in Latin America.

METHODS

The study is a part of the 10/66 Dementia Research Group's population survey and includes 11,472 older adults (baseline mean age 74 years) from Cuba, Dominican Republic, Mexico, Peru, Puerto Rico, and Venezuela. The baseline examinations were done in 2003-2007 and the follow-up examinations 4 years later. Semi-structured psychiatric interviews gave information about ICD-10 depression and sub-syndromal depression (i.e., ≥4 depressive symptoms) at baseline. Information on dementia were collected at the follow-up examination. Competing risk models analyzed the associations between depression and incidence of dementia and the final model were adjusted for age, sex, education, stroke, and diabetes. Separate analyses were conducted for each site and then meta-analyzed by means of fixed effect models.

RESULTS

At baseline, the prevalence of depression was 26.0% (n = 2,980): 5.4% had ICD-10 depression and 20.6% sub-syndromal depression. During the follow-up period, 9.3% (n = 862) developed dementia and 14.3% (n = 1,329) deceased. In the pooled analyses, both ICD-10 depression (adjusted sub-hazard ratio (sHR) 1.63, 95% confidence interval (CI) 1.26-2.11) and sub-syndromal depression (adjusted sHR 1.28, 95% CI: 1.09-1.51) were associated with increased incidence of dementia. The Higging I2 tests showed a moderate heterogeneity across the study sites.

CONCLUSION

Our findings suggest that late-life depression is associated with the incidence of dementia in LMICs in Latin America, which support results from earlier studies conducted in high-income countries.

The -1195A>G polymorphism in Ciclooxygenase-2 gene is associated with lower risk of endometriosis

OBJECTIVES

This study aimed to evaluate the potential role of the PTGS2 single nucleotide polymorphisms (SNPs) -1195 A>G and +8473 T>C in endometriosis' development, and characterizing their association with the prognostic features of the disease.

STUDY DESIGN

DNA from 254 women with endometriosis and 267 controls, recruited from two reference hospitals from the Brazilian public health system, were genotyped using TaqMan allelic discrimination assays. The association between SNPs and endometriosis features was evaluated by multivariate logistic regression, using the adjusted odds ratios (OR) with their respective 95% confidence intervals (95% CI).

RESULTS AND CONCLUSION

There were significant differences between cases and controls regarding age (P < 0.001), body mass index (BMI) (P = 0.001), educational level (P < 0.001), physical activity (P = 0.003), smoking status (P < 0.001), contraception use (P = 0.02), family history of endometriosis (P = 0.002) and all symptoms (P < 0.001). The distribution of -1195 A > G was statistically different between the groups, suggesting a lower risk of developing the disease for the carriers of the -1195 GG genotype (OR = 0.19; 95% CI = 0.04 - 0.93). No differences were found for the +8473 T>C between the two groups and neither in prognostic features of the disease for both PTGS2 SNPs. In conclusion, PTGS2 -1195A>G SNP was negatively associated with development of endometriosis and the two groups were statistically different regarding age, BMI, educational level, physical activity, smoking status, contraception use, history of endometriosis and all endometriosis symptoms.

Towards an understanding of women's brain aging: the immunology of pregnancy and menopause

Women are at significantly greater risk of developing Alzheimer's disease and show higher prevalence of autoimmune conditions relative to men. Women's brain health is historically understudied, and little is therefore known about the mechanisms underlying epidemiological sex differences in neurodegenerative diseases, and how female-specific factors may influence women's brain health across the lifespan. In this review, we summarize recent studies on the immunology of pregnancy and menopause, emphasizing that these major immunoendocrine transition phases may play a critical part in women's brain aging trajectories.

Reproductive period and dementia: A 44-year longitudinal population study of Swedish women

INTRODUCTION

Longitudinal studies examining the effect of endogenous estrogens on dementia risk are needed to understand why women have higher dementia incidence than men after age 85.

METHODS

A population-based sample of women with natural menopause (N = 1364) from Gothenburg, Sweden, was followed from 1968-2012. Information on endogenous estrogens (age at menarche and menopause, number of pregnancies, and months of breastfeeding) was obtained from interviews in 1968-1992. Dementia was diagnosed according to established criteria based on information from neuropsychiatric examinations and close informant interviews.

RESULTS

We found that longer reproductive period was associated with increased risk of dementia (hazard ratio [HR] per year 1.06, 95% confidence interval [CI] 1.03-1.20) and Alzheimer's disease (AD) (1.06, 1.02-1.11), particularly for those with dementia (1.10, 1.04-1.17) and AD (1.15, 1.06-1.26) onset after age 85.

DISCUSSION

These results may explain why women have higher dementia incidence compared to men after age 85, the age with the highest number of dementia cases.

Prior endogenous and exogenous estrogen and incident dementia in the 10th decade of life: The 90+ Study

Objective: This study aimed to investigate the association of endogenous and exogenous estrogen exposure with risk of incident dementia in the oldest-old (age 90+ years).Methods: Participants were part of The 90+ Study, a longitudinal study begun in 2003 of aging and dementia among people aged 90+ years. Menstrual, reproductive, and menopausal data were collected in the 1980s as part of the population-based Leisure World Cohort Study. Cognitive status at baseline was determined from an in-person neurological evaluation with biannual follow-up through June 2019. Hazard ratios (HRs) of dementia associated with estrogen-related variables were estimated using Cox regression analysis. No adjustment was made for multiple comparisons.Results: A total of 424 women without dementia at baseline had at least one follow-up evaluation. The mean age was 68.5 years at enrollment in the Leisure World Cohort Study, 93.2 years at enrollment in The 90+ Study, and 96.5 years at last follow-up. During follow-up (mean 3.4 years) dementia was diagnosed in 209 (49%) participants. No individual menstrual, reproductive, menopausal, or estrogen replacement variable was associated with risk of incident dementia after age 90 years. However, women with a high endogenous estrogen exposure index (summarizing exposure from menarche to menopause) had a non-significant 25% lower risk (HR = 0.75, 95% confidence interval 0.53-1.06).Conclusions: Prior exposure to estrogen, endogenous or exogenous, had little effect on risk of dementia in the 10th decade of life.

Reproductive History and Cognitive Aging: The Bogalusa Heart Study

BACKGROUND

Although it has become increasingly clear that pregnancy-related health predicts later-life cardiometabolic health, the relationship between reproductive history and cognitive health is less frequently studied. Although some research has identified associations between parity or hypertensive disorders of pregnancy and cognitive changes, the evidence is mixed.

OBJECTIVE

To examine the association between reproductive history and midlife cognition in a community-based population.

STUDY DESIGN

Seven hundred and thirty midlife women in the Bogalusa Heart Study completed a brief cognitive battery (memory, attention, executive function, and processing speed) and were interviewed about their reproductive history. Reproductive history (parity, age at first pregnancy, and breastfeeding) and pregnancy complications (low birthweight, preterm birth, hypertensive disorders, and miscarriage) were examined as predictors of cognitive function, with adjustment for potential confounders.

RESULTS

Nulliparous women had an overall lower cognitive score (adjusted beta -1.50, standard error [SE]: 0.41). Adolescent birth was associated with a somewhat better performance on the Trail Making Test (beta -0.31, SE: 0.15 for birth <16 years), while high parity was not strongly associated with any of the cognitive measures. History of pregnancy complications was not strongly associated with cognitive function, whereas history of miscarriage was associated with better cognitive function, as was a history of breastfeeding (beta overall score 0.90, SE: 0.29), particularly noticeable for semantic memory and in those with more total breastfeeding time (beta for overall score among those with >24 weeks lifetime breastfeeding, beta 1.21, SE: 0.44).

CONCLUSION

Nulliparity and breastfeeding are associated with midlife cognition in women. Future studies should examine possible mechanisms by which these associations are created.

Population-based neuroimaging reveals traces of childbirth in the maternal brain

Maternal brain adaptations have been found across pregnancy and postpartum, but little is known about the long-term effects of parity on the maternal brain. Using neuroimaging and machine learning, we investigated structural brain characteristics in 12,021 middle-aged women from the UK Biobank, demonstrating that parous women showed less evidence of brain aging compared to their nulliparous peers. The relationship between childbirths and a "younger-looking" brain could not be explained by common genetic variation or relevant confounders. Although prospective longitudinal studies are needed, the results suggest that parity may involve neural changes that could influence women's brain aging later in life.

Reproductive period and risk of dementia in a diverse cohort of health care members

OBJECTIVE

Women have >50% greater lifetime risk of dementia than men but the role of female-specific endocrine milieu is not well-understood. This study evaluates associations between indicators of estrogen exposure from women's reproductive period and dementia risk in a large diverse population.

METHODS

We evaluated 15,754 female members (29.9% nonwhite) of Kaiser Permanente with clinical examinations and health survey data from 1964 to 1973 and were members as of January 1, 1996. In midlife (mean age 51.1 years), women reported age at menarche and menopause and hysterectomy status. Reproductive span was calculated as menopause age minus menarche age. Dementia diagnoses were abstracted from January 1, 1996 to September 30, 2017 medical records (mean age at start of dementia follow-up 76.5 years). Cox proportional hazard models evaluated associations between aspects of reproductive span and dementia risk adjusting for demographics and life course health indicators.

RESULTS

Forty-two percent of women developed dementia. Compared to menarche at age 13.0 (mean menarche age), menarche at ≥16 was associated with 23% greater dementia risk (adjusted hazard ratio [HR] 1.23; 95% confidence interval [CI] 1.01-1.50) adjusting for demographics and life course health indicators. Natural menopause at age <47.4 (mean menopause age) was associated with 19% elevated dementia risk (HR 1.19; 95% CI 1.07-1.31). Reproductive spans <34.4 years (mean duration) were associated with 20% elevated dementia risk (HR 1.20; 95% CI 1.08-1.32). Hysterectomies were associated with 8% elevated dementia risk (HR 1.08; 95% CI 1.01-1.16).

CONCLUSION

In this large prospective cohort study, endocrine events signaling less estradiol exposure (i.e., later age at menarche, younger age at menopause, shorter reproductive span, and hysterectomies) were associated with elevated risk of dementia.

The long and short term effects of motherhood on the brain

Becoming a mother is associated with dramatic changes in physiology, endocrinology, immune function, and behaviour that begins during pregnancy and persists into the postpartum. Evidence also suggests that motherhood is accompanied by long-term changes in brain function. In this review, we summarize the short (pregnancy and postpartum) and long-term (beyond the postpartum and into middle age) effects of pregnancy and motherhood on cognition, neuroplasticity, and neuroimmune signalling. We also discuss the effects of previous history of pregnancy and motherhood (parity) on brain health and disease (neurodegenerative diseases and stroke outcomes) and on efficacy of hormone and antidepressant treatments. Finally, we argue that pregnancy and motherhood are unique female experiences that need to be taken into account to better understand female brain function and aging.