Reproductive History and Risk of Cognitive Impairment in Elderly Women: A Cross-Sectional Study in Eastern China

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

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

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).

Cognitive disorder and associated factors among pregnant women attending antenatal service at Dilla University Referral Hospital, 2022

Introduction

Cognition is defined as the mental activity or process of learning information and understanding through reason, experience, and the senses. In Sub-Saharan African nations like Ethiopia, such assessments of a pregnant mother's mental health during antenatal care are uncommon procedures. Instead, there is a greater focus on the physical well-being of the woman and her fetus. As a result, this study aimed to evaluate the cognitive deficits and related factors in a pregnant women attending an antenatal care service.

Methods

This hospital-based cross-sectional study included 415 pregnant women who were receiving antenatal care at Dilla University Referral Hospital in Dilla, Gedeo Zone, Ethiopia. In this study, respondents were chosen using systematic random sampling, and study participants were interviewed using administered questions to gather pertinent data. This study used the OSLO Social Support Scale, the Alcohol, Smoking, and Substance Involvement Screening Test, and the Mini-Mental Status Examination to assess the social support, cognitive status, and current substance use history of a respondent. Descriptive statistics including frequencies, graphs, and percentages were used to describe the results. A logistic regression analysis was conducted to determine the connection between independent factors and the outcome variable at a 95 percent confidence level and p < 0.05.

Result

Among all respondents who came for antenatal care visits, only 24 (5.8%) were unmarried (single, divorced, widowed). The mean age of respondents was 26 years old and 155 (37.3%) had attended secondary school. Variables such as strong social support [0.11 (0.03-0.23), p < 0.02], being a follower of orthodox religion [0.24 (0.12-0.39), p < 0.04], ≥5,000 Ethiopian birr monthly income [0.28 (0.17-0.48), p < 0.02], age >26 years old [1.23 (1.14-2.54), p < 0.04], unplanned pregnancy [2.78 (1.45-4.32), p < 0.02], and rural residence [3.90 (2.23-7.34), p < 0.04] were significantly associated with cognitive impairment at 95% confidence interval and a p-value <0.05.

Conclusion

This study found that pregnant women who attended antenatal care experienced a significant reduction in cognitive disorders. Additionally, this study revealed adjustable factors such as unwanted pregnancy, social support, and religiosity. It is preferable to check a pregnant woman's cognitive condition at antenatal services and to follow-up on each additional visit.

Hormonal contraception and cognition: Considering the influence of endogenous ovarian hormones and genes for clinical translation

Despite the well-known influence of ovarian hormones on the brain and widespread use of hormonal contraception (HC) since the 1960s, our knowledge of HC's cognitive effects remains limited. To date, the cognitive findings have been inconsistent. In order to establish what might make HC studies more consistent, we surveyed the literature on HCs and cognition to determine whether studies considered HC formulation, phase, pharmacokinetics, duration, and gene interactions, and assessed whether oversight of these factors might contribute to variable findings. We found that synthetic HC hormones exert dose-dependent effects, the day of oral contraceptive (Pill) ingestion is critical for understanding cognitive changes, and gene-cognition relationships differ in women taking the Pill likely due to suppressed endogenous hormones. When these factors were overlooked, results were not consistent. We close with recommendations for research more likely to yield consistent findings and be therefore, translatable.

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.

Gender-specific association of blood lipids and reproductive trajectory with cognitive impairment: A community based cross-sectional study from India

Background

Abnormal blood lipid levels in the general population and adverse reproductive events among women have been associated with cognitive impairment (CI). However, their relationship has not been extensively studied in community settings. Hence, this study aims to explore the association of CI with blood lipid levels in both sexes and reproductive events/trajectory among women.

Methods

A cross-sectional study was conducted among a North Indian rural population. A total of 808 adults were recruited through door-to-door household survey. Data on socio-demographic variables, reproductive profile of women, and cognitive impairment status were collected. Fasting blood sample was collected to estimate serum lipid profile. Multivariate logistic regression was performed to test for association.

Results

The study demonstrated a lack of association between lipid profile and cognitive impairment among males. Surprisingly, low HDL-C among females was found to be protective against moderate/severe cognitive impairment (value of p = 0.049). Further, menopausal women and those having five or higher live births were found to be at higher risk of CI than pre-menopausal women and those with 1-2 live births, respectively.

Conclusion

The present study hints toward a gender-specific association of blood lipid levels with CI. Further, higher live births and menopause appear to be important risk factors for CI among women.

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.

Fertility experiences and later-life cognitive function among older adults in China

OBJECTIVES

The relationship between fertility history and human health has long fascinated scholars; however, whether there is a link between number of children and cognitive function in older adults remains unclear. We investigated the associations between parity and the timing of first and last births with the cognitive function of older adults over 65.

METHODS

The mini-mental state examination (MMSE) was selected as a tool to measure cognitive function. We analyzed data on 5847 older adults in rural and urban communities in China from the 2018 Chinese Longitudinal Healthy Longevity Survey using ordinary least squares. To further explore the transmission mechanism, we also conducted a mediating effect analysis.

RESULTS

We found a negative association between number of children and cognitive function in older adults. Compared with older adults with four children, the MMSE scores of older adults with more than five children decreased significantly, and the score of older adults with zero to three children increased. Further, a late age at first birth (≥35) and a late age at last birth (≥35) were negatively associated with cognitive function. We also found that the associations between parity and cognition might be partly explained by variations in health.

CONCLUSION

Our analyses provided evidence from China to support the link between fertility history and cognitive function that has been observed in previous international studies: We suggest that high parity (≥5) is negatively associated with cognitive function.

Soy product consumption and the risk of major depressive disorder in older adults: Evidence from a cohort study

Background

To explore the association between soy product consumption and the risk of depression in the community.

Methods

In 2014, a total of 10,901 older people were recruited from Zhejiang province, China, and completed food frequency interviews. Participants were followed up over the next 6 years, and depression was assessed at each visit. Finally, 6,253 participants were included in the present study. Mixed effects models were performed to analyze the association by multivariate adjustments for potential confounders.

Results

Over four-fifths of the eligible participants took soy food at least one day per week. The mixed effects model has shown the adjusted odds ratios (95% CI) of high-frequency consumers (4-7 days per week) were 0.46 (0.39-0.54) for depression with a cut-off score of 5, compared with non-consumers.

Conclusions

More frequent soy product consumption was associated with a lower risk of depression.

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.

Impact of air pollution exposure on the risk of Alzheimer's disease in China: A community-based cohort study

Alzheimer's disease (AD) is the most common type of dementia. Impact of air pollution (AP) on the risk of AD is unclear. It is unknown which air pollutants are independently associated with AD and whether fish consumption mitigated the association. We carried out a community-based cohort of 6115 participants aged ≥60 years in China to examine the association of PM_2.5, PM₁₀, CO, NO₂, SO₂ and O₃ exposure with AD, and differences in the association between people with low and high consumption of fish. The participants were randomly recruited from six counties in Zhejiang province for health survey to document socio-demographic and disease risk factors in 2014, and were followed up to diagnose AD in 2019. A total of 986 cohort members were diagnosed with AD. Based on the daily mean air pollutants monitored in 2013-2015 in the counties, participants were divided into low, middle and high AP exposure groups for subsequent analysis. The multiple adjusted odds ratio (OR) of AD in participants living with the middle and high levels of PM_2.5 exposure versus the low exposure were 1.50 (95% CI 0.90-2.50) and 3.92 (2.09-7.37). The increased ORs were also with PM₁₀ (1.74, 0.65-4.64; 3.00, 1.22-7.41) and CO (2.86, 1.32-6.20; 1.19, 0.45-3.18), but not with NO₂ (0.63, 0.17-2.27; 0.95, 0.28-3.19), SO₂ (0.44, 0.19-1.001; 1.21, 0.56-2.62), and O₃ (0.38, 0.20-0.74; 0.50, 0.21-1.21). There were no significant interaction effects of AP with fish consumption on AD. However, participants with low consumption of fish appeared to have higher ORs in PM_2.5 exposure (1.80, 1.39-2.33; 5.18, 3.93-6.82) than those high consumption (1.38, 0.78-2.47; 2.89, 1.50-5.59). Our findings of PM_2.5, PM₁₀ and CO exposure significantly increased the risk of AD and the potential mitigating effect of fish consumption on the association provide evidence for developing effective strategies for AD reduction and air pollution control.

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.

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.

Associations between reproductive history, hormone use, APOE ε4 genotype and cognition in middle- to older-aged women from the UK Biobank

Introduction

Relative to men, women are at a higher risk of developing age-related neurocognitive disorders including Alzheimer's disease. While women's health has historically been understudied, emerging evidence suggests that reproductive life events such as pregnancy and hormone use may influence women's cognition later in life.

Methods

We investigated the associations between reproductive history, exogenous hormone use, apolipoprotein (APOE) ε4 genotype and cognition in 221,124 middle- to older-aged (mean age 56.2 ± 8.0 years) women from the UK Biobank. Performance on six cognitive tasks was assessed, covering four cognitive domains: episodic visual memory, numeric working memory, processing speed, and executive function.

Results

A longer reproductive span, older age at menopause, older age at first and last birth, and use of hormonal contraceptives were positively associated with cognitive performance later in life. Number of live births, hysterectomy without oophorectomy and use of hormone therapy showed mixed findings, with task-specific positive and negative associations. Effect sizes were generally small (Cohen's d < 0.1). While APOE ε4 genotype was associated with reduced processing speed and executive functioning, in a dose-dependent manner, it did not influence the observed associations between female-specific factors and cognition.

Discussion

Our findings support previous evidence of associations between a broad range of female-specific factors and cognition. The positive association between a history of hormonal contraceptive use and cognition later in life showed the largest effect sizes (max. d = 0.1). More research targeting the long-term effects of female-specific factors on cognition and age-related neurocognitive disorders including Alzheimer's disease is crucial for a better understanding of women's brain health and to support women's health care.

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.

Physical Work and Exercise Reduce the Risk of Cognitive Impairment in Older Adults: A Population-based Longitudinal Study

BACKGROUND

The independent effect of physical work on the risk of cognitive impairment in older Chinese older adults living in rural areas remains to be elucidated.

OBJECTIVE

We aimed to determine whether physical work and physical exercise can reduce the risk of cognitive impairment.

METHODS

We collected data from 7,000 permanent residents without cognitive impairment (age ≥60 years) over a follow-up period of 2 years. We used the Chinese version of the Mini-Mental State Examination (MMSE) to assess cognitive function. We performed multivariate Cox regression analyses to calculate adjusted Hazard Ratios (HRs) and 95% Confidence Intervals (%95 CIs) as measures of the association between physical work/exercise and cognitive impairment while controlling for potential confounders.

RESULTS

Over a median follow-up period of 1.93 years, 1,224 (17.5%) of 7,000 participants developed cognitive impairment, with a total incidence of 97.69 per 1,000 person-years. After adjustment for potential confounders, participating in physical work (HR: 0.51; 95% CI: 0.43-0.60) or physical exercise (HR: 0.53; 95% CI: 0.44-0.65) was associated with a reduced risk of cognitive impairment. Stratified analyses suggested additive and multiplicative interactions between physical work and exercise. Agricultural work (HR: 0.46; 95% CI: 0.38-0.55), walking/tai chi (HR: 0.54; 95% CI: 0.44-0.67), and brisk walking/yangko (HR: 0.57; 95% CI: 0.33-0.97) exerted significant protective effects against cognitive impairment.

CONCLUSION

Both physical work and exercise can reduce the risk of cognitive impairment in older adults. Reasonable types and appropriate intensities of physical activity are recommended to prevent or delay the progression of cognitive impairment.

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.

Blood pressure and cognitive decline over the course of 2 years in elderly people: a community-based prospective cohort study

BACKGROUND

Numerous studies have shown a significant association between blood pressure (BP) and cognition, but little is known about the effect of BP on the rate of cognitive decline.

AIMS

To investigate the relationship between blood pressure and the subsequent rate of cognitive decline in elderly people.

METHODS

Based on a prospective cohort that has been followed since 2014, we collected baseline blood pressures and other covariates in 7874 Chinese individuals aged 60 years or older, and followed their cognitive change using the Mini-Mental State Examination (MMSE) until Dec 31, 2016. Linear mixed-effects models were used to measure changes in MMSE scores over time in relation to blood pressure values, and in addition to the covariates, we included random effects for intercepts and slopes.

RESULTS

In the non-hypertension group, we observed that faster cognitive decline was associated with higher systolic blood pressure, lower diastolic blood pressure, lower mean arterial pressure, and higher pulse pressure. In the hypertension group, lower diastolic blood pressure, lower mean arterial pressure, and higher pulse pressure were associated with faster cognitive decline, but not systolic blood pressure.

CONCLUSION

Higher systolic blood pressure, lower diastolic blood pressure, lower mean arterial pressure, and higher pulse pressure accelerate the subsequent rate of cognitive decline in elderly people. The results of this study may help improve blood-pressure control strategies to prevent cognitive decline.

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.

Parity and the risk of incident dementia: a COSMIC study

AIMS

To investigate the association between parity and the risk of incident dementia in women.

METHODS

We pooled baseline and follow-up data for community-dwelling women aged 60 or older from six population-based, prospective cohort studies from four European and two Asian countries. We investigated the association between parity and incident dementia using Cox proportional hazards regression models adjusted for age, educational level, hypertension, diabetes mellitus and cohort, with additional analysis by dementia subtype (Alzheimer dementia (AD) and non-Alzheimer dementia (NAD)).

RESULTS

Of 9756 women dementia-free at baseline, 7010 completed one or more follow-up assessments. The mean follow-up duration was 5.4 ± 3.1 years and dementia developed in 550 participants. The number of parities was associated with the risk of incident dementia (hazard ratio (HR) = 1.07, 95% confidence interval (CI) = 1.02-1.13). Grand multiparity (five or more parities) increased the risk of dementia by 30% compared to 1-4 parities (HR = 1.30, 95% CI = 1.02-1.67). The risk of NAD increased by 12% for every parity (HR = 1.12, 95% CI = 1.02-1.23) and by 60% for grand multiparity (HR = 1.60, 95% CI = 1.00-2.55), but the risk of AD was not significantly associated with parity.

CONCLUSIONS

Grand multiparity is a significant risk factor for dementia in women. This may have particularly important implications for women in low and middle-income countries where the fertility rate and prevalence of grand multiparity are high.

Impact of Air Pollution on Cognitive Impairment in Older People: A Cohort Study in Rural and Suburban China

Background: The impact of air pollution on cognitive impairment in older people has not been fully understood. It is unclear which air pollutants are the culprit. Objective: We assessed the associations of six air pollutants and air quality index (AQI) with cognitive impairment. Methods: We examined 7,311 participants aged ≥60 years from the ZJMPHS cohort in China. They were interviewed for baseline socio-demographic and disease risk factors in 2014, and re-interviewed in 2015 and 2016, respectively. The presence of cognitive impairment was determined by the Chinese version of the Mini-Mental State Examination. Daily area-level data monitored for air pollution during 2013-2015 was then examined for associations with cognitive impairment in logistic regression models. Results: Over the two years follow-up, 1,652 participants developed cognitive impairment, of which 917 were severe cases. Continuous air pollution data showed the risk of cognitive impairment increased with exposure to PM2.5 (fully adjusted odds ratio [aOR] 1.04, 95% CI 1.01–1.08), PM10 (1.03, 1.001–1.06), and SO2 (1.04, 1.01–1.08), but not with NO2, CO, O3, and AQI. Categorized data analysis for low, middle, and high level exposure demonstrated that the aOR increased with PM2.5 and AQI, somehow with PM10 and CO, but not significantly with SO2 and NO2, and decreased with O3. The patterns for these associations with severe cognitive impairment were stronger. Conclusion: Lowering PM2.5, PM10, SO2, and CO level could reduce the risk of cognitive impairment in older Chinese. Strategies to target most important air pollutants should be an integral component of cognitive interventions.

Reproductive and hormonal factors and risk of cognitive impairment among Singapore Chinese women

BACKGROUND

Epidemiologic studies suggest that declining estrogen levels in menopause may play an important role in the pathogenesis of dementia and contribute to increased risk of cognitive impairment in women. Most previous studies have been conducted in Western populations to investigate the relationship of the length of reproductive periods and use of hormone-replacement therapy with risk of cognitive function and dementia, but the findings are inconclusive. Relevant evidence among Asian populations is limited.

OBJECTIVES

To evaluate the association between reproductive and hormonal factors and the risk of cognitive impairment in Chinese women with natural menopause.

STUDY DESIGN

The Singapore Chinese Health Study is a population-based study that recruited participants aged 45-74 years between 1993 and 1998, and the current study included 8222 women from this cohort who had natural menopause, complete data on reproductive factors and hormonal therapies at baseline (1993-1998), follow-up 1 (1999-2004) and follow-up 2 interviews (2006-2010), and cognitive function evaluated at ages 61-96 years using the Singapore Modified Mini-Mental State Examination during the follow-up 3 visits (2014-2016). Multivariable logistic regression models were used to estimate odds ratios and 95% confidence intervals for the risk of cognitive impairment.

RESULTS

Compared with women with menopause at 50-54 years of age, the odds ratios (95% confidence interval) were 1.67 (1.32-2.11), 1.24 (1.08-1.44), and 1.06 (0.87- 1.29) for women who experienced menopause before 45 years, at 45-49 years of age, and after 54 years, respectively. Compared with women with 35-39 reproductive years from menarche to menopause, the odds ratios (95% confidence interval) were 1.28 (1.11-1.48) for women with <35 reproductive years. Furthermore, compared with women who had 1-2 children, the odds ratios (95% confidence interval) were 1.27 (1.04-1.55) for women who had more than 5 children, and the risk increased significantly by 5% per child birth (odds ratio, 1.05; 95% confidence interval, 1.01-1.09). Compared with those who had never used oral contraceptives, women with short-term use (≤5 years) of oral contraceptives had 26% lower odds of having cognitive impairment (odds ratio, 0.74; 95% confidence interval, 0.63-0.87), whereas the association was not statistically significant for those used for more than 5 years (odds ratio, 0.87; 95% confidence interval, 0.68-1.13). Women who used hormone-replacement therapy had a 39% lower odd of getting cognitive impairment compared with nonusers (odds ratio, 0.61; 95% confidence interval, 0.46-0.80).

CONCLUSION

Our data suggest that shorter reproductive years and greater parity were associated with a greater risk of cognitive impairment in late life, whereas the use of oral contraceptives and hormone-replacement therapy was associated with decreased risk. As the population ages, understanding how these factors affect late-life cognitive function in women may help health professionals develop preventive measures targeting lifetime estrogen exposure from endogenous or exogenous sources.

Multiparity, Brain Atrophy, and Cognitive Decline

Background

Multiparity – grand multiparity (i.e., five or more childbirths) in particular – has been reported to have an association with increased risk of Alzheimer’s disease (AD) dementia or related cognitive decline in women. However, the pathological links underlying this relationship are still unknown. This study was conducted to examine the relationships of multiparity with cerebral amyloid-beta (Aβ) deposition, brain atrophy, and white matter hyperintensities (WMHs).

Methods

In this study, total of 237 older women with 148 cognitively normal and 89 mild cognitive impairment from the Korean Brain Aging Study for Early Diagnosis and Prediction of Alzheimer’s Disease (KBASE) were included. Participants underwent clinical and neuropsychological assessments in addition to ¹¹C-labeled Pittsburgh Compound B positron emission tomography, and magnetic resonance imaging. The associations of parity with Aβ deposition, hippocampal volume, cortical volume, WMH volume and mini-mental status examination (MMSE) score were examined.

Results

Participants with grand multiparity showed significantly reduced adjusted hippocampal volume, spatial pattern of atrophy for recognition of AD volume and spatial pattern of atrophy for recognition of brain aging volume even after controlling for potential confounders. Furthermore, MMSE score was also significantly lower in this group. In contrast, grand multiparity did not show any association with global Aβ retention, Aβ positivity rate, or WMH volume, regardless of covariates.

Conclusion

Our findings suggest that grand multiparity contributes to cognitive decline or increased dementia risk in older women by aggravating amyloid-independent hippocampal or cortical atrophy.

A U-shaped Association of Breastfeeding Duration with Cognitive Impairment in Chinese Postmenopausal Women

Breastfeeding is related to maternal health. However, the association of women’s breastfeeding duration with cognitive function in their later life is limited and inconsistent. The aim of this study was to accurately evaluate the association in Chinese postmenopausal women. We analyzed the data from Zhejiang Ageing and Health Cohort Study including 5487 postmenopausal women. Cognitive impairment was assessed via the Mini-Mental State Examination. Data on breastfeeding duration was collected in the reproductive history section within the questionnaire. Generalized additive models (GAMs) and logistic regression models, controlled for an extensive range of potential confounders, were generated to examine the associations. A U-shaped association was identified between breastfeeding duration and cognitive impairment based on GAM. The nadir with lowest odds of cognitive impairment was ascertained by quadratic model as 12 months. The logistic models showed that compared with women breastfeeding 12 months per child, the fully adjusted odds ratios (ORs) were 1.50 (95% Confidence Interval (CI): 1.20–1.88), 1.58 (95% CI: 1.29–1.93), 1.33 (95% CI: 1.06–1.68), 2.08 (95% CI: 1.64–2.65) for those averagely breastfeeding <6, 6-<12,>12–18,>18 months, respectively. Furthermore, we did not observe significant effect modification of the association. Future longitudinal studies are needed to confirm the association.

The many menopauses: searching the cognitive research literature for menopause types

Objective:

Recent evidence suggests that early or induced menopause increases the risk for cognitive impairment and dementia. Given the potential for different cognitive outcomes due to menopause types, it is important that present research on menopause and cognition distinguishes between types. The aim of this project was to determine to what extent research looking at cognition in postmenopausal women published in one year, 2016, accounted for menopausal type.

Methods:

We searched MEDLINE, EMBASE, and PsychINFO using keywords and MeSH terms for menopause and cognition. We included any research paper reporting a cognitive outcome measure in a menopausal human population. Differentiation between the types of menopause was defined by four categories: undifferentiated, demographic differentiation (menopause type reported but not analyzed), partial differentiation (some but not all types analyzed), and full differentiation (menopause types factored into analysis, or recruitment of only one type).

Results:

Fifty research articles were found and analyzed. Differentiation was distributed as follows: undifferentiated, 38% (19 articles); demographic differentiation, 16% (8); partial differentiation, 28% (14); and full differentiation, 18% (9).

Conclusions:

This review revealed that although some clinical studies differentiated between the many menopauses, most did not. This may limit their relevance to clinical practice. We found that when menopause types are distinguished, the differing cognitive outcomes of each type are clarified, yielding the strongest evidence, which in turn will be able to inform best clinical practice for treating all women.

Passive Smoking Exposure in Living Environments Reduces Cognitive Function: A Prospective Cohort Study in Older Adults

There is currently no consensus regarding the effects of passive smoking exposure on cognitive function in older adults. We evaluated 7000 permanent residents from six regions within Zhejiang Province, China, aged ≥60 years, without cognitive impairment at baseline and during follow-up examinations for two years. The Chinese version of the Mini-Mental State Examination was used to assess the participants’ cognitive function. Multivariate regression analyses were carried out to calculate the adjusted relative risks (RRs) as measures of the association between passive smoking exposure and cognitive impairment after adjusting for potential confounders. The results showed an association between passive smoking exposure in the living environment and increased risk of cognitive impairment (RR: 1.16; 95% confidence interval (CI): 1.01–1.35). No dose–response relationship between the cumulative dose of passive smoking exposure (days) and cognitive impairment was observed. The results of stratified analyses suggested a harmful effect of passive smoking exposure on cognitive function in non-smokers (RR: 1.24; 95% CI: 1.06–1.46), but not in smokers (RR: 1.11; 95% CI: 0.71–1.92). Therefore, passive smoking exposure increased the risk of cognitive impairment in older adults, especially non-smokers. More effective measures to restrict smoking in the living environment should be developed and implemented.

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.

Reproductive history and risk of cognitive impairment in Japanese women

OBJECTIVE

While exposure to endogenous estrogen may be associated with better cognitive performance, it is still unclear whether it has an association with mild cognitive impairment (MCI) or dementia. The aim of this study was to clarify the effects of reproductive history, as a surrogate marker of exposure to endogenous estrogen, on the risk of cognitive impairment (MCI or dementia) in women.

STUDY DESIGN

A total of 747 women aged 40-59 years in the Saku area (Nagano Prefecture) were followed as part of the Japan Public Health Center-based Prospective (JPHC) Study, which started in 1990. Participants had undergone a mental health examination in 2014-2015.

MAIN OUTCOME MEASURES

We used multiple logistic regression to analyze the association between reproductive history, obtained at baseline and 10-year follow-up, with current cognitive impairment diagnosed by a trained psychiatrist, adjusting for various lifestyle factors.

RESULTS

Among 670 eligible women, current cognitive impairment was diagnosed in 227, 196 of whom had MCI and 31 dementia. A longer reproductive period had a significantly inverse association with cognitive impairment (P-trend = 0.032). In particular, women with a reproductive period ≥38 years compared with ≤33 years had a significantly lower risk of cognitive impairment (multivariable adjusted odds ratio=0.62, 95% confidence interval=0.40-0.96).

CONCLUSIONS

A longer reproductive period was associated with a lower risk of cognitive impairment, which suggests that a longer exposure to endogenous estrogen may have a protective effect against cognitive impairment.

Body mass index, waist-to-hip ratio and cognitive function among Chinese elderly: a cross-sectional study

OBJECTIVES

To investigate the associations between body mass index (BMI), waist-to-hip ratio (WHR) and cognitive function among Chinese elderly.

DESIGN

Cross-sectional study.

SETTING

Community.

PARTICIPANTS

Data were obtained from the baseline survey of a community-based cohort in Zhejiang Province, and 9326 persons aged 60 years and older were enrolled.

PRIMARY OUTCOME MEASURES

We investigated the association between BMI and cognition, and then explored the association between WHR and cognition across different quartiles of BMI.

RESULTS

A sample of 9087 persons was used in this study, including 4375 men and 4712 women. Higher WHR increased cognitive impairment risk in those with BMI >25.3 kg/m² (OR (per 0.1 increase) 1.39; 95% CI 1.13 to 1.70). No statistically significant association was found in other BMI categories.

CONCLUSIONS

Higher WHR could increase the risk of cognitive impairment among elderly with BMI >25.3 kg/m². Our results suggest that it could be of benefit to the elderly with high BMI to control WHR.

Differential effects of completed and incomplete pregnancies on the risk of Alzheimer disease

OBJECTIVE

To investigate the effects of completed pregnancy with childbirth and incomplete pregnancy without childbirth on the late-life cognition and the risk of Alzheimer disease (AD) in women.

METHODS

Using the pooled data of 3,549 women provided by 2 population-based cohort studies, we conducted logistic regression analyses to examine retrospectively the associations of completed and incomplete pregnancy with the risks of mild cognitive impairment and AD. For women without dementia, we also conducted analyses of covariance to examine the associations of completed and incomplete pregnancy with Mini-Mental State Examination (MMSE) score.

RESULTS

Grand multiparous women who experienced ≥5 completed pregnancies showed an ≈1.7-fold higher risk of AD than those who experienced 1 to 4 completed pregnancies (odds ratio [OR] 1.68, 95% confidence interval [CI] 1.04-2.72), while those who had incomplete pregnancies showed half the level of AD risk compared with those who never experienced an incomplete pregnancy (OR 0.43, 95% CI 0.24-0.76 for 1 incomplete pregnancy; OR 0.56, 95% CI 0.34-0.92 for ≥2 incomplete pregnancies). In women without dementia, the grand multiparous had worse MMSE scores than those with 1 to 4 completed pregnancies (p < 0.001), while those who experienced ≥1 incomplete pregnancies had better MMSE scores than those who never experienced an incomplete pregnancy (p = 0.008).

CONCLUSIONS

Grand multiparity was associated with high risk of AD, while incomplete pregnancy was associated with low risk of AD in late life.