The impact of age-related ovarian hormone loss on cognitive and neural function

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

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

Estrogen receptor beta in astrocytes modulates cognitive function in mid-age female mice

Menopause is associated with cognitive deficits and brain atrophy, but the brain region and cell-specific mechanisms are not fully understood. Here, we identify a sex hormone by age interaction whereby loss of ovarian hormones in female mice at midlife, but not young age, induced hippocampal-dependent cognitive impairment, dorsal hippocampal atrophy, and astrocyte and microglia activation with synaptic loss. Selective deletion of estrogen receptor beta (ERβ) in astrocytes, but not neurons, in gonadally intact female mice induced the same brain effects. RNA sequencing and pathway analyses of gene expression in hippocampal astrocytes from midlife female astrocyte-ERβ conditional knock out (cKO) mice revealed Gluconeogenesis I and Glycolysis I as the most differentially expressed pathways. Enolase 1 gene expression was increased in hippocampi from both astrocyte-ERβ cKO female mice at midlife and from postmenopausal women. Gain of function studies showed that ERβ ligand treatment of midlife female mice reversed dorsal hippocampal neuropathology.

Altered temporal-parietal morphological similarity networks in non-small cell lung cancer patients following chemotherapy: an MRI preliminary study

Non-small cell lung cancer (NSCLC) accounts for more than 85% of all lung cancer cases, and chemotherapy-related brain changes (known as "chemobrain") in NSCLC patients were found in previous studies. However, the effects of platinum-based chemotherapy on brain structural networks are still unclear. Structural magnetic resonance imaging (sMRI) data were collected from 32 NSCLC patients following platinum-based chemotherapy, 36 NSCLC patients without chemotherapy, and 39 healthy controls. Clinical physiological indicators of patients were collected. Then, morphological similarity networks were constructed using MRI data, and topological properties were calculated using graph theory method. Differences between three groups were investigated using one-way ANOVA and two-sample t-test, and relations between topological properties and clinical physiological indicators were calculated. We found that degree and nodal efficiency in temporal-parietal networks were significantly reduced in NSCLC patients following platinum-based chemotherapy compared to healthy controls/patients without chemotherapy (F-test, p < 0.001; post hoc t-test, p < 0.01, Bonferroni corrected). These changes (p < 0.05) were positively correlated with clinical measures, including thrombocytes, granulocytes and hemoglobin, and were negatively correlated with measures of triglycerides and cholesterol levels. Network properties including clustering coefficient (F(2,104) = 41.435, p < 0.001), number of K-edges (F(2,104) = 40.304, p < 0.001), density of K-edges (F(2,104) = 40.304, p < 0.001), global efficiency (F(2,104) = 42.585, p < 0.001) and small-world (F(2,104) = 37.132, p < 0.001) were also significantly reduced (post hoc t-test, p < 0.01, Bonferroni corrected). These results indicate that platinum-based chemotherapy might cause cerebrovascular damage and clinical indicators' changes, which then cause the properties of morphological similarity networks' changes in the temporal and parietal lobes. This study may help us better understand the "chemobrain" in NSCLC patients.

Menopause does not modify disability trajectories in a longitudinal cohort of women with clinically isolated syndrome and multiple sclerosis followed from disease onset

BACKGROUND AND PURPOSE

To evaluate the effect of menopause on disability accumulation in women followed from their clinically isolated syndrome (CIS).

METHODS

We examined the longitudinal changes in Expanded Disability Status Scale (EDSS) scores from CIS until the last follow-up in women belonging to the Barcelona CIS prospective cohort, followed through their menopausal transition. The analysis is based on 13,718 EDSS measurements, with an average of 28 EDSS measurements per patient. Differences in EDSS trajectories between menopausal and nonmenopausal women, controlling for age and disease duration, were evaluated. We performed two sensitivity analyses in women with confirmed MS and in those experiencing early menopause.

RESULTS

From 764 eligible women, 496 (65%) responded to the questionnaire, and 74 (14.9%) reached menopause over the follow-up. We did not find a significant inflection point in EDSS trajectories around menopause (slope change -0.009; 95% CI -0.066; 0.046). The annual increase in EDSS over the complete course of the disease was significantly higher in menopausal women (0.049; 95% CI, 0.026-0.074) versus nonmenopausal (0.019; 95% CI, 0.008-0.031; interaction p value 0.025). This difference was lost when controlling for age and disease duration (EDSS annual increase of 0.059; 95% CI, 0.025-0.094 vs. 0.038; 95% CI, 0.021-0.057, respectively; interaction p value 0.321). No inflection point was detected when the analysis was restricted to women with confirmed MS or with earlier menopause.

CONCLUSIONS

Menopause is not associated with an increased risk of disability in a CIS population, considering EDSS trajectories throughout the course of the disease together with age and disease duration.

Slow electroencephalographic oscillations and behavioral measures as predictors of high executive processing in early postmenopausal females: A discriminant analysis approach

Decline in cognitive function is frequent in early postmenopause. There are postmenopausal females who show high performance while others display low performance in executive function, modulated by the prefrontal cortex. These differences have led to confusing and inconclusive results, which have not been explained entirely by the decline in estrogens, which affect the prefrontal cortex functions. An analysis of brain function and the application of a discriminant analysis can help to clarify the deficits in executive function shown by some postmenopausal females. The objective was to examine electroencephalographic recording during the performance of an executive function test in early postmenopausal females, ten with a high level of performance and ten with a low level of performance. Absolute power of delta, theta, alpha1, alpha2, beta1 and beta2 and the numbers of completed categories, trials, perseverative errors and overall errors were submitted to stepwise discriminant analysis to identify predictor variables. Four predictors emerged as significant of group membership based on cognitive performance, with the high-performance group characterized by more completed categories, more delta power, less theta power and more alpha1 power. These findings suggest that postmenopausal females classified in the high-performance group displayed appropriate temporary activation in slow oscillations during executive processing.

Oestradiol as a neuromodulator of learning and memory

Although hormones such as glucocorticoids have been broadly accepted in recent decades as general neuromodulators of memory processes, sex steroid hormones such as the potent oestrogen 17β-oestradiol have been less well recognized by the scientific community in this capacity. The predominance of females in studies of oestradiol and memory and the general (but erroneous) perception that oestrogens are 'female' hormones have probably prevented oestradiol from being more widely considered as a key memory modulator in both sexes. Indeed, although considerable evidence supports a crucial role for oestradiol in regulating learning and memory in females, a growing body of literature indicates a similar role in males. This Review discusses the mechanisms of oestradiol signalling and provides an overview of the effects of oestradiol on spatial, object recognition, social and fear memories. Although the primary focus is on data collected in females, effects of oestradiol on memory in males will be discussed, as will sex differences in the molecular mechanisms that regulate oestrogenic modulation of memory, which may have important implications for the development of future cognitive therapeutics.

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.

Menopause and multiple sclerosis: Influence on prognosis and role of disease-modifying drugs and hormonal replacement therapy

Background:

Sex hormones play a role in both the risk and the prognosis of multiple sclerosis (MS). Considering all stages of women’s reproductive life, data regarding the influence of menopause on MS and vice versa are scarce.

Objective:

The aim of this study was to review the evidence addressing the relationship between menopause and MS.

Methods:

A literature search through PubMed was conducted, selecting studies that assessed (1) the influence of menopause in the MS course, (2) the influence of MS and disease-modifying drugs (DMD) on the development of menopause and (3) the effect of hormone replacement therapy (HRT) on symptoms of menopausal MS patients.

Results:

(1) Most studies suggest menopause may transitorily aggravate MS symptoms. Two studies found an inflexion point on the Expanding Disability Status Scale (EDSS) with clinical worsening during the menopausal transition. Another study considering full EDSS trajectories from clinically isolated syndrome to postmenopause did not find such an EDSS inflection; (2) MS and DMD do not seem to alter the age of menopause onset; and (3) HRT in menopausal MS patients has not shown consistent benefits.

Conclusion:

Menopause seems to be associated with transient symptom worsening, but the existence of an inflection in disability progression is still controversial. Properly designed studies are necessary to achieve conclusive results.

Sex effects across the lifespan in women with multiple sclerosis

Multiple sclerosis (MS) is an autoimmune inflammatory demyelinating central nervous system disorder that is more common in women, with onset often during reproductive years. The female:male sex ratio of MS rose in several regions over the last century, suggesting a possible sex by environmental interaction increasing MS risk in women. Since many with MS are in their childbearing years, family planning, including contraceptive and disease-modifying therapy (DMT) counselling, are important aspects of MS care in women. While some DMTs are likely harmful to the developing fetus, others can be used shortly before or until pregnancy is confirmed. Overall, pregnancy decreases risk of MS relapses, whereas relapse risk may increase postpartum, although pregnancy does not appear to be harmful for long-term prognosis of MS. However, ovarian aging may contribute to disability progression in women with MS. Here, we review sex effects across the lifespan in women with MS, including the effect of sex on MS susceptibility, effects of pregnancy on MS disease activity, and management strategies around pregnancy, including risks associated with DMT use before and during pregnancy, and while breastfeeding. We also review reproductive aging and sexual dysfunction in women with MS.

Salvianolic acids improve liver lipid metabolism in ovariectomized rats via blocking STAT-3/SREBP1 signaling

Postmenopausal women, who have reduced circulating estrogen levels, are more prone to develop obesity and related metabolic diseases than premenopausal women. The absence of safe and effective treatments for postmenopausal obesity has changed the focus to natural products as alternative remedies. Total salvianolic acids (TSA) are the major water-soluble ingredients of Danshen. Salvianolic acid (SA) is the major constituent of the TSA. Salvianolic acids, including TSA and SA, are widely used in traditional Chinese medicine. In the present study, ovariectomized rats and LO2 cells were used to study the effects of salvianolic acids on body weight gain and hepatic steatosis. Salvianolic acids reduced ovariectomy (OVX)-induced body weight gain, attenuated the expressions of hepatic lipogenic genes, such as sterol regulatory element binding protein (SREBP)1, fatty acid synthase (FAS), and stearoyl-CoA desaturase (SCD)1, and decreased the liver triglyceride (TG) and total cholesterol (TC). For the molecular mechanisms, OVX and high glucose-induced phosphorylation of signal transducer and activator of transcription (STAT)-3 was inhibited by salvianolic acids treatment. In LO2 cells, inhibition of STAT-3 by siRNA attenuated the increased expression of SREBP1 and TG induced by high glucose. Salvianolic acids reduced the upregulation of SREBP1 and TG induced by high glucose in LO2 cells. In conclusion, these findings illustrated that salvianolic acids markedly alleviated the lipid metabolism disorders and protected against the postmenopausal obesity. The underlying mechanism was probably associated with the regulation of STAT-3 signaling.

Reproductive period and epigenetic modifications of the oxidative phosphorylation pathway in the human prefrontal cortex

PURPOSE

Human females have a unique duration of post-reproductive longevity, during which sex-specific mechanisms ma influence later-life mechanisms of neuronal resilience and vulnerability. The maintenance of energy metabolism, through the oxidative phosphorylation (OXPHOS) apparatus, is essential for brain health. Given the known association between reproductive period (years from menarche to menopause) and cognitive aging, we examined the hypothesis that cumulative estrogen exposure across the lifetime may be associated with differential methylation of genes in the OXPHOS pathway.

METHODS

Using DNA methylation patterns in the post-mortem dorsolateral prefrontal cortex (DLPFC) of 426 women prospectively followed until death in the Religious Orders Study and Rush Memory and Aging Project, we examined the relationship between reproductive period (subtracting age at menarche from age at menopause) and DNA methylation of a published set of autosomal OXPHOS genes previously implicated in stroke susceptibility. We then performed an unsupervised analysis of methylation levels across the Hallmark pathways from the Molecular Signatures Database.

RESULTS

We observed a strong association between reproductive period and DNA methylation status across OXPHOS CpGs. We replicated this association between reproductive period and DNA methylation in a much larger set of OXPHOS genes in our unsupervised analysis. Here, reproductive period also showed associations with methylation in genes related to E2F, MYC and MTORC1 signaling, fatty acid metabolism and DNA repair.

CONCLUSION

This study provides evidence from both a supervised and unsupervised analyses, that lifetime cumulative endogenous steroid exposures may play a role in maintenance of post-menopausal cellular balance, including in brain tissue.

Blocking of STAT-3/SREBP1-mediated glucose-lipid metabolism is involved in dietary phytoestrogen-inhibited ovariectomized-induced body weight gain in rats

Postmenopausal women have a decline in circulating estrogen levels and are more prone to obesity and its related metabolic diseases than premenopausal women are. The absence of safe and effective conventional treatments for postmenopausal obesity has changed the focus to natural products as alternative remedies. Here, ovariectomized rats and LO2 cells were used to study the molecular basis of the effect of dietary phytoestrogens on body weight gain and hepatic steatosis. Dietary phytoestrogens can inhibit ovariectomy (OVX)-induced body weight gain, blood glucose concentration, expression of hepatic lipogenic genes, such as sterol regulatory element binding protein (SREBP)1, acetyl-CoA carboxylase (ACC)1, fatty acid synthase (FAS), and stearoyl-CoA desaturase (SCD)1, and decrease liver triglyceride (TG) content, but later estradiol withdrawal increased expression of SREBP1. Histological analysis of liver showed that dietary phytoestrogens improved OVX-induced morphological abnormalities. OVX and high glucose-induced phosphorylation of signal transducer and activator of transcription (STAT)-3 were inhibited by phytoestrogens treatment. In LO2 cells, inhibition of STAT-3 by siRNA attenuated the increased TG content and expression of SREBP1 induced by high glucose. Phytoestrogens reduced the upregulation of SREBP1 and TG induced by high glucose in LO2 cells. In conclusion, these findings illustrated that dietary phytoestrogens markedly alleviated the derangement of lipid metabolism. The underlying mechanism is probably associated with regulating STAT-3/SREBP1 signaling.

Downregulation of G‑protein‑coupled receptor 30 in the hippocampus attenuates the neuroprotection of estrogen in the critical period hypothesis

The aim of the present study was to investigate the role of G-protein-coupled receptor 30 (GPR30) in long-term 17β-estradiol (E2) deprivation (LTED) in a rat model with global cerebral ischemia (GCI), and its therapeutic target for ischemic stroke in the clinical setting. Following bilateral ovariectomy, GCI was induced in rats 1 or 10 weeks post-surgery. To determine the protein and mRNA expression levels of GPR30 in the hippocampal CA1 region of LTED rats, short-term E2 deprivation (STED) rats and naturally aging rats, western blot analysis and reverse transcription-quantitative polymerase chain reaction were performed. The results of the present study demonstrated that E2 treatment revealed significant neuroprotection post-GCI in STED rats, but not in LTED rats, as well as a decrease in the expression levels of GPR30 in the hippocampal CA1 region. In LTED rats,. Notably, no effects were observed on the ubiquitination of GPR30 following investigation in STED or LTED rats. While the protein and mRNA expression levels of GPR30 were also decreased in the hippocampal CA1 region of female 24-month-old rats compared with 3-month-old rats. E2 treatment initiated for the entire ovariectomy period elevated GPR30 mRNA and protein expression levels, and attenuated the loss of hippocampal neurons in the GCI-induced CA1 region, indicating that E2 treatment exerted robust neuroprotection within LTED rats. However, the neuroprotective effect of E2 may be blocked by G15. The results of the present study revealed that downregulation of GPR30 expression may attenuate the neuroprotection of E2 within LTED conditions in rats post-ovariectomy by leading to neuronal insensitivity to E2 neuroprotection following cerebral ischemia. These results provide evidence that GPR30 may have potential as a novel therapeutic target for the treatment of clinical ischemic stroke.

Reorganization of Functional Networks in Verbal Working Memory Circuitry in Early Midlife: The Impact of Sex and Menopausal Status

Converging preclinical and human evidence indicates that the decline in ovarian estradiol production during the menopausal transition may play a mechanistic role in the neuronal changes that occur early in the aging process. Here, we present findings from a population-based fMRI study characterizing regional and network-level differences in working memory (WM) circuitry in midlife men and women (N = 142; age range 46-53), as a function of sex and reproductive stage. Reproductive histories and hormonal evaluations were used to determine menopausal status. Participants performed a verbal WM task during fMRI scanning. Results revealed robust differences in task-evoked responses in dorsolateral prefrontal cortex and hippocampus as a function of women's reproductive stage, despite minimal variance in chronological age. Sex differences in regional activity and functional connectivity that were pronounced between men and premenopausal women were diminished for postmenopausal women. Critically, analyzing data without regard to sex or reproductive status obscured group differences in the circuit-level neural strategies associated with successful working memory performance. These findings underscore the importance of reproductive age and hormonal status, over and above chronological age, for understanding sex differences in the aging of memory circuitry. Further, these findings suggest that early changes in working memory circuitry are evident decades before the age range typically targeted in cognitive aging studies.

The relationship between phytoestrogens and speed of processing

OBJECTIVE

This study examined the cross-sectional association between phytoestrogens and speed of processing. We hypothesized that higher levels of phytoestrogens would be related to better cognitive performance among older women.

METHODS

Participants were from the National Health and Nutrition Examination Survey and consisted of 200 older women (M = 74.4 y). Stepwise regressions examined indicators of speed of processing, measured by the Digit Symbol Substitution Test. Isoflavones, lignans, and individual phytoestrogens were added to the regression after including covariates of age, education, race, smoking, and creatinine. Isoflavones were further broken into quartiles among the sample to further evaluate the nature of the curvilinear association.

RESULTS

Results showed a relationship between cognition and lignans, explaining 3.8% of the variance after including the covariates, indicating fewer lignans were associated with better speed of processing (P < 0.001). A significant curvilinear relationship with isoflavones explained 1.3% additional variance (P < 0.001). The moderate-high, low-moderate, and the lowest quartile of isoflavones were associated with better cognition, whereas the highest amount was associated with worse speed of processing. Among the individual phytoestrogens, only enterodiol accounted for 4.4% additional variance after taking into account covariates and indicated a negative association with cognition (P = 0.03).

CONCLUSIONS

Results suggest that moderate levels of isoflavones, but not lignans, may be associated with better speed of processing. Caution must remain for high isoflavone amounts due to the negative association with cognition. Given the results, phytoestrogens have the potential to be an intervention target for older females' cognition. To become a viable intervention, further research is needed.

Circulating Estradiol Regulates Brain-Derived Estradiol via Actions at GnRH Receptors to Impact Memory in Ovariectomized Rats

Systemic estradiol treatment enhances hippocampus-dependent memory in ovariectomized rats. Although these enhancements are traditionally thought to be due to circulating estradiol, recent data suggest these changes are brought on by hippocampus-derived estradiol, the synthesis of which depends on gonadotropin-releasing hormone (GnRH) activity. The goal of the current work is to test the hypothesis that peripheral estradiol affects hippocampus-dependent memory through brain-derived estradiol regulated via hippocampal GnRH receptor activity. In the first experiment, intracerebroventricular infusion of letrozole, which prevents the synthesis of estradiol, blocked the ability of peripheral estradiol administration in ovariectomized rats to enhance hippocampus-dependent memory in a radial-maze task. In the second experiment, hippocampal infusion of antide, a long-lasting GnRH receptor antagonist, blocked the ability of peripheral estradiol administration in ovariectomized rats to enhance hippocampus-dependent memory. In the third experiment, hippocampal infusion of GnRH enhanced hippocampus-dependent memory, the effects of which were blocked by letrozole infusion. Results indicate that peripheral estradiol-induced enhancement of cognition is mediated by brain-derived estradiol via hippocampal GnRH receptor activity.

Estrogen receptor beta signals to inhibition of cardiac fibrosis

Cardiac fibrosis evolves from the cardiac hypertrophic state. In this respect, estrogen and estrogen receptor beta (ERβ) inhibit the effects of cardiac hypertrophic peptides that also stimulate fibrosis. Here we determine details of the anti-fibrotic functions of ERβ. In acutely isolated rat cardiac fibroblasts. E2 or a specific ERβ agonist (βLGND2) blocked angiotensin II (AngII) signaling to fibrosis. This resulted from ERβ activating protein kinase A and AMP kinase, inhibiting both AngII de-phosphorylation of RhoA and the resulting stimulation of Rho kinase. Inhibition of Rho kinase from ERβ signaling resulted in marked decrease of TGFβ expression, connective tissue growth factor production and function, matrix metalloproteinases 2 and 9 expression and activity, and the conversion of fibroblasts to myofibroblasts. Production of collagens I and III were also significantly decreased. Several important aspects were corroborated in-vivo from βLGND2-treated mice that underwent AngII-induced cardiac hypertrophy. Thus, ERβ in cardiac fibroblasts prevents key aspects of cardiac fibrosis development.

Impact of Sex and Menopausal Status on Episodic Memory Circuitry in Early Midlife

Cognitive neuroscience of aging studies traditionally target participants age 65 and older. However, epidemiological surveys show that many women report increased forgetfulness earlier in the aging process, as they transition to menopause. In this population-based fMRI study, we stepped back by over a decade to characterize the changes in memory circuitry that occur in early midlife, as a function of sex and women's reproductive stage. Participants (N = 200; age range, 45-55) performed a verbal encoding task during fMRI scanning. Reproductive histories and serologic evaluations were used to determine menopausal status. Results revealed a pronounced impact of reproductive stage on task-evoked hippocampal responses, despite minimal difference in chronological age. Next, we examined the impact of sex and reproductive stage on functional connectivity across task-related brain regions. Postmenopausal women showed enhanced bilateral hippocampal connectivity relative to premenopausal and perimenopausal women. Across women, lower 17β-estradiol concentrations were related to more pronounced alterations in hippocampal connectivity and poorer performance on a subsequent memory retrieval task, strongly implicating sex steroids in the regulation of this circuitry. Finally, subgroup analyses revealed that high-performing postmenopausal women (relative to low and middle performers) exhibited a pattern of brain activity akin to premenopausal women. Together, these findings underscore the importance of considering reproductive stage, not simply chronological age, to identify neuronal and cognitive changes that unfold in the middle decades of life. In keeping with preclinical studies, these human findings suggest that the decline in ovarian estradiol production during menopause plays a significant role in shaping memory circuitry.

SIGNIFICANCE STATEMENT

Maintaining intact memory function with age is one of the greatest public health challenges of our time, and women have an increased risk for memory disorders relative to men later in life. We studied adults early in the aging process, as women transition into menopause, to identify neuronal and cognitive changes that unfold in the middle decades of life. Results demonstrate regional and network-level differences in memory encoding-related activity as a function of women's reproductive stage, independent of chronological age. Analyzing data without regard to sex or menopausal status obscured group differences in circuit-level neural strategies associated with successful memory retrieval. These findings suggest that early changes in memory circuitry are evident decades before the age range traditionally targeted by cognitive neuroscience of aging studies.

Long-term consequences of estrogens administered in midlife on female cognitive aging

This article is part of a Special Issue "Estradiol and cognition". Many of the biochemical, structural, and functional changes that occur as the female brain ages are influenced by changes in levels of estrogens. Administration of estrogens begun during a critical window near menopause is hypothesized to prevent or delay age-associated cognitive decline. However, due to potential health risks women often limit use of estrogen therapy to a few years to treat menopausal symptoms. The long-term consequences for the brain of short-term use of estrogens are unknown. Interestingly, there are preliminary data to suggest that short-term use of estrogens during the menopausal transition may afford long-term cognitive benefits to women as they age. Thus, there is the intriguing possibility that short-term estrogen therapy may provide lasting benefits to the brain and cognition. The focus of the current review is an examination of the long-term impact for cognition of midlife use of estrogens. We review data from our lab and others indicating that the ability of midlife estrogens to impact estrogen receptors in the hippocampus may contribute to its ability to exert lasting impacts on cognition in aging females.

Multiple sclerosis at menopause: Potential neuroprotective effects of estrogen

Multiple sclerosis (MS) is an autoimmune demyelinating and neurodegenerative condition of the central nervous system that preferentially afflicts women more than men. Low estrogen states such as menopause and the postpartum period favor exacerbations of multiple sclerosis in women with the disease. Existing and emerging evidence suggests a role for estrogen in the alleviation of symptoms and reversal of pathology associated with MS. While clinical evidence is sparse regarding the benefit of estrogen therapy for women at risk for MS exacerbations, scientific data demonstrates that estrogen potentiates numerous neuroprotective effects on the central nervous system (CNS). Estrogens play a wide range of roles involved in MS disease pathophysiology, including increasing antiinflammatory cytokines, decreasing demyelination, and enhancing oxidative and energy producing processes in CNS cells.

Age at surgical menopause influences cognitive decline and Alzheimer pathology in older women

OBJECTIVE

To determine the association between age at surgical menopause and both cognitive decline and Alzheimer disease (AD) pathology in 2 longitudinal cohorts.

METHODS

Female subjects from 2 longitudinal studies of cognitive decline (Religious Orders Study and Rush Memory and Aging Project) were included (total n = 1,884). The primary analysis examined the association between age at surgical menopause and decline in a global cognition score. Secondary analyses examined additional outcomes: 1) decline in 5 cognitive subdomains and 2) a global measure of the burden of AD pathology. In exploratory analyses, we examined the effect of hormone replacement therapy (HRT). We adjusted all models for age, education, smoking, and cohort and stratified by surgical vs natural menopause.

RESULTS

For the 32% of subjects with surgical menopause, earlier age at menopause was associated with faster decline in global cognition (p = 0.0007), specifically episodic memory (p = 0.0003) and semantic memory (p = 0.002). Earlier age at menopause was also associated with increased AD neuropathology (p = 0.038), in particular neuritic plaques (p = 0.013). HRT use for at least 10 years, when administered within a 5-year perimenopausal window, was associated with decreased decline in global cognition. No associations were seen in women who had natural menopause.

CONCLUSIONS

Early age at surgical menopause was associated with cognitive decline and AD neuropathology. Ongoing studies should clarify the potential effect of HRT on this relationship.

Menopause in multiple sclerosis: therapeutic considerations

While the onset of multiple sclerosis (MS) typically occurs during the childbearing years, many women living with MS are of perimenopausal age. There is frequent overlap between menopausal and MS-related symptoms and co-morbidities (e.g. sexual dysfunction, mood disorders and bladder function). Furthermore, some MS symptoms may be exacerbated by perimenopausal changes such as hot flashes or sleep disturbance. The MS neurologist may frequently be the first to become aware of these symptoms and to play a role in monitoring and managing them. In this review, we describe immunological and neurologic changes at menopause as they may impact MS. We then review common symptoms, including fatigue, depression, sexual function, pain and insomnia, and provide both behavioral and pharmacological suggestions for their management. Next, we discuss the need for osteoporosis and cancer screening in perimenopausal women with MS. Finally, we highlight important research gaps, including what effect, if any, the menopausal transition may play on MS disease course as well as the potential modulatory role of hormone replacement therapies.

Cognitive complaints after breast cancer treatments: examining the relationship with neuropsychological test performance

BACKGROUND

Cognitive complaints are reported frequently after breast cancer treatments. Their association with neuropsychological (NP) test performance is not well-established.

METHODS

Early-stage, posttreatment breast cancer patients were enrolled in a prospective, longitudinal, cohort study prior to starting endocrine therapy. Evaluation included an NP test battery and self-report questionnaires assessing symptoms, including cognitive complaints. Multivariable regression models assessed associations among cognitive complaints, mood, treatment exposures, and NP test performance.

RESULTS

One hundred eighty-nine breast cancer patients, aged 21-65 years, completed the evaluation; 23.3% endorsed higher memory complaints and 19.0% reported higher executive function complaints (>1 SD above the mean for healthy control sample). Regression modeling demonstrated a statistically significant association of higher memory complaints with combined chemotherapy and radiation treatments (P = .01), poorer NP verbal memory performance (P = .02), and higher depressive symptoms (P < .001), controlling for age and IQ. For executive functioning complaints, multivariable modeling controlling for age, IQ, and other confounds demonstrated statistically significant associations with better NP visual memory performance (P = .03) and higher depressive symptoms (P < .001), whereas combined chemotherapy and radiation treatment (P = .05) approached statistical significance.

CONCLUSIONS

About one in five post-adjuvant treatment breast cancer patients had elevated memory and/or executive function complaints that were statistically significantly associated with domain-specific NP test performances and depressive symptoms; combined chemotherapy and radiation treatment was also statistically significantly associated with memory complaints. These results and other emerging studies suggest that subjective cognitive complaints in part reflect objective NP performance, although their etiology and biology appear to be multifactorial, motivating further transdisciplinary research.

Reduced hippocampal volume and verbal memory performance associated with interleukin-6 and tumor necrosis factor-alpha levels in chemotherapy-treated breast cancer survivors

Many survivors of breast cancer show significant cognitive impairments, including memory deficits. Inflammation induced by chemotherapy may contribute to hippocampal changes that underlie these deficits. In this cross-sectional study, we measured bilateral hippocampal volumes from high-resolution magnetic resonance images in 42 chemotherapy-treated breast cancer survivors and 35 healthy female controls. Patients with breast cancer were, on average, 4.8 ± 3.4 years off-therapy. In a subset of these participants (20 breast cancer, 23 controls), we quantified serum cytokine levels. Left hippocampal volumes and memory performance were significantly reduced and interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNFα) concentrations were significantly elevated in the breast cancer group compared to controls. In the breast cancer group, lower left hippocampal volume was associated with higher levels of TNFα and lower levels of IL-6 with a significant interaction between these two cytokines suggesting a potential modulatory effect of IL-6 on TNFα. Verbal memory performance was associated with cytokine levels and left hippocampal volume in both groups. These findings provide evidence of altered hippocampal volume and verbal memory difficulties following breast cancer chemotherapy that may be mediated by TNFα and IL-6.

Does phytoestrogen supplementation affect cognition differentially in males and females?

Phytoestrogens are plant-derived compounds found mainly in soy with known estrogenic properties and a potential for benefits to human health. Increased intake in phytoestrogens stemmed from the search for safe alternatives to hormone replacement therapies. Based on epidemiologic evidence comparing Western and Asian populations and clinical studies, phytoestrogens show promise to improve health and brain function. This review is focused on the effects of phytoestrogens on cognition by examining clinical and animal studies, with special attention placed on (1) a window of therapeutic opportunity which may explain the discrepancy among studies, and (2) whether a sex/gender difference exists in response to phytoestrogen intake and what the possible underlying mechanisms may be.

Association of menstrual cycle phase with the core components of empathy

Evidence has accumulated that emotion recognition performance varies with menstrual cycle phase. However, according to some empathy models, facial affect recognition constitutes only one component of empathic behavior, besides emotional perspective taking and affective responsiveness. It remains unclear whether menstrual cycle phase and thus estradiol and progesterone levels are also associated with the two other empathy constructs. Therefore, we investigated 40 healthy right-handed females, 20 during their follicular phase and 20 during their midluteal phase and compared their performance in three tasks tapping the empathic components as well as self-report data. Salivary hormone levels were obtained and correlated with performance parameters. Subjects were matched for age and education and did not differ in neuropsychological function. Analysis of empathy performance revealed a significant effect of phase in emotion recognition, showing higher accuracy in the follicular group. Regarding affective responsiveness, we observed a significant difference in reaction times, with faster responses for sad and angry stimuli in the midluteal group. No significant group difference emerged for emotional perspective taking. Furthermore, significant correlations between progesterone levels and emotion recognition accuracy and affective responsiveness emerged only in the luteal group. However, groups did not differ in self-reported empathy. Our results indicate that menstrual cycle phase and thus ovarian hormone concentration are differentially related to empathic behavior, particularly emotion recognition and responsiveness to negative situations, with progesterone covarying with both in the luteal phase.

Altered small-world properties of gray matter networks in breast cancer

Background

Breast cancer survivors, particularly those treated with chemotherapy, are at significantly increased risk for long-term cognitive and neurobiologic impairments. These deficits tend to involve skills that are subserved by distributed brain networks. Additionally, neuroimaging studies have shown a diffuse pattern of brain structure changes in chemotherapy-treated breast cancer survivors that might impact large-scale brain networks.

Methods

We therefore applied graph theoretical analysis to compare the gray matter structural networks of female breast cancer survivors with a history of chemotherapy treatment and healthy age and education matched female controls.

Results

Results revealed reduced clustering coefficient and small-world index in the brain network of the breast cancer patients across a range of network densities. In addition, the network of the breast cancer group had less highly interactive nodes and reduced degree/centrality in the frontotemporal regions compared to controls, which may help explain the common impairments of memory and executive functioning among these patients.

Conclusions

These results suggest that breast cancer and chemotherapy may decrease regional connectivity as well as global network organization and integration, reducing efficiency of the network. To our knowledge, this is the first report of altered large-scale brain networks associated with breast cancer and chemotherapy.

Kalirin, a key player in synapse formation, is implicated in human diseases

Synapse formation is considered to be crucial for learning and memory. Understanding the underlying molecular mechanisms of synapse formation is a key to understanding learning and memory. Kalirin-7, a major isoform of Kalirin in adult rodent brain, is an essential component of mature excitatory synapses. Kalirin-7 interacts with multiple PDZ-domain-containing proteins including PSD95, spinophilin, and GluR1 through its PDZ-binding motif. In cultured hippocampal/cortical neurons, overexpression of Kalirin-7 increases spine density and spine size whereas reduction of endogenous Kalirin-7 expression decreases synapse number, and spine density. In Kalirin-7 knockout mice, spine length, synapse number, and postsynaptic density (PSD) size are decreased in hippocampal CA1 pyramidal neurons; these morphological alterations are accompanied by a deficiency in long-term potentiation (LTP) and a decreased spontaneous excitatory postsynaptic current (sEPSC) frequency. Human Kalirin-7, also known as Duo or Huntingtin-associated protein-interacting protein (HAPIP), is equivalent to rat Kalirin-7. Recent studies show that Kalirin is relevant to many human diseases such as Huntington's Disease, Alzheimer's Disease, ischemic stroke, schizophrenia, depression, and cocaine addiction. This paper summarizes our recent understanding of Kalirin function.

Estrogen neuroprotection and the critical period hypothesis

17β-Estradiol (estradiol or E2) is implicated as a neuroprotective factor in a variety of neurodegenerative disorders. This review focuses on the mechanisms underlying E2 neuroprotection in cerebral ischemia, as well as emerging evidence from basic science and clinical studies, which suggests that there is a "critical period" for estradiol's beneficial effect in the brain. Potential mechanisms underlying the critical period are discussed, as are the neurological consequences of long-term E2 deprivation (LTED) in animals and in humans after natural menopause or surgical menopause. We also summarize the major clinical trials concerning postmenopausal hormone therapy (HT), comparing their outcomes with respect to cardiovascular and neurological disease and discussing their relevance to the critical period hypothesis. Finally, potential caveats, controversies and future directions for the field are highlighted and discussed throughout the review.

Rapid estrogen signaling in the brain: implications for the fine-tuning of neuronal circuitry

Rapid actions of estrogens were first described >40 years ago. However, the importance of rapid estrogen-mediated actions in the CNS is only now becoming apparent. Several lines of evidence demonstrate that rapid estrogen-mediated signaling elicits potent effects on molecular and cellular events, resulting in the "fine-tuning" of neuronal circuitry. At an ultrastructural level, the details of estrogen receptor localization and how these are regulated by the circulating hormone and age are now becoming evident. Furthermore, the mechanisms that allow membrane-associated estrogen receptors to couple with intracellular signaling pathways are also now being revealed. Elucidation of complex actions of rapid estrogen-mediated signaling on synaptic proteins, connectivity, and synaptic function in pyramidal neurons has demonstrated that this neurosteroid engages specific mechanisms in different areas of the brain. The regulation of synaptic properties most likely underlies the fine-tuning of neuronal circuitry. This in turn may influence how learned behaviors are encoded by different circuitry in male and female subjects. Importantly, as estrogens have been suggested as potential treatments of a number of disorders of the CNS, advancements in our understanding of rapid estrogen signaling in the brain will serve to aid in the development of potential novel estrogen-based treatments.