Early postmenopausal hormone therapy may prevent cognitive impairment later in life

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

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

Targets, trials and tribulations in Alzheimer therapeutics

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

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

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

Cardiometabolic health, menopausal estrogen therapy and the brain: How effects of estrogens diverge in healthy and unhealthy preclinical models of aging

Research in preclinical models indicates that estrogens are neuroprotective and positively impact cognitive aging. However, clinical data are equivocal as to the benefits of menopausal estrogen therapy to the brain and cognition. Pre-existing cardiometabolic disease may modulate mechanisms by which estrogens act, potentially reducing or reversing protections they provide against cognitive decline. In the current review we propose mechanisms by which cardiometabolic disease may alter estrogen effects, including both alterations in actions directly on brain memory systems and actions on cardiometabolic systems, which in turn impact brain memory systems. Consideration of mechanisms by which estrogen administration can exert differential effects dependent upon health phenotype is consistent with the move towards precision or personalized medicine, which aims to determine which treatment interventions will work for which individuals. Understanding effects of estrogens in both healthy and unhealthy models of aging is critical to optimizing the translational link between preclinical and clinical research.

Associations Between Midlife Menopausal Hormone Therapy Use, Incident Diabetes, and Late Life Memory in the Wisconsin Longitudinal Study

BACKGROUND

Prior research suggests a link between menopausal hormone therapy (MHT) use, memory function, and diabetes risk. The menopausal transition is a modifiable period to enhance long-term health and cognitive outcomes, although studies have been limited by short follow-up periods precluding a solid understanding of the lasting effects of MHT use on cognition.

OBJECTIVE

We examined the effects of midlife MHT use on subsequent diabetes incidence and late life memory performance in a large, same-aged, population-based cohort. We hypothesized that the beneficial effects of MHT use on late life cognition would be partially mediated by reduced diabetes risk.

METHODS

1,792 women from the Wisconsin Longitudinal Study (WLS) were included in analysis. We employed hierarchical linear regression, Cox regression, and causal mediation models to test the associations between MHT history, diabetes incidence, and late life cognitive performance.

RESULTS

1,088/1,792 women (60.7%) reported a history of midlife MHT use and 220/1,792 (12.3%) reported a history of diabetes. MHT use history was associated with better late life immediate recall (but not delayed recall), as well as a reduced risk of diabetes with protracted time to onset. Causal mediation models suggest that the beneficial effect of midlife MHT use on late life immediate recall were at least partially mediated by diabetes risk.

CONCLUSION

Our data support a beneficial effect of MHT use on late life immediate recall (learning) that was partially mediated by protection against diabetes risk, supporting MHT use in midlife as protective against late life cognitive decline and adverse health outcomes.

Hormone Replacement Therapy After Breast Cancer: It Is Time

ABSTRACT

This article reviews the decades of evidence supporting the reproducible benefits of HRT for menopausal symptom control, improved cardiac health, prevention of hip fracture, reduction in the risk and pace of cognitive decline, and enhanced longevity. It quantifies the increased risk of thromboembolism associated with oral, though not transdermal, HRT. It evaluates the repeated claims that HRT is associated with an increased risk of breast cancer development, and, when administered to breast cancer survivors, an increased risk of breast cancer recurrence. Twenty-five studies of HRT after a breast cancer diagnosis, published between 1980 and 2013, are discussed, as are the 20 reviews of those studies published between 1994 and 2021. Only 1 of the 25 studies, the HABITS trial, demonstrated an increased risk of recurrence, which was limited to local or contralateral, and not distant, recurrence. None of the studies, including HABITS, reported increased breast cancer mortality associated with HRT. Even in the HABITS trial, the absolute increase in the number of women who had a recurrence (localized only) associated with HRT administration was 22. It is on the basis of these 22 patients that HRT, with its demonstrated benefits for so many aspects of women's health, is being denied to millions of breast cancer survivors around the world.

Hormone therapy in the postmenopausal years: considering benefits and risks in clinical practice

BACKGROUND

Menopausal symptoms can be very distressing and considerably affect a woman's personal and social life. It is becoming more and more evident that leaving bothersome symptoms untreated in midlife may lead to altered quality of life, reduced work productivity and, possibly, overall impaired health. Hormone therapy (HT) for the relief of menopausal symptoms has been the object of much controversy over the past two decades. At the beginning of the century, a shadow was cast on the use of HT owing to the concern for cardiovascular and cerebrovascular risks, and breast cancer, arising following publication of a large randomized placebo-controlled trial. Findings of a subanalysis of the trial data and extended follow-up studies, along with other more modern clinical trials and observational studies, have provided new evidence on the effects of HT.

OBJECTIVE AND RATIONALE

The goal of the following paper is to appraise the most significant clinical literature on the effects of hormones in postmenopausal women, and to report the benefits and risks of HT for the relief of menopausal symptoms.

SEARCH METHODS

A Pubmed search of clinical trials was performed using the following terms: estrogens, progestogens, bazedoxifene, tibolone, selective estrogen receptor modulators, tissue-selective estrogen complex, androgens, and menopause.

OUTCOMES

HT is an effective treatment for bothersome menopausal vasomotor symptoms, genitourinary syndrome, and prevention of osteoporotic fractures. Women should be made aware that there is a small increased risk of stroke that tends to persist over the years as well as breast cancer risk with long-term estrogen-progestin use. However, healthy women who begin HT soon after menopause will probably earn more benefit than harm from the treatment. HT can improve bothersome symptoms, all the while conferring offset benefits such as cardiovascular risk reduction, an increase in bone mineral density and a reduction in bone fracture risk. Moreover, a decrease in colorectal cancer risk is obtainable in women treated with estrogen-progestin therapy, and an overall but nonsignificant reduction in mortality has been observed in women treated with conjugated equine estrogens alone or combined with estrogen-progestin therapy. Where possible, transdermal routes of HT administration should be preferred as they have the least impact on coagulation. With combined treatment, natural progesterone should be favored as it is devoid of the antiapoptotic properties of other progestogens on breast cells. When beginning HT, low doses should be used and increased gradually until effective control of symptoms is achieved. Unless contraindications develop, patients may choose to continue HT as long as the benefits outweigh the risks. Regular reassessment of the woman's health status is mandatory. Women with premature menopause who begin HT before 50 years of age seem to have the most significant advantage in terms of longevity.

WIDER IMPLICATIONS

In women with bothersome menopausal symptoms, HT should be considered one of the mainstays of treatment. Clinical practitioners should tailor HT based on patient history, physical characteristics, and current health status so that benefits outweigh the risks.

Previous estradiol treatment during midlife maintains transcriptional regulation of memory-related proteins by ERα in the hippocampus in a rat model of menopause

Previous midlife estradiol treatment, like continuous treatment, improves memory and results in lasting increases in hippocampal levels of estrogen receptor (ER) α and ER-dependent transcription in ovariectomized rodents. We hypothesized that previous and continuous midlife estradiol act to specifically increase levels of nuclear ERα, resulting in transcriptional regulation of proteins that mediate estrogen effects on memory. Ovariectomized middle-aged rats received estradiol or vehicle capsule implants. After 40 days, rats initially receiving vehicle received another vehicle capsule (ovariectomized controls). Rats initially receiving estradiol received either another estradiol (continuous estradiol) or a vehicle (previous estradiol) capsule. One month later, hippocampi were dissected and processed. Continuous and previous estradiol increased levels of nuclear, but not membrane or cytosolic ERα and had no effect on Esr1. Continuous and previous estradiol impacted gene expression and/or protein levels of mediators of estrogenic action on memory including ChAT, BDNF, and PSD-95. Findings demonstrate a long-lasting role for hippocampal ERα as a transcriptional regulator of memory following termination of previous estradiol treatment in a rat model of menopause.

Sex hormones, vascular factors and cognition

After more than a century of research, we have failed to develop a pharmacological prevention or cure for dementia. There are strong indicators that sex hormones influence cognition. In this paper we discuss the role of these hormones at the intersection between vascular disease and dementia, in light of the mounting literature covering the shared risk factors, pathological features alongside the timeline of hormonal change with the evolution of vascular and neurodegenerative disease. Interactive risk factors and the role of inflammation over the duration of disease evolution are highlighted. Our summary tables assessing the impact of estrogen-based hormone therapy on cognition over the past 45 years illustrate the effort expended to determine the ideal age for intervention and the type, dose, administration, and duration of therapy that might improve or protect cognition as well as alleviate menopausal symptoms. As the prevalence of dementia is rising and is higher in women, it is crucial we advance our knowledge from the "inconclusive" position statement on menopausal hormone therapy of the US Preventive Services Task Force.

Association between menopausal hormone therapy and risk of neurodegenerative diseases: Implications for precision hormone therapy

INTRODUCTION

The impact of menopausal hormone therapy (HT) on age-associated Alzheimer's and neurodegenerative diseases (NDDs) remains unresolved. To determine the effect of HT, formulation, type, and duration on risk of NDDs, a retrospective analysis was performed using a 10-year Humana claims dataset.

METHODS

Study population included women aged 45 years or older with or without claim records of HT medications. Patients diagnosed with NDDs including Alzheimer's disease (AD), Parkinson's disease (PD), dementia, multiple sclerosis (MS), and amyotrophic lateral sclerosis (ALS) were identified. Relative risk (RR) ratios and 95% confidence intervals (CI) for combined NDDs, or AD, PD, dementia, MS, and ALS were determined. Cumulative hazard ratios were determined to investigate the association between HT and NDDs at different age groups.

RESULTS

In 379,352 women with or without claim records of HT, use of HT was associated with significantly reduced risk for combined NDDs (RR 0.42, 95% CI 0.40-0.43, P < 0.001). Average follow-up time was 5.1 [2.3] years. Formulations containing natural steroids 17β-estradiol and/or progesterone were associated with greater reduction in NDD risk. Oral- HT users showed significantly reduced RRs (0.42, 0.41-0.44, P < 0.001) for combined NDDs compared to non-HT users. The RRs for transdermal-HT users were significantly decreased for all-cause dementia (0.73, 0.60-0.88, P = 0.001) and MS (0.55, 0.36-0.84, P = 0.005). Greatest reduction in risk of NDD, AD, and dementia emerged in patients aged 65 years or older. Further, the protective effect of long-term therapy (>1 year) on combined NDDs, AD, PD, and dementia was greater compared to short-term therapy (≤1 year).

DISCUSSION

HT was associated with reduced risk of all NDDs including AD and dementia, with greater duration of therapy and natural steroid formulations associated with greater efficacy. These findings advance precision HT to prevent NDDs including AD.

Osthole Ameliorates Estrogen Deficiency-Induced Cognitive Impairment in Female Mice

Loss of endogenous estrogen and dysregulation of the estrogen receptor signaling pathways are associated with an increase in risk for cognitive deficit and depression in women after menopause. Estrogen therapy for menopause increases the risk of breast and ovarian cancers, and stroke. Therefore, it is critical to find an alternate treatment for menopausal women. Osthole (OST), a coumarin, has been reported to have neuroprotective effects. This study examined whether OST improves ovariectomy (OVX)-induced cognitive impairment, and alleviates anxiety- and depression-like behaviors induced by OVX in mice. Adult female C57BL/6J mice were ovariectomized and then treated with OST at a dose of 30 mg/kg for 14 days. At the end of the treatment period, behavioral tests were used to evaluate spatial learning and memory, recognition memory, anxiety- and depression-like behaviors. A cohort of the mice were sacrificed after 14 days of OST treatment and their hippocampi were collected for measurement of the proteins of interest using western blot. OVX-induced alteration in the levels of proteins was accompanied by cognitive deficit, anxiety- and depression-like behaviors. OST treatment improved cognitive deficit, alleviated anxiety- and depression-like behaviors induced by OVX, and reversed OVX-induced alterations in the levels of synaptic proteins and ERα, BDNF, TrKB, p-CREB, p-Akt and Rac1 in the hippocampus. Therefore, reversal of OVX-induced decrease in the levels of hippocampal proteins by OST might contribute to the effects of OST on improving cognitive deficit and alleviating anxiety- and depression-like behaviors induced by OVX.

The role of sex hormones in women with multiple sclerosis: From puberty to assisted reproductive techniques

BACKGROUND

Multiple Sclerosis is a multifactorial chronic autoimmune disease, affecting predominantly females in the fertile age. Sex hormones changes during a woman's life, from puberty to menopause, including pregnancy and puerperium, may influence the onset and course of Multiple Sclerosis. The effect of estrogen levels on immune, clinical and radiological aspects of Multiple Sclerosis, also stimulated investigation on the effect of sexual hormones therapies, such as oral contraceptives and assisted reproductive technique, on the Multiple Sclerosis course.

SEARCH STRATEGY AND SELECTION CRITERIA

A literature search for original articles and reviews was conducted in the databases, including PubMed, Scopus, and ClinicalTrials.gov of the U.S. National Library of Medicine site from 1988 to 2020.

RESULTS AND CONCLUSION

This review reports the effects of the physiological and iatrogenic hormonal changes either on immune or clinical or paraclinical features in the different life stages of women affected by Multiple Sclerosis.

Cognitive performance in patients with chronic tension-type headache and its relation to neuroendocrine hormones

Background

Tension-type headache is the most common headache to be seen in clinical practice. Depression is highly prevalent in chronic tension-type headache (CTTH) patients attending the clinical settings. Cognitive impairment and neuroendocrine dysregulation had been reported in patients with depression and patients with CTTH.

Objective

To assess the cognitive performance and investigate its possible relations to neuroendocrine levels in patients with CTTH.

Subjects and methods

Patients with CTTH, depression, and control subjects were recruited. CTTH was diagnosed according to the International Classification of Headache Disorders. Cognitive performance, depression severity, and pain intensity were assessed by the Montreal Cognitive Assessment Arabic version, Beck’s Depression Inventory, and McGill Pain Questionnaire respectively. Blood samples were collected in the morning within 60 min after waking up from 8:00 to 9:00 a.m. to measure serum levels of basal plasma CRH, ACTH, Cortisol, TSH, FT3, and FT4.

Results

Both patients with CTTH and depression had impaired cognitive performance. Patients with CTTH and patients with depression had altered the hypothalamus-pituitary-adrenal axis, and pituitary-thyroid axis. The hormonal levels significantly correlated with cognitive function in patient groups, especially patients with CTTH.

Conclusion

Patients with CTTH had cognitive dysfunction which could be related to neuroendocrine hormonal dysregulation.

Neuroimmunomodulation by estrogen in health and disease

Systemic homeostasis is maintained by the robust bidirectional regulation of the neuroendocrine-immune network by the active involvement of neural, endocrine and immune mediators. Throughout female reproductive life, gonadal hormones undergo cyclic variations and mediate concomitant modulations of the neuroendocrine-immune network. Dysregulation of the neuroendocrine-immune network occurs during aging as a cumulative effect of declining neural, endocrine and immune functions and loss of compensatory mechanisms including antioxidant enzymes, growth factors and co-factors. This leads to disruption of homeostasis and sets the stage for the development of female-specific age-associated diseases such as autoimmunity, osteoporosis, cardiovascular diseases and hormone-dependent cancers. Ovarian hormones especially estrogen, play a key role in the maintenance of health and homeostasis by modulating the nervous, endocrine and immune functions and thereby altering neuroendocrine-immune homeostasis. Immunologically estrogen's role in the modulation of Th1/Th2 immune functions and contributing to pro-inflammatory conditions and autoimmunity has been widely studied. Centrally, hypothalamic and pituitary hormones influence gonadal hormone secretion in murine models during onset of estrous cycles and are implicated in reproductive aging-associated acyclicity. Loss of estrogen affects neuronal plasticity and the ensuing decline in cognitive functions during reproductive aging in females implicates estrogen in the incidence and progression of neurodegenerative diseases. Peripherally, sympathetic noradrenergic (NA) innervations of lymphoid organs and the presence of both adrenergic (AR) and estrogen receptors (ER) on lymphocytes poise estrogen as a potent neuroimmunomodulator during health and disease. Cyclic variations in estrogen levels throughout reproductive life, perimenopausal surge in estrogen levels followed by its precipitous decline, concomitant with decline in central hypothalamic catecholaminergic activity, peripheral sympathetic NA innervation and associated immunosuppression present an interesting study to explore female-specific age-associated diseases in a new light.

Agrimonia pilosa Ledeb. Ameliorates Hyperglycemia and Hepatic Steatosis in Ovariectomized Rats Fed a High-Fat Diet

Estrogen deficiency is associated with obesity, dyslipidemia, and increased insulin resistance in postmenopausal women. An efficient therapeutic agent prevents or improves postmenopausal conditions induced by estrogen deficiency. Here, we investigated the effects of aqueous Agrimonia pilosa Ledeb. extract on glucose and lipid metabolism in ovariectomized rats fed a high-fat diet (HFD). Female Sprague-Dawley rats were sham-operated or ovariectomized, and 3 weeks later were assigned to the following groups: sham-operated + HFD (S); ovariectomized + HFD (OVX); and ovariectomized + HFD with 0.5% A. pilosa aqueous extract (OVX + 0.5A) groups. Ovariectomy significantly increased body weight and dietary intake relative to the S group. However, A. pilosa treatment did not significantly affect weight gain or dietary intake. Blood triacylglycerol, total cholesterol, and low-density lipoprotein cholesterol levels tended to decrease in the A. pilosa-supplemented group. Blood glucose levels were significantly lower in the OVX + 0.5A group than those in the OVX group. Blood adiponectin and insulin concentrations increased significantly after A. pilosa treatment in the ovariectomized group. A. pilosa supplementation tended to decrease liver weights and prevented lipid accumulation. These effects correlated with reduced hepatic expression of lipogenesis-related genes (fatty acid synthase, acetyl-coenzyme A carboxylase alpha, and 3-hydroxy-3-methylglutaryl-coenzyme A reductase). Therefore, A. pilosa may improve metabolic disorders in ovariectomized rats.

4-Hydroxyestrone, an Endogenous Estrogen Metabolite, Can Strongly Protect Neuronal Cells Against Oxidative Damage

Earlier studies showed that endogenous estrogens have neuroprotective effect against oxidative damage. The present study seeks to investigate the protective effect of various endogenous estrogen metabolites against oxidative neurotoxicity in vitro and in vivo. Using immortalized mouse hippocampal neuronal cells as an in vitro model, 4-hydroxyestrone, an estrone metabolite with little estrogenic activity, is found to have the strongest neuroprotective effect against oxidative neurotoxicity among 25 endogenous estrogen metabolites tested, and its protective effect is stronger than 17β-estradiol. Similarly, 4-Hydroxyestrone also exerts a stronger protective effect than 17β-estradiol against kanic acid-induced hippocampal oxidative damage in rats. Neuroprotection by 4-hydroxyestrone involves increased cytoplasmic translocation of p53 resulting from SIRT1-mediated deacetylation of p53. Analysis of brain microsomal enzymes shows that estrogen 4-hydroxylation is the main metabolic pathway in the central nervous system. Together, these results show that 4-hydroxyestrone is an endogenous neuroestrogen that can strongly protect against oxidative neuronal damage.

The Effect of Estrogen Replacement Therapy on Alzheimer's Disease and Parkinson's Disease in Postmenopausal Women: A Meta-Analysis

Background: Estrogen replacement therapy (ERT) is a common treatment method for menopausal syndrome; however, its therapeutic value for the treatment of neurological diseases is still unclear. Epidemiological studies were performed, and the effect of postmenopausal ERT on treating neurodegenerative diseases, including Alzheimer's disease (AD) and Parkinson's disease (PD), was summarized through a meta-analysis.

Methods: Twenty-one articles were selected using a systematic searching of the contents listed on PubMed and Web of Science before June 1, 2019. Epidemiological studies were extracted, and relevant research data were obtained from the original articles based on the predefined inclusion criteria and data screening principles. The Comprehensive Meta-Analysis Version 2 software was used to pool effective size, test heterogeneity, conduct meta-regression and subgroup analysis, and to calculate publication bias.

Results: Our results showed that ERT significantly decreased the risk of onset and/or development of AD [odds ratio (OR): 0.672; 95% CI: 0.581–0.779; P < 0.001] and PD (OR: 0.470; 95% CI: 0.368–0.600; P < 0.001) compared with the control group. A subgroup and meta-regression analysis showed that study design and measure of effect were the source of heterogeneity. Age, sample size, hormone therapy ascertainment, duration of the treatment, or route of administration did not play a significant role in affecting the outcome of the meta-analysis.

Conclusion: We presented evidence here to support the use of estrogen therapy for the treatment of AD and PD.

Transitions in metabolic and immune systems from pre-menopause to post-menopause: implications for age-associated neurodegenerative diseases

The brain undergoes two aging programs: chronological and endocrinological. This is particularly evident in the female brain, which undergoes programs of aging associated with reproductive competency. Comprehensive understanding of the dynamic metabolic and neuroinflammatory aging process in the female brain can illuminate windows of opportunities to promote healthy brain aging. Bioenergetic crisis and chronic low-grade inflammation are hallmarks of brain aging and menopause and have been implicated as a unifying factor causally connecting genetic risk factors for Alzheimer's disease and other neurodegenerative diseases. In this review, we discuss metabolic phenotypes of pre-menopausal, peri-menopausal, and post-menopausal aging and their consequent impact on the neuroinflammatory profile during each transition state. A critical aspect of the aging process is the dynamic metabolic neuro-inflammatory profiles that emerge during chronological and endocrinological aging. These dynamic systems of biology are relevant to multiple age-associated neurodegenerative diseases and provide a therapeutic framework for prevention and delay of neurodegenerative diseases of aging. While these findings are based on investigations of the female brain, they have a broader fundamental systems of biology strategy for investigating the aging male brain. Molecular characterization of alterations in fuel utilization and neuroinflammatory mechanisms during these neuro-endocrine transition states can inform therapeutic strategies to mitigate the risk of Alzheimer's disease in women. We further discuss a precision hormone replacement therapy approach to target symptom profiles during endocrine and chronological aging to reduce risk for age-related neurodegenerative diseases.

25-hydroxyvitamin D status and its impact on cognitive functions in postmenopausal woman

Aim: The purpose of the study was to analyze the cognitive functions in postmenopausal women carriers of Apolipoprotein E gene polymorphisms (APOE) with different status of vitamin D levels. Material/Methods: 170 ambulatory individuals aged 50 years or older were evaluated. A computerized battery of Central Nervous System Vital Signs (CNS VS) was used for diagnostic cognitive functions. APOE genotype was performed by multiplex PCR. Serum 25(OH)D and estradiol levels were measured using the 25OHD EIA assay and Estradiol ELISA Kits. Results: Considerably worse scores in global cognitive performance index (NCI) were obtained by women with severe deficiency of 25(OH)D (p <0.001). The cognitive effects of very low 25(OH)D levels were apparent in memory, executive functioning, complex attention, and cognitive flexibility. The genotype APOE ε3/ε4 or ε4/ε4 were most common (19.6%; 15.2%, respectively) in women with 25(OH)D severe deficiency which had the weakest average results in terms of NCI value. Conclusions: The severe deficiency of 25(OH)D vitamin was related with a greater likelihood of cognitive impairment and risk of cognitive decline in postmenopausal women with no dementia.

Sexual Behavior and Synaptic Plasticity

Although sex drive is present in many animal species, sexual behavior is not static and, like many other behaviors, can be modified by experience. This modification relies on synaptic plasticity, a sophisticated mechanism through which neurons change how they process a given stimulus, and the neurophysiological basis of learning. This review addresses the main plastic effects of steroid sex hormones in the central nervous system (CNS) and the effects of sexual experience on the CNS, including effects on neurogenesis, intracellular signaling, gene expression, and changes in dendritic spines, as well as behavioral changes.

Cognitive Changes with Reproductive Aging, Perimenopause, and Menopause

This article reviews the role of endogenous estrogen in neural and cognitive processing, followed by an examination of longitudinal cognitive data captured in various stages of the menopausal transition. The remaining text reviews the contradictory results from major hormone therapy trials to date, evidence for the "timing hypothesis," and closes with recommendations for future research and for practicing clinicians.

Lasting impact on memory of midlife exposure to exogenous and endogenous estrogens

We previously demonstrated that 40 days of prior midlife estradiol treatment results in enhanced spatial memory in aging ovariectomized rats long after termination of the estradiol treatment. Our current goal was to determine whether this benefit is due to lasting impacts on memory specifically of previous exogenous estradiol treatment or simply due to delaying cognitive deficits that occur following loss of ovarian hormones. Middle-aged rats were ovariectomized or underwent sham surgery. Ovariectomized rats received estradiol (Previous Estradiol) or vehicle (Previous Vehicle) implants. Rats undergoing sham surgery (Previous Intact) received vehicle implants. Forty days later, Previous Intact rats were ovariectomized, the other 2 groups underwent sham surgeries, and all implants were removed. Thus, no ovarian or exogenously administered hormones were present during behavior testing. Rats underwent 24 days of acquisition training on an 8-arm radial maze. Following acquisition and again 2 months later, rats were tested on delay trials, during which animals had to remember the location of food rewards across time delays inserted between fourth and fifth arm choices. During acquisition, rats that had previous extended exposure to exogenous estradiol (Previous Estradiol) and endogenous ovarian hormones (Previous Intact) significantly outperformed rats that did not experience extended hormone exposure (Previous Vehicle). However, during delays trials the Previous Estradiol group significantly outperformed both the Previous Vehicle and Previous Intact groups. Results demonstrate that whereas extended exposure to endogenous ovarian hormones may provide short-term cognitive benefits, midlife estradiol treatment following ovariectomy provides additional benefits that persist for months following termination of treatment. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Timing of cyclic estradiol treatment differentially affects cognition in aged female rhesus monkeys

Some evidence suggests that there may be a limited "window of opportunity" for beneficial effects of hormone therapy after menopause in women. We tested whether the timing of cyclic estradiol (E2) treatment impacted its effect on cognitive function in aged, surgically menopausal (ovariectomized) rhesus monkeys. Monkeys were assigned to one of four treatment conditions after ovariectomy: either vehicle or E2 treatment for the duration of the protocol, vehicle for the first 2 years of the protocol followed by E2 for the remainder (delayed treatment), or E2 for the first 11 months of the protocol followed by vehicle for the remainder (withdrawn treatment). Delayed treatment addressed the hypothesis that E2 treatment initiated more than 2 years postovariectomy would have a reduced effect on cognitive function. Withdrawn treatment mirrored current clinical advice to women to use hormone therapy in the initial postmenopausal period then discontinue it. Two periods of cognitive testing assessed treatment effects on cognition over time. E2 treatment predominantly affected a prefrontal cortex-dependent test of spatiotemporal working memory (delayed response). Monkeys with delayed E2 treatment modestly improved in delayed response performance over time, whereas vehicle-treated monkeys declined. Monkeys with withdrawn E2 treatment maintained their performance across assessments, as did monkeys treated with E2 across the entire protocol. These findings suggest that a "window of opportunity" for hormone treatment after cessation of ovarian function, if present in nonhuman primates, lasts longer than 2 years. They also support the notion that beneficial effects of hormone therapy may persist after discontinuation of treatment. (PsycINFO Database Record

Brain structure and cognition 3 years after the end of an early menopausal hormone therapy trial

OBJECTIVE

The effects of 2 frequently used formulations of menopausal hormone therapy (mHT) on brain structure and cognition were investigated 3 years after the end of a randomized, placebo-controlled trial in recently menopausal women with good cardiovascular health.

METHODS

Participants (aged 42-56 years; 5-36 months past menopause) were randomized to one of the following: 0.45 mg/d oral conjugated equine estrogen (oCEE); 50 μg/d transdermal 17β-estradiol (tE2); or placebo pills and patch for 4 years. Oral progesterone (200 mg/d) was given to mHT groups for 12 days each month. MRIs were performed at baseline, at the end of 4 years of mHT, and 3 years after the end of mHT (n = 75). A subset of participants also underwent Pittsburgh compound B-PET (n = 68).

RESULTS

Ventricular volumes increased more in the oCEE group compared to placebo during the 4 years of mHT, but the increase in ventricular volumes was not different from placebo 3 years after the discontinuation of mHT. Increase in white matter hyperintensity volume was similar in the oCEE and tE2 groups, but it was statistically significantly greater than placebo only in the oCEE group. The longitudinal decline in dorsolateral prefrontal cortex volumes was less in the tE2 group compared to placebo, which correlated with lower cortical Pittsburgh compound B uptake. Rates of global cognitive change in mHT groups were not different from placebo.

CONCLUSIONS

The effects of oCEE on global brain structure during mHT subside after oCEE discontinuation but white matter hyperintensities continue to increase. The relative preservation of dorsolateral prefrontal cortical volume in the tE2 group over 7 years indicates that mHT may have long-term effects on the brain.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that the rates of change in global brain volumes and cognitive function in recently menopausal women receiving mHT (tE2 or oCEE) were not significantly different from women receiving placebo, as measured 3 years after exposure to mHT.

Estrogens as neuroprotectants: Estrogenic actions in the context of cognitive aging and brain injury

There is ample empirical evidence to support the notion that the biological impacts of estrogen extend beyond the gonads to other bodily systems, including the brain and behavior. Converging preclinical findings have indicated a neuroprotective role for estrogen in a variety of experimental models of cognitive function and brain insult. However, the surprising null or even detrimental findings of several large clinical trials evaluating the ability of estrogen-containing hormone treatments to protect against age-related brain changes and insults, including cognitive aging and brain injury, led to hesitation by both clinicians and patients in the use of exogenous estrogenic treatments for nervous system outcomes. That estrogen-containing therapies are used by tens of millions of women for a variety of health-related applications across the lifespan has made identifying conditions under which benefits with estrogen treatment will be realized an important public health issue. Here we provide a summary of the biological actions of estrogen and estrogen-containing formulations in the context of aging, cognition, stroke, and traumatic brain injury. We have devoted special attention to highlighting the notion that estrogen appears to be a conditional neuroprotectant whose efficacy is modulated by several interacting factors. By developing criteria standards for desired beneficial peripheral and neuroprotective outcomes among unique patient populations, we can optimize estrogen treatments for attenuating the consequences of, and perhaps even preventing, cognitive aging and brain injury.

Age-dependent regulation of obesity and Alzheimer-related outcomes by hormone therapy in female 3xTg-AD mice

Depletion of ovarian hormones at menopause is associated with increased Alzheimer's disease (AD) risk. Hormone loss also increases central adiposity, which promotes AD development. One strategy to improve health outcomes in postmenopausal women is estrogen-based hormone therapy (HT), though its efficacy is controversial. The window of opportunity hypothesis posits that HT is beneficial only if initiated near the onset of menopause. Here, we tested this hypothesis by assessing the efficacy of HT against diet-induced obesity and AD-related pathology in female 3xTg-AD mice at early versus late middle-age. HT protected against obesity and reduced β-amyloid burden only at early middle-age. One mechanism that contributes to AD pathogenesis is microglial activation, which is increased by obesity and reduced by estrogens. In parallel to its effects on β-amyloid accumulation, we observed that HT reduced morphological evidence of microglial activation in early but not late middle-age. These findings suggest that HT may be effective during human perimenopause in reducing indices of obesity and AD-related pathology, a conclusion consistent with the window of opportunity hypothesis.

Postmenopausal hormone therapy and Alzheimer disease: A prospective cohort study

OBJECTIVE

To explore the association between postmenopausal hormone therapy (HT) and Alzheimer disease (AD).

METHODS

Twenty-year follow-up data from the Kuopio Osteoporosis Risk Factor and Prevention study cohort were used. Self-administered questionnaires were sent to all women aged 47-56 years, residing in Kuopio Province starting in 1989 until 2009, every 5th year. Register-based information on HT prescriptions was available since 1995. Probable AD cases, based on DSM-IV and National Institute of Neurological and Communicative Disorders and Stroke-Alzheimer's Disease and Related Disorders Association criteria, were identified from the special reimbursement register (1999-2009). The study population included 8,195 women (227 cases of incident AD).

RESULTS

Postmenopausal estrogen use was not associated with AD risk in register-based or self-reported data (hazard ratio/95% confidence interval 0.92/0.68-1.2, 0.99/0.75-1.3, respectively). Long-term self-reported postmenopausal HT was associated with reduced AD risk (0.53/0.31-0.91). Similar results were obtained with any dementia diagnosis in the hospital discharge register as an outcome.

CONCLUSIONS

Our results do not provide strong evidence for a protective association between postmenopausal HT use and AD or dementia, although we observed a reduced AD risk among those with long-term self-reported HT use.

Back to the future: Hormone replacement therapy as part of a prevention strategy for women at the onset of menopause

In the late 1980s, several observational studies and meta-analyses suggested that hormone replacement therapy (HRT) was beneficial for prevention of osteoporosis, coronary heart disease, dementia and decreased all-cause mortality. In 1992, the American College of Physicians recommended HRT for prevention of coronary disease. In the late 1990s and early 2000s, several randomized trials in older women suggested coronary harm and that the risks, including breast cancer, outweighed any benefit. HRT stopped being prescribed at that time, even for women who had severe symptoms of menopause. Subsequently, reanalyzes of the randomized trial data, using age stratification, as well as newer studies, and meta-analyses have been consistent in showing that younger women, 50-59 years or within 10 years of menopause, have decreased coronary disease and all-cause mortality; and did not have the perceived risks including breast cancer. These newer findings are consistent with the older observational data. It has also been reported that many women who abruptly stopped HRT had more risks, including more osteoporotic fractures. The current data confirm a "timing" hypothesis for benefits and risks of HRT, showing that younger have many benefits and few risks, particularly if therapy is predominantly focused on the estrogen component. We discuss these findings and put into perspective the potential risks of treatment, and suggest that we may have come full circle regarding the use of HRT. In so doing we propose that HRT should be considered as part of a general prevention strategy for women at the onset of menopause.

A microsomal based method to detect aromatase activity in different brain regions of the rat using ultra performance liquid chromatography-mass spectrometry

Aromatase (ARO) is a cytochrome P450 enzyme that accounts for local estrogen production in the brain. The goal of this study was to develop a microsomal based assay to sensitively and reliably detect the low levels of ARO activity in different brain regions. Enzyme activity was detected based on the conversion of testosterone to estradiol. Quantity of estradiol was measured using ultra performance liquid chromatography-mass spectrometry. Detection was linear over a range of 2.5-200pg/ml estradiol, and was reproducible with intra- and inter-assay coefficients of variation (CV) <15%. Estradiol production using isolated microsomes was linear with time up to 30min as well as linearly related to amount of microsome. Substrate concentration curves revealed enzymatic kinetics (hippocampus: Vmax and Km: 0.57pmol estradiol/h per mg microsome and 48.58nM; amygdala: Vmax and Km: 1.69pmol estradiol/h per mg microsome and 48.4nM; preoptic area: Vmax and Km: 0.96pmol estradiol/h per mg microsome and 44.31nM) with testosterone used at a saturating concentration of 400nM. Anastrozole treatment blocked ARO activity in hippocampal and ovarian microsomes, indicating that the assay is specific for ARO. Also, we showed that the distribution of the long form ARO mRNA (CYP19A1) in different regions of the brain is correlated with ARO activity, with highest levels in the amygdala, followed by preoptic area and hippocampus. In the frontal cortex, very little long form ARO mRNA, and little to no ARO activity, were detected. These findings demonstrate that the microsomal incubation (MIB) assay is a sensitive and reliable method for quantifying ARO activity in discrete brain regions.

Previous Midlife Oestradiol Treatment Results in Long-Term Maintenance of Hippocampal Oestrogen Receptor α Levels in Ovariectomised Rats: Mechanisms and Implications for Memory

Ovariectomised rats that have received previous administration of oestradiol in midlife display enhanced cognition and increased hippocampal levels of oestrogen receptor (ER)α months after oestradiol treatment ended compared to ovariectomised controls. The present study aimed to investigate the mechanisms by which ERα levels are maintained following midlife oestradiol exposure and the role of ERα in memory in ageing females in the absence of circulating oestrogens. Unliganded ERα has increased interaction with the ubiquitin ligase, C-terminus of Hsc-70 interacting protein (CHIP), leading to increased degradation of the receptor. In our first experiment, we tested the hypothesis that midlife oestradiol exposure in ovariectomised rats results in decreased interaction between CHIP and hippocampal ERα, leading to increased levels of ERα. Middle-aged rats were ovariectomised and received oestradiol or vehicle implants. After 40 days, implants were removed. One month later, rats were killed and hippocampi were processed for whole protein western blotting and co-immunoprecipitation, in which ERα was immunoprecipitated from lysate. As expected, ERα protein expression was increased in rats previously treated with oestradiol compared to vehicle-treated rats. In rats treated with oestradiol, there was a decrease in CHIP-ERα interaction, suggesting that previous oestradiol treatment reduces interaction, slowing the degradation of ERα. In a second experiment, we determined the impact on memory of antagonism of ER in the absence of circulating oestrogens. Rats were ovariectomised and implanted with oestradiol capsules. Capsules were removed after 40 days. Rats received chronic i.c.v. infusion of ER antagonist, ICI 182 780, or artificial cerebrospinal fluid vehicle and were tested on a spatial memory radial-maze task. Rats treated with ICI 182 780 had significantly worse performance (more errors). These experiments provide evidence that previous midlife oestradiol treatment maintains hippocampal ERα by decreasing its interaction with CHIP and that activation of these receptors provides cognitive benefits in the absence of circulating oestrogens.

Clinical Evaluation of Effects of Chronic Resveratrol Supplementation on Cerebrovascular Function, Cognition, Mood, Physical Function and General Well-Being in Postmenopausal Women-Rationale and Study Design

Background: This methodological paper presents both a scientific rationale and a methodological approach for investigating the effects of resveratrol supplementation on mood and cognitive performance in postmenopausal women. Postmenopausal women have an increased risk of cognitive decline and dementia, which may be at least partly due to loss of beneficial effects of estrogen on the cerebrovasculature. We hypothesise that resveratrol, a phytoestrogen, may counteract this risk by enhancing cerebrovascular function and improving regional blood flow in response to cognitive demands. A clinical trial was designed to test this hypothesis. Method: Healthy postmenopausal women were recruited to participate in a randomised, double-blind, placebo-controlled (parallel comparison) dietary intervention trial to evaluate the effects of resveratrol supplementation (75 mg twice daily) on cognition, cerebrovascular responsiveness to cognitive tasks and overall well-being. They performed the following tests at baseline and after 14 weeks of supplementation: Rey Auditory Verbal Learning Test, Cambridge Semantic Memory Battery, the Double Span and the Trail Making Task. Cerebrovascular function was assessed simultaneously by monitoring blood flow velocity in the middle cerebral arteries using transcranial Doppler ultrasound. Conclusion: This trial provides a model approach to demonstrate that, by optimising circulatory function in the brain, resveratrol and other vasoactive nutrients may enhance mood and cognition and ameliorate the risk of developing dementia in postmenopausal women and other at-risk populations.

Impact of obstructive sleep apnea syndrome on cognition in early postmenopausal women

PURPOSE

Obstructive sleep apnea syndrome (OSAS) has a higher prevalence in postmenopausal women who are not on hormone replacement therapy (HRT), as compared to premenopausal women. Cognitive impairment (CI) is associated with OSAS and the early postmenopausal state. We hypothesized that compared to postmenopausal women at low risk for OSAS, postmenopausal women at high risk for OSAS would report worse cognitive function.

METHODS

Early postmenopausal women not on HRT between the ages of 45 and 60 years, within 5 years of natural menopause, were enrolled. Participants completed a REDCap survey which collected information on demographics and risk factors, Berlin questionnaire to screen subjects for OSAS risk, and the Mail-In Cognitive Function Screening Instrument (MCFSI) score which was used to assess CI.

RESULTS

Of 381 respondents, 127 were omitted due to missing/duplicate data or not meeting inclusion criteria. One hundred fifty-four women were classified as high risk for OSAS (OSAS+), and 100 were classified as low risk for OSAS (OSAS-). OSAS- women reported lifetime smoking, lifetime drinking, and recreational drug use more often than OSAS+ women, while OSAS+ women reported a depression diagnosis more often. The mean MCFSI score in the OSAS+ group was significantly higher (worse cognition) than in the OSAS- group after controlling for covariates (5.59, 95 % CI 5.08-6.11 vs. 4.29, 95 % CI 3.64-4.93, p < 0.05).

CONCLUSION

Early postmenopausal women at high risk for OSAS report more CI than those at low risk for OSAS. Future studies should identify biomarkers of this CI and define the degree of reversibility of CI with OSAS treatment.

Postmenopausal hormone therapy and cognition

This article is part of a Special Issue "Estradiol and cognition". Prior to the publication of findings from the Women's Health Initiative (WHI) in 2002, estrogen-containing hormone therapy (HT) was used to prevent age-related disease, especially cardiovascular disease, and to treat menopausal symptoms such as hot flushes and sleep disruptions. Some observational studies of HT in midlife and aging women suggested that HT might also benefit cognitive function, but randomized clinical trials have produced mixed findings in terms of health and cognitive outcomes. This review focuses on hormone effects on cognition and risk for dementia in naturally menopausal women as well as surgically induced menopause, and highlights findings from the large-scale WHI Memory Study (WHIMS) which, contrary to expectation, showed increased dementia risk and poorer cognitive outcomes in older postmenopausal women randomized to HT versus placebo. We consider the 'critical window hypothesis', which suggests that a window of opportunity may exist shortly after menopause during which estrogen treatments are most effective. In addition, we highlight emerging evidence that potential adverse effects of HT on cognition are most pronounced in women who have other health risks, such as lower global cognition or diabetes. Lastly, we point towards implications for future research and clinical treatments.

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.

Menopause, obesity and inflammation: interactive risk factors for Alzheimer's disease

Alzheimer’s disease (AD) is a multifactorial neurodegenerative disorder, the development of which is regulated by several environmental and genetic risk factors. Two factors theorized to contribute to the initiation and/or progression of AD pathogenesis are age-related increases in inflammation and obesity. These factors may be particularly problematic in women. The onset of menopause in mid-life elevates the vulnerability of women to AD, an increased risk that is likely associated with the depletion of estrogens. Menopause is also linked with an abundance of additional changes, including increased central adiposity and inflammation. Here, we review the current literature to explore the interactions between obesity, inflammation, menopause and AD.

Hippocampal Gene Expression Is Highly Responsive to Estradiol Replacement in Middle-Aged Female Rats

In the hippocampus, estrogens are powerful modulators of neurotransmission, synaptic plasticity and neurogenesis. In women, menopause is associated with increased risk of memory disturbances, which can be attenuated by timely estrogen therapy. In animal models of menopause, 17β-estradiol (E2) replacement improves hippocampus-dependent spatial memory. Here, we explored the effect of E2 replacement on hippocampal gene expression in a rat menopause model. Middle-aged ovariectomized female rats were treated continuously for 29 days with E2, and then, the hippocampal transcriptome was investigated with Affymetrix expression arrays. Microarray data were analyzed by Bioconductor packages and web-based softwares, and verified with quantitative PCR. At standard fold change selection criterion, 156 genes responded to E2. All alterations but 4 were transcriptional activation. Robust activation (fold change > 10) occurred in the case of transthyretin, klotho, claudin 2, prolactin receptor, ectodin, coagulation factor V, Igf2, Igfbp2, and sodium/sulfate symporter. Classification of the 156 genes revealed major groups, including signaling (35 genes), metabolism (31 genes), extracellular matrix (17 genes), and transcription (16 genes). We selected 33 genes for further studies, and all changes were confirmed by real-time PCR. The results suggest that E2 promotes retinoid, growth factor, homeoprotein, neurohormone, and neurotransmitter signaling, changes metabolism, extracellular matrix composition, and transcription, and induces protective mechanisms via genomic effects. We propose that these mechanisms contribute to effects of E2 on neurogenesis, neural plasticity, and memory functions. Our findings provide further support for the rationale to develop safe estrogen receptor ligands for the maintenance of cognitive performance in postmenopausal women.

Effects of Hormone Therapy on Cognition and Mood in Recently Postmenopausal Women: Findings from the Randomized, Controlled KEEPS-Cognitive and Affective Study

BACKGROUND

Menopausal hormone therapy (MHT) reportedly increases the risk of cognitive decline in women over age 65 y. It is unknown whether similar risks exist for recently postmenopausal women, and whether MHT affects mood in younger women. The ancillary Cognitive and Affective Study (KEEPS-Cog) of the Kronos Early Estrogen Prevention Study (KEEPS) examined the effects of up to 4 y of MHT on cognition and mood in recently postmenopausal women.

METHODS AND FINDINGS

KEEPS, a randomized, double-blinded, placebo-controlled clinical trial, was conducted at nine US academic centers. Of the 727 women enrolled in KEEPS, 693 (95.3%) participated in the ancillary KEEPS-Cog, with 220 women randomized to receive 4 y of 0.45 mg/d oral conjugated equine estrogens (o-CEE) plus 200 mg/d micronized progesterone (m-P) for the first 12 d of each month, 211 women randomized to receive 50 μg/d transdermal estradiol (t-E2) plus 200 mg/d m-P for the first 12 d of each month, and 262 women randomized to receive placebo pills and patches. Primary outcomes included the Modified Mini-Mental State examination; four cognitive factors: verbal learning/memory, auditory attention/working memory, visual attention/executive function, and speeded language/mental flexibility; and a mood measure, the Profile of Mood States (POMS). MHT effects were analyzed using linear mixed-effects (LME) models, which make full use of all available data from each participant, including those with missing data. Data from those with and without full data were compared to assess for potential biases resulting from missing observations. For statistically significant results, we calculated effect sizes (ESs) to evaluate the magnitude of changes. On average, participants were 52.6 y old, and 1.4 y past their last menstrual period. By month 48, 169 (24.4%) and 158 (22.8%) of the 693 women who consented for ancillary KEEPS-Cog were lost to follow-up for cognitive assessment (3MS and cognitive factors) and mood evaluations (POMS), respectively. However, because LME models make full use all available data, including data from women with missing data, 95.5% of participants were included in the final analysis (n = 662 in cognitive analyses, and n = 661 in mood analyses). To be included in analyses, women must have provided baseline data, and data from at least one post-baseline visit. The mean length of follow-up was 2.85 y (standard deviation [SD] = 0.49) for cognitive outcomes and 2.76 (SD = 0.57) for mood outcomes. No treatment-related benefits were found on cognitive outcomes. For mood, model estimates indicated that women treated with o-CEE showed improvements in depression and anxiety symptoms over the 48 mo of treatment, compared to women on placebo. The model estimate for the depression subscale was -5.36 × 10(-2) (95% CI, -8.27 × 10(-2) to -2.44 × 10(-2); ES = 0.49, p < 0.001) and for the anxiety subscale was -3.01 × 10(-2) (95% CI, -5.09 × 10(-2) to -9.34 × 10(-3); ES = 0.26, p < 0.001). Mood outcomes for women randomized to t-E2 were similar to those for women on placebo. Importantly, the KEEPS-Cog results cannot be extrapolated to treatment longer than 4 y.

CONCLUSIONS

The KEEPS-Cog findings suggest that for recently postmenopausal women, MHT did not alter cognition as hypothesized. However, beneficial mood effects with small to medium ESs were noted with 4 y of o-CEE, but not with 4 y of t-E2. The generalizability of these findings is limited to recently postmenopausal women with low cardiovascular risk profiles.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00154180 and NCT00623311.

Executive functions in men and postmenopausal women

INTRODUCTION

This study was designed to assess sex differences in older adults (55-65 years old) in executive functions and to examine the influence of hormone therapy (HT) in postmenopausal women.

METHOD

We have assessed task performance in memory, visuospatial, and executive functions in 29 women using HT, 29 women who never used HT, and 30 men.

RESULTS

Men outperformed never users in task switching and updating. HT users outperformed never users in updating. HT users outperformed never users and men in visual divided attention.

DISCUSSION

The present study support previous findings that sex and HT impact cognition and bring new insights on sex and HT-related differences in executive functions.

Enhanced Neuroactivation during Working Memory Task in Postmenopausal Women Receiving Hormone Therapy: A Coordinate-Based Meta-Analysis

BACKGROUND AND AIM

Hormone therapy (HT) has long been thought beneficial for controlling menopausal symptoms and human cognition. Studies have suggested that HT has a positive association with working memory, but no consistent relationship between HT and neural activity has been shown in any cognitive domain. The purpose of this meta-analysis was to assess the convergence of findings from published randomized control trials studies that examined brain activation changes in postmenopausal women.

METHODS

A systematic search for fMRI studies of neural responses during working memory tasks in postmenopausal women was performed. Studies were excluded if they were not treatment studies and did not contain placebo or blank controls. For the purpose of the meta-analysis, 8 studies were identified, with 103 postmenopausal women taking HT and 109 controls.

RESULTS

Compared with controls, postmenopausal women who took HT increased activation in the left frontal lobe, including superior frontal gyrus (BA 8), right middle frontal gyrus (BA 9), anterior lobe, paracentral lobule (BA 7), limbic lobe, and anterior cingulate (BA 32). Additionally, decreased activation is noted in the right limbic lobe, including parahippocampal gyrus (BA 28), left parietal lobe, and superior parietal lobule (BA 7). All regions were significant at p ≤ 0.05 with correction for multiple comparisons.

CONCLUSION

Hormone treatment is associated with BOLD signal activation in key anatomical areas during fMRI working memory tasks in healthy hormone-treated postmenopausal women. A positive correlation between activation and task performance suggests that hormone use may benefit working memory.

The KEEPS-Cognitive and Affective Study: baseline associations between vascular risk factors and cognition

Midlife vascular risk factors influence later cognitive decline and Alzheimer's disease (AD). The decrease in serum estradiol levels during menopause has been associated with cognitive impairment and increased vascular risk, such as high blood pressure (BP), which independently contributes to cognitive dysfunction and AD. We describe the extent to which vascular risk factors relate to cognition in healthy, middle-aged, recently postmenopausal women enrolled in the Kronos Early Estrogen Prevention Cognitive and Affective Study (KEEPS-Cog) at baseline. KEEPS-Cog is a double-blind, randomized, placebo-controlled, parallel group, clinical trial, investigating the efficacy of low-dose, transdermal 17β-estradiol and oral conjugated equine estrogen on cognition. All results are cross-sectional and represent baseline data only. Analyses confirm that the KEEPS-Cog cohort (n = 571) was middle aged (mean 52.7 years, range 42-59 years), healthy, and free of cognitive dysfunction. Higher systolic BP was weakly related to poorer performance in auditory working memory and attention (p = 0.004; adjusted for multiple comparisons p = 0.10). This relationship was not associated with endogenous hormone levels, and systolic BP was not related to any other cognitive domain. BP levels may be more sensitive than other vascular risk factors in detecting subtle differences in cognitive task performance in healthy, recently menopausal women. Lower BP early in menopause may affect cognitive domains known to be associated with AD.

Estradiol and cognitive function: past, present and future

A historical perspective on estradiol's enhancement of cognitive function is presented, and research, primarily in animals, but also in humans, is reviewed. Data regarding the mechanisms underlying the enhancements are discussed. Newer studies showing rapid effects of estradiol on consolidation of memory through membrane interactions and activation of inter-cellular signaling pathways are reviewed as well as studies focused on traditional genomic mechanisms. Recent demonstrations of intra-neuronal estradiol synthesis and possible actions as a neurosteroid to promote memory are discussed. This information is applied to the critical issue of the current lack of effective hormonal (or other) treatments for cognitive decline associated with menopause and aging. Finally, the critical period hypothesis for estradiol effects is discussed along with novel strategies for hormone/drug development. Overall, the historical record documents that estradiol positively impacts some aspects of cognitive function, but effective therapeutic interventions using this hormone have yet to be realized.

Alzheimer's disease: review of hormone therapy trials and implications for treatment and prevention after menopause

Hormonal changes associated with the menopausal transition and postmenopause have the potential to influence processes linked to Alzheimer's disease symptoms and pathogenesis, but effects of menopause on Alzheimer risk can be addressed only indirectly. Nine randomized clinical trials of estrogen-containing hormone therapy in Alzheimer's disease patients were identified by a systematic literature search. Findings suggest that hormone therapy does not improve cognitive symptoms of women with Alzheimer's disease. No clinical trials of hormone therapy address Alzheimer prevention, but one clinical trial provides moderate evidence that continuous, combined estrogen plus progestogen initiated at age 65 years or older increases the risk of dementia. The timing, or critical window, hypothesis suggests that hormone therapy initiated at a younger age in closer temporal proximity to menopause may reduce the risk of Alzheimer's disease. This hypothesis is supported by observational research but is not addressed by clinical trial data. Unrecognized confounding is of concern in interpreting observational results, and research that helps resolve this issue will have important public health implications. Well-designed cohort studies, convergent evidence from appropriate laboratory models, and long-term clinical trials using surrogate biomarkers of brain function and neural pathology could provide relevant answers. Other estrogenic compounds are of theoretical interest with respect to Alzheimer treatment and risk. Effects of selective estrogen receptor modulators such as raloxifene may differ from those of estrogens; potential effects of phytoestrogens are not well studied. This article is part of a Special Issue entitled 'Menopause'.

Estrogen and memory system bias in females across the lifespan

Studies in both rodents and humans have made much progress in shedding light on how fluctuations in ovarian hormones can affect memory in women across the lifespan. Specifically, advances in neuroscience have identified multiple memory systems that are each mediated by different brain areas. Two memory systems used to navigate an environment are ‘place’ and ‘response’ memory. They are defined as either using an allocentric strategy: using a spatial or cognitive map of the surroundings, or an egocentric strategy: using habitual-turns/movements, respectively. Studies in neuroendocrinology have shown that estrogen levels can bias a female to use one memory system over another to solve a task, such that high estrogen levels are associated with using place memory and low levels with using response memory. Furthermore, recent advances in identifying and localizing estrogen receptors in the rodent brain are uncovering which brain regions are affected by estrogen and providing insight into how hormonal fluctuations during the menstrual cycle, pregnancy, and menopause might affect which memory system is facilitated or impaired in women at different life stages. These studies can help point the way to improving cognitive health in women.

Estrogen: a master regulator of bioenergetic systems in the brain and body

Estrogen is a fundamental regulator of the metabolic system of the female brain and body. Within the brain, estrogen regulates glucose transport, aerobic glycolysis, and mitochondrial function to generate ATP. In the body, estrogen protects against adiposity, insulin resistance, and type II diabetes, and regulates energy intake and expenditure. During menopause, decline in circulating estrogen is coincident with decline in brain bioenergetics and shift towards a metabolically compromised phenotype. Compensatory bioenergetic adaptations, or lack thereof, to estrogen loss could determine risk of late-onset Alzheimer's disease. Estrogen coordinates brain and body metabolism, such that peripheral metabolic state can indicate bioenergetic status of the brain. By generating biomarker profiles that encompass peripheral metabolic changes occurring with menopause, individual risk profiles for decreased brain bioenergetics and cognitive decline can be created. Biomarker profiles could identify women at risk while also serving as indicators of efficacy of hormone therapy or other preventative interventions.

Cumulative estrogen exposure, number of menstrual cycles, and Alzheimer's risk in a cohort of British women

The effect of estrogen on Alzheimer's Disease (AD) risk has received substantial research and media attention, especially in terms of hormone replacement therapy. But reproductive history is also an important modifier of estrogenic exposure, and deserves further investigation. Importantly, there is wide variation in reproductive patterns that modifies estrogen exposure during the reproductive span, which previous AD studies have not incorporated into their calculations. We measured degree of Alzheimer's-type dementia in a cohort of elderly British women, and collected detailed reproductive and medical history information, which we used to estimate number of months with estrogen exposure and number of months with menstrual cycles. Using Cox proportional-hazards models, we find that longer duration of estrogen exposure may have a protective effect against AD risk, such that for every additional month with estrogen, women experienced on average a 0.5% decrease in AD risk (N=89, p=0.02). More menstrual cycles may also have a protective effect against AD risk, although this result was of borderline statistical significance (p<0.10). These results build upon previous methodologies by taking into account a variety of parameters including oral contraceptive use, breastfeeding, post-partum anovulation, abortions, and miscarriages. Additionally, Cox models revealed that longer reproductive span, age>21 at first birth, and more months in lifetime spent pregnant had protective effects against AD risk.