Possible acceleration of age effects on cognition following menopause

Maternal steroids during pregnancy and their associations with exposure to lifetime stressful life events, prenatal stress appraisal and psychological functioning

BACKGROUND

During pregnancy, steroids enable physiological adaptations in response to many factors, including maternal stress or psychological functioning. While stress and psychological dysfunction can have endocrine-disrupting effects beyond cortisol disruption, associations between prenatal maternal stress or related psychological dysfunction and the broader steroid milieu remain understudied.

AIM

To assess associations between independent and joint maternal stress and psychological functioning measures and steroid profiles in pregnancy (22-40 gestational weeks) in the Programming of Intergenerational Stress Mechanisms (PRISM) birth cohort (n = 334).

METHODS

Serum metabolomics detected 42 steroids and their metabolites, which were grouped into five classes (pregnenolone, androgens, estrogens, progestin, and corticosteroids). The Perceived Stress Scale, Life Stressor Checklist-Revised, and Edinburgh Postnatal Depression Scale indexed lifetime traumatic/non-traumatic stressors, global prenatal stress appraisal, and depressive symptoms during pregnancy, respectively. Exposures were categorized as high-low using the corresponding 3rd quartiles. We assessed associations between both individual and joint stress exposures with steroid classes using linear mixed effect models and with individual steroids using linear regressions. We also examined fetal sex-specific effects.

RESULTS

High prenatal perceived stress was independently associated with lower levels of androgens and estrogens in the overall sample [β (95%CI): androgens: -0.13 (-0.25;-0.01); estrogens: -0.16 (-0.31;-0.01)], particularly among women carrying males [androgens: -0.22 (-0.39;-0.05); estrogens: -0.28 (-0.50;-0.07)]. Results on estrogens were consistent when considering joint exposure to both greater lifetime stressors and higher prenatal perceived stress. We also found a single testosterone metabolite-5alpha-androstan-3alpha,17alpha-diol disulfate-negatively associated with both individual high perceived stress and joint exposure to high lifetime stressors and high perceived stress among women carrying males.

CONCLUSIONS

Increased maternal perceived stress experienced in pregnancy was independently associated with lower maternal androgen and estrogen levels during pregnancy in the overall sample, particularly among women carrying males. Results on estrogens were consistent when we considered the joint exposure of increased lifetime stressors and higher prenatal perceived stress.

Effect of estradiol replacement on hippocampal concentrations of estrogens in aged rhesus macaques maintained on an obesogenic diet

Replacement involving estrogens has proven efficacy at treating a wide range of disorders that develop with menopause or after surgical removal of the ovaries. Here, we tested whether an estradiol (E2) replacement paradigm that recapitulates physiological E2 levels in the circulation also recapitulates physiological E2 levels within the hippocampus. E2 was delivered continuously to old ovariectomized (OVX) rhesus macaques, maintained on a high-fat, high-sugar Western-style diet (WSD) for ∼30 months, via subcutaneous implants; this resulted in physiological concentrations of both estrone (E1) and E2 in the circulation (determined by LC-MS/MS). Surprisingly, however, hippocampal concentrations of E2 were markedly (P < 0.01) higher than in ovary-intact animals maintained on a regular chow diet. The data suggest that E2 replacement paradigms that appear to recapitulate physiological E2 concentrations in the circulation may produce hyper-physiological E2 levels within some brain areas, especially when individuals are maintained on a WSD.

The X factor in neurodegeneration

Given the aging population, it is important to better understand neurodegeneration in aging healthy people and to address the increasing incidence of neurodegenerative diseases. It is imperative to apply novel strategies to identify neuroprotective therapeutics. The study of sex differences in neurodegeneration can reveal new candidate treatment targets tailored for women and men. Sex chromosome effects on neurodegeneration remain understudied and represent a promising frontier for discovery. Here, we will review sex differences in neurodegeneration, focusing on the study of sex chromosome effects in the context of declining levels of sex hormones during aging.

Sex differences in peripheral monoamine transmitter and related hormone levels in chronic stress mice with a depression-like phenotype

Backgrounds

Chronic stress could induce depression-like phenotype in animal models. Previous data showed that sex differences exist after chronic stress model establishment, however, the detailed information about the difference of blood biochemical indexes is not clear. In this study, we aim to supply comparison of monoamine transmitters and related hormone markers in serum between male and female depressed mice, and in order to better understand the sex difference in transmitters and hormone levels in depression occurrence and development.

Methods

Sixty C57BL/6 mice (both male and female) were divided into two groups by gender. Same gender mice were then divided randomly into the non-treated control group and chronic stress group which was exposed to 8 weeks of chronic unpredictable mild stress (CUMS). Depression-like behavior was assessed with open-field test and sucrose preference test. Blood sample was collected and monoamine transmitter and related hormone in serum were measured by ELISA.

Results

The depression-like phenotype mice model was established successfully after 8 weeks of chronic stress. The locomotion activity scores in male stressed mice declined more than that in female stressed mice, while the exploratory behavior scores in female stressed mice declined more than that in male stressed mice. Compared to non-treated control group mice, mice in the chronic stress group in response to stress showed greater declines in monoamine transmitters (5-HT, dopamine, norepinephrine) and sex hormones (androgen, estrogen, oxytocin and prolactin), while stress hormones (adrenaline, corticosterone and ACTH) were significantly increased. The decrease of norepinephrine, androgen and estrogen in female stressed mice was greater than in male stressed mice, whereas the 5-HT and oxytocin in male stressed mice decreased more than in female stressed mice, and the corticosterone in male stressed mice increased more than in female stressed mice.

Conclusion

Sex differences of monoamine transmitter and related hormone levels in serum occurred in chronic stress induced depression-like phenotype mice model. It may provide a useful reference to guide precise antidepressant treatment in different gender population in clinical care.

Estradiol treatment in young postmenopausal women with self-reported cognitive complaints: Effects on cholinergic-mediated cognitive performance

OBJECTIVE

Older women are at increased risk of developing Alzheimer's disease compared to men. One proposed reason is that following menopause there is a decline in estrogens. Estrogens are important for cholinergic functioning and attenuate the impact of cholinergic antagonists on cognitive performance in postmenopausal women. Self-reported or subjective cognitive complaints in middle or older age may represent a harbinger of cognitive decline and those who endorse cognitive complaints appear more likely to develop future cognitive impairment. However, the response of individuals with cognitive complaints after menopause to estrogen and the relationship to cholinergic functioning has not been investigated. This study investigated the effect of estrogen treatment using 17β-estradiol on cognitive performance following anticholinergic blockade in postmenopausal women and the relationship of this interaction with the level of self-reported (subjective) postmenopausal cognitive complaints.

METHODS

Forty postmenopausal women (aged 50-60 years) completed a 3-month treatment regimen of either 1 mg oral estradiol or placebo. Participants then completed four challenge days in which they completed cognitive and behavioral tasks after one of four cholinergic antagonist drug conditions (oral mecamylamine (MECA), intravenous scopolamine, combined MECA and scopolamine, or PLC).

RESULTS

Compared to PLC, the estradiol treated group performed worse on attention tasks under cholinergic challenge including the choice reaction time task and the critical flicker fusion task. In addition, participants who endorsed greater cognitive complaints showed reduced performance on the N-back working memory task, regardless of whether they received estradiol treatment.

CONCLUSIONS

The findings of this study indicate that estradiol treatment was unable to mitigate anticholinergic blockade in postmenopausal women with subjective cognitive complaints, and worsened performance on attention tasks. Moreover, the present study suggests that greater levels of cognitive complaints following menopause may be associated with an underlying decline in cholinergic function that may manifest as an inability to compensate during working memory tasks.

Sex differences in economic decision-making: Exogenous estradiol has opposing effects on fairness framing in women and men

Burgeoning evidence indicates that women are more sensitive to the context of an offer and show a stronger propensity to adjust their behavior with changing fairness frames. We evaluated whether the sex hormone estradiol and associated stereotypical beliefs contribute to fairness framings by administering topical estradiol (2 mg) to 108 healthy women and 104 heathy men in a randomized, double-blind, placebo-controlled between-subject study design. Participants played the role of the responder in a modified version of the Ultimatum Game (UG), in which identical offers for the division of a given amount of money were framed as either fair or unfair. Furthermore, participants completed an unframed UG and a delayed discounting task to probe possible effects of estradiol on altruistic preferences and delay gratification. Our results show that women were more sensitive to fairness frames than men. Intriguingly, however, estradiol had sex-specific effects on fairness sensitivity by increasing the acceptance rate of proposals with a fair frame in men and reducing it in women. Furthermore, the mere belief of receiving estradiol treatment significantly increased the acceptance of unfair-framed offers in both sexes, but estradiol did not significantly alter the response to unframed offers and impulsive decision-making. Collectively, our findings indicate that estradiol has opposing effects on the sensitivity to the perceived fairness of economic offers in women and men. The profound effects of estradiol treatment and stereotypical beliefs provide support for the notion that sex differences in fairness framing are rooted in both biological and environmental factors.

Hormonal Regulation of Oligodendrogenesis II: Implications for Myelin Repair

Alterations in myelin, the protective and insulating sheath surrounding axons, affect brain function, as is evident in demyelinating diseases where the loss of myelin leads to cognitive and motor dysfunction. Recent evidence suggests that changes in myelination, including both hyper- and hypo-myelination, may also play a role in numerous neurological and psychiatric diseases. Protecting myelin and promoting remyelination is thus crucial for a wide range of disorders. Oligodendrocytes (OLs) are the cells that generate myelin, and oligodendrogenesis, the creation of new OLs, continues throughout life and is necessary for myelin plasticity and remyelination. Understanding the regulation of oligodendrogenesis and myelin plasticity within disease contexts is, therefore, critical for the development of novel therapeutic targets. In our companion manuscript, we review literature demonstrating that multiple hormone classes are involved in the regulation of oligodendrogenesis under physiological conditions. The majority of hormones enhance oligodendrogenesis, increasing oligodendrocyte precursor cell differentiation and inducing maturation and myelin production in OLs. Thus, hormonal treatments present a promising route to promote remyelination. Here, we review the literature on hormonal regulation of oligodendrogenesis within the context of disorders. We focus on steroid hormones, including glucocorticoids and sex hormones, peptide hormones such as insulin-like growth factor 1, and thyroid hormones. For each hormone, we describe whether they aid in OL survival, differentiation, or remyelination, and we discuss their mechanisms of action, if known. Several of these hormones have yielded promising results in both animal models and in human conditions; however, a better understanding of hormonal effects, interactions, and their mechanisms will ultimately lead to more targeted therapeutics for myelin repair.

Bibliometrics Analysis of the Research Status and Trends of the Association Between Depression and Insulin From 2010 to 2020

Depression is one of the common mental illnesses. Because it is an important complication of diabetes, its association with changes in insulin levels and insulin resistance, the causative factors of diabetes, has attracted widespread attention. However, the association between insulin and depression has not been systematically studied through bibliometric and visual analysis. This study is based on 3131 publications of Web of Science to identify the current research status and research trends in this field. The results show that since 2010, the number of publications has been growing rapidly. Cooperative network analysis shows that the United States, the University of Toronto and Roger S Mcintyre are the most influential countries, research institutes and scholars, respectively. Insulin resistance, obesity, and metabolic syndrome are hot topics in this field. Analysis of keywords and references reveals that "sex hormones," is new research area that constantly emerging. As far as we know, this study is the first one to visualize the association between depression and insulin and predict potential future research trends through bibliometric and visual analysis.

Osteocalcin, ovarian senescence, and brain health

Menopause, an inevitable event in a woman's life, significantly increases risk of bone resorption and diseases such as Alzheimer's, vascular dementia, cardiac arrest, and stroke. The sole role of bones, as traditionally regarded, is to provide structural support for skeletal muscles and allow for ambulation, however this concept is becoming quickly outdated. New literature has emerged that suggests the bone cell-derived hormone osteocalcin (OCN) plays a pivotal role in cognition. OCN levels are correlated with bone mass density and bone turnover, and thus are strongly influenced by the changes associated with menopause. The goal of the current review is to discuss potential gaps in our knowledge of OCN and cognition, discrepancies in methods of OCN quantification, and therapies to enhance circulating OCN. A discussion on implementing exercise or low frequency vibration interventions at the menopausal transition to reduce risk and severity of neurological diseases and associated cognitive decline is included.

Impact of Cognitive Aging on Health-Related Quality of Life in Menopausal Women

Objectives

Menopause is a well-known risk factor for accelerating cognitive aging in women. This study aimed to assess differences in cognitive function and health-related quality of life (HRQOL) according to menopausal status to determine whether the menopause significantly affects the relationship between cognitive function and HRQOL.

Methods

This was a cross-sectional comparative study with a convenience sample of 178 Korean women including 89 naturally menopausal women (65 ± 10 years) and 89 non-menopausal women (45 ± 8 years) who met the eligibility criteria and completed neuropsychological tests and self-report questionnaires about their HRQOL, cognitive function, depression, and sleep quality. Multiple regression analyses were performed within and between groups according to menopausal status.

Results

Menopausal women had significantly worse scores on neuropsychological performance and HRQOL than non-menopausal women. A better neuropsychological performance (β = 0.34) was solely associated with a better HRQOL in menopausal women, whilst socioeconomic variables were associated with HRQOL in non-menopausal women.

Conclusion

Menopause is an important risk factor for HRQOL, and the association between cognition and HRQOL may differ according to menopausal status. When developing programs for target groups to improve daily functioning and HRQOL, healthcare professionals need to pay more attention to this relationship.

Do menopausal status and APOE4 genotype alter the long-term effects of intensive lifestyle intervention on cognitive function in women with type 2 diabetes mellitus?

In the Look AHEAD trial, randomization to Intensive Lifestyle Intervention (ILI) or Diabetes Support and Education (DSE) did not result in differences in cognitive outcomes. However, menopause and APOE genotype are factors that affect the response to this intervention. The effect of this intervention on a single cognitive assessment was examined in 3 groups of women: premenopausal or <5 years postmenopausal (N = 594), within 5-10 years (n = 388), and ≥10 years postmenopausal (n = 963), and as a function of continuous years since menopause. The late postmenopausal group in the ILI had worse composite z-scores compared to those in the DSE, whereas the younger premenopausal or early postmenopausal women in the ILI had better composite z-scores than the DSE. A significant interaction between years since menopause and intervention arm, but not baseline age, was observed on executive function domains. ILI appeared only to benefit cognitive function among non-APOE4 carriers during premenopause or early postmenopause. These findings emphasize the importance of assessing menopause and APOE status to understand how weight loss impacts cognition.

Beyond Biological Sex: Interactive Effects of Gender Role and Sex Hormones on Spatial Abilities

Sex differences in spatial abilities are well documented, even though their underlying causes are poorly understood. Some studies assume a biological basis of these differences and study the relationship of sex hormone levels to spatial abilities. Other studies assume social influences and study the relationship of gender role (masculinity/femininity) to spatial abilities. Contemporary theories postulate a psychobiosocial model of sex differences in spatial abilities, in which both biological (e.g., hormonal) and psychosocial (e.g., gender role) variables interactively modulate spatial abilities. However, few studies have addressed both aspects simultaneously. Accordingly, the present study explores potential interactive effects between gender role and sex hormones on spatial performance. 41 men and 41 women completed a mental rotation and a virtual navigation task. Sex hormone levels and gender role were assessed in all participants. Sex differences favoring men were observed in both tasks. We found that neither sex hormones nor gender role alone emerged as mediators of these sex differences. However, several interactive effects between gender role and sex hormones were identified. Combined effects of masculinity and testosterone were observed for those variables that displayed sex differences. Participants with both, high masculinity and high testosterone showed the best performance. However, this association was further modulated by biological sex and progesterone levels. Furthermore, we observed an interactive effect of femininity, estradiol and testosterone on response times in both tasks. Consistent across both tasks and irrespective of biological sex, testosterone related to response times in participants with low estradiol levels, depending on their femininity. In participants with low femininity, testosterone was related to slower reaction times, while in participants with higher femininity, testosterone was related to faster reaction times.

Estrogen, Stress, and Depression: Cognitive and Biological Interactions

This article reviews the interactions of estrogen changes and psychosocial stress in contributing to vulnerability to major depressive disorder (MDD) in women. Estrogen modulates brain networks and processes related to changes in stress response, cognition, and emotional dysregulation that are core characteristics of MDD. Synergistic effects of estrogen on cognitive and emotional function, particularly during psychosocial stress, may underlie the association of ovarian hormone fluctuation and depression in women. We propose a model of estrogen effects on multiple brain systems that interface with stress-related emotional and cognitive processes implicated in MDD and discuss possible mechanisms through which reproductive events and changes in estrogen may contribute to MDD risk in women with other concurrent risk factors.

Examining the Relationship Between Neurosteroids, Cognition, and Menopause With Neuroimaging Methods

PURPOSE OF REVIEW

Previous literature has shown inconsistent findings regarding the effects of neurosteroids on the brain in postmenopausal women. The goal of this paper is to examine how and whether advances in neuroimaging have helped elucidate the relationship between the withdrawal of and/or treatment with neurosteroids and cognition at menopause.

RECENT FINDINGS

Neuroimaging techniques such as structural and functional MRI have been used in recent studies to examine the relationship between neurosteroids and brain structure and functioning. However, the recent literature shows that different formulations of postmenopausal hormones given at different times, through different routes of administration, and in different combinations with progestins result in a variety of relationships with the brain outcomes. We suggest that still further research is needed to understand how the structural changes resulting from estrogen withdrawal or therapy at menopause can influence cognitive functioning. However, imaging studies are time-, resource-, and expertise-intensive. We believe that this information will help uncover the mechanisms and relationships that can aid in the explanation of the individual differences in the effects of menopause on the brain as well as how this menopause-related hormone change influences risk for pathological aging.

Dopamine-dependent cognitive processes after menopause: the relationship between COMT genotype, estradiol, and working memory

The present study examined how a gene related to functioning of the dopaminergic system, catechol-O-methyltransferase (COMT), and estradiol were related to brain functioning in healthy postmenopausal women. Participants were 118 healthy, cognitively normal postmenopausal women between the ages of 50-60 years. All women provided a blood sample for COMT and estradiol analyses and underwent a magnetic resonance imaging scan. Working memory performance and related brain activation were measured with BOLD functional magnetic resonance imaging during the N-back task. Results were examined across each COMT genotype and a median split was performed on the circulating estradiol levels to create high and low estradiol groups for each genotype. COMT genotype and estradiol level were hypothesized to be proxy measures for brain dopamine levels with the Met/Met and high estradiol group having the most dopamine and Val/Val and low estradiol group having the least dopamine. The functional magnetic resonance imaging results showed that the N-back task activated the expected bilateral frontal and bilateral parietal working memory network. However, no main effects of COMT genotype or estradiol group were found. There was COMT-estradiol interaction found in a small area of decreased activation in the right precentral gyrus (Brodmann Area 6) that was related to the increasing hypothesized dopamine level. Specifically, women with a Met/Met genotype in the high estradiol group had the least activation in this frontal lobe working memory region. Women with a Val/Val genotype in the low estradiol group had greater activation in this region relative to the other groups. Performance on the N-back task did not show any group differences. These data indicate that after menopause COMT genotype and potentially the menopause-related changes to the dopaminergic system are not related to cognition. Future studies should examine how the relationship between COMT, estradiol, and cognition around the menopause transition as there appear to be differences in this relationship for premenopausal and postmenopausal women.

Protective Effects of 17β-Estradiol on Hippocampal Myelinated Fibers in Ovariectomized Middle-aged Rats

Estrogen replacement therapy (ERT) improves hippocampus-dependent cognition. This study investigated the impact of estrogen on hippocampal volume, CA1 subfield volume and myelinated fibers in the CA1 subfield of middle-aged ovariectomized rats. Ten-month-old bilaterally ovariectomized (OVX) female rats were randomly divided into OVX + E2 and OVX + Veh groups. After four weeks of subcutaneous injection with 17β-estradiol or a placebo, the OVX + E2 rats exhibited significantly short mean escape latency in a spatial learning task than that in the OVX + Veh rats. Using stereological methods, we did not observe significant differences in the volumes of the hippocampus and CA1 subfields between the two groups. However, using stereological methods and electron microscopy techniques, the total length of myelinated fibers and the total volumes of myelinated fibers, myelin sheaths and myelinated axons in the CA1 subfields of OVX + E2 rats were significantly 38.1%, 34.2%, 36.1% and 32.5%, respectively, higher than those in the OVX + Veh rats. After the parameters were calculated according to different diameter ranges, the estrogen replacement-induced remodeling of myelinated fibers in CA1 was mainly manifested in the myelinated fibers with a diameter of <1.0 μm. Therefore, four weeks of continuous E2 replacement improved the spatial learning capabilities of middle-aged ovariectomized rats. The E2 replacement-induced protection of spatial learning abilities might be associated with the beneficial effects of estrogen on myelinated fibers, particularly those with the diameters less than 1.0 μm, in the hippocampal CA1 region of middle-aged ovariectomized rats.

Effects of estrogen replacement therapy on the myelin sheath ultrastructure of myelinated fibers in the white matter of middle-aged ovariectomized rats

The effects of estrogen replacement therapy (ORT) on white matter and the myelin sheath ultrastructure in the white matter of middle-aged ovariectomized (OVX) rats were investigated in this study. Middle-aged rats were ovariectomized and divided into a placebo replacement (OVX + O) group and an estrogen replacement (OVX + E) group. Then, the Morris water maze, electron microscope techniques, and stereological methods were used to investigate the effects of ORT on spatial learning capacity, white matter volume and the myelin sheath ultrastructure in the white matter. We found that the spatial learning capacity of the OVX + E rats was significantly improved compared with that of the OVX + O rats. When compared with that of OVX + O rats, the total volume of the myelin sheaths in the white matter of the OVX + E rats was significantly increased by 27%, and the difference between the outer perimeter and inner perimeter of the myelin sheaths of the white matter in the OVX + E rats increased significantly by 12.6%. The myelinated fibers with mean diameters of 1.2-1.4 μm were significantly longer (46.1%) in the OVX + E rats; the difference between the mean diameter of myelinated fibers and the mean diameter of axons (0-0.4 μm) was significantly increased by 21.6% in the OVX + E rats. These results suggested that ORT had positive protective effects on the spatial learning ability and on the myelin sheath ultrastructure in the white matter of middle-aged OVX rats.

Strategies for Preventing Cognitive Decline in Healthy Older Adults

OBJECTIVE

Many advances have been made in the understanding of age-related changes in cognition. As research details the cognitive and neurobiological changes that occur in aging, there is increased interest in developing and understanding methods to prevent, slow, or reverse the cognitive decline that may occur in normal healthy older adults. The Institute of Medicine has recently recognized cognitive aging as having important financial and public health implications for society with the increasing older adult population worldwide. Cognitive aging is not dementia and does not result in the loss of neurons but rather changes in neurotransmission that affect brain functioning. The fact that neurons are structurally intact but may be functionally affected by increased age implies that there is potential for remediation.

METHOD AND RESULTS

This review article presents recent work using medication-based strategies for slowing cognitive changes in aging. The primary method presented is a hormonal approach for affecting cognition in older women. In addition, a summary of the work examining modifiable lifestyle factors that have shown promise in benefiting cognition in both older men and women is described.

CONCLUSIONS

Much work remains to be done so that evidence-based recommendations can be made for slowing cognitive decline in healthy older adults. The success of some of these methods thus far indicates that the brains of healthy older adults are plastic enough to be able to respond to these cognitive decline prevention strategies, and further work is needed to define the most beneficial methods.

Estrogen Replacement Improves Verbal Memory and Executive Control in Oligomenorrheic/Amenorrheic Athletes in a Randomized Controlled Trial

OBJECTIVE

Both estrogen and exercise may have cognition enhancing benefits; however, young oligomenorrheic/amenorrheic athletes (OA) with estrogen deficiency have not been evaluated for cognitive deficits. Our objective was to determine whether 6 months of estrogen replacement will impact cognitive domains in OA. We hypothesized that estrogen replacement would improve verbal memory and executive control in OA.

METHODS

We performed cognitive assessments at baseline and after 6 months in 48 OA (14-25 years) randomized to estrogen (EST+) (oral 30 µg ethinyl estradiol [n = 16] or transdermal 100 µg 17-β-estradiol patch [n = 13]) or no estrogen (EST-) (n = 19) in an ongoing clinical trial. Neurocognitive testing included California Verbal Learning Test-Second Edition (CVLT-II) (for verbal memory) and Delis-Kaplan Executive Function System Color-Word Interference Test (D-KEFS-CWIT) (executive control).

RESULTS

On average, subjects (mean ± SEM age: 19.9 ± 3.1 years, body mass index: 20.6 ± 2.3 kg/m²) participated in 10.3 ± 5.9 hours per week of weight-bearing activities of their lower limbs. The EST+ group performed better for CVLT-II verbal memory scores for immediate recall over 6 months of therapy compared to EST- (P < .05) even after controlling for baseline scores and age. Changes in D-KEFS-CWIT scores over 6 months did not differ between the groups. However, the EST+ group had greater improvements in inhibition-switching completion time over 6 months compared with the EST- group after controlling for baseline scores and age (P = .01).

CONCLUSIONS

OA show improvements in verbal memory and executive control following 6 months of estrogen replacement. These findings in athletes, who are in their prime of neurocognitive development, underscore the need for future studies exploring cognition in OA.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT00946192.

Estrogen enhances hippocampal gray-matter volume in young and older postmenopausal women: a prospective dose-response study

Estrogen administration following menopause has been shown to support hippocampally mediated cognitive processes. A number of previous studies have examined the effect of estrogen on hippocampal structure to determine the mechanism underlying estrogen effects on hippocampal function. However, these studies have been largely observational and provided inconsistent results. We examined the effect of short-term estradiol administration on hippocampal gray-matter volume in a prospective study with multiple doses of estradiol (placebo, 1 mg, and 2 mg). Following 3 months of estradiol administration, bilateral posterior hippocampal voxel-based gray-matter volume was increased in women who received 2-mg estradiol. There were no significant differences in total hippocampal volume and no significant effects on gray-matter volume in women who received placebo or 1-mg estradiol. These findings accord with previous animal studies and provide evidence of estrogen effects on hippocampal morphology that may represent a neurobiological mechanism for estrogen effects on cognition in postmenopausal women.

Evidence for Cognitive Aging in Midlife Women: Study of Women's Health Across the Nation

Although cross-sectional studies suggest that cognitive aging starts in midlife, few longitudinal studies have documented within-individual declines in cognitive performance before the seventh decade. Learning from repeat testing, or practice effects, can mask the decline in younger cohorts. In women, the menopause transition also affects test performance and can confound estimates of underlying decline. We designed this study to determine if, after controlling for practice effects, the menopause transition, and the symptoms associated with it, there is evidence of cognitive aging in midlife women. We used data from a longitudinal observational study in 2,124 participants from the Study of Women’s Health Across the Nation. Outcomes examined were scores on annual tests of processing speed, verbal episodic memory (immediate and delayed), and working memory. To reduce the impact of practice effects and of the menopause transition, we used the third cognition testing visit as the baseline. Average age at this baseline was 54 years, and the majority of the women were postmenopausal; half the cohort was 2 or more years beyond the final menstrual period. There were 7,185 cognition assessments with median follow-up time of 6.5 years. In mixed effects regression, adjusted for practice effects, retention, menopause symtoms (depressive, anxiety, vasomotor, and sleep disturbance), and covariates, scores on 2 of 4 cognition tests declined. Mean decline in cognitive speed was 0.28 per year (95% confidence interval [CI] 0.20 to 0.36) or 4.9% in 10 years, and mean decline in verbal episodic memory (delayed testing) was 0.02 per year (95% CI: 0.00 to 0.03) or 2% in 10 years. Our results provide strong, longitudinal evidence of cognitive aging in midlife women, with substantial within-woman declines in processing speed and memory. Further research is needed to identify factors that influence decline rates and to develop interventions that slow cognitive aging.

The Impact of Endocrine Therapy on Cognitive Functions of Breast Cancer Patients: A Systematic Review

BACKGROUND AND OBJECTIVE

The purpose of the present review was to study the impact of endocrine therapy (ET) on the cognitive outcomes of breast cancer patients.

MATERIALS AND METHODS

We systematically searched the literature using the MEDLINE (1966-2015), Scopus (2004-2015), ClinicalTrials.gov (2008-2015) and Cochrane Central Register (CENTRAL) databases, as well as the references of the electronically retrieved articles.

RESULTS

Twelve studies were included in the present systematic review, which assessed the cognitive function of 2756 patients. Among these patients, 2381 received ET, whereas the remaining 375 served as controls (placebo or no therapy). The majority of patients were postmenopausal, and the minimum follow-up period was 3 months and the maximum 2 years. Treatment with ET seems to be accompanied by altered cognitive abilities, including verbal memory, verbal fluency, motor speed, attention and working memory. Tamoxifen seems to be related to decreased cognitive performances compared with treatment with an aromatase inhibitor.

CONCLUSIONS

ET among breast cancer patients seems to negatively alter the cognitive outcomes of breast cancer patients. However, the methodological heterogeneity of the included studies, as well as the relatively small follow-up period, render imperative the conduct of further studies in the field.

Chronic alpha-linolenic acid treatment alleviates age-associated neuropathology: Roles of PERK/eIF2α signaling pathway

Aging is a principal risk factor for neurodegenerative diseases and especially shares similar pathologic mechanisms to Alzheimer's disease (AD). Amyloid-β (Aβ) plaques deposition and neurofibrillary tangles (NFTs) are the prominent age-dependent pathologies implicated in the cognitive deficits. Accumulation of mis-folded proteins in the endoplasmic reticulum triggers a cellular stress response called the unfolded protein response (UPR), the activation of which is increased in AD patients. However, the UPR relates to the pathological hallmarks of aging is still elusive. In this study, we report that long-term supplement of α-linolenic acid (ALA), starting before the onset of disease symptoms (6month-old), prevents the age-related memory deficits during natural aging. The amelioration of the memory impairment is associated with a decrease in UPR related markers [glucose regulated protein 78 (GRP78), protein kinase RNA-like endoplasmic reticulum kinase (PERK), eukaryotic Initiation Factor 2α (eIF2α)]. ALA suppressed the PERK/eIF2α signaling, which may be responsible for multifaceted memory-deteriorating and neurodegenerative mechanisms, including inhibition of Aβ production by suppressing β-site APP-cleaving enzyme 1 (BACE1) expression, enhancement of cAMP response element binding protein (CREB) function via down-regulating activating transcription factor 4 (ATF4), and suppression of Tau phosphorylation by inhibiting glycogen synthase kinase 3β (GSK-3β) pathway. Taken together, our findings provide new insights into the link between ALA and PERK/eIF2α signaling, which could contribute to a better understanding of an ALA-mediated protective effect in aging-associated neuropathology.

17β-estradiol replacement therapy protects myelin sheaths in the white matter of middle-aged female ovariectomized rats: a stereological study

Many studies have shown that estrogen replacement therapy (ERT) can improve cognitive function and affect the structure of the brain, including the white matter, in postmenopausal women. However, it is unclear whether ERT plays an important role in white matter remodeling in postmenopausal women. In the present study, middle-aged (9-12-month-old) female Sprague-Dawley rats were bilaterally ovariectomized (OVX) and randomly allocated to the vehicle treatment (OVX+Veh) group or the 17β-estradiol replacement (OVX+E) group. After 1 month of treatment, spatial learning and memory capacities were assessed using the Morris water maze task. Then, stereological methods were used to quantitatively evaluate white matter volume and myelinated fiber parameters of the white matter in the 2 groups of rats. The results revealed that the mean escape latency of the OVX+E rats in the Morris water maze task was significantly shorter than that of the OVX+Veh rats. The volume density of the myelinated fibers and the volume density and total volume of the myelin sheaths were significantly greater in the OVX+E rats than in the OVX+Veh rats. However, there were no significant differences in white matter volume or in the total length or volume of myelinated fibers in white matter between the 2 groups of rats. Our results showed that 1 month of ERT had significant beneficial effects on spatial learning capacity and on the myelin sheaths and myelinated fibers in the white matter of middle-aged OVX rats.

Blood pressure and neuropsychological test performance in healthy postmenopausal women

PURPOSE

To study the association between blood pressure and neuropsychological test performance in healthy postmenopausal women.

METHODS

Data from 88 healthy postmenopausal women aged 46-73 years, who were not experiencing hot flashes, and who had participated in a prior drug trial, were analyzed to find whether baseline blood pressure was associated with impaired performance on neuropsychological testing done at 3 follow-up visits separated by 4 weeks. Factor analysis was used to reduce the dimensions of neuropsychological test performance. Mixed linear modeling was used to evaluate the association between baseline blood pressure and repeatedly measured neuropsychological test performance at follow-up in a complete case analysis (n=53). In a sensitivity analysis (n=88), multiple-imputation using the Markov Chain Monte Carlo method was used to account for missing data (blood pressure results) for some visits.

RESULTS

The variables recording neuropsychological test performance were reduced to two main factors (Factor 1=selective attention; Factor 2=complex processing). In the complete case analysis, the association between a 20-mmHg increase in diastolic blood pressure and Factor 1 remained statistically significant after adjusting for potential confounders, before adjusting for systolic blood pressure (slope=0.60; 95%CI=0.04,1.16), and after adjusting for systolic blood pressure (slope=0.76; 95%CI=0.06, 1.47). The positive slopes indicated an increase in the time spent performing a given task (i.e., a decrease in neuropsychological test performance). No other significant associations were found between systolic blood pressure and either factor. The results did not materially change after applying the multiple-imputation method.

CONCLUSIONS

An increase in diastolic blood pressure was associated with a decrease in neuropsychological test performance among older healthy postmenopausal women experiencing hot flashes.

Estrogen-cholinergic interactions: Implications for cognitive aging

This article is part of a Special Issue "Estradiol and Cognition". While many studies in humans have investigated the effects of estrogen and hormone therapy on cognition, potential neurobiological correlates of these effects have been less well studied. An important site of action for estrogen in the brain is the cholinergic system. Several decades of research support the critical role of CNS cholinergic systems in cognition in humans, particularly in learning and memory formation and attention. In humans, the cholinergic system has been implicated in many aspects of cognition including the partitioning of attentional resources, working memory, inhibition of irrelevant information, and improved performance on effort-demanding tasks. Studies support the hypothesis that estradiol helps to maintain aspects of attention and verbal and visual memory. Such cognitive domains are exactly those modulated by cholinergic systems and extensive basic and preclinical work over the past several decades has clearly shown that basal forebrain cholinergic systems are dependent on estradiol support for adequate functioning. This paper will review recent human studies from our laboratories and others that have extended preclinical research examining estrogen-cholinergic interactions to humans. Studies examined include estradiol and cholinergic antagonist reversal studies in normal older women, examinations of the neural representations of estrogen-cholinergic interactions using functional brain imaging, and studies of the ability of selective estrogen receptor modulators such as tamoxifen to interact with cholinergic-mediated cognitive performance. We also discuss the implications of these studies for the underlying hypotheses of cholinergic-estrogen interactions and cognitive aging, and indications for prophylactic and therapeutic potential that may exploit these effects.

Role of grandparenting in postmenopausal women's cognitive health: results from the Women's Healthy Aging Project

OBJECTIVE

Preserving aging cognition improves quality of life and delays dementia onset. Previous studies have shown that social engagement can maintain cognition; however, none has examined the effects of grandparenting, an important role among postmenopausal women. This study aims to examine the role of grandparenting in cognition among postmenopausal women.

METHODS

Participants were 186 Australian women from the longitudinal prospective Women's Healthy Aging Project. Cognition was assessed using the Symbol-Digit Modalities Test (SDMT), California Verbal Learning Test, and Tower of London.

RESULTS

Amount of time spent minding grandchildren predicted differences in SDMT performance (P < 0.01). The highest cognitive scores for most tests were seen in participants who minded grandchildren for 1 day/week. Minding grandchildren for 1 day/week was also a significant positive predictor of California Verbal Learning Test immediate recall performance (P < 0.05). However, minding grandchildren for 5 days or more per week predicted lower SDMT performance (P < 0.05).

CONCLUSIONS

The data suggest that the highest cognitive performance is demonstrated by postmenopausal women who spend 1 day/week minding grandchildren; however, minding grandchildren for 5 days or more per week predicts lower working memory performance and processing speed. These results indicate that highly frequent grandparenting predicts lower cognitive performance.

Sex, stress and the brain: interactive actions of hormones on the developing and adult brain

The brain is a target of steroid hormone actions that affect brain architecture, molecular and neurochemical processes, behavior and neuroprotection via both genomic and non-genomic actions. Estrogens have such effects throughout the brain and this article provides an historical and current view of how this new view has come about and how it has affected the study of sex differences, as well as other areas of neuroscience, including the effects of stress on the brain.

Oestradiol modulation of cognition in adult female marmosets (Callithrix jacchus)

The common marmoset (Callithrix jacchus) provides many advantages over traditional rodent and macaque species as a model for human ageing and may be very useful for studying the effects of sex steroids on cognitive and brain ageing. We present the first study examining the effects of oestrogens on cognitive function in female marmosets. Adult monkeys (3-5 years of age) were trained to a specific learning criterion on a battery of cognitive tasks preoperatively (object discrimination, delayed response with increasing delays and detour reaching with opaque box) and were tested on different versions of these tasks (object reversals, delayed response with randomised delays and detour reaching with clear box) after ovariectomy and simultaneous implantation with 17β-oestradiol (E2 ) (n = 6) or blank (n = 6) Silastic capsules. Acquisition of a delayed matching-to-position task with a 1-s delay was also administered after completion of these tests. E2 -treated monkeys were significantly impaired on the second reversal and showed an increase in perseverative responding from reversals 1-3. Their performance also tended to be worse than that of control monkeys on the delayed response task. Performance acquisition on the delayed matching-to-position tended to be better in E2 -treated relative to control monkeys, although the group difference did not reach statistical significance. No effect of treatment was detected for detour reaching or affiliative behaviours. Overall, the findings indicate that E2 compromises performance on prefrontally-mediated tasks. The suggestion that E2 may improve acquisition on tasks dependent on the hippocampus will require further validation. These results are discussed in the context of dopaminergic and serotonergic signalling. We conclude that the marmoset is a useful new primate model for examining the effects of oestrogens on cognitive function.

An update on the cognitive impact of clinically-used hormone therapies in the female rat: models, mazes, and mechanisms

In women, ovarian hormone loss associated with menopause has been related to cognitive decline. Hormone therapy (HT) may ameliorate some of these changes. Understanding the cognitive impact of female steroids, including estrogens, progestogens, and androgens, is key to discovering treatments that promote brain health in women. The preclinical literature has presented elegant and methodical experiments allowing a better understanding of parameters driving the cognitive consequences of ovarian hormone loss and HT. Animal models have been a valuable tool in this regard, and will be vital to future discoveries. Here, we provide an update on the literature evaluating the impact of female steroid hormones on cognition, and the putative mechanisms mediating these effects. We focus on preclinical work that was done with an eye toward clinical realities. Parameters that govern the cognitive efficacy of HT, from what we know thus far, include but are not limited to: type, dose, duration, and route of HT, age at HT initiation, timing of HT relative to ovarian hormone loss, memory type examined, menopause history, and hormone receptor status. Researchers have identified intricate relationships between some of these factors by studying their individual effects on cognition. As of late, there is increased focus on studying interactions between these variables as well as multiple hormone types when administered concomitantly. This is key to translating preclinical data to the clinic, wherein women typically have concurrent exposure to endogenous ovarian hormones as well as exogenous combination HTs, which include both estrogens and progestins. Gains in understanding the parameters of HT effects on cognition provide exciting novel avenues that can inform clinical treatments, eventually expanding the window of opportunity to optimally enhance cognition and brain health in aging women. This article is part of a Special Issue entitled Hormone Therapy.

Translational cognitive endocrinology: designing rodent experiments with the goal to ultimately enhance cognitive health in women

Understanding the cognitive impact of endogenously derived, and exogenously administered, hormone alterations is necessary for developing hormone treatments to support healthy brain function in women, especially during aging. The increasing number of studies in the burgeoning area of translational cognitive neuroendocrinology has revealed numerous factors that influence the extent and direction of female steroid effects on cognition. Here, we discuss the decision processes underlying the design of rodent hormone manipulation experiments evaluating learning and memory. It is noted that even when beginning with a clear hypothesis-driven question, there are numerous factors to consider in order to solidify a sound experimental design that will yield clean, interpretable results. Decisions and considerations include: age of animals at hormone administration and test, ovariectomy implementation, when to administer hormones relative to ovarian hormone loss, how and whether to monitor the estrous cycle if animals are ovary-intact, dose of hormone, administration route of hormone, hormone treatment confirmation protocols, handling procedures required for hormone administration and treatment confirmation, cognitive domains to be tested and which mazes should be utilized to test these cognitive domains, and control measures to be used. A balanced view of optimal design and realistic experimental practice and protocol is presented. The emerging results from translational cognitive neuroendocrinology studies have been diverse, but also enlightening and exciting as we realize the broad scope and powerful nature of ovarian hormone effects on the brain and its function. We must design, implement, and interpret hormone and cognition experiments with sensitivity to these tenets, acknowledging and respecting the breadth and depth of the impact gonadal hormones have on brain functioning and its rich plasticity. This article is part of a Special Issue entitled Hormone Therapy.

Relationship between leukoaraiosis and menopause in healthy middle-aged women

OBJECTIVE

To investigate the relationship between leukoaraiosis (LA) and menopause in healthy middle-aged women.

DESIGN

A retrospective cohort study.

SETTING

Health promotion center of a university hospital.

PATIENT(S)

We studied 262 healthy pre- and postmenopausal women ages 41-60 years who visited the health promotion center for a routine health checkup.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

LA is defined as diffuse white matter abnormalities on computed tomography or magnetic resonance imaging (MRI). LA was assessed by examining MRIs and using the rating scale of the Atherosclerosis Risk in Communities Study. Logistic regression analysis was performed to examine associations between LA and menopause.

RESULT(S)

Women with LA had a significantly higher age than women without LA. Elevated blood pressure (≥ 130/85 mm Hg) and low high-density lipoprotein cholesterol (<50 mg/dL) were frequent abnormal findings in women with LA. The proportion of menopause was significantly higher in women with LA than in those without LA. Menopause was independently associated with the presence of LA (adjusted odds ratio, 2.24; 95% confidence interval, 1.10, 4.60) after adjusting for confounding variables.

CONCLUSION(S)

Menopause was significantly associated with LA. Loss of estrogen may play an important role in the development of LA.

Exploring stress-induced cognitive impairment in middle aged, centrally obese adults

Extensive research has shown that psychosocial stress can induce cognitive impairment. However, few studies have explored impairment following acute stress exposure in individuals with central obesity. Central obesity co-occurs with glucocorticoid excess and can lead to elevated cortisol responses to stress. It is not clear whether centrally obese individuals exhibit greater cognitive impairment following acute stress. Cortisol responses to stress versus no-stress control were compared in 66 high- and low waist to hip ratio (WHR) middle-aged adults (mean age of 46 ± 7.17 years). Cognitive performance post exposure was assessed using Cambridge Automated Neuropsychological Test Battery. It was hypothesised that high WHR would exhibit greater cortisol in response to stress exposure and would show poorer cognitive performance. Males, particularly of high WHR, tended to secrete greater cortisol during stress exposure. Exposure to stress and increasing WHR were specifically associated with poorer performance on declarative memory tasks (spatial recognition memory and paired associates learning). These data tentatively suggest a reduction in cognitive performance in those with central obesity following exposure to acute stress. Further research is needed to elucidate the effects of stress on cognition in this population.

Estrogen and the prefrontal cortex: towards a new understanding of estrogen's effects on executive functions in the menopause transition

Midlife decline in cognition, specifically in areas of executive functioning, is a frequent concern for which menopausal women seek clinical intervention. The dependence of executive processes on prefrontal cortex function suggests estrogen effects on this brain region may be key in identifying the sources of this decline. Recent evidence from rodent, nonhuman primate, and human subject studies indicates the importance of considering interactions of estrogen with neurotransmitter systems, stress, genotype, and individual life events when determining the cognitive effects of menopause and estrogen therapy.

Therapeutic approaches to age-associated neurocognitive disorders

The United Nations projects that the number of individuals with dementia in developed countries alone will be approximately 36,7 million by the year 2050. International recognition of the significant emotional and economic burden of Alzheimer's disease has been matched by a dramatic increase in the development of pharmacological and nonpharmacological approaches to this illness in the past decade. Changing demographics have underscored the necessity to develop similar approaches for the remediation of the cognitive impairment associated with more benign syndromes, such as mild cognitive impairment (MCI) and age-associated cognitive decline (AACD). The present article aims to provide an overview of the most current therapeutic approaches to age-associated neurocognitive disorders. Additionally, it discusses the conceptual and methodological issues that surround the design, implementation, and interpretation of such approaches.

Building a better hormone therapy? How understanding the rapid effects of sex steroid hormones could lead to new therapeutics for age-related memory decline

A wealth of data collected in recent decades has demonstrated that ovarian sex-steroid hormones, particularly 17β-estradiol (E2), are important trophic factors that regulate the function of cognitive regions of the brain such as the hippocampus. The loss of hormone cycling at menopause is associated with cognitive decline and dementia in women, and the onset of memory decline in animal models. However, hormone therapy is not currently recommended to prevent or treat cognitive decline, in part because of its detrimental side effects. In this article, it is proposed that investigations of the rapid effects of E2 on hippocampal function be used to further the design of new drugs that mimic the beneficial effects of E2 on memory without the side effects of current therapies. A conceptual model is presented for elucidating the molecular and biochemical mechanisms through which sex-steroid hormones modulate memory, and a specific hypothesis is proposed to account for the rapid memory-enhancing effects of E2. Empirical support for this hypothesis is discussed as a means of stimulating the consideration of new directions for the development of hormone-based therapies to preserve memory function in menopausal women.

Impact of atomoxetine on subjective attention and memory difficulties in perimenopausal and postmenopausal women

OBJECTIVE

Perimenopausal and postmenopausal women frequently report midlife onset of impairments of attention, organization, and short-term memory. We sought to determine whether these cognitive symptoms in healthy women in the menopause transition without a history of attention-deficit/hyperactivity disorder (ADHD) would respond to treatment with atomoxetine (ATX), a medication demonstrated to be effective in reducing similar cognitive impairments in adults with ADHD.

METHODS

Sixteen healthy women with complaints of midlife-onset subjective difficulties in memory and concentration/attention and without a history of ADHD or other psychiatric disorders were enrolled in a double-blind, placebo-controlled crossover study of ATX 80 mg/day. Treatment arms were 6 weeks long, separated by a 4-week washout. The Brown Attention Deficit Disorder Scale (BADDS) was used to systematically elicit self-report of perceived cognitive difficulties in executive function. Participants also underwent neuropsychological testing, behavioral assessments, and vital signs monitoring.

RESULTS

Mean baseline BADDS scores were 37.9 for all 16 participants and 42.3 for the 12 who completed both arms of the study. Total BADDS scores decreased significantly from baseline during ATX treatment but not placebo treatment. ATX treatment was superior to placebo in reducing the BADDS working memory cluster score, whereas there was a trend for ATX superiority for the BADDS attention/concentration cluster score. ATX did not differ from placebo with respect to effects on neuropsychological tests, behavioral assessments, or cardiac vital signs.

CONCLUSIONS

Perimenopausal and postmenopausal women presenting with midlife-onset subjective cognitive difficulties may experience significant subjective improvement in memory and attention/concentration with ATX treatment.

Membrane-initiated signaling of estrogen related to neuroprotection. "Social networks" are required

Numerous studies indicate that estrogens are crucial in normal brain functioning and preservation against different injuries. At the neuronal membrane, estrogens, binding to estrogen receptors (ERs) or other surface targets, exert rapid actions involving a plethora of signaling pathways that may converge in neuronal survival. Emerging work reveals that at least part of these actions may require the compartmentalization of ERs in signaling platforms, composed of macromolecular signaling proteins and particular lipid composition integrated in lipid rafts. These particular microstructures may provide the optimal microenvironment to trigger multiple ER interactions that may be crucial for neuroprotection against different brain impairments, such as Alzheimer's disease (AD). In this order of ideas, recent evidence has demonstrated that a membrane ER (mER) physically interacts with a voltage-dependent anion channel (VDAC) in lipid rafts from septal, hippocampal and cortical neurons, and these interactions may have important consequences in the alternative mechanisms developed by estrogens to achieve neuroprotection against amyloid beta (Aβ)-induced toxicity. This review includes a survey of some of the rapid mechanisms developed by estrogen to prevent neuronal death, and the ER interactions that are involved in the structural maintenance and signal transduction mechanisms important for neuronal survival against AD neuro-pathology. A special emphasis is put on the biological relevance of neuronal membrane VDAC in Aβ-related neurotoxicity, and the potential modulation of this channel as a part of a signaling complex with mER, which may be modified in AD brains.

Brain biochemical correlates of the plasma homocysteine level: a proton magnetic resonance spectroscopy study in the elderly subjects

BACKGROUND

An elevated plasma homocysteine level has been reported to be associated with various neuropsychiatric diseases. However, little is known about the brain biochemical changes associated with the higher plasma homocysteine level. The main goal of this study was to examine the sex difference in brain biochemical concentrations using brain proton magnetic resonance spectroscopy (H MRS), and to elucidate the biochemical changes associated with plasma homocysteine levels by sex in healthy elderly subjects.

METHODS

Seventy elderly subjects without any clinical psychiatric and neurological disease underwent 3-T brain H MRS. MRS spectra were acquired from voxels placed on the left side of the basal ganglia, frontal lobe, and hippocampus. Brain biochemical concentrations were compared between the elderly male and female participants. Correlations between these biochemical concentrations and plasma homocysteine levels by sex were analyzed.

RESULTS

Female participants had significantly higher levels of choline in the left frontal lobe and hippocampus, and lower creatine and myo-inositol, in the left basal ganglia than did males. A higher homocysteine level was correlated with a lower N-acetylaspartate (NAA) concentration in the left hippocampus in elderly women (r = -0.44; p = 0.03) but not in elderly men.

CONCLUSIONS

This study found that there was a sex difference in brain biochemical concentrations in the elderly participants. A higher plasma homocysteine level was associated with a lower NAA in the hippocampus of elderly women. The sex difference in association between brain biochemical concentrations and plasma homocysteine levels needs further investigation. We speculate that after menopause, women lose protection of estrogen from the neurotoxic effects of homocysteine in the hippocampus. Future studies are required to examine this speculation.

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

On average, women now live one-third of their lives after menopause. Because menopause has been associated with an elevated risk of dementia, an increasing body of research has studied the effects of reproductive senescence on cognitive function. Compelling evidence from humans, nonhuman primates, and rodents suggests that ovarian sex-steroid hormones can have rapid and profound effects on memory, attention, and executive function, and on regions of the brain that mediate these processes, such as the hippocampus and prefrontal cortex. This chapter will provide an overview of studies in humans, nonhuman primates, and rodents that examine the effects of ovarian hormone loss and hormone replacement on cognitive functions mediated by the hippocampus and prefrontal cortex. For humans and each animal model, we outline the effects of aging on reproductive function, describe how ovarian hormones (primarily estrogens) modulate hippocampal and prefrontal physiology, and discuss the effects of both reproductive aging and hormone treatment on cognitive function. Although this review will show that much has been learned about the effects of reproductive senescence on cognition, many critical questions remain for future investigation.

Early menopausal hormone use influences brain regions used for visual working memory

OBJECTIVE

The cognitive benefit of postmenopausal hormone use is controversial; however, timing of treatment close to menopause may increase the likelihood of preserving cognitive function. We examined the effects of early-initiation hormone use on visual working memory, hypothesizing that long-term hormone use is associated with greater brain activation during visual working memory.

METHODS

This was a cross-sectional comparison of long-term early hormone users-current (n = 13) and past (n = 24; 2.1 +/- 1.0 years off hormones)-with never users (n = 18), using a visual memory task and functional magnetic resonance imaging (MRI). We evaluated 55 women older than 60 years at the University of Michigan's General Clinical Research Center. Hormone users had completed at least 10 continuous years of conjugated equine estrogens with or without medroxyprogesterone acetate, begun within 2 years of menopause. Women were excluded for illness, medication, intermittent estrogen use, phytoestrogen use, recent smoking, and MRI contraindications. The primary outcome was functional MRI-detected brain activity during the visual memory task.

RESULTS

Compared with never users, both groups of hormone users had increased activation in the frontal and parietal cortices, insula, hippocampus, and cingulate; combined hormone users also had increased activation in the putamen and raphe (corrected P < 0.05 or uncorrected P < 0.001 with a priori hypothesis). Across the entire sample, the medial temporal cortex (P < 0.0001 right; P < 0.018 left) and right hippocampus (P < 0.0001) positively correlated with task performance.

CONCLUSIONS

Hormone use was associated with increased brain activation during the visual memory task, in regions used for visual working memory. A positive correlation between activation and task performance suggests that early-initiation, long-term postmenopausal hormone use may benefit visual working memory.

Cholinergic modulation of hippocampal activity during episodic memory encoding in postmenopausal women: a pilot study

OBJECTIVE

The cholinergic system has been shown to modulate estrogen effects on cognitive performance in postmenopausal women. In an effort to further understand cholinergic contributions to cognition after menopause, this pilot study investigated the effects of two receptor-specific anticholinergic drugs on brain activation and episodic memory encoding in postmenopausal women not taking estrogen.

METHODS

Six healthy postmenopausal women took part in three drug challenges using the antimuscarinic drug scopolamine (2.5 microg/kg IV), the antinicotinic drug mecamylamine (20 mg PO), and placebo. During functional magnetic resonance imaging, participants performed a visual-verbal continuous recognition memory test that allowed for the separation of encoding and recognition processes.

RESULTS

Functional magnetic resonance imaging results showed greater hippocampal and frontal activation and less occipital activation during encoding relative to retrieval conditions. This pattern of activation was similar under both drug challenges.

CONCLUSIONS

These results suggest that the changes in the cholinergic system may, in part, be responsible for menopause-related increases in brain activation.

Executive functions and selective attention are favored in middle-aged healthy women carriers of the Val/Val genotype of the catechol-o-methyltransferase gene: a behavioral genetic study

BACKGROUND

Cognitive deficits such as poor memory, the inability to concentrate, deficits in abstract reasoning, attention and set-shifting flexibility have been reported in middle-aged women. It has been suggested that cognitive decline may be due to several factors which include hormonal changes, individual differences, normal processes of aging and age-related changes in dopaminergic neurotransmission. Catechol-O-methyltransferase (COMT), a common functional polymorphism, has been related to executive performance in young healthy volunteers, old subjects and schizophrenia patients. The effect of this polymorphism on cognitive function in middle-aged healthy women is not well known. The aim of the current study was to investigate whether measures of executive function, sustained attention, selective attention and verbal fluency would be different depending on the COMT genotype and task demand.

METHOD

We genotyped 74 middle-aged healthy women (48 to 65 years old) for the COMT Val158Met polymorphism. We analyzed the effects of this polymorphism on executive functions (Wisconsin Card Sorting Test), selective attention (Stroop test), sustained attention (Continuous Performance Test) and word generation (Verbal Fluency test), which are cognitive functions that involve the frontal lobe.

RESULTS

There were 27 women with the Val/Val COMT genotype, 15 with the Met/Met genotype, and 32 with the Val/Met genotype. Women carriers of the Val/Val genotype performed better in executive functions, as indicated by a lower number of errors committed in comparison with the Met/Met or Val/Met groups. The correct responses on selective attention were higher in the Val/Val group, and the number of errors committed was higher in the Met/Met group during the incongruence trial in comparison with the Val/Val group. Performance on sustained attention and the number of words generated did not show significant differences between the three genotypes.

CONCLUSION

These findings indicate that middle-aged women carriers of the Val158 allele, associated with high-activity COMT, showed significant advantage over Met allele in executive processes and cognitive flexibility. These results may help to explain, at least in part, individual differences in cognitive decline in middle-aged women with dopamine-related genes.

Neuroscientists as cartographers: mapping the crossroads of gonadal hormones, memory and age using animal models

Cognitive function is multidimensional and complex, and research in multiple species indicates it is considerably impacted by age and gonadal hormone milieu. One domain of cognitive function particularly susceptible to age-related decrements is spatial memory. Gonadal hormones can alter spatial memory, and they are potent modulators of brain microstructure and function in many of the same brain areas affected by aging. In this paper, we review decades of animal and human literature to support a tertiary model representing interactions between gonadal hormones, spatial cognition and age given that: 1) gonadal hormones change with age, 2) age impacts spatial learning and memory, and 3) gonadal hormones impact spatial learning and memory. While much has been discovered regarding these individual tenets, the compass for future aging research points toward clarifying the interactions that exist between these three points, and understanding mediating variables. Indeed, identifying and aligning the various components of the complex interactions between these tenets, including evaluations using basic science, systems, and clinical perspectives, is the optimal approach to attempt to converge the many findings that may currently appear contradictory. In fact, as discoveries are being made it is becoming clear that the findings across studies that appear contradictory are not contradictory at all. Rather, there are mediating variables that are influencing outcome and affecting the extent, and even the direction, of the effects that gonadal hormones have on cognition during aging. These mediating variables are just starting to be understood. By aligning basic scientific discoveries with clinical interpretations, we can maximize the opportunities for discoveries and subsequent interventions to allow individuals to "optimize their aging" and find their own map to cognitive health as aging ensues.

Accelerated postmenopausal cognitive decline is restricted to women with normal BMI: longitudinal evidence from the Betula project

In order to determine whether cognitive performance is influenced by the menopausal transition, we tested cognitive performance at three time points, sampled women in earlier as well as later stages of the menopausal transition (40-65 years of age), and assessed the moderating influence of body mass index (BMI) on rate of change. Multilevel analyses were used to model change in cognitive performance as a function of number of years post menopause over and above chronological age. We investigated change in the menopausal transition for 10 cognitive outcomes in 193 women who were postmenopausal during the last test wave. The model, controlling for age and education, showed that postmenopausal women within the normal range of BMI (BMI 18.5-25) displayed more rapid decline than women with BMI above 25 for measures of visuospatial ability and episodic memory. In addition, there was an accelerated rate of change post menopause for all women on verbal fluency. The results support the notion that the diminished postmenopausal production of endogenous estrogen may have a slight negative influence on cognitive abilities, but mainly for women within a normal BMI range.