Endogenous sex hormone levels and risk of cognitive decline in an older biracial cohort

Association between abdominal adiposity and cognitive decline in older adults: a 10-year community-based study

OBJECTIVES

This study aimed to investigate the association between abdominal adiposity and change in cognitive function in community-dwelling older adults.

DESIGN, SETTING, AND PARTICIPANTS

This longitudinal study included older adults aged ≥60 years without cognitive impairment who participated in the National Institute for Longevity Sciences - Longitudinal Study of Aging.

MEASUREMENTS

Cognitive function was evaluated biennially using the Mini-Mental State Examination (MMSE) over 10 years. Waist circumference (WC) was measured at the naval level, and subcutaneous fat area (SFA) and visceral fat area (VFA) were assessed using baseline computed tomography scans. WC, SFA, and VFA areas were stratified into sex-adjusted tertiles. A linear mixed model was applied separately for men and women.

RESULTS

This study included 873 older adults. In men, the groups with the highest levels of WC, SFA, and VFA exhibited a greater decline in MMSE score than the groups with the lowest levels (β [95% confidence interval]: WC, -0.12 [-0.23 to -0.01]; SFA, -0.13 [-0.24 to -0.02]; VFA, -0.11 [-0.22 to -0.01]). In women, the group with the highest level of WC and SFA showed a greater decline in MMSE score than the group with the lowest level (WC, -0.12 [-0.25 to -0.01]; SFA, -0.18 [-0.30 to -0.06]), but VFA was not associated with cognitive decline.

CONCLUSION

Higher WC, SFA, and VFA in men and higher WC and SFA in women were identified as risk factors for cognitive decline in later life, suggesting that abdominal adiposity involved in cognitive decline may differ according to sex.

Testosterone and aging male, a perspective from a developing country

PURPOSE

Hypogonadism is associated with a wide range of physical and psychological symptoms that can affect the overall health of men. However, in a developing country, there are several imposing challenges in the diagnosis and treatment of hypogonadism, including a lack of awareness and understanding of the condition among healthcare providers and patients, limited resources and the high cost of treatment. This review aimed to examine the potential benefits and risks of testosterone replacement therapy (TRT) and provides a perspective of a developing country on the topic.

MATERIALS AND METHODS

A comprehensive literature review was conducted to gather relevant information on the impact of testosterone deficiency on ageing males and the effectiveness of TRT for treating hypogonadism. Published peer-reviewed articles were analyzed to evaluate the benefits and risks of TRT. Additionally, the unique challenges faced in the diagnosis and treatment of hypogonadism in a developing country were considered.

RESULTS

Testosterone replacement therapy has been shown to be an effective treatment for hypogonadism, particularly in symptomatic men with low testosterone levels. It offers potential benefits such as improvements in symptoms and overall quality of life. However, there are associated risks and side effects that need to be considered. In a developing country, challenges such as limited awareness and understanding of hypogonadism, resource constraints, and high treatment costs pose additional barriers to accessing TRT and comprehensive care.

CONCLUSION

In conclusion, TRT holds promise as a treatment for hypogonadism, but its implementation and accessibility face significant challenges in a developing country. Addressing these challenges, including raising awareness, allocating resources, and finding cost-effective solutions, is crucial for ensuring that men with hypogonadism in such settings receive appropriate diagnosis and treatment. Further research and efforts are needed to improve the management of hypogonadism in developing countries and optimize the potential benefits of TRT for affected individuals.

Different effects of cardiometabolic syndrome on brain age in relation to gender and ethnicity

BACKGROUND

A growing body of evidence shows differences in the prevalence of cardiometabolic syndrome (CMS) and dementia based on gender and ethnicity. However, there is a paucity of information about ethnic- and gender-specific CMS effects on brain age. We investigated the different effects of CMS on brain age by gender in Korean and British cognitively unimpaired (CU) populations. We also determined whether the gender-specific difference in the effects of CMS on brain age changes depending on ethnicity.

METHODS

These analyses used de-identified, cross-sectional data on CU populations from Korea and United Kingdom (UK) that underwent brain MRI. After propensity score matching to balance the age and gender between the Korean and UK populations, 5759 Korean individuals (3042 males and 2717 females) and 9903 individuals from the UK (4736 males and 5167 females) were included in this study. Brain age index (BAI), calculated by the difference between the predicted brain age by the algorithm and the chronological age, was considered as main outcome and presence of CMS, including type 2 diabetes mellitus (T2DM), hypertension, obesity, and underweight was considered as a predictor. Gender (males and females) and ethnicity (Korean and UK) were considered as effect modifiers.

RESULTS

The presence of T2DM and hypertension was associated with a higher BAI regardless of gender and ethnicity (p < 0.001), except for hypertension in Korean males (p = 0.309). Among Koreans, there were interaction effects of gender and the presence of T2DM (p for T2DM*gender = 0.035) and hypertension (p for hypertension*gender = 0.046) on BAI in Koreans, suggesting that T2DM and hypertension are each associated with a higher BAI in females than in males. In contrast, among individuals from the UK, there were no differences in the effects of T2DM (p for T2DM*gender = 0.098) and hypertension (p for hypertension*gender = 0.203) on BAI between males and females.

CONCLUSIONS

Our results highlight gender and ethnic differences as important factors in mediating the effects of CMS on brain age. Furthermore, these results suggest that ethnic- and gender-specific prevention strategies may be needed to protect against accelerated brain aging.

Association between Reduction of Muscle Mass and Faster Declines in Global Cognition among Older People: A 4-Year Prospective Cohort Study

OBJECTIVES

A few studies reported that both decrease and increase in body mass index (BMI) were associated with the development of dementia in later life. However, it is unclear what changes in body composition are associated with cognitive decline. This study investigated the longitudinal influences of changes in body composition on cognitive function among community-dwelling adults.

DESIGN, SETTING AND PARTICIPANTS

This longitudinal study included older adults aged ≥60 years without cognitive impairment who participated in National Institute for Longevity Sciences - Longitudinal Study of Aging.

MEASUREMENTS

Cognitive function was assessed using the MMSE. Body composition was measured by a dual-energy X-ray absorptiometry system. Then, BMI, fat mass index (FMI), fat-free mass index (FFMI), and muscle mass index (MMI) were calculated. The changes in body composition over 6 years (second wave to fifth wave) were calculated, and three groups were created: decreased group, decrease of >5%; stable group, change within 5%, and increased group, increase of >5%. In statistical analysis, a linear mixed model was applied by sex to investigate the influences of body composition changes on cognitive function over 4 years (fifth wave to seventh wave).

RESULTS

This study analyzed 515 participants (mean age, 67.05 years; 53.4% men). Men with decreased group in FFMI and MMI exhibited faster declines in MMSE scores than those with stable group (β [95% CI]: FFMI, -0.293 [-0.719 to -0.020]; MMI, -0.472 [-0.884 to -0.059]). In women, there was no significant association between body composition changes and cognitive functions.

CONCLUSIONS

Decrease in fat-free mass and muscle mass is associated with faster cognitive declines in men. These results suggest the importance of continuous monitoring of muscle mass to prevent cognitive decline in later life.

Associations between pituitary-ovarian hormones and cognition in recently menopausal women independent of type of hormone therapy

OBJECTIVES

To examine associations of pituitary-ovarian hormone levels with cognition before and after different formulations of hormone therapy (HT) or placebo independent of treatment group.

METHODS

Recently menopausal, healthy women were randomized to 0.45 mg/day oral conjugated equine estrogens (o-CEE, n = 109), 50 μg/day transdermal 17β (tE2, n = 107) or placebo pills and patches (n = 146); women on active treatment received oral 200 mg/day micronized progesterone for 12 days per month. Levels of estrone, 17β-estradiol, follicle stimulating hormone, luteinizing hormone, androstenedione, and testosterone were determined prior to and after 48 months of study participation. Neuropsychological testing was administered at baseline, and months 18, 36 and 48. Latent growth curve models controlling for education level, age, APOE allele status, waist circumference, and treatment examined the trajectories of each cognitive domain after accounting for the effect of hormone levels at baseline and months 18, 36 and 48. A linear multivariate mixed model examined the effect of changes in hormone levels on changes in trajectories of complex attention tasks with varying degrees of difficulty.

RESULTS

All women were adherent to treatment at month 48. Higher baseline estrone levels were associated with poorer global cognition, auditory attention and working memory, visual attention, and executive function, but not working memory. Higher levels of baseline 17β-E2 were associated with poorer cognitive performance, with marginal significance at baseline in speeded language and mental flexibility (p = 0.013). Other hormone levels were not associated with cognition. Controlling for all treatments, hormone levels at baseline and at month 48 did not have any significant correlation with cognitive trajectories over time.

SUMMARY

In healthy, recently menopausal women, baseline estrone levels were inversely associated with selected cognitive factors independent of two types of HT or placebo during 4 years of follow-up. Baseline levels of the other pituitary-ovarian hormones studied were not associated with baseline cognition, nor were changes in any hormones associated with changes in cognition during the study. The marginal association between estradiol levels and cognitive factors warrants further investigation.

CLINICALTRIALS

GOV NUMBERS

NCT00154180, NCT00623311.

Longitudinal evaluation of dehydroepiandrosterone (DHEA), its sulfated form and estradiol with cancer-related cognitive impairment in early-stage breast cancer patients receiving chemotherapy

The purpose of this study is to elucidate how patient-reported cognitive symptoms manifest from variations in hormone levels or precursors such as dehydroepiandrosterone (DHEA) and its sulfated form [collectively termed as DHEA(S)] and to investigate their association in breast cancer survivors. Levels of estradiol and DHEA(S) were compared between early-stage breast cancer patients with and without cancer-related cognitive impairment (CRCI) during adjuvant chemotherapy. Data were analyzed from 242 patients (mean age ± SD = 50.8 ± 9.2 years) who had completed FACT-Cog v.3.0, blood draws and questionnaires. Regression model was used to fit the magnitude of change in each respective biomarker levels against overall cognitive impairment status while adjusting for clinically important covariates. There was reduction in mean plasma levels of estradiol and DHEAS during and towards the end of chemotherapy (p-values < 0.001). Compared to non-impaired patients, smaller magnitude of decline was observed in DHEA(S) levels in patients reporting CRCI, with significant association between decline in DHEAS levels and acute onset of CRCI at 6 weeks from baseline (adjusted β of 0.40, p-value of 0.02). In contrast, patients reporting CRCI showed greater magnitude of decline in estradiol compared to non-impaired patients, although this was not found to be statistically significant. There was an association between magnitude of change in biomarker levels with self-reported CRCI which suggests that the hormonal pathway related to DHEAS may be implicated in acute CRCI for breast cancer survivors. Our findings help to improve biological understanding of the pathway from which DHEAS may correlate with cognitive dysfunction and its impact on cancer survivors.

Associations between cognitive function and endogenous levels of estradiol and testosterone in adults with type 2 diabetes

AIMS

To assess associations that endogenous estradiol and testosterone levels have with cognitive function in older adults with Type 2 diabetes mellitus (T2DM).

METHODS

We use data from the Look AHEAD clinical trial of behavioral weight loss. Endogenous estradiol and total testosterone levels were determined using stored serum from 996 individuals, mean age 69 years, at two times (averaging 4 years apart) during years 8-18 of follow-up. One to four standardized assessments of attention, executive function, memory, and verbal fluency were collected during this follow-up. Mixed effects models and multiple imputation were used to assess associations that estradiol and total testosterone levels had with body mass index and cognitive function.

RESULTS

Estradiol levels were not associated with cognitive function in either sex. Total testosterone levels were not associated with cognitive function in women, but greater total testosterone levels were associated with better verbal fluency in men (p < 0.001), most strongly among those carrying the APOE-e4 allele (interaction p = 0.02). The weight loss intervention left a legacy of relatively lower cognitive functioning among women, which was not mediated by current levels of sex hormones.

CONCLUSIONS

Behavioral weight loss intervention does not affect cognitive functioning through mechanisms related to estradiol or testosterone.

CLINICALTRIALS

gov Identifier: NCT00017953.

Estradiol effects on spatial memory in women

To examine the role of estradiol in hippocampal-dependent spatial memory in women, 86 female undergraduates were tested in a virtual Morris water task (VMWT), a virtual radial arm maze (VRAM), and a mental rotation task (MRT) within a single daily session. The VMWT and RAM were also administered 24 h later to examine the effects of estradiol on memory consolidation. Women on oral contraceptives (OCs) or those who were naturally cycling and exhibited low estradiol (LE) or high estradiol (HE), as determined by salivary assays, were included. At the start of day two, the HE group showed superior spatial reference memory on the VMWT relative to the LE group, as evidenced by significantly shorter distances navigating to the hidden platform. The LE group also had the poorest probe trial performance at the start of day two compared to both other groups. There were no group differences in performance on the RAM or MRT. These results provide support for estradiol's role in the consolidation of spatial reference memory in women, and emphasize the differential sensitivities of various virtual memory tasks in assessing spatial memory function in women.

Association of reproductive factors with dementia: A systematic review and dose-response meta-analyses of observational studies

BACKGROUND

Associations between endogenous estrogen exposure indicators and risk of subtypes of dementia have been unclear.

METHODS

Databases (PubMed, EMBASE and Web of Science) were searched electronically on 1st July and updated regularly until 12nd November 2021. Observational studies of English language were selected if reported an effect estimate [e.g., odds ratio (OR), rate ratio (RR) or hazard ratio (HR)] and 95% CI for the association between any exposure (age of menarche, age at menopause, reproductive period, estradiol level) and any endpoint variable [all-cause dementia, Alzheimer's disease (AD), vascular dementia (VD), cognitive impairment (CI)]. Random-effects models and dose-response meta-analyses were used to calculate estimates and to show the linear/nonlinear relationship. PROSPERO CRD42021274827.

FINDINGS

We included 22 studies (475 9764 women) in this analysis. We found no clear relationship between late menarche (≥14 vs <14 years) and dementia, CI in categorical meta-analysis compared to a J-shape relationship in dose-response meta-analyses. Later menopause (≥45 vs <45 years) was consistently associated with a lower risk of all-cause dementia (pooled RR: 0.87, 95%CI: 0.78-0.97, I²=56.0%), AD (0.67, 0.44-0.99, I²=78.3%), VD (0.87, 0.80-0.94) and CI (0.82, 0.71-0.94, I²=19.3%) in categorical meta-analysis, showing similar results in dose-response meta-analyses. An inverse relationship between longer reproductive duration (≥35 vs <35 years) and dementia was observed in dose-response meta-analysis. In addition, estradiol levels after menopause were inversely correlated with the risk of AD and CI.

INTERPRETATION

In this study, later menopause and longer reproductive period were associated with a lower risk of dementia, while the relationship for menarchal age was J-shaped. There was an inverse relationship between higher postmenopausal estrogen levels and risk of AD and CI. Longitudinal study are needed to further explore the association between life-time estrogen exposure and risk of subtypes of dementia.

FUNDING

Start-up Foundation for Scientific Research in Shandong University.

Testosterone and Cognitive Impairment or Dementia in Middle-Aged or Aging Males: Causation and Intervention, a Systematic Review and Meta-Analysis

BACKGROUND AND PURPOSE

To investigate the association between testosterone levels and the risk of dementia and to assess the effectiveness of testosterone supplement treatment in patients with cognitive impairment or dementia.

METHODS

We searched Pubmed, Cochrane Library, and EMBASE on September 30, 2019.

RESULTS

The risk factor portion of the review included 27 studies with 18 599 participants. Studies revealed inconsistent findings on the association between testosterone levels and the risk of all-cause dementia or Alzheimer disease (AD). The result from our meta-analysis showed an increased risk of all-cause dementia with decreasing total testosterone (total-T, 4572 participants, hazard ratio: 1.14, 95% CI: 1.04-1.26). Some studies also found an increased risk of AD with a lower level of total-T, free testosterone, and bioavailable testosterone. Testosterone supplement treatment may improve general cognitive function and motor response in the short term as measured by the Developmental Test of Visual-Motor Integration (mean difference [MD]: 4.4, 95% CI: 1.20-7.59) and the Mini-Mental State Examination (MD: 3.4, 95% CI: 0.83-5.97) and verbal memory as measured by story recall delay at 3 months (MD: 8.4, 95% CI: 0.49-16.3).

CONCLUSION

Lower levels of testosterone may be associated with an increased risk of all-cause dementia or AD. Testosterone supplement treatment may or may not improve general cognitive function in patients with cognitive impairment/AD.

Associations between body composition and cognitive function in an elderly Korean population: A cohort-based cross-sectional study

The prevalence of obesity as well as cognitive impairment increases with age. Previous studies showed that obesity is associated with an increased risk of cognitive impairment and dementia. Body composition changes occur as part of the aging process; therefore, the assessment of obesity in elderly populations should include body composition as well as body weight. This study investigated the relationship between body mass index (BMI), body composition, and cognitive function in a community-dwelling elderly Korean population.This cohort-based cross-sectional analysis included 2386 elderly participants aged between 70 and 84 years from the Korean Frailty and Aging Cohort Study for 2016 to 2017. To investigate the relationship between body composition and cognitive function in community-dwelling individuals, BMI and body composition, including total and trunk fat mass and fat-free mass, were measured by dual-energy X-ray absorptiometry. Fat mass index (FMI), trunk fat mass index (TFMI), and fat-free mass index (FFMI) were used to represent the body composition. A short form of the Korean version of the Consortium to Establish a Registry for Alzheimer disease was used to assess cognitive function. To evaluate the relationship between variables, simple and fully adjusted multivariable analyses were performed using generalized linear regression models.The mean ages were 76.8 years for males and 76.1 years for females. The BMI of male participants was significantly lower than that of females (23.9 ± 2.89 vs 24.7 ± 3.02 kg/m2, P < .001). Among body composition parameters, the differences in FMI (6.44 ± 1.97 vs 9.29 ± 2.3 kg/m2), TFMI (3.68 ± 1.33 vs 5.03 ± 1.43 kg/m2), and FFMI (17.4 ± 1.64 vs 15.3 ± 1.39 kg/m2) were statistically significant. In linear regression analyses, BMI, FMI, and TFMI showed significant positive correlations with mini-mental state examination in the Korean version of the CERAD assessment packet; wordlist memory, recall, and recognition; and frontal assessment battery only in males. The significant positive correlations persisted even after fully adjusting for age, education periods, location of residence, depression, marriage, annual income, presence of diabetes mellitus, dyslipidemia, and hypertension. However, no significant correlations in either sex were observed between FFMI and cognitive functions in the fully adjusted models.In this study, BMI, and fat mass-related indexes including FMI and TFMI showed a positive linear correlation with cognitive functions but not FFMI. Moreover, the findings were significant only in men. Besides the difference between sexes, the results of this study showed a more apparent correlation in fat mass than in fat-free mass that comprises body weight.

Interactions between estradiol, diabetes, and brain aging and the risk for cognitive impairment

The Women's Health Initiative Memory Study reported that older women using conjugated equine estrogens hormone therapy (HT) with or without medroxyprogesterone acetate were at increased risk for probable dementia and smaller brain volumes. These adverse effects were greatest among women who had type 2 diabetes mellitus (T2DM) at baseline or who developed the disease during follow-up. This review summarizes existing literature from randomized trials, observational studies, and preclinical studies to provide a fundamental understanding of the effects of the interaction between T2DM and HT on cognitive and metabolic health changes in brain aging.

Associations of Body Mass Index, Visceral Fat Area, Waist Circumference, and Waist-to-Hip Ratio with Cognitive Function in Western China: Results from WCHAT Study

OBJECTIVES

This study examined the relationship between cognitive performance and obesity parameters, such as body mass index (BMI), visceral fat area (VFA), waist circumference (WC), and waist-to-hip ratio (WHR) in western China.

STUDY DESIGN

A cross-sectional study.

METHODS

3914 participants, aged ≥50 years, were recruited in this study. Anthropometrics measurements, life-style factors, chronic disease comorbidities, and sleep qualities were recorded for each participant. Among the anthropometrics, BMI, WC, and WHR were assessed using standard procedures, while VFA was calculated using bioelectrical impedance analysis. Cognitive performance was estimated using the Short Portable Mental Status Questionnaire (SPMSQ). Finally, relationships between cognitive abilities and BMI, VFA, WC, and WHR were evaluated using univariate and multivariate regression analyses.

RESULTS

Cognitive decline (CD) occurred at a rate of 13.29% among the 3914 participants. A strong correlation was observed between cognitive abilities and BMI of male patients aged 50-59 yrs (OR 1.116,95% CI1.002-1.242), in the adjusted model. Alternately, WHR was shown to be significantly related to CD in females aged ≥70 years (OR 0.041, 95% CI0.002-0.671). WC was shown to have a strong association with CD in males (OR 1.023,95% CI1.003-1.024). Lastly, WHR was closely connected to CD in participants with BMI < 25 kg/m2 (OR 0.022,95% CI0.002-0.209).

CONCLUSIONS

Our findings suggest that a higher middle age BMI is associated with CD, whereas, in the elderly population, a higher WHR is related to improved cognitive performance. Further investigation is warranted to elucidate a relationship between VFA and CD.

Blood-based biomarkers in hypothalamic-pituitary axes for the risk of dementia or cognitive decline: a systematic review and meta-analysis

Blood-based biomarkers are ideal candidates for dementia prediction. This systematic review and meta-analysis aimed to evaluate longitudinal relationships of blood hormones and hormone-binding proteins in hypothalamic-pituitary (HP) axes with dementia or cognitive decline. PubMed, MEDLINE, EMBASE, PsycINFO, and BIOSIS were systematically searched from 1919 to June 2020. Fifteen types of hormones and four types of hormone-binding proteins were measured in 48 prospective studies. Increased risk of dementia or cognitive decline could be predicted by elevated blood concentrations of free-thyroxine (free-T4, RR = 1.06, p = 0.001) and sex hormone-binding globulin (SHBG, RR = 1.10, p = 0.025). Lower thyroid-stimulating hormone (TSH) levels within (RR = 1.28, p < 0.001) and below (RR = 1.27, p = 0.004) the normal range were both risky. Current evidence suggests the alterations of multiple blood molecules in HP axes, especially TSH, free-T4, and SHBG precede the incidence of dementia or cognitive decline. The underpinning etiology remains to be elucidated in the future.

Association between frailty and vitamin B12 in the older Korean population

Frailty is a common geriatric condition due to aging and defined as a decline in strength and a decrease in the physiologic ability to maintain the homeostasis. Vitamin B12 (B12), water-soluble vitamins, are a cofactor in DNA synthesis and involved in the metabolism of every cell in the human body, including the central nervous system. Demyelination neuromuscular symptoms observed in the peripheral nervous system, along with signs of significant damage to nerve fibers, often cause weakness, numbness in distal limbs, impaired balance, gait ataxia, and even physical frailty. In this cross-sectional study, we aimed to investigate the relationship between frailty and B12 level in community-dwelling Korean older adults.Using the data from the Korean Frailty and Aging Cohort Study, 2938 participants (1400 men and 1538 women) were recruited in this study. To evaluate frailty, we compared the frail group and not-frail group based on the modified Korean version of the cardiovascular health study frailty index developed by Fried. SARC-F is used to screen for sarcopenia. The short physical performance battery (SPPB) timed up and go (TUG) test and activities-specific balance confidence scale used to evaluate the physical function and fall risk of participants. B12 concentrations were classified into clinically relevant categories: insufficient (<350 pg/mL) and sufficient (≥350 pg/mL). Linear and logistic regression analyses were used to evaluate the relationship between frailty and B12 levels.The mean age of the frail group was 77.8 (standard deviation = 3.7) years, while that of the not-frail group was 76.7 (SD = 4.0); of which the frail group's mean age was significantly high. In the unadjusted model, frailty was highly prevalent in the B12 insufficient group (odds ratio = 1.298). In the model fully adjusted for demographic data and comorbidities, these associations were attenuated. The B12 sufficiency group showed better total SPPB and TUG test scores. However, they were not statistically significant in the fully adjusted model.In this cross-sectional study, low B12 increased the incidence of frailty and affected physical performance, but it does not increase the incidence of frailty when considering the confounding factors. Frailty is caused by several factors rather than 1 factor, and B12 is one of these factors.

It takes a neural village: Circuit-based approaches for estrogenic regulation of episodic memory

Cognitive behaviors, such as episodic memory formation, are complex processes involving coordinated activity in multiple brain regions. However, much of the research on hormonal regulation of cognition focuses on manipulation of one region at a time or provides a single snapshot of how a systemic treatment affects multiple brain regions without investigating how these regions might interact to mediate hormone effects. Here, we use estrogenic regulation of episodic memory as an example of how circuit-based approaches may be incorporated into future studies of hormones and cognition. We first review basic episodic memory circuitry, rapid mechanisms by which 17β-estradiol can alter circuit activity, and current knowledge about 17β-estradiol's effects on episodic memory. Next, we outline approaches that researchers can employ to consider circuit effects in their estrogen research and provide examples of how these methods have been used to examine hormonal regulation of memory and other behaviors.

Domain-specific contributions of biological sex and sex hormones to what, where and when components of episodic-like memory in adult rats

Episodic memory involves the integration and recall of discrete events that include information about what happened, where it happened and when it occurred. Episodic memory function is critical to daily life, and its dysfunction is both a first identifiable indicator and an enduring core feature of cognitive decline in ageing and in neuropsychiatric disorders including Alzheimer's disease and schizophrenia. Available evidence from human studies suggests that biological sex and sex hormones modulate episodic memory function in health and disease. However, knowledge of how this occurs is constrained by the limited availability and underutilization of validated animal models in investigating hormone impacts on episodic-like memory function. Here, adult female, adult male and gonadally manipulated adult male rats were tested on the what-where-when episodic-like memory task to determine whether rats model human sex differences in episodic memory and how the hormonal milieu impacts episodic-like memory processes in this species. These studies revealed salient ways in which rats model human sex differences in episodic memory, including a male advantage in spatial episodic memory performance. They also identified domain-specific roles for oestrogens and androgens in modulating what, where and when discriminations in male rats that were unlike those engaged in corresponding novel object recognition and novel object location tasks. These studies thus identify rats and the what-where-when task as suitable for investigating the neuroendocrine bases of episodic-like memory, and provide new information about the unique contributions that sex and sex hormones make to this complex mnemonic process.

Risk Factors Associated with Mild Cognitive Impairment among Apparently Healthy People and the Role of MicroRNAs

BACKGROUND:

Mild cognitive impairment (MCI) is a stage between the expected cognitive decline of normal ageing and the serious decline of dementia.

AIM:

To identify risk factors and role of miRNAs associated with mild cognitive impairment (MCI) among employees.

SUBJECTS AND METHOD:

A cross-sectional study was carried out on 186 employees aged between 40 and 65 years. Cognitive function was evaluated using ACEIII, MoCA, and Quick cognitive tests. Medical history and lifestyle were assessed. Family 132 & 134 miRNA expressions were assessed by real-time PCR.

RESULTS:

MCI was detected among 14 / 186 (7.5%). miRNA 132 expression was the only significant miRNAs to detect MCI with low sensitivity and specificity (70%). The logistic analysis revealed that higher miRNA132 expressions, low monthly intake of; vegetables, unroasted nuts, low education and higher ALT levels were predicting factors for MCI with AOR 1.1 (1.01-3.3), 1.2 (1.04-1.43), 0.8 (0.8-0.98), 2.7 (1.9-7.4) and 1.6 (1.1-2.3) respectively.

CONCLUSION:

MiRNAs expression showed low sensitivity and specificity in detecting MCI; only miRNA 132 might be used. Several modifiable factors seem to reduce the risk of MCI.

Aging and the Male Reproductive System

This narrative review presents an overview of current knowledge on fertility and reproductive hormone changes in aging men, the factors driving and modulating these changes, their clinical consequences, and the benefits and risks of testosterone (T) therapy. Aging is accompanied by moderate decline of gamete quality and fertility. Population mean levels show a mild total T decline, an SHBG increase, a steeper free T decline, and a moderate LH increase with important contribution of comorbidities (e.g., obesity) to these changes. Sexual symptoms and lower hematocrit are associated with low T and are partly responsive to T therapy. The relationship of serum T with body composition and metabolic health is bidirectional; limited beneficial effects of T therapy on body composition have only marginal effects on metabolic health and physical function. Skeletal changes are associated primarily with estradiol and SHBG. Cognitive decline is not consistently linked to low T and is not improved by T therapy. Although limited evidence links moderate androgen decline with depressive symptoms, T therapy has small beneficial effects on mood, depressive symptoms, and vitality in elderly patients with low T. Suboptimal T (and/or DHT) has been associated with increased risk of stroke, but not of ischemic heart disease, whereas an association with mortality probably reflects that low T is a marker of poor health. Globally, neither severity of clinical consequences attributable to low T nor the nature and magnitude of beneficial treatment effects justify the concept of some broadly applied "T replacement therapy" in older men with low T. Moreover, long-term safety of T therapy is not established.

Cognitive Impacts of Estrogen Treatment in Androgen-Deprived Males: What Needs to be Resolved

Background:

Many prostate cancer (PCa) patients are on androgen deprivation therapy (ADT) as part of their cancer treatments but ADT may lead to cognitive impairments. ADT depletes men of both androgen and estrogen. Whether estradiol supplementation can improve cognitive impairments in patients on ADT is understudied.

Objective:

To summarize data on the effects of estradiol treatment on cognitive function of androgen-deprived genetic male populations (PCa patients and male-to-female transsexuals) and castrated male animals.

Method:

Publications were identified by a literature search on PubMed and Google Scholar.

Results:

While some studies showed that estradiol improves cognitive function (most notably, spatial ability) for castrated rats, what remains uninvestigated are: 1) whether estradiol can improve cognition after long-term androgen deprivation, 2) how estradiol affects memory retention, and 3) how early vs. delayed estradiol treatment after castration influences cognition. For androgen-deprived genetic males, estradiol treatment may improve some cognitive functions (e.g., verbal and visual memory), but the findings are not consistent due to large variability in the study design between studies.

Conclusion:

Future studies are required to determine the best estradiol treatment protocol to maximize cognitive benefits for androgen-deprived genetic males. Tests that assess comparable cognitive domains in human and rodents are needed. What particularly under-investigated is how the effects of estradiol on cognitive ability intersect with other parameters; sleep, depression and physical fatigue. Such studies have clinical implications to improve the quality of life for both PCa patients on ADT as well as for male-to-female transsexuals.

Debate position: cognition and mood are not improved in men administered exogenous testosterone therapy

PURPOSE OF REVIEW

The purpose of this article is to provide an overview of the increasing evidence suggesting that exogenous testosterone therapy is not associated with improvements in cognition or mood. This article is part of a series, in this issue, in which authors are assigned opinion pieces on controversial topics pertaining to testosterone replacement.

RECENT FINDINGS

Testosterone is increasingly being prescribed. Particularly in the setting of recent data suggestive of possible cardiovascular risk associated with its use; a clear understanding of the domains of health that improve with exogenous testosterone use is important. Data on endogenous and exogenous testosterone with cognition and mood are mixed, likely partly related to methodological differences of type of testosterone, patient population, and dosing.

SUMMARY

Overall, available data are not suggestive of a clear benefit of testosterone supplementation in multiple domains of cognition and in mood. Supraphysiologic testosterone has been associated with adverse psychological outcomes, albeit not uniformly in studies.

Estrogenic regulation of memory consolidation: A look beyond the hippocampus, ovaries, and females

The potent estrogen 17β-estradiol (E2) has long been known to regulate the hippocampus and hippocampal-dependent memories in females, and research from the past decade has begun to shed light on the molecular mechanisms through which E2 mediates memory formation in females. Although E2 can also regulate hippocampal function in males, relatively little is known about how E2 influences memory formation in males, or whether sex differences in underlying mechanisms exist. This review, based on a talk given in April 2017 at the American University symposium entitled, "Sex Differences: From Neuroscience to the Clinic and Beyond", first provides an overview of the molecular mechanisms in the dorsal hippocampus through which E2 enhances memory consolidation in ovariectomized female mice. Next, newer research is described demonstrating key roles for the prefrontal cortex and de novo hippocampal E2 synthesis to the memory-enhancing effects of E2 in females. The review then discusses the effects of de novo and exogenous E2 on hippocampal memory consolidation in both sexes, and putative sex differences in the underlying molecular mechanisms through which E2 enhances memory formation. The review concludes by discussing the importance and implications of sex differences in the molecular mechanisms underlying E2-induced memory consolidation for human health.

Epidemiology of estrogen and dementia in women with Down syndrome

Several lines of investigation have shown a protective role for estrogen in Alzheimer's disease through a number of biological actions. This review examines studies of the role of estrogen-related factors in age at onset and risk for Alzheimer's disease in women with Down syndrome, a population at high risk for early onset of dementia. The studies are consistent in showing that early age at menopause and that low levels of endogenous bioavailable estradiol in postmenopausal women with Down syndrome are associated with earlier age at onset and overall risk for dementia. Polymorphisms in genes associated with estrogen receptor activity and in genes for estrogen biosynthesis affecting endogenous estrogen are related to age at onset and cumulative incidence of dementia, and may serve as biomarkers of risk. To date, no clinical trials of estrogen or hormone replacement therapy (ERT/HRT) have been published for women with Down syndrome. While findings from clinical trials of ERT or HRT for dementia have generally been negative among women in the neurotypical population, the short interval between menopause and onset of cognitive decline, together with a more positive balance between potential benefits and risks, suggests an opportunity to evaluate the efficacy of ERT/HRT for delaying or preventing dementia in this high risk population, although questions concerning the optimal formulation and timing of the hormone therapy are not yet resolved.

Cognitive sequelae of endocrine therapy in women treated for breast cancer: a meta-analysis

PURPOSE

Evidence suggests anti-estrogen endocrine therapy (ET) is associated with adverse cognitive effects; however, findings are based on small samples and vary in the cognitive abilities affected. We conducted a meta-analysis to quantitatively synthesize the evidence.

METHODS

Electronic databases were searched in November 2016. Fourteen studies totaling 911 BC patients on aromatase inhibitors (AIs) or tamoxifen (TAM) and 911 controls (i.e., non-cancer controls and BC controls not using ET) were included. Neuropsychological tests were categorized into six domains. Effect sizes were computed to compare (1) ET patients versus controls and (2) TAM patients versus AI patients.

RESULTS

In cross-sectional comparisons, ET patients performed worse than control groups on verbal learning/memory, visual learning/memory, frontal executive function, and processing speed, but did not differ on psychomotor efficiency or visuospatial function. Subgroup analyses revealed that verbal learning/memory was the only domain where ET patients performed worse than both non-cancer and BC controls. In other domains, ET patients and BC controls performed equivalently. Regarding change from pre-treatment performance, ET patients did not differ from controls on any domain. TAM and AI patients did not from one another differ overall; however, subgroup analyses indicated that TAM patients performed better than non-steroidal AI patients on several domains, but showed few performance differences relative to steroidal AI patients.

CONCLUSIONS

Verbal learning/memory was the only domain where ET patients performed worse than both non-cancer and BC controls, suggesting specific adverse effects on this domain. Additional studies assessing change from pre-treatment performance and differences between steroidal and non-steroidal AIs are warranted.

Sex, age, and sex hormones affect recall of words in a directed forgetting paradigm

During the course of serious discussion, an unexpected interruption may induce forgetting of the original topic of a conversation. Sex, age, and sex hormone levels may affect frequency and extension of forgetting. In a list-method directed forgetting paradigm, subjects have to learn two word lists. After learning list 1, subjects receive either a forget or a remember list 1 cue. When the participants had learned list 2 and completed a distraction task, they were asked to write down as many recalled items as possible, starting either with list 1 or list 2 items. In the present study, 96 naturally cycling women, 60 oral contraceptive users, 56 postmenopausal women, and 41 young men were assigned to one of these different experimental conditions. Forget-cued young subjects recall fewer list 1 items (list 1 forgetting) but more list 2 items (list 2 enhancement) compared with remember-cued subjects. However, forget-cued postmenopausal women showed reduced list 1 forgetting but enhanced list 2 retention. Remember-cued naturally cycling women recalled more list 1 items than oral contraceptive users, young men, and postmenopausal women. In forget-cued follicular women, salivary progesterone correlated positively with recalled list 2 items. Salivary 17β-estradiol did not correlate with recalled list 1 or list 2 items in either remember- or forget-cued young women. However, salivary 17β-estradiol correlated with item recall in remember-cued postmenopausal women. Our findings suggest that sex hormones do not globally modulate verbal memory or forgetting, but selectively affect cue-specific processing. © 2016 Wiley Periodicals, Inc.

Higher level of circulating estradiol is associated with lower frequency of cognitive impairment in Southeast China

BACKGROUND

Estrogen has been proved to have positive effects on the brain cognitive function. However, many clinical studies investigating the associations between cognitive functions and circulating estrogen levels in perimenopausal and postmenopausal women demonstrated controversial results.

METHOD

Circulating estradiol and follicle stimulating hormone (FSH) levels were obtained from 199 perimenopausal and postmenopausal women (mean age: 49.61 years). The cognitive function has been assessed using the Beijing version of the Montreal Cognitive Assessment.

RESULTS

Results revealed that higher estradiol levels were associated with better cognitive function (p < 0.05) both in perimenopausal and postmenopausal women and levels of FSH were unrelated to cognitive performance.

CONCLUSIONS

In perimenopausal and postmenopausal women, higher levels of circulating estradiol are associated with lower risk of cognitive impairment.

Association between low thyroid-stimulating hormone, posterior cortical atrophy and nitro-oxidative stress in elderly patients with cognitive dysfunction

INTRODUCTION

Cortical atrophy is known to be a valuable sign of cognitive decline. The purpose of this study was to assess the association between low thyroid-stimulating hormone (TSH), posterior cortical atrophy (Koedam score - KS) and nitro-oxidative stress in elderly patients.

MATERIAL AND METHODS

A study (SG) and a control group (CG), each subdivided by gender, were investigated. Subjects older than 59 years with low serum TSH level and with mild cognitive impairment were included in the SG. The CG was formed by subjects free of significant cortical atrophy and free or thyroid dysfunction. Demographic and clinical characteristics of the patients (Mini Mental State Examination, MMSE), Koedam score on cranial magnetic resonance imaging, and blood parameters (TSH, FT4, and nitric oxide - NOx) were assessed.

RESULTS

Subjects in the study group had fewer years of education above the 8th grade compared with the control group (p < 0.0001). A significantly higher percentage of subjects in the study group had a Koedam score of 2 or 3 compared with controls, who had in the majority of cases a Koedam score of zero (p < 0.02). Significantly higher NOx levels were observed when study groups of both genders were compared with corresponding controls (p < 0.001). No significant differences were observed with regard to FT4 (p > 0.70). Nitric oxide was found to be significantly associated with TSH (p < 0.03) and KS (p < 0.002) when the whole study group was considered as well as when just the non-smoker study group was investigated.

CONCLUSIONS

Our study revealed an association between subclinical thyroid hypofunction, nitro-oxidative stress, and posterior cortical atrophy as an early stage of global atrophy.

Effects of Testosterone Therapy on Cognitive Function in Aging: A Systematic Review

Endogenous testosterone in the aging man has been scrutinized extensively in regard to its effects on performance in many cognitive domains, especially verbal fluency, visuospatial and visuoperceptual abilities, memory, and executive function. Studies of testosterone supplementation have sought to identify potential cognitive improvements in men with and without baseline cognitive impairment, and have had a wide range of results. The variability in outcomes is likely related, in part, to the lack of consensus on methods for testosterone measurement and supplementation and, in part, to the disparate measures of cognitive function used in randomized controlled studies. Despite the limitations imposed by such inconsistent methods, promising associations have been found between cognition and testosterone supplementation in both eugonadal men and men with low testosterone levels, with and without baseline cognitive dysfunction. This systematic review highlights the cognitive measures used in and the outcomes of existing studies of testosterone and cognition in aging men. The review suggests that larger studies and a more standardized approach to assessment will be needed before we can fully understand and realize sustained benefits from testosterone supplementation in the elderly male population, particularly given the substantial increase in testosterone supplementation in clinical practice.

17β-Estradiol and Agonism of G-protein-Coupled Estrogen Receptor Enhance Hippocampal Memory via Different Cell-Signaling Mechanisms

The ability of 17β-estradiol (E2) to enhance hippocampal object recognition and spatial memory depends on rapid activation of extracellular signal-regulated kinase (ERK) in the dorsal hippocampus (DH). Although this activation can be mediated by the intracellular estrogen receptors ERα and ERβ, little is known about the role that the membrane estrogen receptor GPER plays in regulating ERK or E2-mediated memory formation. In this study, post-training DH infusion of the GPER agonist G-1 enhanced object recognition and spatial memory in ovariectomized female mice, whereas the GPER antagonist G-15 impaired memory, suggesting that GPER activation, like E2, promotes hippocampal memory formation. However, unlike E2, G-1 did not increase ERK phosphorylation, but instead significantly increased phosphorylation of c-Jun N-terminal kinase (JNK) in the DH. Moreover, DH infusion of the JNK inhibitor SP600125 prevented G-1 from enhancing object recognition and spatial memory, but the ERK inhibitor U0126 did not. These data suggest that GPER enhances memory via different cell-signaling mechanisms than E2. This conclusion was supported by data showing that the ability of E2 to facilitate memory and activate ERK signaling was not blocked by G-15 or SP600125, which demonstrates that the memory-enhancing effects of E2 are not dependent on JNK or GPER activation in the DH. Together, these data indicate that GPER regulates memory independently from ERα and ERβ by activating JNK signaling, rather than ERK signaling. Thus, the findings suggest that GPER in the DH may not function as an estrogen receptor to regulate object recognition and spatial memory.

SIGNIFICANCE STATEMENT

Although 17β-estradiol has long been known to regulate memory function, the molecular mechanisms underlying estrogenic memory modulation remain largely unknown. Here, we examined whether the putative membrane estrogen receptor GPER acts like the classical estrogen receptors, ERα and ERβ, to facilitate hippocampal memory in female mice. Although GPER activation did enhance object recognition and spatial memory, it did so by activating different cell-signaling mechanisms from ERα, ERβ, or 17β-estradiol. These data indicate that 17β-estradiol and GPER independently regulate hippocampal memory, and suggest that hippocampal GPER may not function as an estrogen receptor in the dorsal hippocampus. These findings are significant because they provide novel insights about the molecular mechanisms through which 17β-estradiol modulates hippocampal memory.

Hippocampal Wnt Signaling: Memory Regulation and Hormone Interactions

Wnt signaling has emerged in recent years as a major player in both nervous system development and adult synaptic plasticity. Of particular relevance to researchers studying learning and memory, Wnt signaling is critical for normal functioning of the hippocampus, a brain region that is essential for many types of memory formation and whose dysfunction is implicated in numerous neurodegenerative and psychiatric conditions. Impaired hippocampal Wnt signaling is implicated in several of these conditions, however, little is known about how Wnt signaling mediates hippocampal memory formation. This review will provide a general overview of Wnt signaling and discuss evidence demonstrating a key role for Wnt signaling in hippocampal memory formation in both normal and disease states. The regulation of Wnt signaling by ovarian sex steroid hormones will also be highlighted, given that the neuroprotection afforded by Wnt-hormone interactions may have significant implications for cognitive function in aging, neurodegenerative disease, and ischemic injury.

Trajectories of Depressive Symptoms in Older Adults and Risk of Dementia

IMPORTANCE

Depression has been identified as a risk factor for dementia. However, most studies have measured depressive symptoms at only one time point, and older adults may show different patterns of depressive symptoms over time.

OBJECTIVE

To investigate the association between trajectories of depressive symptoms and risk of dementia in older adults.

DESIGN, SETTING, AND PARTICIPANTS

This was a prospective cohort investigation of black and white community-dwelling older adults in the Health, Aging, and Body Composition study. Participants were enrolled between May 1997 and June 1998 and followed up through 2001-2002. The dates of this analysis were September 2014 to December 2015. The setting was community research centers in Memphis, Tennessee, and Pittsburgh, Pennsylvania. Trajectories of depressive symptoms were assessed from baseline to year 5. Symptoms were measured with the Center for Epidemiologic Studies Depression Scale Short Form, and trajectories were calculated using latent class growth curve analysis.

MAIN OUTCOMES AND MEASURES

Incident dementia through year 11, determined by dementia medication use, hospital records, or significant cognitive decline (≥1.5 SD race-specific decline on the Modified Mini-Mental State Examination). We examined the association between depressive symptom trajectories and dementia incidence using Cox proportional hazards regression models adjusted for demographics, health factors that differed between groups, and cognition during the depressive symptom assessment period (baseline to year 5).

RESULTS

The analytic cohort included 2488 black and white older adults with repeated depressive symptom assessments from baseline to year 5 who were free of dementia throughout that period. Their mean (SD) age at baseline was 74.0 (2.8) years, and 53.1% (n = 1322) were female. The following 3 depressive symptom trajectories were identified: consistently minimal symptoms (62.0% [n = 1542] of participants), moderate and increasing symptoms (32.2% [n = 801] of participants), and high and increasing symptoms (5.8% [n = 145] of participants). Compared with the consistently minimal trajectory, having a high and increasing depressive symptom trajectory was associated with significantly increased risk of dementia (fully adjusted hazard ratio, 1.94; 95% CI, 1.30-2.90), while the moderate and increasing trajectory was not associated with risk of dementia after full adjustment. Sensitivity analyses indicated that the high and increasing trajectory was associated with dementia incidence, while depressive symptoms at individual time points were not.

CONCLUSIONS AND RELEVANCE

Older adults with a longitudinal pattern of high and increasing depressive symptoms are at high risk for dementia. Individuals' trajectory of depressive symptoms may inform dementia risk more accurately than one-time assessment of depressive symptoms.

Endogenous sex hormones and cognitive function in older women

INTRODUCTION

We examined the association between endogenous sex hormones and both objective and subjective measures of cognitive function.

METHODS

We followed 3044 women up to 23 years in a prospective cohort study. We measured plasma levels of estrone, estrone sulfate, estradiol, androstenedione, testosterone, dehydroepiandrosterone (DHEA), and dehydroepiandrosterone sulfate (DHEA-S) in 1989-1990, conducted neuropsychologic testing in 1999-2008, and inquired about subjective cognition in 2012.

RESULTS

Overall, we observed little relation between plasma levels of hormones and either neuropsychologic test performance or subjective cognition. However, after adjustment for age and education, we observed a borderline significant association of higher levels of plasma estrone with higher scores for both overall cognition (P trend = .10) and verbal memory (P trend = .08).

DISCUSSION

There were no clear associations of endogenous hormone levels at midlife and cognition in later life, although a suggested finding of higher levels of plasma estrone associated with better cognitive function merits further research.

Endogenous sex hormones and cognitive function in the elderly

BACKGROUND

Estrogen and testosterone may influence cognitive function in the older adult, but the relationship between sex hormones and cognitive function is complex.

AIM

To examine associations of sex hormones and cognitive function among older adults ≥65 years old.

METHODS

Using a cross-sectional research design, data were collected once from 71 elderly (mean age 86.4 years). Global cognitive function and executive function were measured with standardized instruments, and saliva samples were collected for salivary estradiol and testosterone.

RESULTS

Estradiol was significantly and positively correlated with global cognitive function in men only (r = 0.54, p < 0.05). Testosterone was not significantly correlated with global cognitive function or executive function in either gender.

DISCUSSION AND CONCLUSION

Associations between sex hormones and cognitive function were mostly non-significant. However, higher estradiol was significantly correlated with better global cognitive function in men, suggesting gender-specific differences. Along with sex hormones, other comorbidity may need to be assessed together in relation to cognitive function in the elderly. Accordingly, clinicians play an important role in educating and promoting beneficial actions to preserve cognitive function.

Molecular mechanisms underlying the memory-enhancing effects of estradiol

This article is part of a Special Issue "Estradiol and cognition". Since the publication of the 1998 special issue of Hormones and Behavior on estrogens and cognition, substantial progress has been made towards understanding the molecular mechanisms through which 17β-estradiol (E2) regulates hippocampal plasticity and memory. Recent research has demonstrated that rapid effects of E2 on hippocampal cell signaling, epigenetic processes, and local protein synthesis are necessary for E2 to facilitate the consolidation of object recognition and spatial memories in ovariectomized female rodents. These effects appear to be mediated by non-classical actions of the intracellular estrogen receptors ERα and ERβ, and possibly by membrane-bound ERs such as the G-protein-coupled estrogen receptor (GPER). New findings also suggest a key role of hippocampally-synthesized E2 in regulating hippocampal memory formation. The present review discusses these findings in detail and suggests avenues for future study.

Postmenopausal hormone therapy, type 2 diabetes mellitus, and brain volumes

OBJECTIVE

To examine whether the effect of postmenopausal hormone therapy (HT) on brain volumes in women aged 65-79 years differs depending on type 2 diabetes status during postintervention follow-up of a randomized controlled clinical trial.

METHODS

The Women's Health Initiative randomized clinical trials assigned women to HT (0.625 mg/day conjugated equine estrogens with or without 2.5 mg/day medroxyprogesterone acetate) or placebo for an average of 5.6 years. A total of 1,402 trial participants underwent brain MRI 2.4 years after the trials; these were repeated in 699 women 4.7 years later. General linear models were used to assess the interaction between diabetes status and HT assignment on brain volumes.

RESULTS

Women with diabetes at baseline or during follow-up who had been assigned to HT compared to placebo had mean decrement in total brain volume of -18.6 mL (95% confidence interval [CI] -29.6, -7.6). For women without diabetes, this mean decrement was -0.4 (95% CI -3.8, 3.0) (interaction p=0.002). This interaction was evident for total gray matter (p<0.001) and hippocampal (p=0.006) volumes. It was not evident for changes in brain volumes over follow-up or for ischemic lesion volumes and was not influenced by diabetes duration or oral medications.

CONCLUSIONS

For women aged 65 years or older who are at increased risk for brain atrophy due to type 2 diabetes, prescription of postmenopausal HT is associated with lower gray matter (total and hippocampal) volumes. Interactions with diabetes and insulin resistance may explain divergent findings on how estrogen influences brain volume among older women.

Cognitive resilience to apolipoprotein E ε4: contributing factors in black and white older adults

IMPORTANCE

Apolipoprotein E (APOE) ε4 is an established risk factor for cognitive decline and the development of dementia, but other factors may help to minimize its effects.

OBJECTIVE

Using APOE ε4 as an indicator of high risk, we investigated factors associated with cognitive resilience among black and white older adults who are APOE ε4 carriers.

DESIGN, SETTING, AND PARTICIPANTS

Participants included 2487 community-dwelling older (aged 69-80 years at baseline) black and white adults examined at 2 community clinics in the prospective cohort Health, Aging, and Body Composition (Health ABC) study. The baseline visits occurred from May 1997 through June 1998. Our primary analytic cohort consisted of 670 APOE ε4 carriers (329 black and 341 white participants) who were free of cognitive impairment at baseline and underwent repeated cognitive testing during an 11-year follow-up (through 2008) using the Modified Mini-Mental State Examination.

MAIN OUTCOMES AND MEASURES

We stratified all analyses by race. Using the Modified Mini-Mental State Examination scores, we assessed normative cognitive change in the entire cohort (n = 2487) and classified the APOE ε4 carriers as being cognitively resilient vs nonresilient by comparing their cognitive trajectories with those of the entire cohort. We then conducted bivariate analyses and multivariable random forest and logistic regression analyses to explore factors predictive of cognitive resilience in APOE ε4 carriers.

RESULTS

Among white APOE ε4 carriers, the strongest predictors of cognitive resilience were, in relative order of importance, no recent negative life events, a higher literacy level, advanced age, a higher educational level, and more time spent reading. Among black APOE ε4 carriers, the strongest predictors of cognitive resilience were, in relative order of importance, a higher literacy level, a higher educational level, female sex, and the absence of diabetes mellitus. In follow-up logistic regression models, higher literacy level (adjusted odds ratio [OR], 9.50 [95% CI, 2.67-60.89]), a higher educational level (adjusted OR for college graduate vs less than high school, 3.81 [95% CI, 1.13-17.56]), and age (adjusted OR for 73-76 vs 69-72 years, 2.01 [95% CI, 1.13-3.63]) had significant independent effects in predicting cognitive resilience among white APOE ε4 carriers. Among black APOE ε4 carriers, a higher literacy level (adjusted OR, 2.27 [95% CI, 1.29-4.06]) and a higher educational level (adjusted OR for high school graduate/some college vs less than high school, 2.86 [95% CI, 1.54-5.49]; adjusted OR for college graduate vs less than high school, 2.52 [95% CI, 1.14-5.62]) had significant independent effects in predicting cognitive resilience.

CONCLUSIONS AND RELEVANCE

Although APOE ε4 carriers are at high risk for cognitive decline, our findings suggest possible intervention targets, including the enhancement of cognitive reserve and improvement of other psychosocial and health factors, to promote cognitive resilience among black and white APOE ε4 carriers.

[Gender and the effects of steroid hormones in the central nervous system]

Degenerative diseases of the central nervous system, the incidence and prevalence of which vary between men and women, often manifest in the hippocampus. Neurosteroids are hormones that are synthesized in the CNS, and it is here that they exert their influence. Estrogen and testosterone are examples of neurosteroid hormones. In the hippocampus, an area of the brain closely associated with learning and memory, the local synthesis of estrogen in females, but not in males, is essential for the plasticity and stability of the synapses. The inhibition of estrogen synthesis in the female hippocampus causes a reduction in long-term potentiation (LTP), an electrophysiological parameter of learning and memory, thus resulting in a significant loss of synapses. In light of this, the fact that estrogen has been attributed with many neuroprotective functions in degenerative diseases of the CNS suggests that therapeutic concepts involving the use of estrogen are possibly only effective in women, but not in men. These findings similarly provide a basis for explaining the gender dimorphism that has been found in certain degenerative illnesses of the CNS.

DHEA and cognitive function in the elderly

The adrenal prohormone dehydroepiandrosterone (DHEA) and its sulphate conjugate (DHEAS) steadily decrease with age by 10% per decade reaching a nadir after the age of 80. Both DHEA and DHEAS (DHEA/S) exert many biological activities in different tissues and organs. In particular, DHEA and DHEAS are produced de novo in the brain, hence their classification as neurosteroids. In humans, the brain-to-plasma ratios for DHEA and DHEAS are 4-6.5 and 8.5, respectively, indicating a specific neuroendocrine role for these hormones. DHEA/S stimulates neurite growth, neurogenesis and neuronal survival, apoptosis, catecholamine synthesis and secretion. Together with antioxidant, anti-inflammatory and anti-glucocorticoid properties, it has been hypothesized a neuroprotective effect for DHEA/S. We conducted an accurate research of the literature using PubMed. In the period of time between 1994 and 2013, we selected the observational human studies testing the relationship between DHEA/S and cognitive function in both sexes. The studies are presented according to the cross-sectional and longitudinal design and to the positive or neutral effects on different domains of cognitive function. We also analysed the Clinical Trials, available in the literature, having cognitive domains as the main or secondary outcome. Although the cross-sectional evidence of a positive association between DHEA/S and cognitive function, longitudinal studies and RCTs using DHEA oral treatment (50mg/day) in normal or demented adult-older subjects, have produced conflicting and inconsistent results. In summary, the current data do not provide clear evidence for the usefulness of DHEA treatment to improve cognitive function in adult-older subjects. This article is part of a Special Issue entitled 'Essential role of DHEA'.

The utility and dynamics of salivary sex hormone measurements in the National Social Life, Health, and Aging Project, Wave 2

OBJECTIVES

Sex hormones affect physical, mental, and social health, yet their role in mediating social effects on aging is understudied. To facilitate such analyses with the National Social Life, Health & Aging Project Wave 2, we summarize the conceptual background, collection protocols, laboratory assays, and data analysis strategies for biologically active (free) levels of testosterone, estradiol, progesterone, and dehydroepiandrosterone (DHEA).

METHOD

Saliva from passive drool was collected from returning Wave 1 respondents and non-respondents as well as their partners during an in-home interview. Specimens were frozen and sent to Dresden LabService GmbH for duplicate assays of biologically active steroids using identical assay kits from National Social Life, Health, and Aging Project (NSHAP) Wave 1 (SaliCap, Catalog No. RE69995). Overall, 2,772 testosterone, 2,504 estradiol, 2,714 progesterone, and 2,800 DHEA measurements are publically available for Wave 2 analyses. Through a series of weighted linear regressions, all 4 steroids are compared by gender and age and to Wave 1 measurements.

RESULTS

Men had higher levels of both free testosterone and progesterone than women; women and men had the same levels of estradiol and DHEA. Both free testosterone and DHEA decreased with age. We also found significant wave effects for all 4 sex hormones.

CONCLUSION

NSHAP Waves 1 and 2 are the first U.S. probability sample studies to measure these 4 salivary sex hormones simultaneously, providing individual profiles 5 years apart. Wave 2 data demonstrate differences by gender and trends by age that are similar to those found in other saliva-based and serum-based studies of free steroid levels. The differences between waves arising from the change in assay laboratory need to be adjusted in future longitudinal analyses using NSHAP Wave 1 and Wave 2 steroid data.

Epigenetic regulation of estrogen-dependent memory

Hippocampal memory formation is highly regulated by post-translational histone modifications and DNA methylation. Accordingly, these epigenetic processes play a major role in the effects of modulatory factors, such as sex steroid hormones, on hippocampal memory. Our laboratory recently demonstrated that the ability of the potent estrogen 17β-estradiol (E2) to enhance hippocampal-dependent novel object recognition memory in ovariectomized female mice requires ERK-dependent histone H3 acetylation and DNA methylation in the dorsal hippocampus. Although these data provide valuable insight into the chromatin modifications that mediate the memory-enhancing effects of E2, epigenetic regulation of gene expression is enormously complex. Therefore, more research is needed to fully understand how E2 and other hormones employ epigenetic alterations to shape behavior. This review discusses the epigenetic alterations shown thus far to regulate hippocampal memory, briefly reviews the effects of E2 on hippocampal function, and describes in detail our work on epigenetic regulation of estrogenic memory enhancement.

17β-Estradiol regulates histone alterations associated with memory consolidation and increases Bdnf promoter acetylation in middle-aged female mice

Histone acetylation is essential for hippocampal memory formation in young adult rodents. Although dysfunctional histone acetylation has been associated with age-related memory decline in male rodents, little is known about whether histone acetylation is altered by aging in female rodents. In young female mice, the ability of 17β-estradiol (E₂) to enhance object recognition memory consolidation requires histone H3 acetylation in the dorsal hippocampus. However, the extent to which histone acetylation is regulated by E₂ in middle-aged females is unknown. The mnemonic benefits of E₂ in aging females appear to be greatest in middle age, and so pinpointing the molecular mechanisms through which E₂ enhances memory at this age could lead to the development of safer and more effective treatments for maintaining memory function without the side effects of current therapies. Here, we show that dorsal hippocampal infusion of E₂ rapidly enhanced object recognition and spatial memory, and increased histone H3 acetylation in the dorsal hippocampus, while also significantly reducing levels of histone deacetylase (HDAC2 and HDAC3) proteins. E₂ specifically increased histone H3 acetylation at Bdnf promoters pII and pIV in the dorsal hippocampus of both young and middle-aged mice, despite age-related decreases in pI and pIV acetylation. Furthermore, levels of mature BDNF and pro-BDNF proteins in the dorsal hippocampus were increased by E₂ in middle-aged females. Together, these data suggest that the middle-aged female dorsal hippocampus remains epigenetically responsive to E₂, and that E₂ may enhance memory in middle-aged females via epigenetic regulation of Bdnf.

Regulation of object recognition and object placement by ovarian sex steroid hormones

The ovarian hormones 17β-estradiol (E2) and progesterone (P4) are potent modulators of hippocampal memory formation. Both hormones have been demonstrated to enhance hippocampal memory by regulating the cellular and molecular mechanisms thought to underlie memory formation. Behavioral neuroendocrinologists have increasingly used the object recognition and object placement (object location) tasks to investigate the role of E2 and P4 in regulating hippocampal memory formation in rodents. These one-trial learning tasks are ideal for studying acute effects of hormone treatments on different phases of memory because they can be administered during acquisition (pre-training), consolidation (post-training), or retrieval (pre-testing). This review synthesizes the rodent literature testing the effects of E2 and P4 on object recognition (OR) and object placement (OP), and the molecular mechanisms in the hippocampus supporting memory formation in these tasks. Some general trends emerge from the data. Among gonadally intact females, object memory tends to be best when E2 and P4 levels are elevated during the estrous cycle, pregnancy, and in middle age. In ovariectomized females, E2 given before or immediately after testing generally enhances OR and OP in young and middle-aged rats and mice, although effects are mixed in aged rodents. Effects of E2 treatment on OR and OP memory consolidation can be mediated by both classical estrogen receptors (ERα and ERβ), and depend on glutamate receptors (NMDA, mGluR1) and activation of numerous cell signaling cascades (e.g., ERK, PI3K/Akt, mTOR) and epigenetic processes (e.g., histone acetylation, DNA methylation). Acute P4 treatment given immediately after training also enhances OR and OP in young and middle-aged ovariectomized females by activating similar cell signaling pathways as E2 (e.g., ERK, mTOR). The few studies that have administered both hormones in combination suggest that treatment can enhance OR and OP, but that effects are highly dependent on factors such as dose and timing of administration. In addition to providing more detail on these general conclusions, this review will discuss directions for future avenues of research into the hormonal regulation of object memory.

Older adults with limited literacy are at increased risk for likely dementia

BACKGROUND

Low literacy is common among the elderly and possibly more reflective of educational attainment than years of school completed. We examined the association between literacy and risk of likely dementia in older adults.

METHODS

Participants were 2,458 black and white elders (aged 71-82) from the Health, Aging and Body Composition study, who completed the Rapid Estimate of Adult Literacy in Medicine and were followed for 8 years. Participants were free of dementia at baseline; incidence of likely dementia was defined by hospital records, prescription for dementia medication, or decline in Modified Mini-Mental State Examination score. We conducted Cox proportional hazard models to evaluate the association between literacy and incidence of likely dementia. Demographics, education, income, comorbidities, lifestyle variables, and apolipoprotein E (APOE) ε4 status were included in adjusted analyses.

RESULTS

Twenty-three percent of participants had limited literacy (<9th-grade level). Limited literacy, as opposed to adequate literacy (≥9th-grade level), was associated with greater incidence of likely dementia (25.5% vs17.0%; unadjusted hazard ratio [HR] = 1.75, 95% confidence interval 1.44-2.13); this association remained significant after adjustment. There was a trend for an interaction between literacy and APOE ε4 status (p = .07); the association between limited literacy and greater incidence of likely dementia was strong among ε4 noncarriers (unadjusted HR = 1.85) but nonsignificant among ε4 carriers (unadjusted HR = 1.25).

CONCLUSIONS

Limited literacy is an important risk factor for likely dementia, especially among APOE ε4-negative older adults, and may prove fruitful to target in interventions aimed at reducing dementia risk.

Predictors of memory performance among Taiwanese postmenopausal women with heart failure

BACKGROUND

There are no studies describing the nature of memory deficits among women with heart failure (HF).

OBJECTIVES

The aims of this study were to examine memory performance among Taiwanese women with HF compared with age- and education-matched healthy women, and to evaluate factors that explain memory performance in women with HF.

METHODS AND RESULTS

Seventy-six women with HF and 64 healthy women were recruited in Taiwan. Women completed working, verbal, and visual memory tests; HF severity was collected from the medical records. Women with HF performed significantly worse than healthy women on tests of working memory and verbal memory. Among women with HF, older age explained poorer working memory, and older age, higher HF severity, more comorbidities, and systolic HF explained poorer verbal memory. Menopausal symptoms were not associated with memory performance.

CONCLUSIONS

Results of the study validate findings of memory loss in HF patients from the United States and Europe in a culturally different sample of women. Working memory and verbal memory were worse in Taiwanese women with HF compared with healthy participants. Studies are needed to determine mechanisms of memory deficits in these women and develop interventions to improve memory.

The demographic and medical correlates of plasma aβ40 and aβ42

Plasma amyloid β-42 (Aβ42) and Aβ42/Aβ40 are increasingly recognized as biomarkers for dementia, with low levels indicating increased risk. Little is known about the demographic and medical correlates of plasma Aβ40 or Aβ42. In 997 community-dwelling, nondemented older adults from the Health, Aging, and Body Composition Study, we determined the cross-sectional association between a wide range of demographic and medical variables with Aβ40 and Aβ42. In multivariate stepwise linear regression models, Aβ40 was significantly associated with race (β=-14.70, F=22.01, P<0.0001), age (β=1.34, F=6.39, P=0.01), creatinine (β=52.91, F=151.77, P<0.0001), and the serum brain-derived neurotrophic factor (β=-0.0004, F=7.34, P=0.007); Aβ42 was significantly associated with race (β=-3.72, F=30.83, P<0.0001), sex (β=1.39, F=4.32, P=0.04), education (β=1.50, F=4.78, P=0.03), apolipoprotein E e4 genotype (β=-2.82, F=16.57, P<0.0001), and creatinine (β=9.32, F=120.09, P<0.0001). These correlates should be considered as potential confounders in future studies investigating plasma Aβ as a biomarker of dementia. Understanding fully how these correlates mediate or modify the association between plasma Aβ and dementia will be a fundamental step in determining the biological pathways through which plasma Aβ40 and Aβ42 are associated with dementia, and in determining their full potential as biomarkers.

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.

Cognition, mood, and physiological concentrations of sex hormones in the early and late postmenopause

Variations in the hormonal milieu after menopause may influence neural processes concerned with cognition, cognitive aging, and mood, but findings are inconsistent. In particular, cognitive effects of estradiol may vary with time since menopause, but this prediction has not been assessed directly using serum hormone concentrations. We studied 643 healthy postmenopausal women not using hormone therapy who were recruited into early (<6 y after menopause) and late (10+ y after menopause) groups. Women were administered a comprehensive neuropsychological battery and assessed with the Center for Epidemiologic Studies Depression Scale. They provided serum for free estradiol, estrone, progesterone, free testosterone, and sex hormone binding globulin measurements. Cognitive outcomes were standardized composite measures of verbal episodic memory, executive functions, and global cognition. Covariate-adjusted linear regression analyses were conducted for each hormone separately and after adjustment for other hormone levels. Endogenous sex steroid levels were unassociated with cognitive composites, but sex hormone binding globulin was positively associated with verbal memory. Results for early and late groups did not differ significantly, although progesterone concentrations were significantly positively associated with verbal memory and global cognition in early group women. Hormone concentrations were not significantly related to mood. Results fail to support the hypothesis that temporal proximity to menopause modifies the relation between endogenous serum levels of estradiol and verbal memory, executive functions, or global cognition. Physiological variations in endogenous postmenopausal levels of sex steroid hormones are not substantially related to these aspects of cognition or mood; positive associations for progesterone and sex hormone binding globulin merit additional study.