Meta-analyses of the effect of hormone treatment on cognitive function in postmenopausal women

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

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

Systematic review and meta-analysis of the effects of menopause hormone therapy on cognition

Introduction

Despite evidence from preclinical studies suggesting estrogen's neuroprotective effects, the use of menopausal hormone therapy (MHT) to support cognitive function remains controversial.

Methods

We used random-effect meta-analysis and multi-level meta-regression to derive pooled standardized mean difference (SMD) and 95% confidence intervals (C.I.) from 34 randomized controlled trials, including 14,914 treated and 12,679 placebo participants.

Results

Associations between MHT and cognitive function in some domains and tests of interest varied by formulation and treatment timing. While MHT had no overall effects on cognitive domain scores, treatment for surgical menopause, mostly estrogen-only therapy, improved global cognition (SMD=1.575, 95% CI 0.228, 2.921; P=0.043) compared to placebo. When initiated specifically in midlife or close to menopause onset, estrogen therapy was associated with improved verbal memory (SMD=0.394, 95% CI 0.014, 0.774; P=0.046), while late-life initiation had no effects. Overall, estrogen-progestogen therapy for spontaneous menopause was associated with a decline in Mini Mental State Exam (MMSE) scores as compared to placebo, with most studies administering treatment in a late-life population (SMD=-1.853, 95% CI -2.974, -0.733; P = 0.030). In analysis of timing of initiation, estrogen-progestogen therapy had no significant effects in midlife but was associated with improved verbal memory in late-life (P = 0.049). Duration of treatment >1 year was associated with worsening in visual memory as compared to shorter duration. Analysis of individual cognitive tests yielded more variable results of positive and negative effects associated with MHT.

Discussion

These findings suggest time-dependent effects of MHT on certain aspects of cognition, with variations based on formulation and timing of initiation, underscoring the need for further research with larger samples and more homogeneous study designs.

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

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

Hormone replacement therapy for postmenopausal atherosclerosis is offset by late age iron deposition

Postmenopausal atherosclerosis (AS) has been attributed to estrogen deficiency. However, the beneficial effect of hormone replacement therapy (HRT) is lost in late postmenopausal women with atherogenesis. We asked whether aging-related iron accumulation affects estrogen receptor α (ERα) expression, thus explaining HRT inefficacy. A negative correlation has been observed between aging-related systemic iron deposition and ERα expression in postmenopausal AS patients. In an ovariectomized Apoe-/- mouse model, estradiol treatment had contrasting effects on ERα expression in early versus late postmenopausal mice. ERα expression was inhibited by iron treatment in cell culture and iron-overloaded mice. Combined treatment with estradiol and iron further decreased ERα expression, and the latter effect was mediated by iron-regulated E3 ligase Mdm2. In line with these observations, cellular cholesterol efflux was reduced, and endothelial homeostasis was disrupted. Consequently, AS was aggravated. Accordingly, systemic iron chelation attenuated estradiol-triggered progressive AS in late postmenopausal mice. Thus, iron and estradiol together downregulate ERα through Mdm2-mediated proteolysis, providing a potential explanation for failures of HRT in late postmenopausal subjects with aging-related iron accumulation. This study suggests that immediate HRT after menopause, along with appropriate iron chelation, might provide benefits from AS.

[Menopause hormone therapy and cognition. Postmenopausal women management: CNGOF and GEMVi clinical practice guidelines]

The results of the WHI, which reported a doubling of the risk of Alzheimer's disease (AD) and a decline in cognitive function in women who were given menopause hormone therapy (MHT), have raised concerns on the deleterious impact of MHT on the central nervous system. Such as for the cardiovascular system, the very late age of initiation of treatment and the nature of the molecules have led to conclusions that cannot be extended to women in their fifties, at the onset of their menopause which is the usual age of MHT initiation. The molecules, which are used in France, 17-beta estradiol and natural progesterone (or its isomer, dydrogesterone) are very different from the equine conjugated estrogens and medroxyprogesterone acetate used in the WHI. It can now be stated that if MHT is started within the window of opportunity (i.e. before the age of 60 or within the first 10years after the beginning of menopause) no deleterious effect on cognition is observed. Moreover, cognition remains relatively stable at the beginning of menopause since the cognitive reserve as well as the different compensation circuits allow compensation for estrogen deficiency. This does not in any way prejudge a possible positive effect of MHT on AD, which is very difficult to demonstrate, as the age of onset of this dementia is very late, 20 or 30years after the initiation of treatment.

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

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

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

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

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

Cognitive effects of adjuvant endocrine therapy in older women treated for early-stage breast cancer: a 1-year longitudinal study

PURPOSE

Evidence suggests endocrine therapy (ET) for breast cancer (BC) has adverse cognitive effects, but its specific effects on older women are unknown. This is despite the fact that older women are at increased risk of both breast cancer (BC) and cognitive decline relative to younger women. This study prospectively examined the cognitive effects of ET in a cohort of older BC patients. Our primary outcome measure was change in verbal memory, the cognitive domain most consistently affected by estrogen deprivation.

METHODS

Forty-two chemotherapy-naïve women age 60+, without dementia and recently diagnosed with hormone receptor-positive BC, completed neuropsychological tests at the time of ET initiation and after 1 year of treatment. Change in age-standardized verbal memory performance was examined using paired t tests. To assess a broader range of potential cognitive effects, we also examined changes in visual memory, processing speed, frontal executive function, and perceptual reasoning.

RESULTS

Participants exhibited significant decline from baseline to 1 year in verbal memory (p = 0.01). This decline was small to moderate in effect size (d = - 0.40). Performance on other domains did not change significantly over the year (all p > 0.05).

CONCLUSIONS

Our findings suggest potentially detrimental effects of ET on verbal memory in older women after just 1 year of treatment. Given that ET is prescribed for courses of 5 to 10 years, additional studies examining longer-term effects of treatment in older women are critical.

Critical window hypothesis of hormone therapy and cognition: a scientific update on clinical studies

OBJECTIVE

The critical window hypothesis of hormone therapy (HT) and cognitive function states that the effects of HT depend on timing of initiation with respect to age, the menopausal transition, or both, and that optimal effects are evident with early initiation. This article reviews clinical studies that bear on this hypothesis.

METHODS

Recognizing that the typical pattern of HT use is early HT initiation, this review describes findings from observational studies of ever use of HT and observational studies that looked specifically at the timing of HT on Alzheimer's disease (AD) and cognitive test performance. Randomized trials of HT and verbal memory are discussed, and neuroimaging studies bearing on the hypothesis are reviewed.

RESULTS

Observational data suggest that HT generally reduces the risk of AD. Three of three observational studies that specifically examined the timing of initiation in relation to AD risk each provide support for the window, whereas three of five observational studies of HT timing and cognitive test performance do. Randomized clinical trials of estrogen therapy in younger women find support for the hypothesis. Conjugated equine estrogens/medroxyprogesterone acetate increases risks regardless of timing. Little is known about the cognitive effects of other combination HT formulations.

CONCLUSIONS

A definitive trial to test the critical window hypothesis is not feasible. Evidence drawn from other sources provides initial support for the hypothesis. Although these findings are relevant to women who use HT to treat vasomotor symptoms, HT is currently not indicated for the treatment of cognitive complaints or for dementia prevention.

Are optimal levels of testosterone associated with better cognitive function in healthy older women and men?

BACKGROUND

Sex steroids can positively affect the brain and from this it would follow that high levels of sex steroids could be associated with better cognitive function in older men and women.

METHODS

This Healthy Ageing Study sample comprised of 521 older participants (51% women) without dementia at baseline, with an age range from 64 to 94 years. Testosterone and sex hormone binding globulin were measured using the automated Immulite 2000 and analyzed in association with baseline memory, global cognitive function and decline (assessed using the Mini-Mental Status Examination or MMSE) and controlling for potential confounds such as age, education, vascular disease, smoking, diabetes, thyroid function, and body mass index.

RESULTS

In healthy older men and women, optimal levels of testosterone were associated with better MMSE scores at baseline. Follow-up analyses indicated that in men, low testosterone levels (OR=.94, 95% CI=.88 to 1.00) were a risk factor for a sharp cognitive decline after 2 years, perhaps indicative of dementia. Associations were independent of covariates and baseline MMSE. Conversely, women at risk for a sharp drop in cognitive function showed some evidence for higher calculated free testosterone levels at baseline.

CONCLUSIONS

Results replicate earlier cross-sectional findings that high levels of sex steroids are not associated with better cognitive function in older people. In men, age accelerated endocrinological change could be associated with dementia pathology.

GENERAL SIGNIFICANCE

These data do not support increasing testosterone levels to prevent cognitive decline in men and women over 65 years of age.

Hormone replacement therapy to maintain cognitive function in women with dementia

BACKGROUND

As estrogens have been shown to have several potentially beneficial effects on the central nervous system, it is biologically plausible that maintaining high levels of estrogens in postmenopausal women by means of estrogen replacement therapy (ERT) could be protective against cognitive decline in women with Alzheimer's disease (AD) or other dementia syndromes.

OBJECTIVES

To investigate the effects of ERT (estrogens only) or HRT (estrogens combined with a progestagen) compared with placebo in randomized controlled trials (RCTs) on cognitive function of postmenopausal women with dementia.

SEARCH STRATEGY

The Cochrane Dementia and Cognitive Improvement Group Specialized Register, which contains records from many medical databases, The Cochrane Library, EMBASE, MEDLINE, CINAHL, PsycINFO and LILACS were searched on 7 November 2007 using the terms ORT, PORT, ERT, HRT, estrogen*, oestrogen* and progesterone*.

SELECTION CRITERIA

All double-blind randomized controlled trials (RCTs) into the effect of ERT or HRT for cognitive function with a treatment period of at least two weeks in postmenopausal women with AD or other types of dementia.

DATA COLLECTION AND ANALYSIS

Abstracts of the references retrieved by the searches were read by two reviewers (EH and KY) independently in order to discard those that were clearly not eligible for inclusion. The two reviewers studied the full text of the remaining references and independently selected studies for inclusion. Any disparity in the ensuing lists was resolved by discussion with all reviewers in order to arrive at the final list of included studies. The selection criteria ensured that the blinding and randomization of the included studies was adequate. The two reviewers also assessed the quality of other aspects of the included trials. One reviewer (EH) extracted the data from the studies, but was aided and checked by JB from Cochrane.

MAIN RESULTS

A total of seven trials including 351 women with AD were analysed. Because different drugs were used at different studies it was not possible to combine more than two studies in any analysis.On a clinical global rating, clinicians scored patients taking CEE as significantly worse compared with the placebo group on the Clinical Dementia Rating scale after 12 months (overall WMD = 0.35, 95% CI = 0.01 to 0.69, z = 1.99, P < 0.05).Patients taking CEE had a worse performance on the delayed recall of the Paragraph Test (overall WMD = -0.45, 95% CI = -0.79 to -0.11, z = 2.60, P < 0.01) after one month than those taking placebo. They had a worse performance on Finger Tapping after 12 months (WMD = -3.90, 95% CI = -7.85 to 0.05, z = 1.93, P < 0.05).Limited positive effects were found for the lower dosage of CEE (0.625 mg/day) which showed a significant improvement in MMSE score only when assessed at two months, and disappeared after correction for multiple testing. No significant effects for MMSE were found at longer end points (3, 6 and 12 months of treatment). With a dosage of 1.25 mg/d CEE, short-term significant effects were found for Trial-Making test B at one month and Digit Span backward at four months. After two months of transdermal diestradiol (E2) treatment, a highly significant effect was observed for the word recall test (WMD = 6.50, 95% CI = 4.04 to 8.96, z = 5.19, P < 0.0001). No other significant effects were found for other outcomes measured.

AUTHORS' CONCLUSIONS

Currently, HRT or ERT for cognitive improvement or maintenance is not indicated for women with AD.

WHI and WHIMS follow-up and human studies of soy isoflavones on cognition

Recent follow-up analyses of the previous findings from the Women's Health Initiative and the Women's Health Initiative Memory Study confirmed some health benefits of estrogen-containing hormone therapy (HT) in women within 10 years from the onset of menopause. However, the potential risks associated with long-term administration of HT, such as breast cancer and stroke, remain a concern for therapy recipients, underlying the need for an alternative treatment that is functionally equivalent but with a greater safety profile. Owing to their structural and functional resemblance to mammalian estrogens and lack of evident adverse effects, research interest in plant-derived phytoestrogens has increased in the past decade. While multiple health-promoting benefits of phytoestrogens have been proposed from basic science, the clinical data remain inconclusive. This review provides a comparative analysis of human studies on the effects of soy-based isoflavones on cognition. Of the eight studies published in 2000-2007, seven were conducted in postmenopausal women, four of which revealed a positive impact of isoflavones on cognitive function. Multiple factors could have contributed to the discrepant outcomes across studies, such as variation in the composition of phytoestrogen interventions and the heterogeneous characteristics of the study population. Thus, a well-designed clinical study based on a standardized stable formulation in a well-characterized study population is required in order to reach a clinical consensus. A formulation composed of select estrogen receptor beta-selective phytoestrogens with a rationally designed composition would avoid the potential antagonism present in a mixture and thus enhance therapeutic efficacy. In addition, inclusion of equol in a study formulation offers a potential synergistic effect from equol in both equol-producing and nonproducing individuals, as well as added benefits for men. With respect to the design of study population, a clinically consistent effect could potentially be achieved by stratifying populations based on genotype, age, hormonal history and even diets. Development of an effective phytoestrogen formulation would benefit both women and men to prevent or treat hormone-dependent conditions and, most of all, to improve neurological health and reduce the risk of Alzheimer's disease.