Estrogen replacement therapy may protect against intellectual decline in postmenopausal women

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.

Systematic review and meta-analysis of the effects of menopause hormone therapy on risk of Alzheimer's disease and dementia

Introduction

Despite a large preclinical literature demonstrating neuroprotective effects of estrogen, use of menopausal hormone therapy (HT) for Alzheimer's disease (AD) risk reduction has been controversial. Herein, we conducted a systematic review and meta-analysis of HT effects on AD and dementia risk.

Methods

Our systematic search yielded 6 RCT reports (21,065 treated and 20,997 placebo participants) and 45 observational reports (768,866 patient cases and 5.5 million controls). We used fixed and random effect meta-analysis to derive pooled relative risk (RR) and 95% confidence intervals (C.I.) from these studies.

Results

Randomized controlled trials conducted in postmenopausal women ages 65 and older show an increased risk of dementia with HT use compared with placebo [RR = 1.38, 95% C.I. 1.16-1.64, p < 0.001], driven by estrogen-plus-progestogen therapy (EPT) [RR = 1.64, 95% C.I. 1.20-2.25, p = 0.002] and no significant effects of estrogen-only therapy (ET) [RR = 1.19, 95% C.I. 0.92-1.54, p = 0.18]. Conversely, observational studies indicate a reduced risk of AD [RR = 0.78, 95% C.I. 0.64-0.95, p = 0.013] and all-cause dementia [RR = .81, 95% C.I. 0.70-0.94, p = 0.007] with HT use, with protective effects noted with ET [RR = 0.86, 95% C.I. 0.77-0.95, p = 0.002] but not with EPT [RR = 0.910, 95% C.I. 0.775-1.069, p = 0.251]. Stratified analysis of pooled estimates indicates a 32% reduced risk of dementia with midlife ET [RR = 0.685, 95% C.I. 0.513-0.915, p = 0.010] and non-significant reductions with midlife EPT [RR = 0.775, 95% C.I. 0.474-1.266, p = 0.309]. Late-life HT use was associated with increased risk, albeit not significant [EPT: RR = 1.323, 95% C.I. 0.979-1.789, p = 0.069; ET: RR = 1.066, 95% C.I. 0.996-1.140, p = 0.066].

Discussion

These findings support renewed research interest in evaluating midlife estrogen therapy for AD risk reduction.

Hormone therapy for sexual function in perimenopausal and postmenopausal women

BACKGROUND

The perimenopausal and postmenopausal periods are associated with many symptoms, including sexual complaints. This review is an update of a review first published in 2013.

OBJECTIVES

We aimed to assess the effect of hormone therapy on sexual function in perimenopausal and postmenopausal women.

SEARCH METHODS

On 19 December 2022 we searched the Gynaecology and Fertility Group Specialised Register, CENTRAL, MEDLINE, Embase, PsycINFO, CINAHL, LILACS, ISI Web of Science, two trials registries, and OpenGrey, together with reference checking and contact with experts in the field for any additional studies.

SELECTION CRITERIA

We included randomized controlled trials that compared hormone therapy to either placebo or no intervention (control) using any validated assessment tool to evaluate sexual function. We considered hormone therapy: estrogen alone; estrogen in combination with progestogens; synthetic steroids, for example, tibolone; selective estrogen receptor modulators (SERMs), for example, raloxifene, bazedoxifene; and SERMs in combination with estrogen.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures recommended by Cochrane. We analyzed data using mean differences (MDs) and standardized mean differences (SMDs). The primary outcome was the sexual function score. Secondary outcomes were the domains of sexual response: desire; arousal; lubrication; orgasm; satisfaction; and pain. We assessed the certainty of the evidence using the GRADE approach.

MAIN RESULTS

We included 36 studies (23,299 women; 12,225 intervention group; 11,074 control group), of which 35 evaluated postmenopausal women; only one study evaluated perimenopausal women. The 'symptomatic or early postmenopausal women' subgroup included 10 studies, which included women experiencing menopausal symptoms (symptoms such as hot flushes, night sweats, sleep disturbance, vaginal atrophy, and dyspareunia) or early postmenopausal women (within five years after menopause). The 'unselected postmenopausal women' subgroup included 26 studies, which included women regardless of menopausal symptoms and women whose last menstrual period was more than five years earlier. No study included only women with sexual dysfunction and only seven studies evaluated sexual function as a primary outcome. We deemed 20 studies at high risk of bias, two studies at low risk, and the other 14 studies at unclear risk of bias. Nineteen studies received commercial funding. Estrogen alone versus control probably slightly improves the sexual function composite score in symptomatic or early postmenopausal women (SMD 0.50, 95% confidence interval (CI) (0.04 to 0.96; I² = 88%; 3 studies, 699 women; moderate-quality evidence), and probably makes little or no difference to the sexual function composite score in unselected postmenopausal women (SMD 0.64, 95% CI -0.12 to 1.41; I² = 94%; 6 studies, 608 women; moderate-quality evidence). The pooled result suggests that estrogen alone versus placebo or no intervention probably slightly improves sexual function composite score (SMD 0.60, 95% CI 0.16 to 1.04; I² = 92%; 9 studies, 1307 women, moderate-quality evidence). We are uncertain of the effect of estrogen combined with progestogens versus placebo or no intervention on the sexual function composite score in unselected postmenopausal women (MD 0.08 95% CI -1.52 to 1.68; 1 study, 104 women; very low-quality evidence). We are uncertain of the effect of synthetic steroids versus control on the sexual function composite score in symptomatic or early postmenopausal women (SMD 1.32, 95% CI 1.18 to 1.47; 1 study, 883 women; very low-quality evidence) and of their effect in unselected postmenopausal women (SMD 0.46, 95% CI 0.07 to 0.85; 1 study, 105 women; very low-quality evidence). We are uncertain of the effect of SERMs versus control on the sexual function composite score in symptomatic or early postmenopausal women (MD -1.00, 95% CI -2.00 to -0.00; 1 study, 215 women; very low-quality evidence) and of their effect in unselected postmenopausal women (MD 2.24, 95% 1.37 to 3.11 2 studies, 1525 women, I² = 1%, low-quality evidence). We are uncertain of the effect of SERMs combined with estrogen versus control on the sexual function composite score in symptomatic or early postmenopausal women (SMD 0.22, 95% CI 0.00 to 0.43; 1 study, 542 women; very low-quality evidence) and of their effect in unselected postmenopausal women (SMD 2.79, 95% CI 2.41 to 3.18; 1 study, 272 women; very low-quality evidence). The observed heterogeneity in many analyses may be caused by variations in the interventions and doses used, and by different tools used for assessment.

AUTHORS' CONCLUSIONS

Hormone therapy treatment with estrogen alone probably slightly improves the sexual function composite score in women with menopausal symptoms or in early postmenopause (within five years of amenorrhoea), and in unselected postmenopausal women, especially in the lubrication, pain, and satisfaction domains. We are uncertain whether estrogen combined with progestogens improves the sexual function composite score in unselected postmenopausal women. Evidence regarding other hormone therapies (synthetic steroids and SERMs) is of very low quality and we are uncertain of their effect on sexual function. The current evidence does not suggest the beneficial effects of synthetic steroids (for example tibolone) or SERMs alone or combined with estrogen on sexual function. More studies that evaluate the effect of estrogen combined with progestogens, synthetic steroids, SERMs, and SERMs combined with estrogen would improve the quality of the evidence for the effect of these treatments on sexual function in perimenopausal and postmenopausal women.

The Effect of Cumulative Lifetime Estrogen Exposure on Cognition in Depressed Versus Non-Depressed Older Women

OBJECTIVES

Two-thirds of individuals living with Alzheimer's disease are women. Declining estrogen levels influence mood and cognition. Cumulative lifetime estrogen exposure (CLEE) correlates with cognition later in life. We examined the relationship of CLEE to depression and cognition in older women with major depression compared to non-depressed women.

DESIGN

Older women (age ≥60 years) with depression were compared to non-depressed women using a lifetime estrogen exposure questionnaire. CLEE was defined as combined durations of reproductive span (age of menopause minus age of menarche) and any post-menopausal hormone replacement therapy use. Higher vs lower CLEE groups were based on a median of 474 months of estrogen exposure.

SETTING

University hospital outpatient research program.

PARTICIPANTS

135 women ≥60 years; 64 depressed and 71 non-depressed.

MEASURMENTS

Participants completed a comprehensive cognitive test battery. General linear models were used to examine the association between cognitive domain scores and CLEE in depressed and non-depressed women, controlling for age, education, and ethnicity.

RESULTS

Depressed and non-depressed groups had significantly different levels of CLEE, measured in months: mean 495.7 (SD 108.6) vs 456.4 (SD 66.0) months, F(1,130) = 5.01, p = .03. Within the non-depressed participants, higher CLEE was associated with improved delayed recall (F(1,59) = 5.94, p = .02, effect size = .61), while no such relationship was observed in the depressed group.

CONCLUSION

Higher CLEE was associated with improvement in delayed recall among non-depressed, but not among depressed participants. This suggests a protective role of estrogen on memory in non-depressed older postmenopausal women. Further research should examine the role of the CLEE in antidepressant response and cognitive decline.

Sex-specific features of spine densities in the hippocampus

Previously, we found that in dissociated hippocampal cultures the proportion of large spines (head diameter ≥ 0.6 μm) was larger in cultures from female than from male animals. In order to rule out that this result is an in vitro phenomenon, we analyzed the density of large spines in fixed hippocampal vibratome sections of Thy1-GFP mice, in which GFP is expressed only in subpopulations of neurons. We compared spine numbers of the four estrus cycle stages in females with those of male mice. Remarkably, total spine numbers did not vary during the estrus cycle, while estrus cyclicity was evident regarding the number of large spines and was highest during diestrus, when estradiol levels start to rise. The average total spine number in females was identical with the spine number in male animals. The density of large spines, however, was significantly lower in male than in female animals in each stage of the estrus cycle. Interestingly, the number of spine apparatuses, a typical feature of large spines, did not differ between the sexes. Accordingly, NMDA-R1 and NMDA-R2A/B expression were lower in the hippocampus and in postsynaptic density fractions of adult male animals than in those of female animals. This difference could already be observed at birth for NMDA-R1, but not for NMDA-R2A/B expression. In dissociated embryonic hippocampal cultures, no difference was seen after 21 days in culture, while the difference was evident in postnatal cultures. Our data indicate that hippocampal neurons are differentiated in a sex-dependent manner, this differentiation being likely to develop during the perinatal period.

Ovariectomy Induces Microglial Cell Activation and Inflammatory Response in Rat Prefrontal Cortices to Accelerate the Chronic Unpredictable Stress-Mediated Anxiety and Depression

Perimenopausal women are associated with increased risks of depression and anxiety, which may be potentially related to the lack of ovarian hormone with antidepression activity in the body. However, the precise mechanism remains unclear so far. This study first adopted the Sprague-Dawley (SD) female rats to construct the ovariectomy (OVX) combined with a chronic unpredictable stress (CUS) model. Then, a series of behavioral experimental results revealed that the ovariectomized rats receiving CUS had remarkably elevated anxiety and depression behaviors relative to those in sham group rats, and the sucrose preference rate in the sucrose preference test (SPT) was evidently reduced. In elevated plus maze test (EPM) experiment, the open arm entry time and open arm duration were decreased. In the open field test (OFT), the number of line crossings, rearing number, center square entries, and center square duration were reduced; the grooming time was extended; and the number of fecal particles in rats was increased. In the forced swimming test (FST), the rat immobility rate was increased, while the numbers of swimming and crawling were decreased. Afterwards, we discovered that OVX downregulated the serum levels of estradiol and corticosterone in rats. Thereafter, IF results suggested that OVX dramatically induced the increasing of the number of activated microglial cells in prefrontal cortices and the level of M1-type marker iNOS. Finally, PCR results demonstrated that, compared with the sham group, the proinflammatory and prooxidative genes, such as IL-1β, IL-6, TNF-α, iNOS, and CX3CR1, were upregulated in the prefrontal cortices of OVX rats after CUS stimulation, whereas the anti-inflammatory factor Arg1 and microglial cell negative regulatory factor CD200 were downregulated. To sum up, OVX enhances the CUS-mediated anxiety and depression phenomena in rats, and its mechanism may be related to inducing the activation and polarization of microglial cells in the prefrontal cortex of animal and to accelerating the inflammatory response.

Evaluating the neuroprotective effect of 17β-estradiol in rodent models of oxidative retinopathies

PURPOSE

To determine the neuroprotective effect of estrogen on the structure and function of the retina exposed to an oxidative stress.

METHODS

Male Sprague-Dawley rat pups were exposed to either hyperoxia (O₂E: from P8 to P14) or bright light (LE: from P14 to P28) with or without 17 β-estradiol (βE₂) treatment. Retinal structure (histology) and function (ERG) were assessed at selected time points.

RESULTS

In the O₂E model, βE₂ injections caused a significant reduction of the ERG and a significantly thinner OPL compared to untreated oxygen-exposed group (O₂-exposed) rats. In contrast, in the LE model βE₂, treatment was beneficial to the retinal structure (thicker ONL) and function (better preserved ERG amplitudes) compared to untreated light-exposed group (light-exposed rats).

CONCLUSION

Our results show that in conditions where the primary target of the oxidative stress is the outer retina (i.e., the photoreceptors) estrogen can protect the retina, while in situations where the inner retina (or retinal vasculature) is the main site of oxidative damage, estrogen may potentiate the detrimental effect of oxidative stress on the retina.

Estrogen Interactions With Lipid Rafts Related to Neuroprotection. Impact of Brain Ageing and Menopause

Estrogens (E2) exert a plethora of neuroprotective actions against aged-associated brain diseases, including Alzheimer's disease (AD). Part of these actions takes place through binding to estrogen receptors (ER) embedded in signalosomes, where numerous signaling proteins are clustered. Signalosomes are preferentially located in lipid rafts which are dynamic membrane microstructures characterized by a peculiar lipid composition enriched in gangliosides, saturated fatty acids, cholesterol, and sphingolipids. Rapid E2 interactions with ER-related signalosomes appear to trigger intracellular signaling ultimately leading to the activation of molecular mechanisms against AD. We have previously observed that the reduction of E2 blood levels occurring during menopause induced disruption of ER-signalosomes at frontal cortical brain areas. These molecular changes may reduce neuronal protection activities, as similar ER signalosome derangements were observed in AD brains. The molecular impairments may be associated with changes in the lipid composition of lipid rafts observed in neurons during menopause and AD. These evidences indicate that the changes in lipid raft structure during aging may be at the basis of alterations in the activity of ER and other neuroprotective proteins integrated in these membrane microstructures. Moreover, E2 is a homeostatic modulator of lipid rafts. Recent work has pointed to this relevant aspect of E2 activity to preserve brain integrity, through mechanisms affecting lipid uptake and local biosynthesis in the brain. Some evidences have demonstrated that estrogens and the docosahexaenoic acid (DHA) exert synergistic effects to stabilize brain lipid matrix. DHA is essential to enhance molecular fluidity at the plasma membrane, promoting functional macromolecular interactions in signaling platforms. In support of this, DHA detriment in neuronal lipid rafts has been associated with the most common age-associated neuropathologies, namely AD and Parkinson disease. Altogether, these findings indicate that E2 may participate in brain preservation through a dual membrane-related mechanism. On the one hand, E2 interacting with ER related signalosomes may protect against neurotoxic insults. On the other hand, E2 may exert lipostatic actions to preserve lipid balance in neuronal membrane microdomains. The different aspects of the emerging multifunctional role of estrogens in membrane-related signalosomes will be discussed in this review.

Estrogen-cholinergic interactions: Implications for cognitive aging

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

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

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

Continuously delivered ovarian steroids do not alter dendritic spine density or morphology in macaque dorsolateral prefrontal cortical neurons

Aged ovariectomized (OVX) female monkeys, a model for menopause in humans, show a decline in spine density in the dorsolateral prefrontal cortex (dlPFC) and diminished performance in cognitive tasks requiring this brain region. Previous studies in our laboratory have shown that long-term cyclic treatment with 17β-estradiol (E) produces an increase in spine density and in the proportion of thinner spines in layer III pyramidal neurons in the dlPFC of both young and aged OVX rhesus monkeys. Here we used 3D reconstruction of Lucifer yellow-loaded neurons to investigate whether clinically relevant schedules of hormone therapy would produce similar changes in prefrontal cortical neuronal morphology as long-term cyclic E treatment in young female monkeys. We found that continuously delivered E, with or without a cyclic progesterone treatment, did not alter spine density or morphology in the dlPFC of young adult OVX rhesus monkeys. We also found that the increased density of thinner spines evident in the dlPFC 24h after E administration in the context of long-term cyclic E therapy is no longer detectable 20days after E treatment. When compared with the results of our previously published investigations, our results suggest that cyclic fluctuations in serum E levels may cause corresponding fluctuations in the density of thin spines in the dlPFC. By contrast, continuous administration of E does not support sustained increases in thin spine density. Physiological fluctuations in E concentration may be necessary to maintain the morphological sensitivity of the dlPFC to E.

Hormone therapy for sexual function in perimenopausal and postmenopausal women

BACKGROUND

The perimenopausal and postmenopausal periods are associated with many symptoms, including sexual complaints.

OBJECTIVES

To assess the effect of hormone therapy (HT) on sexual function in perimenopausal and postmenopausal women.

SEARCH METHODS

We searched for articles in the Cochrane Menstrual Disorders and Subfertility Group (MDSG) Specialised Register, CENTRAL, MEDLINE, EMBASE, CINAHL, PsycINFO, LILACS, ClinicalTrials.gov, Current Controlled Trials, WHO International Clinical Trials Registry Platform, ISI Web of Knowledge and OpenGrey. The last search was performed in December 2012.

SELECTION CRITERIA

We included randomised controlled trials comparing HT to either placebo or no intervention (control). We considered as HT estrogens alone; estrogens in combination with progestogens; synthetic steroids (for example tibolone); or selective estrogen receptor modulators (SERMs) (for example raloxifene, bazedoxifene). Studies of other drugs possibly used in the relief of menopausal symptoms were excluded. We included studies that evaluated sexual function using any validated assessment tool. The primary outcome was a composite score for sexual function and the scores for individual domains (arousal and sexual interest, orgasm, and pain) were secondary outcomes. Studies were selected by two authors independently.

DATA COLLECTION AND ANALYSIS

Data were independently extracted by two authors and checked by a third. Risk of bias assessment was performed independently by two authors. We contacted study investigators as required. Data were analysed using standardized mean difference (SMD) and relative risk (RR). We stratified the analysis by participant characteristics with regard to menopausal symptoms. The overall quality of the evidence for the primary outcome was evaluated using the GRADE criteria.

MAIN RESULTS

The search retrieved 2351 records from which 27 studies (16,393 women) were included. The 'symptomatic or early post-menopausal' subgroup included nine studies: perimenopausal women (one study), up to 36 months postmenopause (one study), up to five years postmenopause (one study), experiencing vasomotor or other menopausal symptoms (five studies), or experiencing hot flushes and sexual dysfunction (one study). The 'unselected postmenopausal women' subgroup included 18 studies, which included women regardless of menopausal symptoms and permitted the inclusion of women with more than five years since the final menstrual period. No studies were restricted to women with sexual dysfunction. Only five studies evaluated sexual function as a primary outcome. Eighteen studies were deemed at high risk of bias, and the other nine studies were at unclear risk of bias. Twenty studies received commercial funding.Findings for sexual function (measured by composite score):For estrogens alone versus control, in symptomatic or early postmenopausal women the SMD and 95% CI were compatible with a small to moderate benefit in sexual function for the HT group (SMD 0.38, 95% CI 0.23 to 0.54, P < 0.00001, 3 studies, 699 women, I² = 55%, high-quality evidence). In unselected postmenopausal women, the 95% CI was compatible with no effect to a small benefit (SMD 0.16, 95% CI -0.02 to 0.34, P = 0.08, 2 studies, 478 women, I² = 44%, low-quality evidence). The subgroups were not pooled because of considerable heterogeneity.For estrogens combined with progestogens versus control, in symptomatic or early postmenopausal women the 95% CI was compatible with a small to moderate benefit for sexual function in the HT group (SMD 0.42, 95% CI 0.19 to 0.64, P = 0.0003, 1 study, 335 women, moderate-quality evidence). In unselected postmenopausal women, the 95% CI was compatible with no effect to a small benefit (SMD 0.09, 95% CI -0.02 to 0.20, P = 0.10, 3 studies, 1314 women, I² = 0%, moderate-quality evidence). The subgroups were not pooled because of considerable heterogeneity.For tibolone versus control, in symptomatic or early postmenopausal women the 95% CI was compatible with no effect to a small benefit for sexual function in the HT group (SMD 0.13, 95% CI 0.00 to 0.26, P = 0.05, 1 study, 883 women, low-quality evidence). In unselected postmenopausal women, the 95% CI was compatible with no effect to a moderate benefit (SMD 0.38, 95% CI 0.04 to 0.71, P = 0.03, 2 studies, 142 women, I² = 0%, low-quality evidence). In the combined analysis, the 95% CI was compatible with no effect to a small benefit (SMD 0.17, 95% CI 0.04 to 0.29, P = 0.008, 3 studies, 1025 women, I² = 20%).For SERMs versus control, in symptomatic or early postmenopausal women the 95% CI was compatible with no effect to a moderate benefit for sexual function in the HT group (SMD 0.23, 95% CI -0.04 to 0.50, P = 0.09, 1 study, 215 women, low-quality evidence). In unselected postmenopausal women, the 95% CI was compatible with small harm to a small benefit (SMD 0.04, 95% CI -0.20 to 0.29, P = 0.72, 1 study, 283 women, low-quality evidence). In the combined analysis, the 95% CI was compatible with no effect to a small benefit (SMD 0.13, 95% CI -0.05 to 0.31, P = 0.16, 2 studies, 498 women, I² = 2%).A comparison of SERMs combined with estrogens versus control was only evaluated in symptomatic or early postmenopausal women. The 95% CI was compatible with no effect to a small benefit for sexual function in the HT group (SMD 0.21, 95% CI 0.00 to 0.43, P = 0.05, 1 study, 542 women, moderate-quality evidence).

AUTHORS' CONCLUSIONS

HT treatment with estrogens alone or in combination with progestogens was associated with a small to moderate improvement in sexual function, particularly in pain, when used in women with menopausal symptoms or in early postmenopause (within five years of amenorrhoea), but not in unselected postmenopausal women. Evidence regarding other HTs (synthetic steroids and SERMs) is of low quality and we are uncertain of their effect on sexual function. The current evidence does not suggest an important effect of tibolone or of SERMs alone or combined with estrogens on sexual function. More studies evaluating the effect of synthetic steroids, SERMS and the association of SERM + estrogens would improve the quality of the evidence for the effect of these treatments on sexual function in peri and postmenopausal women. Future studies should also evaluate the effect of HT solely among women with sexual complaints.

Clinically relevant hormone treatments fail to induce spinogenesis in prefrontal cortex of aged female rhesus monkeys

Preclinical animal models have provided strong evidence that estrogen (E) therapy (ET) enhances cognition and induces spinogenesis in neuronal circuits. However, clinical studies have been inconsistent, with some studies revealing adverse effects of ET, including an increased risk of dementia. In an effort to bridge this disconnect between the preclinical and clinical data, we have developed a nonhuman primate (NHP) model of ET combined with high-resolution dendritic spine analysis of dorsolateral prefrontal cortical (dlPFC) neurons. Previously, we reported cyclic ET in aged, ovariectomized NHPs increased spine density on dlPFC neurons. Here, we report that monkeys treated with cyclic E treatment paired with cyclic progesterone (P), continuous E combined with P (either cyclic or continuous), or unopposed continuous E failed to increase spines on dlPFC neurons. Given that the most prevalent form of ET prescribed to women is a combined and continuous E and P, these data bring into convergence the human neuropsychological findings and preclinical neurobiological evidence that standard hormone therapy in women is unlikely to yield the synaptic benefit presumed to underlie the cognitive enhancement reported in animal models.

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

As we age, most of us experience a certain degree of cognitive decline. In most cases, this decline is gradual. However, in some cases, cognitive impairment is so severe that it can be classified as dementia and this impacts greatly on activities of daily living. Alzheimer's disease, the most common form of dementia, has been linked to the reduction in estrogen levels that comes with aging. More specifically, many researchers have hypothesized that estrogen, and hence estrogen replacement via hormone therapy, could protect against cognitive decline in women. However, recent randomized, controlled trials did not reflect this. In fact, some reports showed that hormone therapy could have detrimental effects on cognitive function in older postmenopausal women. The most publicized of these has been the Women's Health Initiative Memory Study. Studies have thus yielded conflicting results and conclusions. The reasons for this may be due to a number of factors, such as the age of participants, the time of hormone therapy onset ('window of opportunity' theory), type of treatment, type of menopause (surgical or natural) and, possibly, genetic risk factors. We performed quantitative and qualitative meta-analyses and reviewed each of these factors in detail. The future may lie in combining these factors in order to fully understand the potential mechanisms behind estrogen and its effect on cognition.

Estrogen replacement therapy and cognitive functions in healthy postmenopausal women: a randomized trial

This study aimed to evaluate the effect of estrogen replacement therapy on verbal cognitive performance of middle-aged postmenopausal women. Middle-aged (40 to 59 years) hysterectomized, oligosymptomatic women receiving 0.625 mg/day of conjugated equine estrogens (N = 27) or placebo (N = 32) in a double-blind parallel group design were compared according to their performance on a verbal memory battery before and after six 28-day cycles of treatment. Both groups had similar age and educational level. The estrogen group performed better on digit span-forward and on the recall of the easy stimuli on the verbal-paired associates test regardless of age, education, physical symptoms, number of years of menopause, or blood estradiol levels. However, the small magnitude of difference in the effect on attentional span suggests that the estrogen-related improvement is unlikely to be of clinical relevance. Estrogen replacement therapy did not improve verbal memory in middle-aged, hysterectomized, postmenopausal, asymptomatic women.

Interactive effects of age and estrogen on cortical neurons: implications for cognitive aging

In the past few decades it has become clear that estrogen signaling plays a much larger role in modulating the cognitive centers of the brain than previously thought possible. We have developed a nonhuman primate (NHP) model to investigate the relationships between estradiol (E) and cognitive aging. Our studies of cyclical E treatment in ovariectomized (OVX) young and aged rhesus monkeys have revealed compelling cognitive and synaptic effects of E in the context of aging. Delayed response (DR), a task that is particularly dependent on integrity of dorsolateral prefrontal cortex (dlPFC) area 46 revealed the following: (1) that young OVX rhesus monkeys perform equally well whether treated with E or vehicle (V), and (2) that aged OVX animals given E perform as well as young adults with or without E, whereas OVX V-treated aged animals display significant DR impairment. We have analyzed the structure of layer III pyramidal cells in area 46 in these same monkeys. We found both age and treatment effects on these neurons that are consistent with behavioral data. Briefly, reconstructions of pyramidal neurons in area 46 from these monkeys showed that cyclical E increased the density of small, thin spines in both young and aged monkeys. However, this effect of E was against a background of age-related loss of small, thin spines, leaving aged V-treated monkeys with a particularly low density of these highly plastic spines, and vulnerable to cognitive decline. Our current interpretation is that E not only plays a critically important role in maintaining spine number, but also enables synaptic plasticity through a cyclical increase in small highly plastic spines that may be stabilized in the context of learning. Interestingly, recent studies demonstrate that chronic E is less effective at inducing spinogenesis than cyclical E. We have begun to link certain molecular attributes of excitatory synapses in area 46 to E effects and cognitive performance in these monkeys. Given the importance of synaptic estrogen receptor α (ER-α) in rat hippocampus, we focused our initial studies on synaptic ER-α in area 46. Three key findings have emerged from these studies: (1) synaptic ER-α is present in axospinous synapses in area 46; (2) it is stable across treatment and age groups (which is not the case in rat hippocampus); and (3) the abundance and distribution of synaptic ER-α is a key correlate of individual variation in cognitive performance in certain age and treatment groups. These findings have important implications for the design of hormone treatment strategies for both surgically and naturally menopausal women. This article is part of a Special Issue entitled: Neuroactive Steroids: Focus on Human Brain.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Estrogen treatment impairs cognitive performance after psychosocial stress and monoamine depletion in postmenopausal women

OBJECTIVE

Recent studies have shown that women experience an acceleration of cognitive problems after menopause and that estrogen treatment can improve or at least maintain current levels of cognitive functioning in postmenopausal women. However, we have previously shown that the negative emotional effects of psychosocial stress are magnified in normal postmenopausal women after estrogen treatment. This study examined whether estradiol (E2) administration can modify cognitive performance after exposure to psychological stress and monoamine depletion.

METHODS

Participants consisted of 22 postmenopausal women placed on either oral placebo or 17beta-E2 (1 mg/d for 1 mo, then 2 mg/d for 2 mo). At the end of the 3-month treatment phase, participants underwent three depletion challenges in which they ingested one of three amino acid mixtures: deficient in tryptophan, deficient in phenylalanine/tyrosine, or balanced. Five hours later, participants performed the Trier Social Stress Test (TSST), followed by mood and anxiety ratings and cognitive testing. Cognitive measures included tests of attention, psychomotor function, and verbal episodic memory.

RESULTS

E2-treated compared with placebo-treated participants exhibited significant worsening of cognitive performance on tasks measuring attentional performance and psychomotor speed. Similar trends for impairment were seen in measures of long-term episodic memory compared with placebo-treated postmenopausal women. E2-treated participants also showed a significant increase in negative mood and anxiety compared with placebo-treated women after, but not before, the TSST, although the worsening of both cognitive and behavioral functioning was not correlated. These effects were independent of tryptophan or tyrosine/phenylalanine depletion and were not manifested before the TSST or at baseline.

CONCLUSIONS

These data suggest that the relationship between estrogen administration and cognitive/behavioral performance in postmenopausal women may be more complex than initially appreciated and that the effects of psychosocial stress may influence whether hormone effects are beneficial.

Effect of traditional Chinese herbal Bu-Wang-San on synaptic plasticity in ovariectomised rats

Objectives

The neuroprotective effects of Bu-Wang-San (BWS) and its effects on spine synapse plasticity were investigated in ovariectomised rats.

Methods

Thirty-six ovariectomised rats were divided into three groups: untreated controls, treatment with 17β-estradiol or with BWS. After 3 months, spatial acquisition and spatial retention were measured using the Morris water maze. Swim time, swim distance, swim speed, quadrant time and platform crossing were recorded. Spine synapse density in the hippocampus was examined by transmission electron microscopy. The expression of synaptophysin P38 (P38) mRNA was examined by real-time PCR and the protein expression of P38 was examined by Western blot.

Key findings

In spatial acquisition and spatial retention, the BWS group functioned significantly better than the control group. Ultrastructural observation of the hippocampus showed that BWS significantly increased spine synapse density compared with the ovariectomised group. In addition, BWS significantly increased P38 mRNA and protein expression in the hippocampus. Thus, the positive effect of BWS on learning and memory in rats was associated with increased spinal synapse density and increased P38 mRNA and protein expression in the hippocampus following menopause-induced injury.

Conclusions

These results suggest that BWS could improve cognitive ability following menopause-induced impairment of learning and memory.

Is cognitive functioning detrimentally affected after early, induced menopause?

OBJECTIVE

Investigations into the cognitive effects of surgically and chemically induced menopause are frequently combined with naturally occurring menopause and hormone therapy. However, there is some evidence that women who undergo surgical menopause may experience more cognitive decline post surgery as well as more benefit from subsequent hormone therapy use than women who experience naturally occurring menopause. Little is known about the effects of chemically induced menopause on cognitive function. The aim of this review was to examine whether premature menopause affects cognitive functioning.

DESIGN

PubMed, MEDLINE, and PsychINFO searches of the literature published from 1988 to 2007 pertaining to the understanding of the relationships between induced menopause and cognitive dysfunction were reviewed. Those combining induced menopause with natural menopause, those involving a disease process (eg, dementia), and animal studies were excluded.

RESULTS AND CONCLUSIONS

Although smaller prospective studies have found that surgical menopause is associated with specific deficits in the memory (visual and verbal) and verbal fluency domains, larger randomized, controlled trials have generally found no effect of surgical menopause on cognitive functioning. The effects of chemical menopause are harder to assess as only three prospective trials have explicitly investigated the effect of induced menopause in the context of breast cancer treatment, and the results remain inconclusive. However, as surgical and chemical menopause both comprise the abrupt withdrawal of estrogen, there is the potential that this process may exert neurobiological effects that are different from those occurring with natural menopause and further prospective investigations comprising pre- and postsurgical/chemotherapy neuropsychological assessments are warranted.

Cognitive effects of Tamoxifen in pre-menopausal women with breast cancer compared to healthy controls

INTRODUCTION

The selective estrogen receptor modulator, Tamoxifen (TAM), is one of the most frequently prescribed drugs for the treatment of breast cancer; however, its effects on the cognition of users have not been adequately studied. Although TAM is an effective anti-estrogen that blocks tumour growth in the breast, it could also influence the activity of other target estrogen sites, including the brain. The exact nature of this interaction is unknown.

METHODS

A cross-sectional design was used to compare cognitive task performance of two treatment groups: 1) women using TAM for the treatment of early breast cancer (n = 23); and 2) age-matched, healthy women not using TAM (n = 23). All participants were pre-menopausal, and recipients of chemotherapy were excluded from the study.

RESULTS

It was found that TAM users scored significantly worse than controls on tasks of immediate and delayed visual memory, verbal fluency, immediate verbal memory, visuo-spatial ability, and processing speed.

DISCUSSIONS/CONCLUSIONS

Although limited by the lack of baseline data and pre-morbid intelligence measures, the results of this exploratory study suggest that at least in pre-menopausal women, TAM may exert a widespread negative influence on cognitive abilities.

IMPLICATIONS FOR CANCER SURVIVORS

Larger, randomized, prospective trials are required to confirm these results; however, TAM use in pre-menopausal breast cancer may be associated with cognitive difficulties. Knowledge and understanding of these complications will be important for professionals in communicating both the benefits and risks of TAM use in breast cancer survivors.

Enhanced neuroactivation during verbal memory processing in postmenopausal women receiving short-term hormone therapy

OBJECTIVE

To study the effects of hormone therapy on brain activation patterns during verbal memory in postmenopausal women.

DESIGN

A randomized, double-blind placebo-controlled cross-over study was performed.

SETTING

A tertiary care university medical center.

PATIENT(S)

Ten healthy postmenopausal women (age range 56-60 years) were recruited from the local community.

INTERVENTION(S)

Women were randomized to the order they received combined hormone therapy, 5 microg of ethinyl E(2) and 1 mg of norethindrone acetate, and placebo. Volunteers received hormone therapy or placebo for 4 weeks, followed by a 1-month washout period, and then received the other treatment for 4 weeks. A functional magnetic resonance imaging (fMRI) was performed at the end of each 4-week treatment using a verbal memory task.

MAIN OUTCOME MEASURE(S)

Brain activation patterns were compared between hormone therapy and placebo.

RESULT(S)

Hormone therapy was associated with increased activation in the left middle/superior frontal cortex (BA 6,9), medial frontal cortex and dorsal anterior cingulate (BA 24,32), posterior cingulate (BA 6), and left inferior parietal cortex (BA 40) during memory encoding. All regions were significant with correction for multiple comparisons.

CONCLUSION(S)

Hormone therapy increased neural activation in frontal and parietal areas in postmenopausal women during a verbal memory task.

The effects of an herbal medicine Bu-Wang-San on learning and memory of ovariectomized female rat

ETHNOPHARMACOLOGICAL SIGNIFICANCE

Bu-Wang-San (BWS) is a traditional Chinese herbal medicine for the treatment of learning and memory impairment. The effect of BWS on neuroprotection and how BWS increases CA1 dendritic spine synapse density in menopaused women was investigated in the model of ovariectomized (OVX) rats.

MATERIALS AND METHODS

Sixteen OVX rats were divided into two groups, the OVX group and OVX+BWS group. After 3 months, Morris water maze was used to assess spatial acquisition and spatial retention. Swim time, swim distance, swim speed, quadrant time and platform crossing were recorded. The ultrastructure of the pyramidal cell and spine synapse density were examined by transmission electron microscopy (TEM).

RESULTS

In the spatial acquisition and spatial retention phase of testing, BWS group functioned significantly better than control group. Ultrastructural observation of the hippocampal CA1 region of OVX group showed swelling of mitochondria, the broken and reduced cristas and even crista dissolution; however, the mitochondria were protected well in BWS group. In addition, BWS significantly increased spine synapse density.

CONCLUSIONS

These results suggested that BWS could improve cognitive ability of menopause-induced learning and memory impairment. The positive effect of BWS on rat learning and memory was associated with increase of spinal synapse density and protection of mitochondrial function of the pyramidal cell in hippocampal CA1 region from menopause-induced injury.

Brain aging modulates the neuroprotective effects of estrogen on selective aspects of cognition in women: a critical review

Although there is now a substantial literature on the putative neuroprotective effects of estrogen on cognitive functioning in postmenopausal women, it is replete with inconsistencies. The critical period hypothesis, posited several years ago, attempts to account for the discrepancies in this literature by positing that estrogen treatment (ET) will protect aspects of cognition in older women only when treatment is initiated soon after the menopause. Indeed, evidence from basic neuroscience and from the animal and human literature reviewed herein provides compelling support for the critical period hypothesis. Although it is not known with certainty why estrogen does not protect cognition and may even cause harm when administered to women over the age of 65years, it is likely that the events that characterize brain aging, such as a reduction in brain volume and in neuronal size, alterations in neurotransmitter systems, and a decrease in dendritic spine numbers, form an unfavorable background that precludes a neuroprotective effects of exogenous estrogen on the brain. Other factors that have likely contributed to the discrepancies in the estrogen-cognition literature include differences in the estrogen compounds used, their route of administration, cyclic versus continuous regimens, and the concomitant use of progestins. This critical analysis attempts to define conditions under which ET may protect aspects of cognition in aging women while also considering the cost/benefit ratio for the treatment of women aged 50-59years. Suggestions for specific future research questions are also addressed.

The effects of raloxifen on depression and cognition in ovariectomized rats

This study investigates the effects of raloxifen on cognition and depression in an animal model.

No differences in performance on test of working memory and executive functioning between healthy elderly postmenopausal women using or not using hormone therapy

BACKGROUND

On average, ovarian function ceases at the age of 52 years so that estrogen (E) levels are chronically low following the menopause. Numerous studies have found that hormone therapy (HT) helps to protect verbal memory, a hippocampal function. Estrogen receptors are also found in the prefrontal cortex (PFC), suggesting that estrogen may modulate executive and working memory functions, both mediated by the PFC. The possible role of progesterone (P) on executive functions and working memory is unknown.

OBJECTIVE

To examine the relationship between neuropsychological performance, age of initiation of HT, and duration of HT use.

METHOD

In this cross-sectional study, the neuropsychological performance of 37 postmenopausal women (mean age, 65 years) who used either estrogen-only or sequential E + P (E-alone group)(n = 22) or E + P continuously (n = 15) was compared to that of 28 healthy postmenopausal women matched for age and education who had never used HT. It was hypothesized that the E-only users would perform better then the E + P and the never-users on neuropsychological tests of verbal memory, executive function and working memory.

RESULTS

Results showed only minor between-group differences on working memory scores such that the E + P users were slowest to generate a response on the N-Back test of working memory. No group differences on tests of executive functions were found.

CONCLUSION

There was no relationship between neuropsychological performance, age of initiation of HT, or duration of HT use.

The clinical relevance of the relationship between estrogen and cognition in women

Randomized controlled trials (RCTs) and observational and longitudinal studies provide positive, albeit, inconsistent evidence that estrogen might protect against cognitive decline in postmenopausal women. The fact that the Women's Health Initiative Memory Study (WHIMS), the largest RCT to date, failed to find that estrogen therapy (ET) had a protective effect against cognitive aging led to the formulation of the critical period hypothesis which holds that ET will effectively protect against memory decline when it is initiated around the time of menopause but not when considerable time has elapsed since the menopause. Evidence from basic neuroscience, and from rodent, nonhuman primate, and human studies that supports this theory is presented. Although much work remains to be done on the timing of initiation of treatment, on the most effective hormonal compounds and on their routes of administration, the hope is that, eventually, hormonal treatments may be able to attenuate or prevent the decline in aspects of cognition that occur with normal aging.

Effects of soy isoflavone supplementation on cognitive function in Chinese postmenopausal women: a double-blind, randomized, controlled trial

OBJECTIVE

To investigate whether soy-derived isoflavone extract improves performance in cognitive function and quality of life in Chinese postmenopausal women.

DESIGN

The study was a 6-month double-blind, randomized, placebo-controlled, parallel group trial. Participants were community-dwelling women aged 55 to 76 years; 191 eligible women were randomly assigned to receive a daily oral intake of 80 mg soy-derived isoflavones or an identical-appearing placebo for 6 months. Standardized neuropsychological tests of memory, executive function, attention, motor control, language, and visual perception and a global cognitive function assessment were administered face-to-face individually at baseline and at 6-months posttreatment. The validated Chinese version of the Short Form-36 was used for quality of life measurements.

RESULTS

Of the participants, 88% (168 women: 80 among the supplementation group and 88 among the placebo group) completed the trial. Intention-to-treat analysis, conducted for 176 participants with 6-month assessment results, revealed no significant differences in outcome measures between treatment groups. Subgroup analysis among the good compliers only (consumed at least 80% of the supplements or placebo; n = 168) and among the age groups younger or older than 65 years also indicated no significant differences for any outcome measures. Types of complaints of adverse events were similar in both treatment groups and included mainly gastrointestinal and musculoskeletal problems.

CONCLUSIONS

This 6-month trial indicates that 80-mg soy-derived isoflavone supplementation did not improve performance on standard neuropsychological tests and overall quality of life in generally healthy Chinese postmenopausal women.

Effects of hormone replacement therapy and aging on cognition: evidence for executive dysfunction

The present study was designed to explore whether the frontal lobe hypothesis of cognitive aging may be extended to describe the cognitive effects associated with estrogen use in postmenopausal women. Postmenopausal estrogen-only users, estrogen + progesterone users, and non-users (60-80 years old), as well as young, regularly cycling women (18-30 years old) completed an item and source memory task. Since source memory is thought to rely more on executive processes than item memory, we hypothesized that aging and estrogen effects would be greater for source memory than for item memory. Neuropsychological tests explored whether the effects of aging and estrogen use were revealed on other tests of frontal lobe function. Results from the experimental task revealed greater aging and estrogen effects for source memory than for item memory, and neuropsychological results revealed aging and estrogen effects on a subset of tests of executive function. Women on estrogen + progesterone therapy did not outperform non-users, suggesting that the addition of progesterone to hormone therapy may mitigate the benefits induced by estrogen use alone. Overall, findings support the hypothesis that estrogen use may temper age-related cognitive decline by helping to maintain functions subserved by the frontal lobes.

Estrogen treatment effects on cognition, memory and mood in male-to-female transsexuals

Gonadal hormones, particularly estrogens, have been suggested to influence memory and cognitive tasks that show sex differences. Previously, we reported that male-to-female (M-F) transsexuals undergoing estrogen treatment for sex re-assignment scored higher on verbal Paired Associate Learning (PAL) than a transsexual control group awaiting estrogen treatment. The present study used a more robust design to examine further associations between estrogen and cognition. We assessed additional aspects of memory, including visual, spatial, object and location memory, other cognitive abilities that show reliable sex differences, including verbal and visual-spatial abilities, and mood variables that could mediate associations between estrogen and cognition. In addition to comparing groups of individuals on and off estrogen, we used two repeated measures designs (AB and BA). The AB group was tested prior to hormone treatment and then again after treatment had begun; the BA group was tested while on estrogen treatment and then again when hormones had been withdrawn prior to surgery. Few changes in memory or cognition were observed, and changes that were observed were not consistent across study designs. The lack of significant effects did not relate to mood changes or to the sexual orientation of participants. These findings suggest that estrogen treatment associated with sex change for M-F transsexuals has little or no influence on sex-typed aspects of cognition or memory.

Impact of combined estradiol and norethindrone therapy on visuospatial working memory assessed by functional magnetic resonance imaging

CONTEXT

Hormones regulate neuronal function in brain regions critical to cognition; however, the cognitive effects of postmenopausal hormone therapy are controversial.

OBJECTIVE

The goal was to evaluate the effect of postmenopausal hormone therapy on neural circuitry involved in spatial working memory.

DESIGN

A randomized, double-blind, placebo-controlled crossover study was performed.

SETTING

The study was performed in a tertiary care university medical center.

PARTICIPANTS

Ten healthy postmenopausal women of average age 56.9 yr were recruited.

INTERVENTIONS

Volunteers were randomized to the order they received hormone therapy (5 microg ethinyl estradiol and 1 mg norethindrone acetate). Subjects received hormone therapy or placebo for 4 wk, followed by a 1-month washout period with no medications, and then received the other treatment for 4 wk. At the end of each 4-wk treatment period, a functional magnetic resonance imaging study was performed using a nonverbal (spatial) working memory task, the Visual Delayed Matching to Sample task.

MAIN OUTCOME MEASURE

The effects of hormone therapy on brain activation patterns were compared with placebo.

RESULTS

Compared with the placebo condition, hormone therapy was associated with a more pronounced activation in the prefrontal cortex (BA 44 and 45), bilaterally (P < 0.001).

CONCLUSIONS

Hormone therapy was associated with more effective activation of a brain region critical in primary visual working memory tasks. The data suggest a functional plasticity of memory systems in older women that can be altered by hormones.

Verified hormone therapy improves episodic memory performance in healthy postmenopausal women

Studies of hormone therapy (HT) and cognition have yielded conflicting results. The aim of this observational study was to examine the effect of estradiol, via serum verified HT (estradiol, estriol, progesterone) and endogenous estradiol, on 108 healthy postmenopausal women's cognitive performance. The results demonstrated that the 43 HT-users performed at a significantly higher level than non-users on episodic memory tasks and on a verbal fluency task, whereas HT-users and non-users did not differ on tasks assessing semantic memory and spatial visualization. In addition, there was a positive relationship between serum estradiol level and episodic memory performance, indicating that postmenopausal HT is associated with enhanced episodic memory and verbal fluency, independent of age and education. These observational results suggest that HT use may be sufficient to exert small, yet positive effects on female sensitive cognitive tasks. Hormone therapy compliance and formulation is discussed as confounding factors in previous research.

Traumatic brain injury outcomes in pre- and post- menopausal females versus age-matched males

Gender differences in outcomes from major trauma have been described previously, and exogenous female hormone administration appears to be neuroprotective following traumatic brain injury (TBI). This analysis explored outcomes in pre- and post-menopausal females versus age-matched males. A total of 13,437 patients (n = 3,178 females, n = 10,259 males) with moderate-to-severe TBI (head AIS > or = 3) were identified from our county trauma registry. Overall mortality was similar between males and females (22% for both). Logistic regression was used to compare gender outcome differences, with a separate analysis performed for premenopausal (< 50 years) versus postmenopausal (> or = 50 years) patients, and after stratification by decade of life. No statistically significant difference in outcomes was observed for pre-menopausal females versus males (odds ratio [OR] 1.06; 95% confidence interval [CI] 0.83, 1.35; p = 0.633), but outcomes were significantly better in postmenopausal females versus males (OR 0.63, 95% CI 0.48-0.81, p < 0.001) after adjusting for age, mechanism of injury, Glasgow Coma Scale (GCS), hypotension (SBP < or = 90 mm Hg), head Abbreviated Injury Score (AIS), and Injury Severity Score (ISS). Stratification by decade of life revealed the gender survival differential inflection point to occur between ages 40-49 (OR 1.06, 95% CI 0.66-1.71, p = 0.798) and ages 50-59 (OR 0.38, 95% CI 0.20-0.74, p = 0.005). In addition, Revised Trauma Score and Injury Severity Score (TRISS) was used to calculate probability of survival (PS); all patients were then stratified by decade of life, and males and females were compared with regard to mean survival differential (outcome - PS). The identical pattern of improved outcomes in post-menopausal but not pre-menopausal females versus age-matched males was observed. These data suggest that endogenous female sex hormone production is not neuroprotective.

Hormone replacement therapy and cognitive performance in postmenopausal women—a review by cognitive domain

Laboratory, animal and neuroimaging evidences suggest that hormone replacement therapy (HRT) may be beneficial to human cognition. This systematic review includes 26 studies on the association between HRT and cognition and 17 studies on HRT and risk of dementia. It was hypothesised that HRT would have a positive association with cognitive speed and verbal memory and possibly visual memory but not with executive functioning, and would be associated with a decreased risk of dementia. Evidence for HRT's neuroenhancing and neuroprotective properties was also evaluated. There was significant statistical and clinical heterogeneity among studies precluding meta-analysis. Results showed no consistent relationship between HRT and performance in any cognitive domain. Cross-sectional studies tended to report more positive results than longitudinal studies and randomised-controlled trials, particularly in the areas of verbal memory and executive functioning. HRT was associated with decreased risk of dementia in observational studies, but with increased risk in one randomised-controlled trial. Cognitive improvement or maintenance are not secondary benefits of HRT.

Hormone replacement therapy and cognitive function in postmenopausal women

OBJECTIVES

The study investigated the effect of hormone replacement therapy (HRT) on cognitive processes in healthy, naturally postmenopausal women.

METHOD

Participants were 64 volunteer postmenopausal women (27 in HRT, 37 in non-HRT group). Groups were matched for age, level of education and postmenopausal period. Duration of HRT was more than 12 months. Cognitive processes were measured through 44 scores obtained from Wechsler Memory Scale-Revised, Line Orientation Test, Cancellation Test and Raven Standard Progressive Matrices. All of these tests had been studied with respect to their psychometric properties in the Turkish culture [for review, Karakaş S. BILNOT battery: research and development of neuropsychological tests. Ankara, Turkey: Dizayn Ofset; 2004].

RESULTS

Multivariate analysis of variance was performed where HRT and estradiol level were predictive (independent) variables and test scores were predicted (dependent) variables. The studied variables did not have a significant effect on a broad spectrum of neuropsychological scores that measured immediate and delayed visual and verbal memory, visuospatial perception and orientation, sustained attention/vigilance, visual search and scan, impulsivity and response speed, executive functions and general intelligence. Logistic regression analysis demonstrated a prediction rate of 86.89% of HRT status; the model was, however, based on four scores whose scientific relevance could not at this point be ascertained.

CONCLUSION

The research design of the present observational study applied control techniques to demographic (age, level of education), menopausal (length of menopausal period, duration of HRT), and hormonal variables. The cognitive changes that some studies found concerning the effect of replacement therapy could not be found when the potentially confounding variables were thus controlled.

Estrogen and cognitive aging in women

Although several randomized controlled trials of surgically menopausal women have provided evidence that estrogen protects aspects of memory, many cross-sectional and longitudinal studies, including those from the Women's Health Initiative Memory Study, have failed to confirm these findings. One critical difference between studies that found a protective effect of estrogen on memory and those that did not is that, in the former studies, treatment with estrogen began at the time of menopause and in the latter studies, it was first administered many years after the menopause had occurred. Recent evidence from rodent, nonhuman primate, and human studies consistently suggests that the timing of the initiation of estrogen treatment with regard to the menopause may be critical to our understanding of the estrogenic effect on memory. Results of these animal and human studies indicate that the initiation of estrogen treatment at the time of menopause, or soon after ovariectomy, provides a window of opportunity for the protection of memory in females whereas the administration of the hormone following a considerable delay in time after ovariectomy or following a natural menopause has little or no beneficial effect on cognition.

Endogenous and exogenous hormone exposure and risk of cognitive impairment in Swedish twins: a preliminary study

PURPOSE

To analyze the risk of cognitive impairment among female Swedish Twins with regard to endogenous and exogenous hormone exposure.

DESIGN AND SETTING

A cross-sectional analysis of data from the HARMONY Study, a population-based cohort study of cognitive impairment in the Swedish Twin Registry.

METHODS

Information regarding age at menarche and menopause, parity, and length and type of hormone therapy (HT) was collected via a telephone interview from 6604 women, aged 65-84. Cognitive impairment was assessed with the TELE, a brief telephone cognitive screen.

RESULTS

Length of reproductive period was inversely associated with risk of cognitive impairment (p<0.01). The OR was 1.15 (CI 95% 0.96-1.36) for women with reproductive periods <35 years and 0.82 (CI 95% 0.66-1.00) for women with reproductive periods >39 years. Age at menopause was inversely associated with risk of cognitive impairment. Use of HT was associated with average 40% decline in the risk of cognitive impairment, independent of type and timing of treatment.

CONCLUSION

Our results suggest that both increased length of reproductive period and HT are associated with reduced risk of cognitive impairment.

Early postmenopausal hormone therapy may prevent cognitive impairment later in life

OBJECTIVE

Estrogen deficiency has been implicated as a risk factor for cognitive impairment in elderly women, yet the role of hormone therapy (HT) to prevent this event remains controversial. The aim of this study was to investigate the impact of administration of HT for 2 to 3 years in the early postmenopausal years on the risk of cognitive impairment 5 to 15 years later.

DESIGN

We followed a group of 343 women who had received HT in randomized, placebo-controlled trials and were reexamined 5, 11, or 15 years after completion of therapy. Of these women, 261 received either HT or placebo for 2 to 3 years during the trials with no further hormone treatment until follow-up, and the remaining 82 women reported either prolonged or current use of HT at reexamination. Outcome of the study was cognitive function assessed by the short Blessed test that includes tests of orientation, concentration, and memory function on a scale of 0 to 28 (score > or =6 indicates cognitive impairment).

RESULTS

The mean age of participants at follow-up was 65 +/- 3 years. There was no difference in the mean cognitive scores between ever HT users and never users. For women who received 2 to 3 years of HT, the risk of cognitive impairment (cognitive score > or =6) was decreased by 64% (odds ratio [OR]: 0.36, 95% CI: 0.15-0.90; P = 0.03). A similar OR was found in long-term/current HT users. Adjustment for age, alcohol intake, current smoking, and education did not alter the results.

CONCLUSION

The results of the present study suggest that previous short-term HT administered in the early phase of the menopause may provide a long-term protection against cognitive impairment.

Short-term transdermal estradiol therapy, cognition and depressive symptoms in healthy older women. A randomised placebo controlled pilot cross-over study

The potential role of estrogen in protecting women from cognitive decline and reducing depressive symptoms is of great therapeutic interest. In a pilot randomised placebo controlled cross-over study, we aimed to determine the short-term effects of transdermal estradiol therapy on cognition and depressive symptoms in healthy cognitively normal post-menopausal women over 60 years of age. Nineteen cognitively normal women, without clinical depression whom had undergone a hysterectomy in the past were recruited. Women were randomised to receive either transdermal estradiol 50 microg/24 h (Femseven) or transdermal placebo for 12 weeks before crossing over to the other medication for a further 12 weeks. Cognition was assessed every 6 weeks by the cognitive drug research (CDR) computerised assessment which recorded both accuracy and speed in the following cognitive tests; simple reaction time, choice reaction time, digit vigilance, visual tracking, spatial working memory, immediate and delayed word recall and delayed face and picture recall. Depressive symptoms were measured using the brief assessment scale depression card (BASDEC) depression rating scale at baseline, 12 and 24 weeks. Participants had a mean age of 71, IQ of 115 and MMSE of 29. Simple reaction time and the BASDEC depression rating scale improved after 12 weeks of estradiol use. All other tests were unaltered by estradiol. Twelve weeks of transdermal estradiol therapy did not consistently improve the speed or accuracy of older women in various cognitive tests. However, the results do support the concept that depressive symptoms may be reduced by estradiol, and not simply due to the relief of climacteric symptoms.

Sex differences in age-related motor slowing in the rhesus monkey: behavioral and neuroimaging data

The nigrostriatal system is critical for fine motor function and its deterioration during aging is thought to underlie the decline in fine manual ability of old persons. Because estrogen has a neuroprotective effect on this system, one might expect women's motor function to be less vulnerable to the detrimental effects of aging than that of men. We examined this hypothesis in the rhesus monkey, which has been established as an excellent model of human age-related motor impairment. We tested 28 young and old rhesus monkeys of both sexes in a task involving the retrieval of a Life Saver candy from rods of different complexity to determine whether fine motor ability (1) is sexually dimorphic, (2) declines with age and (3) declines differently in males and females. In addition, we measured the whole brain volume, the volumes of the caudate, putamen, hippocampal formation and the area of the corpus callosum in a subset of the monkeys (n=15) for which magnetic resonance images of the brain were available. All monkeys performed similarly in the test with the simplest rod. In the test with complex rods; however, age-related slowing of motor function was evident in males, but not in females. Age-related decreases in the normalized caudate and putamen volumes were similar in males and in females. In addition, motor speed was not significantly correlated to any of the neuroanatomical measures under study. Further studies will be necessary to uncover the neurohormonal bases of the differential age-related motor decline between males and females.

Reproductive events modify the effects of estrogen replacement therapy on cognition in healthy postmenopausal women

The question of whether estrogen replacement therapy (ERT) is beneficial to cognitive functioning in postmenopausal women has become controversial in the past several years. Early studies suggested that ERT improved cognitive functioning and decreased the risk of Alzheimer's disease, but recent studies have failed to find any benefit. However, studies have varied in terms of the age of participants, the estrogen preparation used, whether progesterone is administered concurrently, and the study design. The present study used a randomized, placebo-controlled design and a transdermal estrogen preparation composed of 17-beta estradiol. A neuropsychological battery was administered at baseline and after completion of the 10-week trial, and test scores were grouped into four composite scores using psychometric techniques. Baseline to follow-up change was analyzed using multiple regression techniques. Results indicate that while little overall beneficial effect of estrogen was found, years since menopause was significantly related to change in executive functioning in the estrogen but not the placebo group, such that more recently postmenopausal women demonstrated greater positive change than older women. Body mass index, a gross estimate of circulating estrogen, was significantly positively related to change in attentional and psychomotor processes regardless of treatment group, and to a weaker extent, verbal memory, but only in the estrogen-treated group. These results suggest that reproductive events and levels of endogenous estrogen are related to the clinical response to ERT, but larger studies with longer follow-up periods are needed to determine the strength of these effects.

Inter- and intraindividual variability in recognition memory: effects of aging and estrogen use

Traditionally, studies of cognitive aging have focused on comparing the average performance of younger and older adults, whereas variability around the mean has been attributed to task-irrelevant noise. The present study examined the hypothesis that variability in memory performance increases with age and that estrogen helps temper age-related increases in variability. Postmenopausal estrogen users, estrogen and progestin (est + prog) users, and nonusers, as well as younger women, completed 16 blocks of an item-source memory task. Older women showed greater variability than younger women on measures of dispersion and consistency. Estrogen users, but not est + prog users, performed more consistently than nonusers. Overall, age-related increases in variability differed with the type of variability measured, and estrogen use, but not est + prog use, appeared to reduce age-related increases in at least 1 form of variability.

Sex Differences and Individual Differences in Cognitive Performance and Their Relationship to Endogenous Gonadal Hormones and Gonadotropins

Sexually dimorphic cognitive performance in men (n=42) and women (n=42) was related to testosterone, estradiol, progesterone, luteinizing hormone, follicle-stimulating hormone, and sex hormone binding globulin, measured in 10-ml blood samples collected between 0900 and 1030 and, among women, during the follicular phase of the menstrual cycle. Significant sex differences favored men on spatial tasks (Mental Rotation and Judgment of Line Orientation) and on an inhibition task and favored women on a verbal task (category fluency). However, there were no significant relationships between any of the hormones and cognitive performance, suggesting that there are few, if any, consistent, substantial relationships between endogenous, nonfluctuating levels of gonadal hormones or gonadotropins and these cognitive abilities in men or women.

In vivo occupancy of female rat brain estrogen receptors by 17β-estradiol and tamoxifen

Estrogens or antiestrogens are currently used by millions of women, but the interaction of these hormonal agents with brain estrogen receptors (ER) in vivo has not been characterized to date. Our goal was to assess, in vivo, the extent and regional distribution of brain ER occupancy in rats chronically exposed to 17beta-estradiol (E(2)) or tamoxifen (TAM). For that purpose, female ovariectomized Sprague-Dawley rats were implanted with subcutaneous pellets containing either placebo (OVX), E(2), or TAM for 3 weeks. ER occupancy in grossly dissected regions was quantified with 16alpha-[(18)F]fluoroestradiol ([(18)F]FES). Both E(2) and TAM produced significant decreases in radioligand uptake in the brain although the effect of E(2) was larger and more widespread than the effect of TAM. Detailed regional analysis of the interaction was then undertaken using a radioiodinated ligand, 11beta-methoxy-16alpha-[(125)I]iodo-estradiol ([(125)I]MIE(2)), and quantitative ex vivo autoradiography. E(2) treatment resulted in near-complete (86.6 +/- 17.5%) inhibition of radioligand accumulation throughout the brain, while ER occupancy in the TAM group showed a marked regional distribution such that percentage inhibition ranged from 40.5 +/- 15.6 in the ventrolateral part of the ventromedial hypothalamic nucleus to 84.6 +/- 4.5 in the cortical amygdala. These results show that exposure to pharmacologically relevant levels of TAM produces a variable, region-specific pattern of brain ER occupancy, which may be influenced by the regional proportion of ER receptor subtypes. These findings may partially explain the highly variable and region-specific effects observed in neurochemical, metabolic, and functional studies of the effects of TAM in the brain of experimental animals as well as human subjects.

The other side of estrogen replacement therapy: outcome study results of mood improvement in estrogen users and nonusers

The effect of estrogen on the brain and body of women is a controversial topic that has received a tremendous amount of attention in the past few years. Recent reviews have focused on hormone replacement therapy (HRT), medical risks, and effects on brain metabolism, cognition, risk of Alzheimer's disease, and mood. This article summarizes HRT and mood improvement in postmenopausal women. For nondepressed women, experimental designs provide no clear evidence for mood improvement associated with HRT, whereas observational studies are more likely to report mood improvement. There appears to be moderate evidence that HRT facilitates the improvement of clinical depression and the efficacy of antidepressants. Heterogeneity among studies makes it difficult to generalize and recommend HRT for mood improvement in postmenopausal women, but there is a clear need to examine the necessary duration of HRT for neuroprotection to decrease a woman's risk for depression, cognitive dysfunction, and development of Alzheimer's disease.