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

Brain plasticity and ginseng

Brain plasticity refers to the brain's ability to modify its structure, accompanied by its functional changes. It is influenced by learning, experiences, and dietary factors, even in later life. Accumulated researches have indicated that ginseng may protect the brain and enhance its function in pathological conditions. There is a compelling need for a more comprehensive understanding of ginseng's role in the physiological condition because many individuals without specific diseases seek to improve their health by incorporating ginseng into their routines. This review aims to deepen our understanding of how ginseng affects brain plasticity of people undergoing normal aging process. We provided a summary of studies that reported the impact of ginseng on brain plasticity and related factors in human clinical studies. Furthermore, we explored researches focused on the molecular mechanisms underpinning the influence of ginseng on brain plasticity and factors contributing to brain plasticity. Evidences indicate that ginseng has the potential to enhance brain plasticity in the context of normal aging by mediating both central and peripheral systems, thereby expecting to improve age-related declines in brain function. Moreover, given modern western diet can damage neuroplasticity in the long term, ginseng can be a beneficial supplement for better brain health.

Menopause-Associated Depression: Impact of Oxidative Stress and Neuroinflammation on the Central Nervous System-A Review

Perimenopausal depression, occurring shortly before or after menopause, is characterized by symptoms such as emotional depression, anxiety, and stress, often accompanied by endocrine dysfunction, particularly hypogonadism and senescence. Current treatments for perimenopausal depression primarily provide symptomatic relief but often come with undesirable side effects. The development of agents targeting the specific pathologies of perimenopausal depression has been relatively slow. The erratic fluctuations in estrogen and progesterone levels during the perimenopausal stage expose women to the risk of developing perimenopausal-associated depression. These hormonal changes trigger the production of proinflammatory mediators and induce oxidative stress, leading to progressive neuronal damage. This review serves as a comprehensive overview of the underlying mechanisms contributing to perimenopausal depression. It aims to shed light on the complex relationship between perimenopausal hormones, neurotransmitters, brain-derived neurotrophic factors, chronic inflammation, oxidative stress, and perimenopausal depression. By summarizing the intricate interplay between hormonal fluctuations, neurotransmitter activity, brain-derived neurotrophic factors, chronic inflammation, oxidative stress, and perimenopausal depression, this review aims to stimulate further research in this field. The hope is that an increased understanding of these mechanisms will pave the way for the development of more effective therapeutic targets, ultimately reducing the risk of depression during the menopausal stage for the betterment of psychological wellbeing.

Neuroactive steroids and Parkinson's disease: Review of human and animal studies

The greater prevalence and incidence of Parkinson's disease (PD) in men suggest a beneficial effect of sex hormones. Neuroactive steroids have neuroprotective activities thus offering interesting option for disease-modifying therapy for PD. Neuroactive steroids are also neuromodulators of neurotransmitter systems and may thus help to control PD symptoms and side effect of dopamine medication. Here, we review the effect on sex hormones (estrogen, androgen, progesterone and its metabolites) as well as androstenediol, pregnenolone and dehydroepiandrosterone) in human studies and in animal models of PD. The effect of neuroactive steroids is reviewed by considering sex and hormonal status to help identify specifically for women and men with PD what might be a preventive approach or a symptomatic treatment. PD is a complex disease and the pathogenesis likely involves multiple cellular processes. Thus it might be useful to target different cellular mechanisms that contribute to neuronal loss and neuroactive steroids provide therapeutics options as they have multiple mechanisms of action.

Autonomic nervous system dysfunction throughout menopausal transition: A potential mechanism underpinning cardiovascular and cognitive alterations during female ageing

Cardiovascular diseases (CVD) and neurodegenerative disorders, such as Alzheimer's disease (AD), are highly prevalent conditions in middle-aged women that severely impair quality of life. Recent evidence suggests the existence of an intimate cross-talk between the heart and the brain, resulting from a complex network of neurohumoral circuits. From a pathophysiological perspective, the higher prevalence of AD in women may be explained, at least in part, by sex-related differences in the incidence/prevalence of CVD. Notably, the autonomic nervous system, the main heart-brain axis physiological orchestrator, has been suggested to play a role in the incidence of adverse cardiovascular events in middle-aged women because of decreases in oestrogen-related signalling during transition into menopause. Despite its overt relevance for public health, this hypothesis has not been thoroughly tested. Accordingly, in this review, we aim to provide up to date evidence supporting how changes in circulating oestrogen levels during transition to menopause may trigger autonomic dysfunction, thus promoting cardiovascular and cognitive decline in women. A main focus on the effects of oestrogen-mediated signalling at CNS structures related to autonomic regulation is provided, particularly on the role of oestrogens in sympathoexcitation. Improving the understanding of the contribution of the autonomic nervous system on the development, maintenance and/or progression of both cardiovascular and cognitive dysfunction during the transition to menopause should help improve the clinical management of elderly women, with the outcome being an improved life quality during the natural ageing process.

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.

Lifespan-extending interventions induce consistent patterns of fatty acid oxidation in mouse livers

Aging manifests as progressive deteriorations in homeostasis, requiring systems-level perspectives to investigate the gradual molecular dysregulation of underlying biological processes. Here, we report systemic changes in the molecular regulation of biological processes under multiple lifespan-extending interventions. Differential Rank Conservation (DIRAC) analyses of mouse liver proteomics and transcriptomics data show that mechanistically distinct lifespan-extending interventions (acarbose, 17α-estradiol, rapamycin, and calorie restriction) generally tighten the regulation of biological modules. These tightening patterns are similar across the interventions, particularly in processes such as fatty acid oxidation, immune response, and stress response. Differences in DIRAC patterns between proteins and transcripts highlight specific modules which may be tightened via augmented cap-independent translation. Moreover, the systemic shifts in fatty acid metabolism are supported through integrated analysis of liver transcriptomics data with a mouse genome-scale metabolic model. Our findings highlight the power of systems-level approaches for identifying and characterizing the biological processes involved in aging and longevity.

Respirasome Proteins Are Regulated by Sex-Hormone Interactions in the Brain

The existence of sex differences in disease incidence is attributed, in part, to sex differences in metabolism. Uncovering the precise mechanism driving these differences is an extraordinarily complex process influenced by genetics, endogenous hormones, sex-specific lifetime events, individual differences and external environmental/social factors. In fact, such differences may be subtle, but across a life span, increase susceptibility to a pathology. Whilst research persists in the hope of discovering an elegant biological mechanism to underpin sex differences in disease, here, we show, for the first time, that such a mechanism may be subtle in nature but influenced by multiple sex-specific factors. A proteomic dataset was generated from a gonadectomized mouse model treated with Tibolone, a menopausal hormone therapy. Following functional enrichment analysis, we identified that Alzheimer's disease and the electron transport chain-associated pathways were regulated by sex-hormone interactions. Specifically, we identified that the expression of three respirasome proteins, NDUFA2, NDUFA7 and UQCR10, is significantly altered by compounding factors that contribute to sex differences. These proteins function in bioenergetics and produce reactive oxygen species, which are each dysregulated in many diseases with sex differences in incidence. We show sex-specific reprogrammed responses to Tibolone following gonadectomy, which primarily influence the expression of proteins contributing to metabolic pathways. This further infers that metabolic differences may underpin the observed sex differences in disease, but also that hormone therapy research now has potential in exploring sex-specific interventions to produce an effective method of prevention or treatment.

Age and sex differences on anti-hyperglycemic medication exposure and risk of newly diagnosed multiple sclerosis in propensity score matched type 2 diabetics

Background

The association between exposure to anti-hyperglycemic medications (A-HgM) for Type 2 Diabetes Mellitus (T2D) treatment and Multiple Sclerosis (MS) in T2D patients is unclear.

Methods

This retrospective cohort analysis used the Mariner claims database. Patient records were surveyed for a diagnosis of MS starting 12 months after diagnosis of T2D. Patients were required to be actively enrolled in the Mariner claims records for six months prior and at least three years after the diagnosis of T2D without a history of previous neurodegenerative disease. Survival analysis was used to determine the association between A-HgM exposure and diagnosis of MS. A propensity score approach was used to minimize measured and unmeasured selection bias. The analyses were conducted between January 1st and April 28th, 2021.

Findings

In T2D patients younger than 45, A-HgM exposure was associated with a reduced risk of developing MS (RR: 0.22, 95%CI: 0.17–0.29, p-value <0.001). In contrast, A-HgM exposure in patients older than 45 was associated with an increased risk of MS with women exhibiting greater risk (RR: 1.53, 95%CI: 1.39–1.69, p < 0.001) than men (RR: 1.17, 95%CI: 1.01–1.37, p = 0 · 04). Patients who developed MS had a higher incidence of baseline comorbidities. Mean follow-up was 6.2 years with a standard deviation of 1.8 years.

Interpretation

In this study, A-HgM exposure in patients with T2D was associated with reduced risk of MS in patients younger than 45 whereas in patients older than 45, exposure to A-HgM was associated with an increased risk of newly diagnosed MS, particularly in women.

Menopause hormone therapy significantly alters pathophysiological biomarkers of Alzheimer's disease

INTRODUCTION

This increasing body of literature indicates that menopause hormonal replacement therapy (MHT) may substantially mitigate the risk of developing late-life cognitive decline due to progressive Alzheimer's disease (AD) pathophysiology. For the first time, we investigated the question whether MHT impacts AD biomarker-informed pathophysiological dynamics in de-novo diagnosed menopausal women.

METHODS

We analyzed baseline and longitudinal differences between MHT-taking and -not women in terms of concentrations of core pathophysiological AD plasma biomarkers, validated in symptomatic and cognitively healthy individuals, including biomarkers of (1) the amyloid-β (Aβ) pathway, (2) tau pathophysiology, (3) neuronal loss, and (4) axonal damage and neurodegeneration.

RESULTS

We report a prominent and significant treatment response at the Aβ pathway biomarker level. Women at genetic risk for AD (APOE e4 allele carriers) have particularly shown favorable results from treatment.

DISCUSSION

To our knowledge, we present first prospective clinical evidence on effects of MHT on AD pathophysiology during menopause.

Alzheimer’s Disease and Inflammaging

Alzheimer’s disease is one of the most common age-related neurodegenerative disorders. The main theory of Alzheimer’s disease progress is the amyloid-β cascade hypothesis. However, the initial mechanisms of insoluble forms of amyloid-β formation and hyperphosphorylated tau protein in neurons remain unclear. One of the factors, which might play a key role in senile plaques and tau fibrils generation due to Alzheimer’s disease, is inflammaging, i.e., systemic chronic low-grade age-related inflammation. The activation of the proinflammatory cell phenotype is observed during aging, which might be one of the pivotal mechanisms for the development of chronic inflammatory diseases, e.g., atherosclerosis, metabolic syndrome, type 2 diabetes mellitus, and Alzheimer’s disease. This review discusses the role of the inflammatory processes in developing neurodegeneration, activated during physiological aging and due to various diseases such as atherosclerosis, obesity, type 2 diabetes mellitus, and depressive disorders.

Increased eHSP70-to-iHSP70 ratio in prediabetic and diabetic postmenopausal women: a biomarker of cardiometabolic risk

Decreased estrogen levels in menopause are associated with anthropometric, metabolic, and inflammatory impairments, predisposing women to cardiometabolic risk factors such as diabetes. Menopause and type two diabetes (DM2) are marked by altered heat shock response (HSR), shown by decreased expression of the 70-kDa heat shock protein in the intracellular milieu (iHSP70). While iHSP70 plays an anti-inflammatory role, extracellular HSP70 (eHSP70) may mediate pro-inflammatory pathways and has been associated with insulin resistance in DM2. Considering the roles of these proteins according to localization, the eHSP70-to-iHSP70 ratio (H-index) has been proposed as a biomarker for HSR. We, therefore, evaluated whether this biomarker is associated with glycemic and inflammatory status in postmenopausal women. In this transversal study, 36 postmenopausal women were grouped according to fasting glycemia status as either the control group (normoglycemic, ≤ 99 mg/dL) or DM2 (prediabetic and diabetic, glycemia ≥ 100 mg/dL). DM2 group showed higher triglyceride/glucose (TyG) index and plasma atherogenic index (PAI), both of which are indicators of cardiometabolic risk. In addition, we found that the eHSP70-to-iHSP70 ratio (plasma/peripheral blood mononuclear cells-PBMC ratio) was higher in the DM2 group, compared with the control group. Furthermore, blood leukocyte and glycemia levels were positively correlated with the eHSP70-to-iHSP70 ratio in women that presented H-index values above 1.0 (a.u.). Taken together, our results highlight the eHSP70-to-iHSP70 ratio as a biomarker of altered HSR in DM2 postmenopausal women.

Estrogen deficiency exacerbates learning and memory deficits associated with glucose metabolism disorder in APP/PS1 double transgenic female mice

Alterations in glucose metabolism occur in the brain in the early stage of Alzheimer's disease (AD), and menopausal women have more severe metabolic dysfunction and are more prone to dementia than men. Although estrogen deficiency-induced changes in glucose metabolism have been previously studied in animal models, their molecular mechanisms in AD remain elusive. To investigate this issue, double transgenic (APP/PS1) female mice were subjected to bilateral ovariectomy at 3 months of age and were sacrificed 1 week, 1 month and 3 months after surgery to simulate early, middle and late postmenopause, respectively. Our analysis demonstrated that estrogen deficiency exacerbates learning and memory deficits in this mouse model of postmenopause. Estrogen deficiency impairs the function of mitochondria in glucose metabolism. It is possible that the occurrence of AD is associated with the aberrant mitochondrial ERβ-mediated IGF-1/IGF-1R/GSK-3β signaling pathway. In this study, we established a potential mechanism for the increased risk of AD in postmenopausal women and proposed a therapeutic target for AD due to postmenopause.

Ferula communis L. (Apiaceae) Root Acetone-Water Extract: Phytochemical Analysis, Cytotoxicity and In Vitro Evaluation of Estrogenic Properties

Ferula communis L. (F. communis) belongs to the Apiaceae family and is a herbaceous plant with various pharmaceutical properties, due to the different contents of bioactive compounds extracted mainly from its roots, as well as its leaves and rhizome. To date, this plant extract has demonstrated estrogenic, anti-inflammatory, antiproliferative, cytotoxic, antimicrobial and anti-neoplastic properties. Its estrogenic activity is justified by the presence of ferutinin, an ester of a sesquiterpenic alcohol that acts as an agonist for estrogen receptors, with a chemical formula equal to C22H3O4. The component present in F. communis responsible for the toxicity of the plant is ferulenol, a prenylated coumarin with the chemical formula C24H30O3. This compound is capable of inducing mortality via its strong anti-coagulant properties, leading to a lethal hemorrhagic syndrome, ferulosis, in animals that feed on a chemotype of F. communis containing a high amount of ferulenol. The removal of the component ferulenol makes extracts of Ferula non-toxic. In fact, the remaining prenylated coumarins are not present in concentrations sufficient to induce toxicity. The intake of high concentrations of the extract of this plant leads a double dose-dependent effect that is typical of sesquiterpenes such as ferutinin. Here, we assessed the cytotoxicity and the estrogenic properties of the F. communis phytocomplex obtained through extraction using a mixture of acetone and water. Among the active constituents of F. communis, the identification of ferutinin and ferulenol was performed using HPLC. The effects of the extract were evaluated, following the removal of ferulenol, on three cell lines: human breast cancer MCF-7, human cervical cancer HeLa and human osteoblastic sarcoma Saos-2. The choice of these cell lines was justified by the need to mimic certain processes which may occur in vivo and which are estrogen-dependent. The obtained results demonstrated that F. communis extract, in addition to possessing an estrogenic-like property, showed a dose-dependent effect. Low concentrations (0.1–0.8 μM) demonstrated a hyperproliferative effect, whereas higher concentrations (1.6–50 μM) were toxic. Therefore, this extract could be an excellent candidate to make up for a reduction or lack of estrogen.

Ovarian steroid hormones: A long overlooked but critical contributor to brain aging and Alzheimer's disease

Ovarian hormones, particularly 17β-estradiol, are involved in numerous neurophysiological and neurochemical processes, including those subserving cognitive function. Estradiol plays a key role in the neurobiology of aging, in part due to extensive interconnectivity of the neural and endocrine system. This aspect of aging is fundamental for women's brains as all women experience a drop in circulating estradiol levels in midlife, after menopause. Given the importance of estradiol for brain function, it is not surprising that up to 80% of peri-menopausal and post-menopausal women report neurological symptoms including changes in thermoregulation (vasomotor symptoms), mood, sleep, and cognitive performance. Preclinical evidence for neuroprotective effects of 17β-estradiol also indicate associations between menopause, cognitive aging, and Alzheimer's disease (AD), the most common cause of dementia affecting nearly twice more women than men. Brain imaging studies demonstrated that middle-aged women exhibit increased indicators of AD endophenotype as compared to men of the same age, with onset in perimenopause. Herein, we take a translational approach to illustrate the contribution of ovarian hormones in maintaining cognition in women, with evidence implicating menopause-related declines in 17β-estradiol in cognitive aging and AD risk. We will review research focused on the role of endogenous and exogenous estrogen exposure as a key underlying mechanism to neuropathological aging in women, with a focus on whether brain structure, function and neurochemistry respond to hormone treatment. While still in development, this research area offers a new sex-based perspective on brain aging and risk of AD, while also highlighting an urgent need for better integration between neurology, psychiatry, and women's health practices.

Endogenous and Exogenous Estrogen Exposures: How Women's Reproductive Health Can Drive Brain Aging and Inform Alzheimer's Prevention

After advanced age, female sex is the major risk factor for late-onset Alzheimer's disease (AD), the most common cause of dementia affecting over 24 million people worldwide. The prevalence of AD is higher in women than in men, with postmenopausal women accounting for over 60% of all those affected. While most research has focused on gender-combined risk, emerging data indicate sex and gender differences in AD pathophysiology, onset, and progression, which may help account for the higher prevalence in women. Notably, AD-related brain changes develop during a 10-20 year prodromal phase originating in midlife, thus proximate with the hormonal transitions of endocrine aging characteristic of the menopause transition in women. Preclinical evidence for neuroprotective effects of gonadal sex steroid hormones, especially 17β-estradiol, strongly argue for associations between female fertility, reproductive history, and AD risk. The level of gonadal hormones to which the female brain is exposed changes considerably across the lifespan, with relevance to AD risk. However, the neurobiological consequences of hormonal fluctuations, as well as that of hormone therapies, are yet to be fully understood. Epidemiological studies have yielded contrasting results of protective, deleterious and null effects of estrogen exposure on dementia risk. In contrast, brain imaging studies provide encouraging evidence for positive associations between greater cumulative lifetime estrogen exposure and lower AD risk in women, whereas estrogen deprivation is associated with negative consequences on brain structure, function, and biochemistry. Herein, we review the existing literature and evaluate the strength of observed associations between female-specific reproductive health factors and AD risk in women, with a focus on the role of endogenous and exogenous estrogen exposures as a key underlying mechanism. Chief among these variables are reproductive lifespan, menopause status, type of menopause (spontaneous vs. induced), number of pregnancies, and exposure to hormonal therapy, including hormonal contraceptives, hormonal therapy for menopause, and anti-estrogen treatment. As aging is the greatest risk factor for AD followed by female sex, understanding sex-specific biological pathways through which reproductive history modulates brain aging is crucial to inform preventative and therapeutic strategies for AD.

The Cause of Alzheimer's Disease: The Theory of Multipathology Convergence to Chronic Neuronal Stress

The field of Alzheimer's disease (AD) research critically lacks an all-inclusive etiology theory that would integrate existing hypotheses and explain the heterogeneity of disease trajectory and pathologies observed in each individual patient. Here, we propose a novel comprehensive theory that we named: the multipathology convergence to chronic neuronal stress. Our new theory reconsiders long-standing dogmas advanced by previous incomplete theories. Firstly, while it is undeniable that amyloid beta (Aβ) is involved in AD, in the seminal stage of the disease Aβ is unlikely pathogenic. Instead, we hypothesize that the root cause of AD is neuronal stress in the central nervous system (CNS), and Aβ is expressed as part of the physiological response to protect CNS neurons from stress. If there is no return to homeostasis, then Aβ becomes overexpressed, and this includes the generation of longer forms that are more toxic and prone to oligomerization. Secondly, AD etiology is plausibly not strictly compartmentalized within the CNS but may also result from the dysfunction of other physiological systems in the entire body. This view implies that AD may not have a single cause, but rather needs to be considered as a spectrum of multiple chronic pathological modalities converging to the persistent stressing of CNS neurons. These chronic pathological modalities, which include cardiovascular disease, metabolic disorders, and CNS structural changes, often start individually, and over time combine with other chronic modalities to incrementally escalate the amount of stress applied to CNS neurons. We present the case for considering Aβ as a marker of neuronal stress in response to hypoxic, toxic, and starvation events, rather than solely a marker of AD. We also detail numerous human chronic conditions that can lead to neuronal stress in the CNS, making the link with co-morbidities encountered in daily clinical AD practice. Finally, we explain how our theory could be leveraged to improve clinical care for AD and related dementia in personalized medicine paradigms in the near future.

Sex Differences in Locus Coeruleus: A Heuristic Approach That May Explain the Increased Risk of Alzheimer's Disease in Females

This article aims to reevaluate our approach to female vulnerability to Alzheimer's disease (AD) and put forth a new hypothesis considering how sex differences in the locus coeruleus-noradrenaline (LC-NA) structure and function could account for why females are more likely to develop AD. We specifically focus our attention on locus coeruleus (LC) morphology, the paucity of estrogens, neuroinflammation, blood-brain barrier permeability, apolipoprotein ɛ4 polymorphism (APOEɛ4), and cognitive reserve. The role of the LC-NA system and sex differences are two of the most rapidly emerging topics in AD research. Current literature either investigates the LC due to it being one of the first brain areas to develop AD pathology or acknowledges the neuroprotective effects of estrogens and how the loss of these female hormones have the capacity to contribute to the sex differences seen in AD; however, existing research has neglected to concurrently examine these two rationales and therefore leaving our hypothesis undetermined. Collectively, this article should assist in alleviating current challenges surrounding female AD by providing thought-provoking connections into the interrelationship between the disruption of the female LC-NA system, the decline of estrogens, and AD vulnerability. It is therefore likely that treatment for this heterogeneous disease may need to be distinctly developed for females and males separately, and may require a precision medicine approach.

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

INTRODUCTION

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

METHODS

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

RESULTS

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

DISCUSSION

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

Precision hormone therapy: identification of positive responders

Since the introduction of menopausal hormone therapy (MHT) in the 1940s, randomized clinical trials and observational studies have been performed to determine the benefits and risks of MHT. However, MHT therapeutic impact remains under debate as multiple factors including genetic biomarkers and medical history contribute to inter-individual variations in neurodegenerative diseases. Herein, we review the characteristics of women who participated in clinical studies and methodological approaches for study analyses to assess the critical variables influencing an association between MHT and risk of neurodegenerative diseases. Outcomes of the review indicated that: (1) observational studies assessed outcomes of MHT in symptomatic women whereas MHT clinical trials were conducted in asymptomatic postmenopausal women not treated for menopausal symptoms, (2) in asymptomatic postmenopausal women, late MHT intervention was of no benefit, (3) different MHT treatments and regimens between observational studies and clinical trials may impact outcomes, and (4) observational studies may provide greater predictive validity for long-term neurological health outcomes as MHT was introduced in symptomatic women and administered over a long period of time. Going forward, achieving precision hormone therapy will require a priori identification of symptomatic women appropriate for MHT and the type and dose of MHT appropriate for their genetic profile and health risks.

Estrogen, brain structure, and cognition in postmenopausal women

Declining estrogen levels before, during, and after menopause can affect memory and risk for Alzheimer's disease. Undesirable side effects of hormone variations emphasize a role for hormone therapy (HT) where possible benefits include a delay in the onset of dementia-yet findings are inconsistent. Effects of HT may be mediated by estrogen receptors found throughout the brain. Effects may also depend on lifestyle factors, timing of use, and genetic risk. We studied the impact of self-reported HT use on brain volume in 562 elderly women (71-94 years) with mixed cognitive status while adjusting for aforementioned factors. Covariate-adjusted voxelwise linear regression analyses using a model with 16 predictors showed HT use as positively associated with regional brain volumes, regardless of cognitive status. Examinations of other factors related to menopause, oophorectomy and hysterectomy status independently yielded positive effects on brain volume when added to our model. One interaction term, HTxBMI, out of several examined, revealed significant negative association with overall brain volume, suggesting a greater reduction in brain volume than BMI alone. Our main findings relating HT to regional brain volume were as hypothesized, but some exploratory analyses were not in line with existing hypotheses. Studies suggest lower levels of estrogen resulting from oophorectomy and hysterectomy affect brain volume negatively, and the addition of HT modifies the relation between BMI and brain volume positively. Effects of HT may depend on the age range assessed, motivating studies with a wider age range as well as a randomized design.

Dynamic Neuroimmune Profile during Mid-life Aging in the Female Brain and Implications for Alzheimer Risk

Aging and endocrine transition states can significantly impact inflammation across organ systems. Neuroinflammation is well documented in Alzheimer disease (AD). Herein, we investigated neuroinflammation that emerges during mid-life aging, chronological and endocrinological, in the female brain as an early initiating mechanism driving AD risk later in life. Analyses were conducted in a translational rodent model of mid-life chronological and endocrinological aging followed by validation in transcriptomic profiles from women versus age-matched men. In the translational model, the neuroinflammatory profile of mid-life aging in females was endocrine and chronological state specific, dynamic, anatomically distributed, and persistent. Microarray dataset analyses of aging human hippocampus indicated a sex difference in neuroinflammatory profile in which women exhibited a profile comparable to the pattern discovered in our translational rodent model, whereas age-matched men exhibited a profile consistent with low neuroimmune activation. Translationally, these findings have implications for therapeutic interventions during mid-life to decrease late-onset AD risk.

Neuroimmunomodulation by estrogen in health and disease

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

Vitamin D Insufficiency and Deficiency and Mortality from Respiratory Diseases in a Cohort of Older Adults: Potential for Limiting the Death Toll during and beyond the COVID-19 Pandemic?

The COVID-19 pandemic goes along with increased mortality from acute respiratory disease. It has been suggested that vitamin D3 supplementation might help to reduce respiratory disease mortality. We assessed the prevalence of vitamin D insufficiency and deficiency, defined by 25-hydroxyvitamin D (25(OH)D) blood levels of 30-50 and <30 nmol/L, respectively, and their association with mortality from respiratory diseases during 15 years of follow-up in a cohort of 9548 adults aged 50-75 years from Saarland, Germany. Vitamin D insufficiency and deficiency were common (44% and 15%, respectively). Compared to those with sufficient vitamin D status, participants with vitamin D insufficiency and deficiency had strongly increased respiratory mortality, with adjusted hazard ratios (95% confidence intervals) of 2.1 (1.3-3.2) and 3.0 (1.8-5.2) overall, 4.3 (1.3-14.4) and 8.5 (2.4-30.1) among women, and 1.9 (1.1-3.2) and 2.3 (1.1-4.4) among men. Overall, 41% (95% confidence interval: 20-58%) of respiratory disease mortality was statistically attributable to vitamin D insufficiency or deficiency. Vitamin D insufficiency and deficiency are common and account for a large proportion of respiratory disease mortality in older adults, supporting the hypothesis that vitamin D3 supplementation could be helpful to limit the burden of the COVID-19 pandemic, particularly among women.

The Differential Role of Cytokines on Stress Responses in a Menopause Rat Model

Menopause is a risk factor of anxiety and depression. Also, psychoneurological symptoms are shown in almost all women in the perimenopausal period. The present study investigated if repeated stress modulates behavioral changes or the balance of pro- and anti-inflammatory cytokines in ovariectomized (OVX) rats. Albino SD female rats were randomly divided into four groups: the naïve normal group (NOR), a surgically ovariectomized group (OVX), the only stressed group (ST), and the OVX and stressed groups (OVX + ST). We performed a battery of tests such as the forced swimming test (FST), the sucrose intake, and social exploration. In the same animals, corticosterone (CORT) was assessed in the serum, and also, two representative cytokines (IL-1β and IL-4) were examined in different brain regions after all the behavior sessions for all the experimental groups. The OVX + ST group showed more immobility time in FST than the OVX group or the ST group. Also, the OVX + ST group tended to have a decreased active social exploration and sucrose solution intake compared to the OVX group or ST group. The serum concentration of CORT of the OVX + ST group was higher than the OVX group or ST group and also the level of CORT in OVX + ST was markedly increased compared to the NOR group. In the brain, the number of IL-1β immunoreactive neurons of the OVX + ST group was increased compared to the NOR group. The OVX + ST group tended to have an increase in IL-1β-positive neurons compared to the OVX or ST group. However, the number of IL-4 immunoreactive neurons of the OVX + ST group was markedly decreased compared with the NOR group. Also, the IL-4-positive neurons in the OVX + ST group was significantly decreased when compared to the ST group. These results indicate that ovariectomy and stress combine to increase the depressive-like behaviors and neuroinflammatory responses. Together, these data show neuroinflammation as a potential contributor to depressive-like symptoms during menopausal transition.