Hormonal influences on cognition and risk for Alzheimer's disease

Mind Gaps and Bone Snaps: Exploring the Connection Between Alzheimer's Disease and Osteoporosis

PURPOSE OF REVIEW

This comprehensive review discusses the complex relationship between Alzheimer's disease (AD) and osteoporosis, two conditions that are prevalent in the aging population and result in adverse complications on quality of life. The purpose of this review is to succinctly elucidate the many commonalities between the two conditions, including shared pathways, inflammatory and oxidative mechanisms, and hormonal deficiencies.

RECENT FINDINGS

AD and osteoporosis share many aspects of their respective disease-defining pathophysiology. These commonalities include amyloid beta deposition, the Wnt/β-catenin signaling pathway, and estrogen deficiency. The shared mechanisms and risk factors associated with AD and osteoporosis result in a large percentage of patients that develop both diseases. Previous literature has established that the progression of AD increases the risk of sustaining a fracture. Recent findings demonstrate that the reverse may also be true, suggesting that a fracture early in the life course can predispose one to developing AD due to the activation of these shared mechanisms. The discovery of these commonalities further guides the development of novel therapeutics in which both conditions are targeted. This detailed review delves into the commonalities between AD and osteoporosis to uncover the shared players that bring these two seemingly unrelated conditions together. The discussion throughout this review ultimately posits that the occurrence of fractures and the mechanism behind fracture healing can predispose one to developing AD later on in life, similar to how AD patients are at an increased risk of developing fractures. By focusing on the shared mechanisms between AD and osteoporosis, one can better understand the conditions individually and as a unit, thus informing therapeutic approaches and further research. This review article is part of a series of multiple manuscripts designed to determine the utility of using artificial intelligence for writing scientific reviews.

Hormone therapy is associated with lower Alzheimer's disease tau biomarkers in post-menopausal females -evidence from two independent cohorts

BACKGROUND

Females represent approximately 70% of the Alzheimer's disease (AD) cases and the literature has proposed a connection between the decreased estrogen levels during menopause and an increased AD risk. Previous investigations have predominantly focused on assessing how hormone therapy (HT) affects the likelihood of AD development and cognitive deterioration. However, as the research framework has shifted toward a biomarker-defined AD and alterations in specific biomarkers could take place years before cognitive decline becomes discernible, it is crucial to examine how HT influences AD biomarkers. The main goal of this study was to evaluate the impact of HT on AD biomarker-informed pathophysiology in both cognitively unimpaired (CU) and cognitively impaired (CI) post-menopausal females across the aging and AD spectrum.

METHODS

This cross-sectional study included post-menopausal females without HT history (HT-) and with HT (HT+) at the time of PET imaging assessment from two cohorts: the Translational Biomarkers in Aging and Dementia (TRIAD) cohort, and the Alzheimer's Disease Neuroimaging Initiative (ADNI). Participants underwent magnetic resonance imaging (MRI), positron emission tomography (PET) and biofluid collection. Voxel-based t-tests were performed to assess the differences in amyloid-β (Aβ) and tau neurofibrillary tangles (NFTs) loads between HT- and HT + females. Linear regression models with interaction terms were also conducted to examine the interactive effects of HT and Aβ-PET on regional tau-PET.

RESULTS

HT + females demonstrated significantly lower tau-PET standardized uptake value ratio (SUVR) in Braak I-II ROIs (P < 0.05, Hedges' g = 0.73), Braak III-IV ROIs (P < 0.0001, Hedges' g = 0.74) and Braak V-VI ROIs (P < 0.0001, Hedges' g = 0.69) compared to HT- females. HT + females also showed significantly lower CSF p-tau181 (P < 0.001) and plasma p-tau181 (P < 0.0001) concentrations. Additionally, results from multivariate linear regression models indicated that HT interacts with cortical Aβ and is associated with lower regional NFT load.

CONCLUSIONS

Overall, findings from this observational study suggest that HT is associated with lower tau neuroimaging and fluid biomarkers in postmenopausal females. Due to the close link between tau and cognition, this study highlights the need for large randomized controlled trials designed to systemically study the influences of HT on AD biomarkers and disease progression.

Advanced Glycation End Products-Induced Alzheimer's Disease and Its Novel Therapeutic Approaches: A Comprehensive Review

Advanced glycation end products (AGEs) accumulate in the brain, leading to neurodegenerative conditions such as Alzheimer's disease (AD). The pathophysiology of AD is influenced by receptors for AGEs and toll-like receptor 4 (TLR4). Protein glycation results in irreversible AGEs through a complicated series of reactions involving the formation of Schiff's base, the Amadori reaction, followed by the Maillard reaction, which causes abnormal brain glucose metabolism, oxidative stress, malfunctioning mitochondria, plaque deposition, and neuronal death. Amyloid plaque and other stimuli activate macrophages, which are crucial immune cells in AD development, triggering the production of inflammatory molecules and contributing to the disease's pathogenesis. The risk of AD is doubled by risk factors for atherosclerosis, dementia, advanced age, and type 2 diabetic mellitus (DM). As individuals age, the prevalence of neurological illnesses such as AD increases due to a decrease in glyoxalase levels and an increase in AGE accumulation. Insulin's role in proteostasis influences hallmarks of AD-like tau phosphorylation and amyloid β peptide clearance, affecting lipid metabolism, inflammation, vasoreactivity, and vascular function. The high-mobility group box 1 (HMGB1) protein, a key initiator and activator of a neuroinflammatory response, has been linked to the development of neurodegenerative diseases such as AD. The TLR4 inhibitor was found to improve memory and learning impairment and decrease Aβ build-up. Therapeutic research into anti-glycation agents, receptor for advanced glycation end products (RAGE) inhibitors, and AGE breakers offers hope for intervention strategies. Dietary and lifestyle modifications can also slow AD progression. Newer therapeutic approaches targeting AGE-related pathways are needed.

Estradiol enhanced neuronal plasticity and ameliorated astrogliosis in human iPSC-derived neural models

Introduction

17β-Estradiol (E2) is a sex hormone that has been previously demonstrated to have neurotherapeutic effects on animal models of Alzheimer's disease (AD). However, clinical trials on E2 replacement therapy for preventing AD onset yielded inconsistent results. Therefore, it is imperative to clarify the therapeutic effects of E2 on human cells. In this study, we utilized induced pluripotent stem cells (iPSCs) derived from multiple AD donors to explore the therapeutic effects of E2 on the in vitro model of human cells.

Methods

We conducted a systematic review and meta-analysis using a random-effects model of the previously reported AD clinical trials to summarize the effects of E2 replacement therapy on AD prevention. Subsequently, we induced iPSCs from the donors of the healthy control (1210B2 line (female) and 201B7 line (female)), the familial AD (APP V717L line (female) and APP KM670/671NL line (female)), and the sporadic AD (UCSD-SAD3.7 line (APOE ε3/ε3) (male), UCSD-SAD7D line (APOE ε3/ε4) (male), and TMGH-1 line (APOE ε3/ε3) (female)), then differentiated to neurons. In addition to the mono-culture model of the neurons, we also examined the effects of E2 on the co-culture model of neurons and astrocytes.

Results

The meta-analysis of the clinical trials concluded that E2 replacement therapy reduced the risk of AD onset (OR, 0.69; 95 % confidence interval [CI], 0.53-0.91; I2 = 82 %). Neural models from the iPSCs of AD donors showed an increase in secreted amyloid-beta (Aβ) levels in the mono-culture model and an astrogliosis-like phenotype in the co-culture model. E2 treatment to the neuronal models derived from the iPSCs enhanced neuronal activity and increased neurite complexity. Furthermore, E2 treatment of the co-culture model ameliorated the astrogliosis-like phenotype. However, in contrast to the previous reports using mouse models, E2 treatment did not change AD pathogenesis, including Aβ secretion and phosphorylated tau (pTau) accumulation.

Conclusion

E2 treatment of the human cellular model did not impact Aβ secretion and pTau accumulation, but promoted neuronal plasticity and alleviated the astrogliosis-like phenotype. The limited effects of E2 may give a clue for the mixed results of E2 clinical trials.

From the Mind to the Spine: The Intersecting World of Alzheimer's and Osteoporosis

PURPOSE OF REVIEW

This comprehensive review delves into the intricate interplay between Alzheimer's disease (AD) and osteoporosis, two prevalent conditions with significant implications for individuals' quality of life. The purpose is to explore their bidirectional association, underpinned by common pathological processes such as aging, genetic factors, inflammation, and estrogen deficiency.

RECENT FINDINGS

Recent advances have shown promise in treating both Alzheimer's disease (AD) and osteoporosis by targeting disease-specific proteins and bone metabolism regulators. Monoclonal antibodies against beta-amyloid and tau for AD, as well as RANKL and sclerostin for osteoporosis, have displayed therapeutic potential. Additionally, ongoing research has identified neuroinflammatory genes shared between AD and osteoporosis, offering insight into the interconnected inflammatory mechanisms. This knowledge opens avenues for innovative dual-purpose therapies that could address both conditions, potentially revolutionizing treatment approaches for AD and osteoporosis simultaneously. This review underscores the potential for groundbreaking advancements in early diagnosis and treatment by unraveling the intricate connection between AD and bone health. It advocates for a holistic, patient-centered approach to medical care that considers both cognitive and bone health, ultimately aiming to enhance the overall well-being of individuals affected by these conditions. This review article is part of a series of multiple manuscripts designed to determine the utility of using artificial intelligence for writing scientific reviews.

The Potential of a Stratified Approach to Drug Repurposing in Alzheimer's Disease

Alzheimer's disease (AD) is a complex neurodegenerative condition that is characterized by the build-up of amyloid-beta plaques and neurofibrillary tangles. While multiple theories explaining the aetiology of the disease have been suggested, the underlying cause of the disease is still unknown. Despite this, several modifiable and non-modifiable factors that increase the risk of developing AD have been identified. To date, only eight AD drugs have ever gained regulatory approval, including six symptomatic and two disease-modifying drugs. However, not all are available in all countries and high costs associated with new disease-modifying biologics prevent large proportions of the patient population from accessing them. With the current patient population expected to triple by 2050, it is imperative that new, effective, and affordable drugs become available to patients. Traditional drug development strategies have a 99% failure rate in AD, which is far higher than in other disease areas. Even when a drug does reach the market, additional barriers such as high cost and lack of accessibility prevent patients from benefiting from them. In this review, we discuss how a stratified medicine drug repurposing approach may address some of the limitations and barriers that traditional strategies face in relation to drug development in AD. We believe that novel, stratified drug repurposing studies may expedite the discovery of alternative, effective, and more affordable treatment options for a rapidly expanding patient population in comparison with traditional drug development methods.

The Role of Steroidomics in the Diagnosis of Alzheimer's Disease and Type 2 Diabetes Mellitus

Epidemiological studies suggest an association between Alzheimer's disease (AD) and type 2 diabetes mellitus (T2DM). This study aimed to investigate the pathophysiological markers of AD vs. T2DM for each sex separately and propose models that would distinguish control, AD, T2DM, and AD-T2DM comorbidity groups. AD and T2DM differed in levels of some circulating steroids (measured mostly by GC-MS) and in other observed characteristics, such as markers of obesity, glucose metabolism, and liver function tests. Regarding steroid metabolism, AD patients (both sexes) had significantly higher sex hormone binding globulin (SHBG), cortisol, and 17-hydroxy progesterone, and lower estradiol and 5α-androstane-3α,17β-diol, compared to T2DM patients. However, compared to healthy controls, changes in the steroid spectrum (especially increases in levels of steroids from the C21 group, including their 5α/β-reduced forms, androstenedione, etc.) were similar in patients with AD and patients with T2DM, though more expressed in diabetics. It can be assumed that many of these steroids are involved in counter-regulatory protective mechanisms that mitigate the development and progression of AD and T2DM. In conclusion, our results demonstrated the ability to effectively differentiate AD, T2DM, and controls in both men and women, distinguish the two pathologies from each other, and differentiate patients with AD and T2DM comorbidities.

Antioxidants: an approach for restricting oxidative stress induced neurodegeneration in Alzheimer's disease

Alzheimer's disease (AD) is the leading cause of dementia, affecting millions of people worldwide. Oxidative stress contributes towards induction of neurodegeneration. It is one of the reasons behind initiation and progression of Alzheimer's disease. Understanding of oxidative balance and restoration of oxidative stress has demonstrated its effectiveness in the management of AD. Various natural and synthetic molecules have been found to be effective in different models of AD. Some clinical studies also support the use of antioxidants for prevention of neurodegeneration in AD. In this review we are summarizing the development of antioxidants to restrict oxidative stress induced neurodegeneration in AD.

Development of dementia in patients who underwent bariatric surgery

BACKGROUND

Dementia, including Alzheimer's disease, interfere with daily function and are one of the major causes of disability, institutionalization, and death. Obesity is associated with an increased risk of dementia. However, the effect of significant and sustained weight loss following bariatric surgery on dementia is not known. The purpose of this study was to assess the long-term risk of dementia following bariatric surgery.

METHODS

A surgical cohort was identified from the Utah Bariatric Surgery Registry and was linked to the Utah Population Database that includes electronic medical records, death records, and State Facility data. Adult subjects (≥ 18 years old) at time of surgery (1996-2016) were matched with non-surgical subjects. The final sample included 51,078 subjects (1:2 matching); surgery group n = 17,026; non-surgery subjects n = 34,052). Dementia were identified by ICD-9/10 diagnosis codes following surgery year or matched baseline year. Cox proportional hazard model was used to calculate the hazard ratio in the outcome between the groups.

RESULTS

Average (SD) age of the subjects was 42 (12) years old at surgery or matched baseline year, 78% were female and mean follow-up time was 10.5 years. 1.4% of the surgery group and 0.5% of the control group had an incidence of dementia. Controlling the covariates in the Cox regression, the surgery group had a higher risk for dementia incidence than the matched non-surgery subjects (HR = 1.33, p = 0.02).

CONCLUSIONS

The study showed an increased hazard for dementia in individuals who underwent bariatric surgery compared to matched non-surgical subjects. Additional long-term data is needed to verify this association.

Amyloid Beta in Aging and Alzheimer's Disease

Alzheimer's disease (AD), is a progressive neurodegenerative disease that affects behavior, thinking, learning, and memory in elderly individuals. AD occurs in two forms, early onset familial and late-onset sporadic; genetic mutations in PS1, PS2, and APP genes cause early onset familial AD, and a combination of lifestyle, environment and genetic factors causes the late-onset sporadic form of the disease. However, accelerated disease progression is noticed in patients with familial AD. Disease-causing pathological changes are synaptic damage, and mitochondrial structural and functional changes, in addition to increased production and accumulation of phosphorylated tau (p-tau), and amyloid beta (Aβ) in the affected brain regions in AD patients. Aβ is a peptide derived from amyloid precursor protein (APP) by proteolytic cleavage of beta and gamma secretases. APP is a glycoprotein that plays a significant role in maintaining neuronal homeostasis like signaling, neuronal development, and intracellular transport. Aβ is reported to have both protective and toxic effects in neurons. The purpose of our article is to summarize recent developments of Aβ and its association with synapses, mitochondria, microglia, astrocytes, and its interaction with p-tau. Our article also covers the therapeutic strategies that reduce Aβ toxicities in disease progression and discusses the reasons for the failures of Aβ therapeutics.

Membrane estrogen receptor ERα activation improves tau clearance via autophagy induction in a tauopathy cell model

Alzheimer's disease (AD) is the most prevalent aging-associated neurodegenerative disease, with a higher incidence in women than men. There is evidence that sex hormone replacement therapy, particularly estrogen, reduces memory loss in menopausal women. Neurofibrillary tangles are associated with tau protein aggregation, a characteristic of AD and other tauopathies. In this sense, autophagy is a promising cellular process to remove these protein aggregates. This study evaluated the autophagy mechanisms involved in neuroprotection induced by 17β-estradiol (E2) in a Tet-On inducible expression tauopathy cell model (EGFP-tau WT or with the P301L mutation, 0N4R isoform). The results indicated that 17β-estradiol induces autophagy by activating AMPK in a concentration-dependent manner, independent of mTOR signals. The estrogen receptor α (ERα) agonist, PPT, also induced autophagy, while the ERα antagonist, MPP, substantially attenuated the 17β-estradiol-mediated autophagy induction. Notably, 17β-estradiol increased LC3-II levels and phosphorylated and total tau protein clearance in the EGFP-tau WT cell line but not in EGPF-tau P301L. Similar results were observed with E2-BSA, a plasma membrane-impermeable estrogen, suggesting membrane ERα involvement in non-genomic estrogenic pathway activation. Furthermore, 17β-estradiol-induced autophagy led to EGFP-tau protein clearance. These results demonstrate that modulating autophagy via the estrogenic pathway may represent a new therapeutic target for treating AD.

Sex Hormones, Sleep, and Memory: Interrelationships Across the Adult Female Lifespan

As the population of older adults grows, so will the prevalence of aging-related conditions, including memory impairments and sleep disturbances, both of which are more common among women. Compared to older men, older women are up to twice as likely to experience sleep disturbances and are at a higher risk of cognitive decline and Alzheimer's disease and related dementias (ADRD). These sex differences may be attributed in part to fluctuations in levels of female sex hormones (i.e., estrogen and progesterone) that occur across the adult female lifespan. Though women tend to experience the most significant sleep and memory problems during the peri-menopausal period, changes in memory and sleep have also been observed across the menstrual cycle and during pregnancy. Here, we review current knowledge on the interrelationships among female sex hormones, sleep, and memory across the female lifespan, propose possible mediating and moderating mechanisms linking these variables and describe implications for ADRD risk in later life.

MethReg: estimating the regulatory potential of DNA methylation in gene transcription

Epigenome-wide association studies often detect many differentially methylated sites, and many are located in distal regulatory regions. To further prioritize these significant sites, there is a critical need to better understand the functional impact of CpG methylation. Recent studies demonstrated that CpG methylation-dependent transcriptional regulation is a widespread phenomenon. Here, we present MethReg, an R/Bioconductor package that analyzes matched DNA methylation and gene expression data, along with external transcription factor (TF) binding information, to evaluate, prioritize and annotate CpG sites with high regulatory potential. At these CpG sites, TF-target gene associations are often only present in a subset of samples with high (or low) methylation levels, so they can be missed by analyses that use all samples. Using colorectal cancer and Alzheimer's disease datasets, we show MethReg significantly enhances our understanding of the regulatory roles of DNA methylation in complex diseases.

Hormones and Sex-Specific Medicine in Human Physiopathology

A prodigious increment of scientific evidence in both preclinical and clinical studies is narrowing a major gap in knowledge regarding sex-specific biological responses observed in numerous branches of clinical practices. Some paradigmatic examples include neurodegenerative and mental disorders, immune-related disorders such as pathogenic infections and autoimmune diseases, oncologic conditions, and cardiovascular morbidities. The male-to-female proportion in a population is expressed as sex ratio and varies eminently with respect to the pathophysiology, natural history, incidence, prevalence, and mortality rates. The factors that determine this scenario incorporate both sex-associated biological differences and gender-dependent sociocultural issues. A broad narrative review focused on the current knowledge about the role of hormone regulation in gender medicine and gender peculiarities across key clinical areas is provided. Sex differences in immune response, cardiovascular diseases, neurological disorders, cancer, and COVID-19 are some of the hints reported. Moreover, gender implications in occupational health and health policy are offered to support the need for more personalized clinical medicine and public health approaches to achieve an ameliorated quality of life of patients and better outcomes in population health.

Multifocal Cerebral Microinfarcts Modulate Early Alzheimer’s Disease Pathology in a Sex-Dependent Manner

Alzheimer’s disease (AD) constitutes a major cause of dementia, affecting more women than men. It is characterized by amyloid-β (Aβ) deposition and neurofibrillary tangles (NFTs) formation, associated with a progressive cognitive decline. Evidence indicates that AD onset increases the prevalence of cerebral microinfarcts caused by vascular pathologies, which occur in approximately in half of AD patients. In this project, we postulated that multifocal cerebral microinfarcts decisively influence early AD-like pathology progression in a sex dependent manner in young APP/PS1 mice. For this purpose, we used a novel approach to model multifocal microinfarcts in APP/PS1 mice via the sporadic occlusions of the microvasculature. Our findings indicate that microinfarcts reduced Aβ deposits without affecting soluble Aβ levels in the brain of male and female APP/PS1 mice, while causing rapid and prolonged cognitive deficits in males, and a mild and transient cognitive decline in females. In male APP/PS1 mice, microinfarcts triggered an acute hypoperfusion followed by a chronic hyperperfusion. Whereas in female APP/PS1 mice, microinfarcts caused an acute hypoperfusion, which was recovered in the chronic phase. Microinfarcts triggered a robust microglial activation and recruitment of peripheral monocytes to the lesion sites and Aβ plaques more potently in female APP/PS1 mice, possibly accounting for the reduced Aβ deposition. Finally, expression of Dickkopf-1 (DKK1), which plays a key role in mediating synaptic and neuronal dysfunction in AD, was strongly induced at the lesion sites of male APP/PS1 mice, while its expression was reduced in females. Our findings suggest that multifocal microinfarcts accelerate AD pathology more potently in young males compared to young females independently upon Aβ pathology via modulation of neurovascular coupling, inflammatory response, and DKK1 expression. Our results suggest that the effects of microinfarcts should be taken into consideration in AD diagnosis, prognosis, and therapies.

Association of Depressive Symptoms and Cognition in Older Adults Without Dementia Across Different Biomarker Profiles

BACKGROUND

Depression is a late-life risk factor for cognitive decline. Evidence suggests an association between Alzheimer's disease (AD) associated pathologic changes and depressive symptoms.

OBJECTIVE

To investigate the influence of AT(N) biomarker profile (amyloid-β [A], p-tau [T], and neurodegeneration [N]) and gender on cross-sectional associations between subclinical depressive symptoms and cognitive function among older adults without dementia.

METHODS

Participants included 868 individuals without dementia from the Alzheimer's Disease Neuroimaging Initiative (ADNI). Depressive symptoms were measured using the Geriatric Depression Scale (GDS). ADNI neuropsychological composite scores assessed memory and executive function (EF). PET, cerebrospinal fluid, and MRI modalities classified the study sample into biomarker profiles: normal biomarkers (A-T-N-), AD continuum (A+T±N±), and suspect non-AD pathology (SNAP; A-T±N-or A-T-N±). Multivariate regression models were used to investigate associations between GDS and cognitive domains.

RESULTS

GDS was negatively associated with memory (β= -0.156, p < 0.001) and EF (β= -0.147, p < 0.001) in the whole sample. When classified by biomarker profile, GDS was negatively associated with memory and EF in AD continuum (memory: β= -0.174, p < 0.001; EF: β= -0.129 p = 0.003) and SNAP (memory: β= -0.172, p = 0.005; EF: β= -0.197, p = 0.001) subgroups. When stratified by sex, GDS was negatively associated with memory (β= -0.227, p < 0.001) and EF (β= -0.205, p < 0.001) in men only.

CONCLUSION

The association between subclinical depressive symptoms and cognitive function is highly influenced by the AT(N) biomarker profile.

Neurodegenerative Disease: Roles for Sex, Hormones, and Oxidative Stress

Neurodegenerative diseases cause severe impairments in cognitive and motor function. With an increasing aging population and the onset of these diseases between 50 and 70 years, the consequences are bound to be devastating. While age and longevity are the main risk factors for neurodegenerative diseases, sex is also an important risk factor. The characteristic of sex is multifaceted, encompassing sex chromosome complement, sex hormones (estrogens and androgens), and sex hormone receptors. Sex hormone receptors can induce various signaling cascades, ranging from genomic transcription to intracellular signaling pathways that are dependent on the health of the cell. Oxidative stress, associated with aging, can impact the health of the cell. Sex hormones can be neuroprotective under low oxidative stress conditions but not in high oxidative stress conditions. An understudied sex hormone receptor that can induce activation of oxidative stress signaling is the membrane androgen receptor (mAR). mAR can mediate nicotinamide adenine dinucleotide-phosphate (NADPH) oxidase (NOX)-generated oxidative stress that is associated with several neurodegenerative diseases, such as Alzheimer disease. Further complicating this is that aging can alter sex hormone signaling. Prior to menopause, women experience more estrogens than androgens. During menopause, this sex hormone profile switches in women due to the dramatic ovarian loss of 17β-estradiol with maintained ovarian androgen (testosterone, androstenedione) production. Indeed, aging men have higher estrogens than aging women due to aromatization of androgens to estrogens. Therefore, higher activation of mAR-NOX signaling could occur in menopausal women compared with aged men, mediating the observed sex differences. Understanding of these signaling cascades could provide therapeutic targets for neurodegenerative diseases.

Estrogen receptor beta (ESR2) gene polymorphism and susceptibility to dementia

Strong evidence supports the involvement of sex steroid hormones in the development and progression of dementia. Attention has been largely focused on the association between genetic variants of estrogen receptor alpha (ERα, ESR1) with dementia, although several studies indicate that ERβ is predominantly expressed in the brain. Interestingly, however, a limited number of studies evaluate the role of ERβ (ESR2) in dementia. Therefore, a meta-analysis was conducted to clarify the association between ESR2 genetic polymorphisms and the risk of dementia. All the relevant studies evaluating ESR2 genetic polymorphisms and dementia were identified through online databases. In total, 14 studies including 20,609 subjects were analyzed. Collectively, it was found that a combined data set of ESR2 polymorphisms was not associated with dementia risk. Interestingly, ESR2 rs4986938 polymorphism is significantly associated with dementia in the Asian population (OR = 0.73, 95% CI 0.59-0.91, P = 0.006). The carrier of A allele in rs4986938 exhibits a protective effect against dementia (A vs. G, OR = 0.6633, P = 0.012; AA + GA vs. GG, OR = 0.6499, P = 0.014; GA vs. AA + GG, OR = 0.6672, P = 0.025; GA vs. GG, OR = 0.6617, P = 0.022). In conclusion, our study suggests that ESR2 genetic polymorphisms are not significantly associated with dementia risk. ESR2 rs4986938 may have potential as a genetic marker for dementia in the Asian population. However, further studies need to verify this conclusion.

In Vitro and In Vivo Evaluation of GSK-3 Radioligands in Alzheimer's Disease: Preliminary Evidence of Sex Differences

Glycogen synthase kinase-3 (GSK-3) is a positron emission tomography (PET) imaging target with implications in the pathogenesis of Alzheimer's disease (AD). This preliminary study evaluates human AD and transgenic P301L mouse brain tissues using the GSK-3-targeting radiotracers [³H]PF-367 and [³H]OCM-44 in radioligand binding assays. A saturation analysis showed decreased GSK-3 density in female human AD compared to a normal healthy brain. Equivalence in density (B _max), affinity (K _d), and apparent affinity (K _i) of both radiotracers was demonstrated to enable their interchangeability for in vitro evaluations of GSK-3 expression. An evaluation of P301L mouse brain by [³H]/[¹¹C]OCM-44 delineated differences in the B _max of GSK-3 between the control and transgenic mice within male subjects. PET imaging showed similar trends to those observed in vitro. Sex differences are revealed as a potential parameter to consider in the development of GSK-3-targeted diagnostics and therapeutics and could guide recruitment for clinical studies.

Long-Term Gender-Affirming Hormone Therapy and Cognitive Functioning in Older Transgender Women Compared With Cisgender Women and Men

BACKGROUND

Long-term gender-affirming hormone therapy (GHT) in older transgender individuals could have beneficial effects on cognitive functioning. Cardiovascular risk factors and psychological factors are known determinants of cognition. Despite the rising number of older transgender individuals, only few studies have examined cognitive functioning in this population.

AIM

We aimed to assess differences in cognitive functioning between transgender women, and non-transgender (cisgender) women and men, and investigated the contribution of cardiovascular risk factors and psychological factors on these differences.

METHODS

In this study, 37 transgender women (age range 55 to 69) receiving GHT for at least ten years (range 10.2 to 41.6) were examined, and their cognitive functioning was compared to an age and education level matched cohort consisting of 222 cisgender women and men from the Longitudinal Aging Study Amsterdam. Linear regression analyses were performed.

OUTCOMES

Cognitive functioning was assessed by neuropsychological tests including Mini-Mental State Examination (MMSE), Category Fluency animals, Letter Fluency D, 15-Word test (15WT) immediate and delayed recall. Additionally, cardiovascular risk factors and psychological factors such as cardiovascular disease, hypertension, antihypertensive use, statin use, diabetes mellitus, overweight, smoking, alcohol consumption, psychopharmaceutical use, anxiety and depression symptoms were collected.

RESULTS

Transgender women had higher MMSE scores compared with cisgender women (+0.9, 95% CI 0.4 to 1.5), and cisgender men (+1.1, 95% CI 0.4 to 1.8). On all other tests transgender women performed similar to cisgender men. Transgender women performed at a lower level than cisgender women on 15WT immediate recall, -5.5, 95% CI -7.6 to -3.4, and 15WT delayed recall, -2.7, 95% CI -3.7 to -1.7, and equal to cisgender women on Fluency animals and Fluency D. Cardiovascular and psychological factors (i.e., cardiovascular disease and depression symptoms) partly explained differences on MMSE score between transgender women and cisgender-control groups.

CLINICAL IMPLICATIONS

The results of this study do not indicate a need for tailored hormone treatment strategies for older transgender women, based on cognitive aspects after long-term GHT.

STRENGTHS & LIMITATIONS

As one of the first studies, this study compared older transgender women to a large cohort of cisgender men and women regarding cognitive functioning and took into account numerous potential influencing factors. Limitations include difference in test procedures and the cross-sectional design of the study.

CONCLUSION

Cognitive differences between transgender women and cisgender women and men were small, albeit significant. This may suggest that long-term GHT effects on cognitive functioning in older transgender women are minimal. van Heesewijk JO, Dreijerink KMA, Wiepjes CM, et al. Long-Term Gender-Affirming Hormone Therapy and Cognitive Functioning in Older Transgender Women Compared With Cisgender Women and Men. J Sex Med 2021;18:1434-1443.

Interactive rather than independent effect of APOE and sex potentiates tau deposition in women

The apolipoprotein E gene (APOE) is the most important genetic risk factor for sporadic Alzheimer disease, with the ε4 allele being associated with increased cerebral amyloid-β and tau pathologies. Although APOE has been suggested to have a stronger effect in women as compared to men, there is a lack of comprehensive assessment on how the interactive effect of APOE and sex modulates regional vulnerability to tau accumulation. We previously have shown the regional vulnerability to the interactive effect of tau and APOE, yet the sex difference was not specifically addressed. In this study, we leveraged PET imaging data from the Translational Biomarkers in Aging and Dementia cohort at McGill University Research Centre for Studies in Aging to elucidate the APOE-by-sex interactive effect on tau burden. We hypothesized sex-dependent regional vulnerability to tau deposition. PET radiopharmaceuticals [18F]AZD4694 and [18F]MK6240 were used to assess amyloid-β and tau level respectively in 277 subjects from the Translational Biomarkers in Aging and Dementia cohort. We found that the interaction between APOE and sex, rather than their independent main effects, was associated with abnormal tau accumulation in medial temporal regions. Specifically, we found that female APOEε4 carriers showed significantly higher tau burden in early tau deposition regions including the hippocampus, entorhinal and parahippocampal cortices, after accounting for age, educational attainment, clinical diagnosis and neocortical amyloid load. We replicated these findings in 221 subjects from the Alzheimer's Disease Neuroimaging Initiative cohort, in which a different tau-PET radioligand, [18F]flortaucipir, was used to assess tau burden. In conclusion, this study provides evidence from two cohort studies that interactive rather than independent effect of APOE and sex potentiates early tau deposition in women. Our results have important implications for clinical trials and practice, which should take into consideration both APOEε4 carriage status and sex for identifying individuals with the highest probability of developing tau accumulation and clinical progression.

Dimethyl fumarate abridged tauo-/amyloidopathy in a D-Galactose/ovariectomy-induced Alzheimer's-like disease: Modulation of AMPK/SIRT-1, AKT/CREB/BDNF, AKT/GSK-3β, adiponectin/Adipo1R, and NF-κB/IL-1β/ROS trajectories

Since the role of estrogen in postmenauposal-associated dementia is still debatable, this issue urges the search for other medications. Dimethyl fumarate (DMF) is a drug used for the treatment of multiple sclerosis and has shown a neuroprotective effect against other neurodegenerative diseases. Accordingly, the present study aimed to evaluate the effect of DMF on an experimental model of Alzheimer disease (AD) using D-galactose (D-Gal) administered to ovariectomized (OVX) rats, resembling a postmenopausal dementia paradigm. Adult 18-month old female Wistar rats were allocated into sham-operated and OVX/D-Gal groups that were either left untreated or treated with DMF for 56 days starting three weeks after sham-operation or ovariectomy. DMF succeeded to ameliorate cognitive (learning/short- and long-term memory) deficits and to enhance the dampened overall activity (NOR, Barnes-/Y-maze tests). These behavioral upturns were associated with increased intact neurons (Nissl stain) and a reduction in OVX/D-Gal-mediated hippocampal CA1 neurodegeneration and astrocyte activation assessed as GFAP immunoreactivity. Mechanistically, DMF suppressed the hippocampal contents of AD-surrogate markers; viz., apolipoprotein (APO)-E1, BACE1, Aβ42, and hyperphosphorylated Tau. Additionally, DMF has augmented the neuroprotective parameters p-AKT, its downstream target CREB and BDNF. Besides, it activated AMPK, and enhanced SIRT-1, as well as antioxidant defenses (SOD, GSH). On the other hand, DMF inhibited the transcription factor NF-κB, IL-1β, adiponectin/adiponectin receptor type (AdipoR)1, GSK-3β, and MDA. Accordingly, in this postmenopausal AD model, DMF treatment by pursuing the adiponectin/AdipoR1, AMPK/SIRT-1, AKT/CREB/BDNF, AKT/GSK-3β, and APO-E1 quartet hampered the associated tauo-/amyloidopathy and NF-κB-mediated oxidative/inflammatory responses to advance insights into its anti-amnesic effect.

Sex-Steroid Signaling in Lung Diseases and Inflammation

Sex/gender difference exists in the physiology of multiple organs. Recent epidemiological reports suggest the influence of sex-steroids in modulating a wide variety of disease conditions. Sex-based discrepancies have been reported in pulmonary physiology and various chronic inflammatory responses associated with lung diseases like asthma, chronic obstructive pulmonary disease (COPD), pulmonary fibrosis, and rare lung diseases. Notably, emerging clinical evidence suggests that several respiratory diseases affect women to a greater degree, with increased severity and prevalence than men. Although sex-specific differences in various lung diseases are evident, such differences are inherent to sex-steroids, which are major biological variables in men and women who play a central role to control these differences. The focus of this chapter is to comprehend the sex-steroid biology in inflammatory lung diseases and to understand the mechanistic role of sex-steroids signaling in regulating these diseases. Exploring the roles of sex-steroid signaling in the regulation of lung diseases and inflammation is crucial for the development of novel and effective therapy. Overall, we will illustrate the importance of differential sex-steroid signaling in lung diseases and their possible clinical implications for the development of complementary and alternative medicine to treat lung diseases.

Kidney function and dementia risk in community-dwelling older adults: the Shanghai Aging Study

BACKGROUND

Association between kidney dysfunction and dementia has been studied in western cohorts, but with inconsistent conclusions which may be due to the different measurements of kidney function. We aim to verify the hypothesis that lower levels of kidney function would be associated with increased risk of incident dementia in Chinese elderly.

METHODS

One thousand four hundred twelve dementia-free participants aged 60 years or older from the Shanghai Aging Study were enrolled and followed up for 5.3 years on average. Glomerular filtration rate (GFR) was calculated by using combined creatinine-cystatin C CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) equation. Diagnoses of incident dementia and Alzheimer's disease (AD) were established using DSM-IV and NINCDS-ADRDA criteria based on medical, neurological, and neuropsychological examinations to each participant. Cox proportional regression was used to analyze the association of baseline GFR_crcys levels with incident dementia/AD, adjusting age, gender, education years, APOE-ε4, diabetes, hypertension, baseline Mini-Mental State Examination score, and proteinuria.

RESULTS

A total of 113 (8%) and 84 (7%) participants developed dementia and AD. Comparing to participants with high GFR_crcys (≥ 80 ml/min/1.73 m²), participants with low (< 67 ml/min/1.73 m²) and moderate GFR_crcys (67 ≤ GFR < 80 ml/min/1.73 m²) had increased risk of incident dementia with hazard ratios (HRs) of 1.87 (95% CI 1.02-3.44) and 2.19 (95% CI 1.21-3.95) after adjustment for confounders, respectively. Low (HR = 2.27 [95%CI 1.10-4.68]) and moderate (HR = 2.14 [95% CI 1.04-4.40]) GFR_crcys at baseline was also independently associated with incident AD after adjustments when comparing to high GFR_crcys. The significant association between GFR_crcys and dementia risk was observed in female but not in male participants.

CONCLUSIONS

GFR_crcys may be considered as a marker of an individual's vulnerability to the increased risk of cognitive decline.

Intraindividual variability in neural activity in the prefrontal cortex during active walking in older adults

Intraindividual variability in gait and cognitive performance is distinct from central-tendency measures and associated with clinical outcomes in aging. Knowledge concerning intraindividual variability in neural activity, however, has been relatively scarce, and no research to date has reported on such variability during active walking. The current study addressed this major gap in knowledge. Participants were community-residing older adults (n = 394; mean age = 76.29 ± 6.65 years; %female = 55). Functional near-infrared spectroscopy (fNIRS) was used to measure oxygenated hemoglobin (HbO2) in the prefrontal cortex under three experimental conditions: single-task-walk, single-task-alpha (cognitive task), and dual-task-walk, which required the participants to perform the two single tasks simultaneously. Intraindividual variability in neural activity was operationalized using the standard deviation of fNIRS-derived HbO2 observations assessed during a 30-s interval in each experimental condition. The increase in intraindividual variability in neural activity in the dual-task-walk condition compared to both single-task conditions was associated with the presence of cognitive impairments and being a male. Furthermore, measures of intraindividual variability in neural activity and gait performance were positively correlated only under the dual-task-walk condition. Intraindividual variability in the neural activity of gait may be a novel marker for age-related impairments in mobility and cognitive function. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Gender differences in presentation of behavioral and psychological symptoms in Alzheimer's disease in Taiwan

Objectives: Behavioral and psychological symptoms of dementia (BPSD) are frequently met in Alzheimer's disease (AD), especially in their late stages. BPSD has been reported to be associated with gender for its biological characteristics and severity of dementia. We aimed to investigate the gender differences in presentation of BPSD in AD in Taiwan.Methods: We recruited patients with clinically diagnosed AD by National Institute of Neurological Disorders and Stroke (NINCDS) - Alzheimer's Disease and Related Disorders Association (ADRDA) criteria. Demographic data and annual psychometrics, including Mini-Mental State Examination (MMSE), Clinical Dementia Rating (CDR) and Neuropsychiatric Inventory (NPI), consisting sub-items of delusions, hallucinations, aggression, depression, anxiety, elation, apathy, disinhibition, irritability, aberrant motor, nighttime behavior and eating were all administered to evaluate BPSD. Apolipoprotein E (APOE) allele was genotyped for each recruited AD subject. Differences between gender and variables were compared and significant NPI sub-items associated with gender were determined, while linear regression analyses were determined as the independent factor for BPSD.Results: In total, 280 female and 180 male AD patients were recruited into statistical analyses. Males had longer education duration and higher MMSE scores than females. Female had higher presence of delusion and disinhibition. In linear regression, being female and CDR stage were two independent factors for delusion (for female, B = 0.95, 95% CI = 0.17-1.73, p = 0.017) and disinhibition (for female, B = 0.49, 95% CI = 0.08-0.90, p = 0.019) after adjusting for confounding factors.Conclusions: The presentation of delusion and disinhibition in BPSD is associated with the female gender and staging of AD. Disinhibition was not necessarily associated with late stage of AD.

Development of Classification Models for the Prediction of Alzheimer's Disease Utilizing Circulating Sex Hormone Ratios

BACKGROUND

While sex hormones are essential for normal cognitive health, those individuals with greater endocrine dyscrasia around menopause and with andropause are more likely to develop cognitive loss and Alzheimer's disease (AD).

OBJECTIVE

To assess whether circulating sex hormones may provide an etiologically significant, surrogate biomarker, for cognitive decline.

METHODS

Plasma (n = 152) and serum (n = 107) samples from age- and gender-matched AD and control subjects from the Wisconsin Alzheimer's Disease Research Center (ADRC) were analyzed for 11 steroids and follicle-stimulating hormone. Logistic regression (LR), correlation analyses, and recursive partitioning (RP) were used to examine the interactions of hormones and hormone ratios and their association with AD. Models generated were then tested on an additional 43 ADRC samples.

RESULTS

The wide variation and substantial overlap in the concentrations of all circulating sex steroids across control and AD groups precluded their use for predicting AD. Classification tree analyses (RP) revealed interactions among single hormones and hormone ratios that associated with AD status, the most predictive including only the hormone ratios identified by LR. The strongest associations were observed between cortisol, cortisone, and androstenedione with AD, with contributions from progesterone and 17β-estradiol. Utilizing this model, we correctly predicted 81% of AD test cases and 64% of control test cases.

CONCLUSION

We have developed a diagnostic model for AD, the Wisconsin Hormone Algorithm Test for Cognition (WHAT-Cog), that utilizes classification tree analyses of hormone ratios. Further refinement of this technology could provide a quick and cheap diagnostic method for screening those with AD.

The Role of Sex and Sex Hormones in Neurodegenerative Diseases

Neurodegenerative diseases (NDs) are a wide class of disorders of the central nervous system (CNS) with unknown etiology. Several factors were hypothesized to be involved in the pathogenesis of these diseases, including genetic and environmental factors. Many of these diseases show a sex prevalence and sex steroids were shown to have a role in the progression of specific forms of neurodegeneration. Estrogens were reported to be neuroprotective through their action on cognate nuclear and membrane receptors, while adverse effects of male hormones have been described on neuronal cells, although some data also suggest neuroprotective activities. The response of the CNS to sex steroids is a complex and integrated process that depends on (i) the type and amount of the cognate steroid receptor and (ii) the target cell type-either neurons, glia, or microglia. Moreover, the levels of sex steroids in the CNS fluctuate due to gonadal activities and to local metabolism and synthesis. Importantly, biochemical processes involved in the pathogenesis of NDs are increasingly being recognized as different between the two sexes and as influenced by sex steroids. The aim of this review is to present current state-of-the-art understanding on the potential role of sex steroids and their receptors on the onset and progression of major neurodegenerative disorders, namely, Alzheimer's disease, Parkinson's diseases, amyotrophic lateral sclerosis, and the peculiar motoneuron disease spinal and bulbar muscular atrophy, in which hormonal therapy is potentially useful as disease modifier.

Association Between Hormone-Modulating Breast Cancer Therapies and Incidence of Neurodegenerative Outcomes for Women With Breast Cancer

Importance

The association between exposure to hormone-modulating therapy (HMT) as breast cancer treatment and neurodegenerative disease (NDD) is unclear.

Objective

To determine whether HMT exposure is associated with the risk of NDD in women with breast cancer.

Design, Setting, and Participants

This retrospective cohort study used the Humana claims data set from January 1, 2007, to March 31, 2017. The Humana data set contains claims from private-payer and Medicare insurance data sets from across the United States with a population primarily residing in the Southeast. Patient claims records were surveyed for a diagnosis of NDD starting 1 year after breast cancer diagnosis for the duration of enrollment in the claims database. Participants were 57 843 women aged 45 years or older with a diagnosis of breast cancer. Patients were required to be actively enrolled in Humana claims records for 6 months prior to and at least 3 years after the diagnosis of breast cancer. The analyses were conducted between January 1 and 15, 2020.

Exposure

Hormone-modulating therapy (selective estrogen receptor modulators, estrogen receptor antagonists, and aromatase inhibitors).

Main Outcomes and Measures

Patients receiving HMT for breast cancer treatment were identified. Survival analysis was used to determine the association between HMT exposure and diagnosis of NDD. A propensity score approach was used to minimize measured and unmeasured selection bias.

Results

Of the 326 485 women with breast cancer in the Humana data set between 2007 and 2017, 57 843 met the study criteria. Of these, 18 126 (31.3%; mean [SD] age, 76.2 [7.0] years) received HMT, whereas 39 717 (68.7%; mean [SD] age, 76.8 [7.0] years) did not receive HMT. Mean (SD) follow-up was 5.5 (1.8) years. In the propensity score-matched population, exposure to HMT was associated with a decrease in the number of women who received a diagnosis of NDD (2229 of 17 878 [12.5%] vs 2559 of 17 878 [14.3%]; relative risk, 0.89; 95% CI, 0.84-0.93; P < .001), Alzheimer disease (877 of 17 878 [4.9%] vs 1068 of 17 878 [6.0%]; relative risk, 0.82; 95% CI, 0.75-0.90; P < .001), and dementia (1862 of 17 878 [10.4%] vs 2116 of 17 878 [11.8%]; relative risk, 0.88; 95% CI, 0.83-0.93; P < .001). The number needed to treat was 62.51 for all NDDs, 93.61 for Alzheimer disease, and 69.56 for dementia.

Conclusions and Relevance

Among patients with breast cancer, tamoxifen and steroidal aromatase inhibitors were associated with a decrease in the number who received a diagnosis of NDD, specifically Alzheimer disease and dementia.

Genistein protects against amyloid-beta-induced toxicity in SH-SY5Y cells by regulation of Akt and Tau phosphorylation

Alzheimer's disease is a neurodegenerative disorder characterized by extracellular deposition of amyloid-β (Aβ) peptide and hyperphosphorylation of Tau protein, which ultimately leads to the formation of intracellular neurofibrillary tangles and cell death. Increasing evidence indicates that genistein, a soy isoflavone, has neuroprotective effects against Aβ-induced toxicity. However, the molecular mechanisms involved in its neuroprotection are not well understood. In this study, we have established a neuronal damage model using retinoic-acid differentiated SH-SY5Y cells treated with different concentrations of Aβ_25-35 to investigate the effect of genistein against Aβ-induced cell death and the possible involvement of protein kinase B (PKB, also termed Akt), glycogen synthase kinase 3β (GSK-3β), and Tau as an underlying mechanism to this neuroprotection. Differentiated SH-SY5Y cells were pre-treated for 24 hr with genistein (1 and 10 nM) and exposed to Aβ_25-35 (25 μM), and we found that genistein partially inhibited Aβ induced cell death, primarily apoptosis. Furthermore, the protective effect of genistein was associated with the inhibition of Aβ-induced Akt inactivation and Tau hyperphosphorylation. These findings reinforce the neuroprotective effects of genistein against Aβ toxicity and provide evidence that its mechanism may involve regulation of Akt and Tau proteins.

Neurosteroids as regulators of neuroinflammation

Neuroinflammation is a physiological protective response in the context of infection and injury. However, neuroinflammation, especially if chronic, may also drive neurodegeneration. Neurodegenerative diseases, such as multiple sclerosis (MS), Alzheimer's disease (AD), Parkinson's disease (PD) and traumatic brain injury (TBI), display inflammatory activation of microglia and astrocytes. Intriguingly, the central nervous system (CNS) is a highly steroidogenic environment synthesizing steroids de novo, as well as metabolizing steroids deriving from the circulation. Neurosteroid synthesis can be substantially affected by neuroinflammation, while, in turn, several steroids, such as 17β-estradiol, dehydroepiandrosterone (DHEA) and allopregnanolone, can regulate neuroinflammatory responses. Here, we review the role of neurosteroids in neuroinflammation in the context of MS, AD, PD and TBI and describe underlying molecular mechanisms. Moreover, we introduce the concept that synthetic neurosteroid analogues could be potentially utilized for the treatment of neurodegenerative diseases in the future.

Emerging Signal Regulating Potential of Genistein Against Alzheimer's Disease: A Promising Molecule of Interest

Alzheimer’s disease (AD) is a progressive, irreversible brain disorder characterized by pathological aggregation of the amyloid-β peptide (Aβ) and tau protein; both of these are toxic to neurons. Currently, natural products are regarded as an alternative approach to discover novel multipotent drugs against AD. Dietary soy isoflavone genistein is one of the examples of such agents that occurs naturally and is known to exert a number of beneficial health effects. It has been observed that genistein has the capacity to improve the impairments triggered by Aβ and also it possesses the antioxidant potential to scavenge the AD-mediated generation of free radicals. Furthermore, genistein can interact directly with the targeted signaling proteins and also can stabilize their activity to combat AD. In order to advance the development of AD treatment, a better comprehension of the direct interactions of target proteins and genistein might prove beneficial. Therefore, this article focuses on the therapeutic effects and molecular targets of genistein, which has been found to target directly the Aβ and tau to control the intracellular signaling pathways responsible for neurons death in the AD brain.

Cognitive impairment in heart failure is associated with altered Wnt signaling in the hippocampus

Age represents the highest risk factor for death due to cardiovascular disease. Heart failure (HF) is the most common cardiovascular disease in elder population and it is associated with cognitive impairment (CI), diminishing learning and memory process affecting life quality and mortality in these patients. In HF, CI has been associated with inadequate O₂ supply to the brain; however, an important subset of HF patients displays CI with almost no alteration in cerebral blood flow. Importantly, nothing is known about the pathophysiological mechanisms underpinning CI in HF with no change in brain tissue perfusion. Here, we aimed to study memory performance and learning function in a rodent model of HF that shows no change in blood flow going to the brain. We found that HF rats presented learning impairments and memory loss. In addition, HF rats displayed a decreased level of Wnt/β-catenin signaling downstream elements in the hippocampus, one pathway implicated largely in aging diseases. Taken together, our results suggest that in HF rats CI is associated with dysfunction of the Wnt/β-catenin signaling pathway. The mechanisms involved in the alterations of Wnt/β-catenin signaling in HF and its contribution to the development/maintenance of CI deserves future investigations.

Inhibitory mechanism of 17β-aminoestrogens in the formation of Aβ aggregates

Alzheimer's disease (AD) is a complex neurodegenerative disorder associated with the aggregation of the amyloid-beta peptide (Aβ) into large oligomers and fibrils that damage healthy brain cells. The predominant peptide fragments in the plaques are mainly formed by the Aβ_1-40 and Aβ_1-42 peptides, albeit the eleven-residue Aβ_25-35 segment is largely used in biological studies because it retains the neurotoxic properties of the longer Aβ peptides. Recent studies indicate that treatment with therapeutic steroid hormones reduces the progress of the disease in AD models. Particularly, treatment with 17β-aminoestrogens (AEs) has shown a significant alleviation of the AD development by inhibiting oxidative stress and neuronal death. Yet, the mechanism by which the AE molecules exhibit their beneficial effects remains speculative. To shed light into the molecular mechanism of inhibition of the AD development by AEs, we investigated the possibility of direct interaction with the Aβ_25-35 peptide. First, we calculate various interacting electronic properties of three AE derivatives as follows: prolame, butolame, and pentolame by performing DFT calculations. To account for the polymorphic nature of the Aβ aggregates, we considered four different Aβ_25-35 systems extracted from AD relevant fibril structures. From the calculation of different electron density properties, specific interacting loci were identified that guided the construction and optimization of various complexes. Interestingly, the results suggest a similar inhibitory mechanism based on the direct interaction between the AEs and the M35 residue that seems to be general and independent of the polymorphic properties of the Aβ aggregates. Our analysis of the complex formation provides a structural framework for understanding the AE therapeutic properties in the molecular inhibitory mechanism of Aβ aggregation.

Possible Existence of the Hypothalamic-Pituitary-Hippocampal (HPH) Axis: A Reciprocal Relationship Between Hippocampal Specific Neuroestradiol Synthesis and Neuroblastosis in Ageing Brains with Special Reference to Menopause and Neurocognitive Disorders

The hippocampus-derived neuroestradiol plays a major role in neuroplasticity, independent of circulating estradiol that originates from gonads. The response of hypothalamus-pituitary regions towards the synthesis of neuroestradiol in the hippocampus is an emerging scientific concept in cognitive neuroscience. Hippocampal plasticity has been proposed to be regulated via neuroblasts, a major cellular determinant of functional neurogenesis in the adult brain. Defects in differentiation, integration and survival of neuroblasts in the hippocampus appear to be an underlying cause of neurocognitive disorders. Gonadotropin receptors and steroidogenic enzymes have been found to be expressed in neuroblasts in the hippocampus of the brain. However, the reciprocal relationship between hippocampal-specific neuroestradiol synthesis along neuroblastosis and response of pituitary based feedback regulation towards regulation of estradiol level in the hippocampus have not completely been ascertained. Therefore, this conceptual article revisits (1) the cellular basis of neuroestradiol synthesis (2) a potential relationship between neuroestradiol synthesis and neuroblastosis in the hippocampus (3) the possible involvement of aberrant neuroestradiol production with mitochondrial dysfunctions and dyslipidemia in menopause and adult-onset neurodegenerative disorders and (4) provides a hypothesis for the possible existence of the hypothalamic-pituitary-hippocampal (HPH) axis in the adult brain. Eventually, understanding the regulation of hippocampal neurogenesis by abnormal levels of neuroestradiol concentration in association with the feedback regulation of HPH axis might provide additional cues to establish a neuroregenerative therapeutic management for mood swings, depression and cognitive decline in menopause and neurocognitive disorders.

Natural Antioxidant Anthocyanins-A Hidden Therapeutic Candidate in Metabolic Disorders with Major Focus in Neurodegeneration

All over the world, metabolic syndrome constitutes severe health problems. Multiple factors have been reported in the pathogenesis of metabolic syndrome. Metabolic disorders result in reactive oxygen species (ROS) induced oxidative stress, playing a vital role in the development and pathogenesis of major health issues, including neurological disorders Alzheimer's disease (AD) Parkinson's disease (PD). Considerable increasing evidence indicates the substantial contribution of ROS-induced oxidative stress in neurodegenerative diseases. An imbalanced metabolism results in a defective antioxidant defense system, free radicals causing inflammation, cellular apoptosis, and tissue damage. Due to the annual increase in financial and social burdens, in addition to the adverse effects associated with available synthetic agents, treatment diversion from synthetic to natural approaches has occurred. Antioxidants are now being considered as convincing therapeutic agents against various neurodegenerative disorders. Therefore, medicinal herbs and fruits currently receive substantially more attention as commercial sources of antioxidants. In this review, we argue that ROS-targeted therapeutic interventions with naturally occurring antioxidant flavonoid, anthocyanin, and anthocyanin-loaded nanoparticles might be the ultimate treatment against devastating illnesses. Furthermore, we elucidate the hidden potential of the neuroprotective role of anthocyanins and anthocyanin-loaded nanoparticles in AD and PD neuropathies, which lack sufficient attention compared with other polyphenols, despite their strong antioxidant potential. Moreover, we address the need for future research studies of native anthocyanins and nano-based-anthocyanins, which will be helpful in developing anthocyanin treatments as therapeutic mitochondrial antioxidant drug-like regimens to delay or prevent the progression of neurodegenerative diseases, such as AD and PD.

Crucial players in Alzheimer's disease and diabetes mellitus: Friends or foes?

Alzheimer's disease (AD) and diabetes mellitus, especially type 2 (T2DM), are very common and widespread diseases in contemporary societies, and their incidence is steadily on the increase. T2DM is a multiple metabolic disorder, with several mechanisms including hyperglycaemia, insulin resistance, insulin receptor and insulin growth factor disturbances, glucose toxicity, formation of advanced glycation end products (AGEs) and the activity of their receptors. AD is the most common form of dementia, characterized by the accumulation of extracellular beta amyloid peptide aggregates and intracellular hyper-phosphorylated tau proteins, which are thought to drive and/or accelerate inflammatory and oxidative stress processes leading to neurodegeneration. The aim of this paper is to provide a comprehensive review of the evidence linking T2DM to the onset and development of AD and highlight the unknown or poorly studied "nooks and crannies" of this interesting relationship, hence providing an opportunity to stimulate new ideas for the analysis of comorbidities between AD and DM. Despite, indication of possible biomarkers of early diagnosis of T2DM and AD, this review is also an attempt to answer the question as to whether the crucial factors in the development of both conditions support the link between DM and AD.

Down syndrome and infertility: what support should we provide?

Down syndrome (DS) is the most common genetic disease at birth; on average, it affects 1 in 700 newborns. The syndrome features cognitive impairment, susceptibility to certain diseases, and (in some cases) congenital malformations. Improvements in medical care for people with DS have led to an increase in life expectancy. Furthermore, the systematic provision of specific support during childhood improves cognitive function and autonomy in adulthood. Consequently, patients and their families are now seeking the same rights as healthy people. Access to procreation is an emerging debate. The presumption of infertility in DS is based on a few old studies. Down syndrome appears to cause spermatogenesis defects in men and premature menopause in women. When assisted reproductive technology makes it possible to solve these problems, the question of fertility in DS must be addressed. Without entering into highly controversial ethical considerations related to parenthood for people with DS, we reviewed the literature on fertility in DS and tried to specify the associated genetic risk.

Antarctic Krill (Euphausia superba) Oil: A Comprehensive Review of Chemical Composition, Extraction Technologies, Health Benefits, and Current Applications

Antarctic krill (Euphausia superba) oil has been receiving increasing attention due to its nutritional and functional potentials. However, its application as a novel food ingredient has not yet been fully explored. This review summarizes the chemical composition, extraction technologies, potential health benefits, and current applications of krill oil, with the aim of providing suggestions for its exploitation. Krill oil is a unique lipid consisting of diverse lipid classes and is characterized by a high concentration (39.29% to 80.69%) of phospholipids (PLs) associated with eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). It also contains considerable amounts of bioactive minor components such as astaxanthin, sterols, tocopherols, vitamin A, flavonoids, and minerals. The current technologies used in krill oil production are solvent extraction, nonsolvent extraction, super/subcritical fluid extraction, and enzyme-assisted pretreatment extraction, which all greatly influence the yield and quality of the end-product. In addition, krill oil has been documented to have various health benefits, including anti-inflammatory effects, cardiovascular disease (CVD) prevention, women's health, neuroprotection, and anticancer activities. Although krill oil products used for dietary supplements have been commercially available, few studies have attempted to explore the underlying molecular mechanisms to elucidate how exactly the krill oil exerts different biological activities. Further studies should focus on this to improve the development of krill oil products for human consumption.

The puzzle of sex, gender and Alzheimer’s disease: Why are women more often affected than men?

Objective:

There are impressive differences in the incidence, prevalence and experience of women and men with Alzheimer’s Disease (AD). Notably, two-thirds of those with AD, the most common form of dementia, are women. Our objective was to provide a literature-based framework to understand these sex and gender differences in AD.

Methods:

We conducted a narrative review to examine sex and gender influences on AD.

Results:

We present a framework to understanding why these sex and gender differences exist in AD. This includes the influence of longevity (women live longer than men), biological differences (hormonal differences, epigenetics and frailty), differences in cognitive performance (women and men tend to perform differently on some cognitive tests), and gendered social roles and opportunities (educational and occupational opportunities, functional roles post-retirement). Our review clearly indicates the complex interaction of these sex and gender differences and variability within each.

Conclusions:

Given these important sex and gender differences in AD, we provide recommendations and steps forward describing how both sex and gender should be considered in dementia diagnosis and management and in the design and implementation of dementia research, including studies of caregiving interventions and models of dementia care.

Estrogen deficiency exacerbates Aβ-induced memory impairment through enhancement of neuroinflammation, amyloidogenesis and NF-ĸB activation in ovariectomized mice

Estrogen is well known to have a preventative effect in Alzheimer's disease (AD) pathology. Several studies have demonstrated that nuclear factor kappa-B (NF-ĸB) can contribute to the effects of estrogen on the development of AD. We investigated whether NF-ĸB affects amyloid-beta (Aβ)-induced memory impairment in an estrogen-lacking condition. In the present study, nine-week-old Institute cancer research (ICR) mice were ovariectomized to block estrogen stimulation. Ten weeks after the ovariectomization, mice were administered with Aβ (300 pmol) via intracerebroventricular (ICV) infusion for 2 weeks. Memory impairment, neuroinflammatory protein expression, and amyloidogenic pathways were then measured. Ovariectomized mice demonstrated severe memory impairment, Aβ accumulation, neprilysin downregulation, and activation of NF-ĸB signaling compared to sham-control mice. In vitro experiments demonstrated that β-estradiol (10 μM) inhibited Aβ (1 μM)-induced neuroinflammation in microglial BV-2 cells and prevented Aβ-induced cell death in primary cultured neuronal cells. As in in vivo experiments, NF-ĸB activation was significantly upregulated in in vitro experiments. Furthermore β-estradiol treatment inhibited NF-ĸB activation in both of microglial BV-2 cells and cultured neuronal cells. These findings suggest that estrogen may protect against memory impairment through the regulation of Aβ accumulation and neurogenic inflammation by inhibiting NF-κB activity.

Clinical dementia severity associated with ventricular size is differentially moderated by cognitive reserve in men and women

Background

Interindividual differences in cognitive reserve (CR) are associated with complex and dynamic clinical phenotypes observed in cognitive impairment and dementia. We tested whether (1) CR early in life (E-CR; measured by education and IQ), (2) CR later in life (L-CR; measured by occupation), and (3) CR panel (CR-P) with the additive effects of E-CR and L-CR, act as moderating factors between baseline ventricular size and clinical dementia severity at baseline and across 2 years. We further examined whether this moderation is differentially represented by sex.

Methods

We examined a longitudinal model using patients (N = 723; mean age = 70.8 ± 9.4 years; age range = 38–90 years; females = 374) from the Sunnybrook Dementia Study. The patients represented Alzheimer’s disease (n = 439), mild cognitive impairment (n = 77), vascular cognitive impairment (n = 52), Lewy body disease (n = 30), and frontotemporal dementia (n = 125). Statistical analyses included (1) latent growth modeling to determine how clinical dementia severity changes over 2 years (measured by performance on the Dementia Rating Scale), (2) confirmatory factor analysis to establish a baseline E-CR factor, and (3) path analysis to predict dementia severity. Baseline age (continuous) and Apolipoprotein E status (ɛ4−/ɛ4+) were included as covariates.

Results

The association between higher baseline ventricular size and dementia severity was moderated by (1) E-CR and L-CR and (2) CR-P. This association was differentially represented in men and women. Specifically, men in only the low CR-P had higher baseline clinical dementia severity with larger baseline ventricular size. However, women in the low CR-P showed the (1) highest baseline dementia severity and (2) fastest 2-year decline with larger baseline ventricular size.

Conclusions

Clinical dementia severity associated with ventricular size may be (1) selectively moderated by complex and additive CR networks and (2) differentially represented by sex.

Trials registration

ClinicalTrials.gov, NCT01800214. Registered on 27 February 2013.

Electronic supplementary material

The online version of this article (10.1186/s13195-018-0419-2) contains supplementary material, which is available to authorized users.

Hormonal Influences on Cognitive Function

This article examines how hormonal changes may affect the neuronal networking and mechanisms of cognitive function. Hormones are the chemical regulators of the human body and function critically to maintain various processes, such as growth, emotions and even cognition. Numerous studies have examined the relationship between hormonal effects and cognitive function; these studies have investigated different factors, such as aging, pregnancy, post-natal states, emotions and stress. Different types of hormones produce different outcomes for the human body and mind. Hormones may also contribute to both positive and negative outcomes, depending on whether the hormone levels are too low or too high. To investigate the hormonal effects on cognitive function, the sources of localisation must be localised, so that the neuronal network can be realised. Furthermore, cognitive function does not rely on a specific brain region but is determined by the neuronal network interactions. Thus, it is worthwhile to know the neural mechanisms behind cognitive functions that are affected by hormones.

Comparative assessment of methylcobalamin and ascorbic acid on cognitive function in post-menopausal women - A randomized, double-blind trial

Introduction

A decline in cognitive function occurs as women progress through the menopausal transition.

Objective

The present study was designed to compare the effect of Methylcobalamin and Ascorbic Acid on Cognitive Function in post-menopausal women.

Methods

A randomized, double-blind trial was conducted in postmenopausal women with mild to moderate cognitive dysfunction. Eligible 56 subjects were randomized, the effect of ascorbic acid (500 mg OD) and methylcobalamin (50 mcg OD) was compared after 12 weeks of treatment. MMSE Questionnaire was used to assess the cognitive function, and β-amyloid42 was estimated in serum by enzyme-linked immunosorbent assay (ELISA).

Results

In MMSE score, delayed verbal recall (P = 0.027), naming (P = 0.042) and repetition (P = 0.031) scores were significantly improved in ascorbic acid group when compared to baseline. The β-amyloid42 level was decreased significantly in subjects receiving ascorbic acid (P = 0.04) when compared to Methylcobalamin group (P = 0.31). The inverse relationship between β-amyloid42 levels and the MMSE score was found in ascorbic acid treatment (r = 0.6324, P = 0.0004).

Conclusion

Based on MMSE and β-amyloid42 results, ascorbic acid showed improvement in cognitive function among post-menopausal women when compared to methylcobalamin supplement.