Sexual dimorphism of physical activity on cognitive aging: Role of immune functioning

Failure of senolytic treatment to prevent cognitive decline in a female rodent model of aging

There are sex differences in vulnerability and resilience to the stressors of aging and subsequent age-related cognitive decline. Cellular senescence occurs as a response to damaging or stress-inducing stimuli. The response includes a state of irreversible growth arrest, the development of a senescence-associated secretory phenotype, and the release of pro-inflammatory cytokines associated with aging and age-related diseases. Senolytics are compounds designed to eliminate senescent cells. Our recent work indicates that senolytic treatment preserves cognitive function in aging male F344 rats. The current study examined the effect of senolytic treatment on cognitive function in aging female rats. Female F344 rats (12 months) were treated with dasatinib (1.2 mg/kg) + quercetin (12 mg/kg) or ABT-263 (12 mg/kg) or vehicle for 7 months. Examination of the estrus cycle indicated that females had undergone estropause during treatment. Senolytic treatment may have increased sex differences in behavioral stress responsivity, particularly for the initial training on the cued version of the watermaze. However, pre-training on the cue task reduced stress responsivity for subsequent spatial training and all groups learned the spatial discrimination. In contrast to preserved memory observed in senolytic-treated males, all older females exhibited impaired episodic memory relative to young (6-month) females. We suggest that the senolytic treatment may not have been able to compensate for the loss of estradiol, which can act on aging mechanisms for anxiety and memory independent of cellular senescence.

Characterising the covariance pattern between lifestyle factors and structural brain measures: a multivariable replication study of two independent ageing cohorts

Modifiable lifestyle factors have been shown to promote healthy brain ageing. However, studies have typically focused on a single factor at a time. Given that lifestyle factors do not occur in isolation, multivariable analyses provide a more realistic model of the lifestyle-brain relationship. Here, canonical correlation analyses (CCA) examined the relationship between nine lifestyle factors and seven MRI-derived indices of brain structure. The resulting covariance pattern was further explored with Bayesian regressions. CCA analyses were first conducted on a Danish cohort of older adults (n = 251) and then replicated in a British cohort (n = 668). In both cohorts, the latent factors of lifestyle and brain structure were positively correlated (UK: r = .37, p < 0.001; Denmark: r = .27, p < 0.001). In the cross-validation study, the correlation between lifestyle-brain latent factors was r = .10, p = 0.008. However, the pattern of associations differed between datasets. These findings suggest that baseline characterisation and tailoring towards the study sample may be beneficial for achieving targeted lifestyle interventions.

Data-driven physical actigraphy patterns relate to cognitive and vascular health in older adults

Health benefits of physical activity (PA) are well known; however, specific PA patterns that relate most strongly to cognitive aging outcomes are poorly understood. We characterized latent profiles of PA among older adults and examined associations with cognition and vascular burden. 124 functionally normal older adults wore a Fitbit™ for 30 days. Daily average step count, sedentary time (0 steps/min), and high-intensity time (≥120 steps/min) were calculated. Participants completed neurocognitive testing assessing cognitive domains of executive functioning and memory; medical history, from which vascular burden (i.e., a count of cardiovascular conditions) was calculated; and brain MRI (n = 44). Subgroups with similar PA patterns were identified via latent profile analysis. Three latent PA classes emerged: Class 1Low PA (n = 49), Class 2Average PA (n = 59), and Class 3High-intensity PA (n = 16). PA class related to executive functioning and vascular burden, driven by better outcomes in Class 3 than Class 1. Sex-stratified analyses revealed these associations were strongest in males. Post hoc analyses showed a positive association between high-intensity PA and white matter integrity among males. High-intensity PA related to better cognitive and vascular health, particularly among males. Findings inform physical activity-specific and person-specific recommendations for optimal cognitive aging.

Effect of peripheral cellular senescence on brain aging and cognitive decline

We examine similar and differential effects of two senolytic treatments, ABT-263 and dasatinib + quercetin (D + Q), in preserving cognition, markers of peripheral senescence, and markers of brain aging thought to underlie cognitive decline. Male F344 rats were treated from 12 to 18 months of age with D + Q, ABT-263, or vehicle, and were compared to young (6 months). Both senolytic treatments rescued memory, preserved the blood-brain barrier (BBB) integrity, and prevented the age-related decline in hippocampal N-methyl-D-aspartate receptor (NMDAR) function associated with impaired cognition. Senolytic treatments decreased senescence-associated secretory phenotype (SASP) and inflammatory cytokines/chemokines in the plasma (IL-1β, IP-10, and RANTES), with some markers more responsive to D + Q (TNFα) or ABT-263 (IFNγ, leptin, EGF). ABT-263 was more effective in decreasing senescence genes in the spleen. Both senolytic treatments decreased the expression of immune response and oxidative stress genes and increased the expression of synaptic genes in the dentate gyrus (DG). However, D + Q influenced twice as many genes as ABT-263. Relative to D + Q, the ABT-263 group exhibited increased expression of DG genes linked to cell death and negative regulation of apoptosis and microglial cell activation. Furthermore, D + Q was more effective at decreasing morphological markers of microglial activation. The results indicate that preserved cognition was associated with the removal of peripheral senescent cells, decreasing systemic inflammation that normally drives neuroinflammation, BBB breakdown, and impaired synaptic function. Dissimilarities associated with brain transcription indicate divergence in central mechanisms, possibly due to differential access.

Assessing the interaction effects of brain structure longitudinal changes and life environmental factors on depression and anxiety

Disrupted brain structures and several life environmental factors have been shown to influence depression and anxiety, but their interactions with anxiety and depression remain elusive. Genome-wide association study datasets of 15 brain structure longitudinal changes (N = 15,640) were obtained from the published study. Genotype and phenotype-related data of depression, anxiety, and life environmental factors (including smoking, alcohol drinking, coffee intake, maternal smoking, physical activity, vitamin D, insomnia, sleep duration, and family satisfaction) were collected from UK Biobank. We calculated the polygenic risk scores (PRS) of 15 brain structure changes and then conducted linear regression analyses to explore the interactions of brain structure changes and life environmental factors on depression and anxiety using 15 brain structure change-related PRS, life environmental factors and interactions of them as instrumental variables, and depression score or anxiety score as outcomes. Sex stratification in all analyses was performed to reveal sex-specific differences in the interactions. We found 14 shared interactions related to both depression and anxiety in total sample, such as alcohol drinking × cerebellum white matter 3 (WM; beta = -.003, p = .018 for depression; beta = -003, p = .008 for anxiety) and maternal smoking × nucleus accumbens 2 (beta = .088, p = .002 for depression; beta = .070, p = .008 for anxiety). We also observed sex-specific differences in the interactions, for instance, alcohol drinking × cerebellum WM 3 was negatively associated with depression and anxiety in males (beta = -.004, p = .020 for depression; beta = -.005, p = .002 for anxiety). Our study results reveal the important interactions between brain structure changes and several life environmental factors on depression and anxiety, which may help to explore the pathogenesis of depression and anxiety.

Sex-specific relationships between obesity, physical activity, and gray and white matter volume in cognitively unimpaired older adults

Independently, obesity and physical activity (PA) influence cerebral structure in aging, yet their interaction has not been investigated. We examined sex differences in the relationships among PA, obesity, and cerebral structure in aging with 340 participants who completed magnetic resonance imaging (MRI) acquisition to quantify grey matter volume (GMV) and white matter volume (WMV). Height and weight were measured to calculate body mass index (BMI). A PA questionnaire was used to estimate weekly Metabolic Equivalents. The relationships between BMI, PA, and their interaction on GMV Regions of Interest (ROIs) and WMV ROIs were examined. Increased BMI was associated with higher GMV in females, an inverse U relationship was found between PA and GMV in females, and the interaction indicated that regardless of BMI greater PA was associated with enhanced GMV. Males demonstrated an inverse U shape between BMI and GMV, and in males with high PA and had normal weight demonstrated greater GMV than normal weight low PA revealed by the interaction. WMV ROIs had a linear relationship with moderate PA in females, whereas in males, increased BMI was associated with lower WMV as well as a positive relationship with moderate PA and WMV. Males and females have unique relationships among GMV, PA and BMI, suggesting sex-aggregated analyses may lead to biased or non-significant results. These results suggest higher BMI, and PA are associated with increased GMV in females, uniquely different from males, highlighting the importance of sex-disaggregated models. Future work should include other imaging parameters, such as perfusion, to identify if these differences co-occur in the same regions as GMV.

Touchscreen-Based Cognitive Training Alters Functional Connectivity Patterns in Aged But Not Young Male Rats

Age-related cognitive decline is related to cellular and systems-level disruptions across multiple brain regions. Because age-related cellular changes within different structures do not show the same patterns of dysfunction, interventions aimed at optimizing function of large-scale brain networks may show greater efficacy at improving cognitive outcomes in older adults than traditional pharmacotherapies. The current study aimed to leverage a preclinical rat model of aging to determine whether cognitive training in young and aged male rats with a computerized paired-associates learning (PAL) task resulted in changes in global resting-state functional connectivity. Moreover, seed-based functional connectivity was used to examine resting state connectivity of cortical areas involved in object-location associative memory and vulnerable in old age, namely the medial temporal lobe (MTL; hippocampal cortex and perirhinal cortex), retrosplenial cortex (RSC), and frontal cortical areas (prelimbic and infralimbic cortices). There was an age-related increase in global functional connectivity between baseline and post-training resting state scans in aged, cognitively trained rats. This change in connectivity following cognitive training was not observed in young animals, or rats that traversed a track for a reward between scan sessions. Relatedly, an increase in connectivity between perirhinal and prelimbic cortices, as well as reduced reciprocal connectivity within the RSC, was found in aged rats that underwent cognitive training, but not the other groups. Subnetwork activation was associated with task performance across age groups. Greater global functional connectivity and connectivity between task-relevant brain regions may elucidate compensatory mechanisms that can be engaged by cognitive training.

Age-related brain atrophy is not a homogenous process: Different functional brain networks associate differentially with aging and blood factors

Aging is characterized by a progressive loss of brain volume at an estimated rate of 5% per decade after age 40. While these morphometric changes, especially those affecting gray matter and atrophy of the temporal lobe, are predictors of cognitive performance, the strong association with aging obscures the potential parallel, but more specific role, of individual subject physiology. Here, we studied a cohort of 554 human subjects who were monitored using structural MRI scans and blood immune protein concentrations. Using machine learning, we derived a cytokine clock (CyClo), which predicted age with good accuracy (Mean Absolute Error = 6 y) based on the expression of a subset of immune proteins. These proteins included, among others, Placenta Growth Factor (PLGF) and Vascular Endothelial Growth Factor (VEGF), both involved in angiogenesis, the chemoattractant vascular cell adhesion molecule 1 (VCAM-1), the canonical inflammatory proteins interleukin-6 (IL-6) and tumor necrosis factor alpha (TNFα), the chemoattractant IP-10 (CXCL10), and eotaxin-1 (CCL11), previously involved in brain disorders. Age, sex, and the CyClo were independently associated with different functionally defined cortical networks in the brain. While age was mostly correlated with changes in the somatomotor system, sex was associated with variability in the frontoparietal, ventral attention, and visual networks. Significant canonical correlation was observed for the CyClo and the default mode, limbic, and dorsal attention networks, indicating that immune circulating proteins preferentially affect brain processes such as focused attention, emotion, memory, response to social stress, internal evaluation, and access to consciousness. Thus, we identified immune biomarkers of brain aging which could be potential therapeutic targets for the prevention of age-related cognitive decline.

Precision Exercise Medicine: Sex Specific Differences in Immune and CNS Responses to Physical Activity

Physical activity is a powerful lifestyle factor capable of improving cognitive function, modifying the risk for dementia associated with neurodegeneration and possibly slowing neurodegenerative disease progression in both men and women. However, men and women show differences in the biological responses to physical activity and in the vulnerabilities to the onset, progression and outcome of neurodegenerative diseases, prompting the question of whether sex-specific regulatory mechanisms might differentially modulate the benefits of exercise on the brain. Mechanistic studies aimed to better understand how physical activity improves brain health and function suggest that the brain responds to physical exercise by overall reducing neuroinflammation and increasing neuroplasticity. Here, we review the emerging literature considering sex-specific differences in the immune system response to exercise as a potential mechanism by which physical activity affects the brain. Although the literature addressing sex differences in this light is limited, the initial findings suggest a potential influence of biological sex in the brain benefits of exercise, and lay out a scientific foundation to support very much needed studies investigating the potential effects of sex-differences on exercise neurobiology. Considering biological sex and sex-differences in the neurobiological hallmarks of exercise will help to enhance our understanding of the mechanisms by which physical activity benefits the brain and also improve the development of treatments and interventions for diseases of the central nervous system.

Men and women show partly distinct effects of physical activity on brain integrity

Introduction

Physical inactivity and female sex are independently associated with increased Alzheimer's disease (AD) lifetime risk. This study investigates the possible interactions between sex and physical activity on neuroimaging biomarkers.

Methods

In 134 cognitively unimpaired older adults (≥65 years, 82 women) from the Age‐Well randomized controlled trial (baseline data), we investigated the association between physical activity and multimodal neuroimaging (gray matter volume, glucose metabolism, perfusion, and amyloid burden), and how sex modulates these associations.

Results

The anterior cingulate cortex volume was independently associated with sex and physical activity. Sex and physical activity interacted on perfusion and amyloid deposition in medial parietal regions, such that physical activity was related to perfusion only in women, and to amyloid burden only in men.

Discussion

Physical activity has both sex‐dependent and sex‐independent associations with brain integrity. Our findings highlight partly distinct reserve mechanisms in men and women, which might in turn influence their risk of AD.

Highlights

Sex and physical activity have been linked to Alzheimer's disease (AD) progression.

The association of sex and physical activity with brain health is partly independent.

Different reserve mechanisms exist in men and women.

Modulation of Plasma Proteomic Profile by Regular Training in Male and Female Basketball Players: A Preliminary Study

Monitoring fatigue and recovery during training periods contributes to identifying the best training methods to achieve sports performance. To date, little is known about sex-related differences in sports adaptations. The aim of the present study is to identify sex-related sports adaptation proteins in female basketball players and male basketball players using proteomics approach on plasma samples withdrawn from athletes during in-season training period but far from a competition. A cohort of 20 professional basketball players, 10 female (BF) and 10 male (BM), and 20 sedentary male (10 CM) and female (10 CF) as control, of comparable age and BMI, were involved in this study. Protein profiles of plasma samples obtained from BM, BF, CM, and CF were analyzed by two-dimensional electrophoresis (2-DE). Differentially expressed proteins were identified by mass spectrometry. The computational 2-DE gel image analysis pointed out 33 differentially expressed protein spots (ANOVA p-value < 0.05) and differences between male and female basketball players are more evident among the players than controls. The expression profile of 54.5% of the total proteins is affected by sports activity. Furthermore, 14 proteins are differentially expressed in basket female players in comparison with their relative controls while seven are differentially expressed in basket male players in comparison with their controls. In conclusion, we identify in female athletes a reduction in proteins related to transcription regulation, most of these modulate chronic inflammation confirming the anti-inflammatory effect of regular training in female muscle metabolism. In male and female athletes, we found a decrease in Transthyretin involved in muscle homeostasis and regeneration and Dermcidin a stress-induced myokine linked to inflammatory and it will be interesting to fully understand the role of its different isoforms in male and female skeletal muscle contraction.

Symptoms of obstructive sleep apnea are associated with less frequent exercise and worse subjective cognitive function across adulthood

STUDY OBJECTIVES

To determine whether subjective measures of exercise and sleep are associated with cognitive complaints and whether exercise effects are mediated by sleep.

METHODS

This study analyzed questionnaire data from adults (18-89) enrolled in a recruitment registry. The Cognitive Function Instrument (CFI) assessed cognitive complaints. Medical Outcomes Study Sleep Scale (MOS-SS) subscales and factor scores assessed sleep quality, daytime sleepiness, nighttime disturbance, and insomnia and obstructive sleep apnea (OSA)-like symptoms. Exercise frequency was defined as the weekly number of exercise sessions. Exercise frequency, MOS-SS subscales, and factor scores were examined as predictors of CFI score, adjusting for age, body mass index, education, sex, cancer diagnosis, antidepressant usage, psychiatric conditions, and medical comorbidities. Analyses of covariance examined the relationship between sleep duration groups (short, mid-range, and long) and CFI score, adjusting for covariates. Mediation by sleep in the exercise-CFI score relationship was tested.

RESULTS

Data from 2106 adults were analyzed. Exercise and MOS-SS subscales and factor scores were associated with CFI score. Higher Sleep Adequacy scores were associated with fewer cognitive complaints, whereas higher Sleep Somnolence, Sleep Disturbance, Sleep Problems Index I, Sleep Problems Index II, and factor scores were associated with more cognitive complaints. MOS-SS subscales and factor scores, except Sleep Disturbance and the insomnia factor score, mediated the association between exercise and cognitive complaints.

CONCLUSIONS

The relationship between exercise frequency and subjective cognitive performance is mediated by sleep. In particular, the mediation effect appears to be driven by symptoms possibly suggestive of OSA which are negatively associated with exercise engagement, sleep quality, daytime sleepiness, and subjective cognitive performance.

Interbatch Reliability of Blood-Based Cytokine and Chemokine Measurements in Community-Dwelling Older Adults: A Cross-Sectional Study

Blood-based inflammatory markers hold considerable promise for diagnosis and prognostication of age-related neurodegenerative disease, though a paucity of research has empirically tested how reliably they can be measured across different experimental runs ("batches"). We quantified the interbatch reliability of 13 cytokines and chemokines in a cross-sectional study of 92 community-dwelling older adults (mean age = 74; 48% female). Plasma aliquots from the same blood draw were parallelly processed in 2 separate batches using the same analytic platform and procedures (high-performance electrochemiluminescence by Meso Scale Discovery). Interbatch correlations (Pearson's r) ranged from small and nonsignificant (r = .13 for macrophage inflammatory protein-1 alpha [MIP-1α]) to very large (r > .90 for interferon gamma [IFNγ], interleukin-10 [IL-10], interferon gamma-induced protein 10 [IP-10], MIP-1β, thymus and activation-regulated chemokine [TARC]) with most markers falling somewhere in between (.67 ≤ r ≤ .90 for IL-6, tumor necrosis factor alpha [TNF-α], Eotaxin, Eotaxin-3, monocyte chemoattractant protein-1 [MCP-1], MCP-4, macrophage-derived chemokine [MDC]). All markers, except for IL-6 and MCP-4, showed significant differences in absolute values between batches, with discrepancies ranging in effect size (Cohen's d) from small to moderate (0.2 ≤ |d| ≤ 0.5 for IL-10, IP-10, MDC) to large or very large (0.68 ≤ |d| ≤ 1.5 for IFNγ, TNF-α, Eotaxin, Eotaxin-3, MCP-1, MIP-1α, MIP-1β, TARC). Relatively consistent associations with external variables of interest (age, sex, systolic blood pressure, body mass index, cognition) were observed across batches. Taken together, our results suggest heterogeneity in measurement reliability of blood-based cytokines and chemokines, with some analytes outperforming others. Future work is needed to evaluate the generalizability of these findings while identifying potential sources of batch effect measurement error.

Truly Cross-fit: The Association of Exercise and Clinical Outcomes: Introduction to a JINS Special Section

We introduce a JINS special section inspired by a symposium presented at INS 2020 in Denver. The symposium was entitled Truly Cross-fit: The Association of Exercise and Cognitive Reserve. The collection of papers herein spans diverse methods, a range of developmental and clinical conditions, and a variety of outcomes all reflecting on the association of exercise and cognition-related outcomes. Taken together, the studies in this Special Section direct us to the variety of dimensions to be considered in understanding this association including what mode, intensity, duration, and timing of physical activity and aspects of age, sex, genetics, baseline characteristics, and disease status moderate these findings. We hope this Special Section will not only provide a framing for important future research on exercise and clinical outcomes but also inspiration to pursue them.

Small molecule cognitive enhancer reverses age-related memory decline in mice

With increased life expectancy, age-associated cognitive decline becomes a growing concern, even in the absence of recognizable neurodegenerative disease. The integrated stress response (ISR) is activated during aging and contributes to age-related brain phenotypes. We demonstrate that treatment with the drug-like small-molecule ISR inhibitor ISRIB reverses ISR activation in the brain, as indicated by decreased levels of activating transcription factor 4 (ATF4) and phosphorylated eukaryotic translation initiation factor eIF2. Furthermore, ISRIB treatment reverses spatial memory deficits and ameliorates working memory in old mice. At the cellular level in the hippocampus, ISR inhibition (i) rescues intrinsic neuronal electrophysiological properties, (ii) restores spine density and (iii) reduces immune profiles, specifically interferon and T cell-mediated responses. Thus, pharmacological interference with the ISR emerges as a promising intervention strategy for combating age-related cognitive decline in otherwise healthy individuals.