Diversity of daily activities is associated with greater hippocampal volume

Vascular-related biological stress, DNA methylation, allostatic load and domain-specific cognition: an integrated machine learning and causal inference approach

BACKGROUND

Vascular disease in aging populations spans a wide range of disorders including strokes, circulation disorders and hypertension. As individuals age, vascular disorders co-occur and hence exert combined effects. In the present study we introduce vascular-related biological stress as a novel biomarker to capture the combined effects of vascular disease burden for more precision in early detection of cognitive changes in aging.

OBJECTIVE

to determine the role of vascular-related biological Stress, DNA methylation-based biological aging and Allostatic Load in the relationship between vascular disorders and major cognitive domains including global cognition, episodic memory and executive function in a representative sample of adults across the age span.

METHODS

The present study included participants from MIDUS refresher sample. Vascular-related biological stress included: BMI, Average blood pressure, sitting, Waist-hip ratio, Blood hemoglobin A1c percent, Blood dehydroepiandrosterone (ng/mL), Blood fasting insulin levels uIU/mL, Blood serum interleukin-8 (pg/mL), Blood serum interleukin-6 (pg/mL), Blood fasting glucose levels mg/dL and Blood fibrinogen (mg/dL). DNA methylation-based biological age measures included GrimAge2 that was constructed based on DNA methylation surrogate markers for select plasma proteins and smoking-pack years. Allostatic load scores were calculated based on biomarkers commonly used in allostatic load calculations: cortisol (urine), norepinephrine (urine), epinephrine (urine), dopamine (urine), glycosylated hemoglobin (HBA1C, blood), low density lipoprotein (LDL, blood), C-reactive protein (CRP, blood) dehydroepiandrosterone sulfate (DHEAS, blood), high-density lipoprotein (HDL, blood) and systolic blood pressure (average, sitting). Least Absolute Shrinkage and Selection Operator (LASSO) and response models (item and continuous) were used to calculate vascular-related biological stress and theta scores. Four-way decomposition modeling approach was used to calculate the natural direct and indirect effects in the relationship between vascular disease and major cognitive domains.

RESULTS

550 individuals with data on biomarkers, DNA methylation and cognition assessments were included in the present study. Median age was 54 (range = 26, 78) with females representing 48% of the sample. In the relationship between vascular disease and cognition, the overall proportions mediated through vascular-related biological stress (item-response scale) were 0.60 (P = 0.01); 1.1 (P = 0.308); 0.53 (P = 0.002) for global cognition, episodic memory and executive function respectively. The overall proportions mediated through DNA methylation (GrimAge2) were 0.27 (P = 0.002); 0.39 (P = 0.102); 0.20, (P = 0.002) for global cognition, episodic memory and executive function respectively and 0.10 (P = 0.08); 0.09 (P = 0.5); 0.07 (P = 0.18) through allostatic load (sum scores).

CONCLUSIONS

Our findings suggest that vascular-related biological stress, DNA methylation and to some extent allostatic load mediate the effects of vascular disease on global cognition and executive function.

Internet-Based Social Activities and Cognitive Functioning 2 Years Later Among Middle-Aged and Older Adults: Prospective Cohort Study

Background

A number of studies document the benefits of face-to-face social interactions for cognitive functioning among middle-aged and older adults. Social activities in virtual worlds may confer similar if not enhanced cognitive benefits as face-to-face social activities, given that virtual interactions require the additional cognitive tasks of learning and navigating communicative tools and technology platforms. Yet, few studies have examined whether social activities in internet-based settings may have synergistic effects on cognitive functioning beyond those of face-to-face interactions.

Objective

This study examined whether internet-based social activity participation is associated with concurrent and later cognitive functioning, after adjusting for face-to-face social activity participation and sociodemographic covariates.

Methods

For cross-sectional analyses, we included 3650 adults aged 50 years and older who completed questions in the 2020 Health and Retirement Study about social activity participation, including specific internet-based social activities such as emailing or accessing social networks. Cognitive functioning was measured using the standardized cognitive tasks assessing working memory, episodic memory, and attention and processing speed. The longitudinal analyses included the 2034 participants who also completed follow-up cognitive assessments in 2022.

Results

Our results revealed that those with higher levels of internet-based social activity participation had higher levels of concurrent cognitive functioning than those with low levels of internet-based social activity participation, after adjusting for demographic and health-related factors and face-to-face social activity participation (b=0.44, SE 0.07; P<.001). More internet-based social activity participation also predicted better cognitive functioning 2 years later, even when adjusting for baseline cognitive functioning and other covariates (b=0.35, SE 0.09; P<.001).

Conclusions

Our findings suggest that greater engagement in internet-based social activities is associated with higher levels of concurrent cognitive functioning and slower cognitive decline in middle-aged and older adults.

The BDNF-Interactive Model for Sustainable Hippocampal Neurogenesis in Humans: Synergistic Effects of Environmentally-Mediated Physical Activity, Cognitive Stimulation, and Mindfulness

This paper bridges critical gaps through proposing a novel, environmentally mediated brain-derived neurotrophic factor (BDNF)-interactive model that promises to sustain adult hippocampal neurogenesis in humans. It explains how three environmental enrichment mechanisms (physical activity, cognitive stimulation, and mindfulness) can integratively regulate BDNF and other growth factors and neurotransmitters to support neurogenesis at various stages, and how those mechanisms can be promoted by the physical environment. The approach enables the isolation of specific environmental factors and their molecular effects to promote sustainable BDNF regulation by testing the environment's ability to increase BDNF immediately or shortly before it is consumed for muscle repair or brain update. This model offers a novel, feasible method to research environment enrichment and neurogenesis dynamics in real-world human contexts at the immediate molecular level, overcoming the confounds of complex environment settings and challenges of long-term exposure and structural plasticity changes. The model promises to advance understanding of environmental influences on the hippocampus to enhance brain health and cognition. This work bridges fundamental gaps in methodology and knowledge to facilitate more research on the enrichment-neuroplasticity interplay for humans without methodological limitations.

Examining resilience to Alzheimer's disease through the lens of monoaminergic neuromodulator systems

The monoaminergic nuclei are thought to be some of the earliest sites of Alzheimer's disease (AD) pathology in the brain, with tau-containing pretangles appearing in these nuclei decades before the onset of clinical impairments. It has increasingly been recognized that monoamine systems represent a critical target of investigation towards understanding the progression of AD and designing early detection and treatment approaches. This review synthesizes evidence across animal studies, human neuropathology, and state-of-the-art neuroimaging and daily life assessment methods in humans, which demonstrate robust relationships between monoamine systems and AD pathophysiology and behavior. Further, the review highlights the promise of multimethod, multisystem approaches to studying monoaminergic mechanisms of resilience to AD pathology.

Depressive symptoms during the transition to adolescence: Left hippocampal volume as a marker of social context sensitivity

The transition to adolescence is a critical period for mental health development. Socio-experiential environments play an important role in the emergence of depressive symptoms with some adolescents showing more sensitivity to social contexts than others. Drawing on recent developmental neuroscience advances, we examined whether hippocampal volume amplifies social context effects in the transition to adolescence. We analyzed 2-y longitudinal data from the Adolescent Brain Cognitive Development (ABCD®) study in a diverse sample of 11,832 youth (mean age: 9.914 y; range: 8.917 to 11.083 y; 47.8% girls) from 21 sites across the United States. Socio-experiential environments (i.e., family conflict, primary caregiver's depressive symptoms, parental warmth, peer victimization, and prosocial school environment), hippocampal volume, and a wide range of demographic characteristics were measured at baseline. Youth's symptoms of major depressive disorder were assessed at both baseline and 2 y later. Multilevel mixed-effects linear regression analyses showed that negative social environments (i.e., family conflict, primary caregiver's depressive symptoms, and peer victimization) and the absence of positive social environments (i.e., parental warmth and prosocial school environment) predicted greater increases in youth's depressive symptoms over 2 y. Importantly, left hippocampal volume amplified social context effects such that youth with larger left hippocampal volume experienced greater increases in depressive symptoms in more negative and less positive social environments. Consistent with brain-environment interaction models of mental health, these findings underscore the importance of families, peers, and schools in the development of depression during the transition to adolescence and show how neural structure amplifies social context sensitivity.

Neurosustainability

While the human brain has evolved extraordinary abilities to dominate nature, modern living has paradoxically trapped it in a contemporary "cage" that stifles neuroplasticity. Within this modern environment lurk unseen natural laws with power to sustain the human brain's adaptive capacities - if consciously orchestrated into the environments we design. For too long our contemporary environments have imposed an unyielding static state, while still neglecting the brain's constant adaptive nature as it evolves to dominate the natural world with increasing sophistication. The theory introduced in this article aims to go back in nature without having to go back in time, introducing and expounding Neurosustainability as a novel paradigm seeing beyond the contemporary confines to architect environments and brains in parallel. Its integrated neuro-evidenced framework proposes four enrichment scopes-spatial, natural, aesthetic, and social-each holding multifaceted attributes promising to sustain regions like the hippocampus, cortex and amygdala. Neurosustainability aims to liberate the quintessential essence of nature to sustain and enhance neuroplastic processes through a cycle that begins with design and extends through epigenetic changes. This paradigm shift aims to foster cognitive health and wellness by addressing issues like stress, depression, anxiety and cognitive decline common in the contemporary era thereby offering a path toward a more neurosustainable era aiming to nurture the evolution of the human brain now and beyond.

Environmental enrichment: a systematic review on the effect of a changing spatial complexity on hippocampal neurogenesis and plasticity in rodents, with considerations for translation to urban and built environments for humans

Introduction

Hippocampal neurogenesis is critical for improving learning, memory, and spatial navigation. Inhabiting and navigating spatial complexity is key to stimulating adult hippocampal neurogenesis (AHN) in rodents because they share similar hippocampal neuroplasticity characteristics with humans. AHN in humans has recently been found to persist until the tenth decade of life, but it declines with aging and is influenced by environmental enrichment. This systematic review investigated the impact of spatial complexity on neurogenesis and hippocampal plasticity in rodents, and discussed the translatability of these findings to human interventions.

Methods

Comprehensive searches were conducted on three databases in English: PubMed, Web of Science, and Scopus. All literature published until December 2023 was screened and assessed for eligibility. A total of 32 studies with original data were included, and the process is reported in accordance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement and checklist.

Results

The studies evaluated various models of spatial complexity in rodents, including environmental enrichment, changes to in-cage elements, complex layouts, and navigational mazes featuring novelty and intermittent complexity. A regression equation was formulated to synthesize key factors influencing neurogenesis, such as duration, physical activity, frequency of changes, diversity of complexity, age, living space size, and temperature.

Conclusion

Findings underscore the cognitive benefits of spatial complexity interventions and inform future translational research from rodents to humans. Home-cage enrichment and models like the Hamlet complex maze and the Marlau cage offer insight into how architectural design and urban navigational complexity can impact neurogenesis in humans. In-space changing complexity, with and without physical activity, is effective for stimulating neurogenesis. While evidence on intermittent spatial complexity in humans is limited, data from the COVID-19 pandemic lockdowns provide preliminary evidence. Existing equations relating rodent and human ages may allow for the translation of enrichment protocol durations from rodents to humans.

The bidirectional relationship between brain structure and physical activity: A longitudinal analysis in the UK Biobank

Physical activity is a protective factor against brain atrophy, while loss of brain volume could also be a determinant of physical activity. Therefore, we aimed to explore the bidirectional association of physical activity with brain structures in middle-aged and older adults from the UK Biobank. Overall, 3027 participants (62.45 ± 7.27 years old, 51.3% females) had data at two time points. Hippocampal volume was associated with total (β=0.048, pFDR=0.016) and household (β=0.075, pFDR<0.001) physical activity. Global fractional anisotropy (β=0.042, pFDR=0.028) was also associated with household physical activity. In the opposite direction, walking was negatively associated with white matter volume (β=-0.026, pFDR=0.008). All these associations were confirmed by the linear mixed models. Interestingly, sports at baseline were linked to hippocampal and frontal cortex volumes at follow-up but these associations disappeared after adjusting for multiple comparisons (pall>0.104). In conclusion, we found more consistent evidence that a healthier brain structure predicted higher physical activity levels than for the inverse, more established relationship.

The bi-directional relationships between diversified leisure activity participation and cognitive function in older adults in China: separating between-person effects from within-person effects

OBJECTIVE

To examine the bi-directorial association between diversified leisure activity participation and cognitive function over a 7-year period.

METHODS

Data analyzed was from the Chinese Longitudinal Healthy Longevity Survey (CLHLS), a large-scale longitudinal national study. The baseline survey was conducted in 2011 with follow-up every three years. We traced a total of 2718 participants over a period of 7 years. We used adjusted random intercept cross-lagged panel models (RI-CLPMs) to examine the bi-directorial associations between diversified leisure activity participation and cognitive function.

RESULTS

We observed bi-directorial associations between diversity of leisure activity and cognitive function across waves at the between-person and within-person levels. The adjusted random intercept cross-lagged panel models fitted the data appropriately, and the 3-year cross-lagged effects of prior diversified leisure activity participation on cognitive function (β = 0.058, p < 0.01) and cognitive function on subsequent diversified leisure activity participation (β = 0.047, p < 0.05) were significant. The results remained after adjusting the model for baseline sex, age, educational level, marital status and current residence, the number of chronic diseases, ADL, depressive symptoms, sleep quality, smoking, and drinking.

CONCLUSION

This study suggests that a reciprocal causality relationship between diversified leisure activity participation and cognitive function, indicating a "positive circle" that further promotes cognition over time.

Diversity of network communication mode and interpersonal interactions: Relationship with social support and well-being

Social interactions today expand beyond in-person interactions. Therefore, it is important to recognize that social interactions can occur with social network members across multiple communication modes (in-person, phone, and online). The current study explored the role that social support plays in the relationship between mode frequency (in-person, phone, and online), network communication mode diversity (breadth and evenness of communicating with network members via different communication modes), and well-being (positive affect, stress, and loneliness) from the 3-year UCNET (UC Berkley Social Networks Study, N = 1159) dataset. The study contained samples for two age groups (cohorts) - 21-31 year-olds and 50-70 year-olds, which also allowed for an exploration of age differences in these relationships. Longitudinal random-intercept cross-lagged panel models (RI-CLPM) showed a high degree of stability over the 3 years for all variables. Cross-sectional structural equation mediation models showed that social support mediated the relationships of mode frequency (in-person, phone, and online) and network communication mode diversity with well-being (more positive affect and less loneliness and stress). Age differences were found in the relationship between frequency of communication modes and social support, in that the frequency of communication mode was positively related to social support for younger adults, but not for middle-aged/older adults. Current findings provided future research directions geared toward further understanding of the mode frequency and network communication mode diversity constructs and how they relate to various psychosocial outcomes.

Rewarded Maze Training Increases Approach Behavior in Rats Through Neurogenesis-Dependent Growth of Ventral Hippocampus-Prelimbic Circuits

Background

Learning complex navigation routes increases hippocampal volume in humans, but it is not clear whether this growth impacts behaviors outside the learning situation or what cellular mechanisms are involved.

Methods

We trained rats with pharmacogenetic suppression of adult neurogenesis and littermate controls in 3 mazes over 3 weeks and tested novelty approach behavior several days after maze exposure. We then measured hippocampus and prelimbic cortex volumes using magnetic resonance imaging and assessed neuronal and astrocyte morphology. Finally, we investigated the activation and behavioral role of the ventral CA1 (vCA1)-to-prelimbic pathway using immediate-early genes and DREADDs (designer receptors exclusively activated by designer drugs).

Results

Maze training led to volume increase of both the vCA1 region of the hippocampus and the prelimbic region of the neocortex compared with rats that followed fixed paths. Growth was also apparent in individual neurons and astrocytes in these 2 regions, and behavioral testing showed increased novelty approach in maze-trained rats in 2 different tests. Suppressing adult neurogenesis prevented the effects on structure and approach behavior after maze training without affecting maze learning itself. The vCA1 neurons projecting to the prelimbic area were more activated by novelty in maze-trained animals, and suppression of this pathway decreased approach behavior.

Conclusions

Rewarded navigational learning experiences induce volumetric and morphologic growth in the vCA1 and prelimbic cortex and enhance activation of the circuit connecting these 2 regions. Both the structural and behavioral effects of maze training require ongoing adult neurogenesis, suggesting a role for new neurons in experience-driven increases in novelty exploration.

Social activity diversity as a lifestyle factor to alleviate loneliness and chronic pain

OBJECTIVE

This study examined whether social activity diversity, a novel concept indicating an active social lifestyle, is associated with lower subsequent loneliness, and decreased loneliness is further associated with less chronic pain over time.

METHODS

2528 adults from the Midlife in the United States Study (Mage = 54 yrs) provided data at baseline (2004-2009) and 9 years later. Social activity diversity was operationalized by Shannon's entropy that captures the variety and evenness of engagement across 13 social activities (0-1). Participants reported feelings of loneliness (1-5), presence of any chronic pain (yes/no), the degree of chronic pain-related interference (0-10), and the number of chronic pain locations. Indirect associations of social activity diversity with chronic pain through loneliness were evaluated, adjusting for sociodemographics, living alone, and chronic conditions.

RESULTS

Higher social activity diversity at baseline (B = -0.21, 95%CI = [-0.41, -0.02]) and an increase in social activity diversity over time (B = -0.24, 95%CI = [-0.42, -0.06]) were associated with lower loneliness 9 years later. An increase in loneliness was associated with 24% higher risk of any chronic pain (95%CI = [1.11, 1.38]), greater chronic pain-related interference (B = 0.36, 95%CI = [0.14, 0.58]), and 17% increase in the number of chronic pain locations (95%CI = [1.10, 1.25]) at the follow-up, after controlling for corresponding chronic pain at baseline and covariates. Social activity diversity was not directly was associated with chronic pain, but there were indirect associations through its association with loneliness.

CONCLUSION

Diversity in social life may be associated with decreased loneliness, which in turn, may be associated with less chronic pain, two of the prevalent concerns in adulthood.

Adults Older Than Age 55 Engage in Less Diverse Activities Than Those 18 Years Ago

OBJECTIVES

Life-span perspectives have long acknowledged that individual functioning is shaped by historical and sociocultural contexts. Secular increases favoring recent cohorts are widely documented. However, little is known about secular trends in day-to-day activities and whether historical changes have occurred in younger and older adults alike.

METHODS

We compared data from 2 independent cohort samples of the daily diary portion of the Midlife in the United States Study obtained 18 years apart (1995/1996 cohort: n = 1,499 vs 2013/2014 cohort: n = 782) and identified case-matched cohorts (n = 757 per cohort) based on age, gender, education, and race. An activity diversity score was calculated based on 7 common daily activities, using Shannon's entropy method. We additionally examined the roles of age and other sociodemographic and health characteristics in cohort differences in activity diversity.

RESULTS

Results revealed that the 2013/2014 cohort experienced lower daily activity diversity than the 1995/1996 cohort. Age was positively associated with activity diversity in the 1995/1996 cohort, whereas age was negatively associated with activity diversity in the 2013/2014 cohort. These associations were significant for those who were older than age 55. Cohorts also differed in the types of most dominant activities and average time spent on those activities.

DISCUSSION

Findings show changes in the lifestyles and daily activities of U.S. adults across 2 decades. Contrasting to the common belief that today's adults may be healthier and more active, they seem engaging in less diverse daily activities, which can be a risk for future health outcomes.

Altered Grey Matter-Brain Healthcare Quotient: Interventions of Olfactory Training and Learning of Neuroplasticity

Recent studies revealed that grey matter (GM) changes due to various training and learning experiences, using magnetic resonance imaging. In this study, we investigate the effect of psychological characteristics and attitudes toward training and learning on GM changes. Ninety participants were recruited and distributed into three groups: an olfactory training group that underwent 40 olfactory training sessions designed for odour classification tasks, a group classified for learning of neuroplasticity and brain healthcare using a TED Talk video and 28 daily brain healthcare messages, and a control group. Further, we assessed psychological characteristics, such as curiosity and personal growth initiatives. In the olfactory training group, we conducted a questionnaire survey on olfactory training regarding their interests and sense of accomplishment. In the olfactory training group, the GM change was significantly correlated with the sense of achievement and interest in training. The learning of neuroplasticity and brain healthcare group showed a significantly smaller 2-month GM decline than did the control group. The Curiosity and Exploration Inventory-II scores were significantly correlated with GM changes in both intervention groups only. In conclusion, our result suggested that training or learning with a sense of accomplishment, interest, and curiosity would lead to greater GM changes.