Diversity in Social Networks and Brain Aging - IN COMMUNITY-DWELLING OLDER ADULTS IN JAPAN: THE NEIGE STUDY

Sep 29, 2026

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As populations age worldwide, understanding drivers of brain health in older adults is vital for limiting cognitive decline. This longitudinal NEIGE Study examined how social network structure relates to brain aging in Japanese community-dwelling adults aged 65–84. Using MRI at baseline (2017) and follow-up (2021), factor analysis identified two network types. Regression with inverse probability weighting showed homogeneous networks were not linked to brain volume change, while lower social-network heterogeneity predicted greater hippocampal volume decline, especially in the right hippocampus, with no significant effects for gray matter or prefrontal cortex.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages1

Reading Time3 min

AccessFree to download

Study background

Aging and brain-health relevance

Methods

NEIGE longitudinal cohort and participants

MRI assessment and network typing

Statistical analysis approach

Results

Homogeneous vs heterogeneous social networks

Hippocampal effects and laterality

No findings for other brain regions

Implications and future work

Potential cognitive benefits of social diversity

876 Innovation in Aging, 2025, Vol. 9, No. S2 As the global population ages, understanding factors influencing brain health in older adults is crucial due to its impact on cognitive decline. Age-related changes in key regions like the hippocampus, gray matter, and prefrontal cortex are associated with cognitive decline. This study investigated the influence of social network structure on brain aging in older Japanese adults, focusing on regions linked to cognitive decline. We used longitudinal data from the Neuron to Environmental Impact across Generations Study (NEIGE Study), which is a prospective cohort study of randomly-sampled community-dwelling individuals aged 65–84 years living in Tokamachi City, Niigata Prefecture, Japan. The baseline survey was conducted in 2017 and included 527 independent older people. The follow-up survey was completed in 2021. This study analyzed 279 who had magnetic resonance imaging at both baseline and follow-up (47.6% men; mean age: 73.0 ± 5.1 years) . Social network homogeneity/heterogeneity was assessed based on similarities or diversity in relationships, and factor analysis identified t wo n etwork t ypes. Multiple linear regression analyses with inverse probability weighting indicated that homogeneous social networks were not associated with brain volume changes. However, lower heterogeneity in social networks was linked to greater hippocampal volume decline, after adjusting for sociodemographic factors and health behaviors. This association was prominent in right hippocampus. No significant associations were observed for gray matter or prefrontal cortex. More heterogeneous social networks may help mitigate age-related decline in hippocampal volume in older adults, suggesting the cognitive health benefits of social diversity. Further research is needed to explore underlying mechanisms. Abstract citation ID: igaf122.2963 DIVERSITY IN SOCIAL NETWORKS AND BRAIN AGING IN COMMUNITY-DWELLING OLDER ADULTS IN JAPAN: THE NEIGE STUDY Hiroshi Murayama1, Shiho Amagasa2, Masaki Machida3, Shigeru Inoue3, Takeo Fujiwara4, and Yugo Shobugawa5, 1. Tokyo Metropolitan Institute for Geriatrics and Gerontology, Tokyo, Japan, 2. Teikyo University, Tokyo, Tokyo, Japan, 3. Tokyo Medical University, Tokyo Medical University, Tokyo, Japan, 4. Institute of Science Tokyo, Tokyo, Tokyo, Japan, 5. Niigata University, Niigata, Niigata, Japan

FAQs

What population and study design were used to examine social networks and brain aging?

The NEIGE Study is a prospective cohort of randomly sampled Japanese community-dwelling adults aged 65–84. Baseline data were collected in 2017 and follow-up was completed in 2021 with MRI at both time points for the analyzed subset.

How did the study measure social network structure?

Social network homogeneity and heterogeneity were assessed using similarities or diversity in relationships. Factor analysis identified two network types for subsequent modeling.

What relationship did social network heterogeneity show with brain aging outcomes?

Lower heterogeneity in social networks was linked to greater decline in hippocampal volume after adjusting for sociodemographic factors and health behaviors. The association was especially notable for the right hippocampus, while gray matter and prefrontal cortex showed no significant associations.

Sep 29, 2026

Upload by Liam