Murayama Hiroshi, Iizuka Ai, Machida Masaki, Amagasa Shiho, Inoue Shigeru, Fujiwara Takeo, Shobugawa Yugo
Research Team for Social Participation and Healthy Aging, Tokyo Metropolitan Institute for Geriatrics and Gerontology, Tokyo, Japan.
Research Team for Social Participation and Healthy Aging, Tokyo Metropolitan Institute for Geriatrics and Gerontology, Tokyo, Japan.
Arch Gerontol Geriatr. 2025 Feb;129:105642. doi: 10.1016/j.archger.2024.105642. Epub 2024 Sep 23.
Several studies have shown that social isolation is a risk factor for cognitive decline and dementia; however, its neurological mechanisms are not fully understood. Using longitudinal data, this study examined the effects of social isolation on hippocampal and total gray matter volumes in community-dwelling older Japanese individuals.
Data were obtained from the Neuron to Environmental Impact Across Generations (NEIGE) Study conducted in Tokamachi City (Niigata Prefecture, Japan), including 279 community-dwelling persons aged 65-84 years who underwent brain magnetic resonance imaging in 2017 and 2021 (male: 47.6 %; mean age: 73.0 years). We investigated two dimensions of social isolation: poor social networks and solitary living.
Multiple regression analysis with inverse probability weighting showed that individuals with a social contact frequency of <1 time/week had a greater decrease in hippocampal volume than those with a contact frequency of more than or equal to 4 times/week, whereas those who lived alone tended to have a smaller decrease in hippocampal volume than those who lived with others. We found no association between the frequency of social contact, living alone, and total gray matter volume. Furthermore, there was no interaction between sex and age for any of the outcomes.
Our longitudinal analysis suggested that the relationship between social isolation and dementia onset may be mediated by hippocampal atrophy; however, the direction of the influence depends on the isolation type. These findings are expected to contribute to the elucidation of the social mechanisms underlying dementia onset.
多项研究表明，社会隔离是认知能力下降和痴呆症的一个风险因素；然而，其神经学机制尚未完全明确。本研究利用纵向数据，调查了社会隔离对居住在社区的日本老年人海马体和全脑灰质体积的影响。
数据来自于在日本新潟县十日町市开展的“跨代神经元对环境影响”（NEIGE）研究，包括279名年龄在65 - 84岁之间、于2017年和2021年接受脑磁共振成像检查的社区居民（男性占47.6%；平均年龄73.0岁）。我们调查了社会隔离的两个维度：社交网络不佳和独居。
采用逆概率加权的多元回归分析显示，社交接触频率<1次/周的个体海马体体积的减少幅度大于社交接触频率≥4次/周的个体，而独居者海马体体积的减少幅度往往小于与他人同住者。我们发现社交接触频率、独居与全脑灰质体积之间无关联。此外，在任何结果中，性别和年龄之间均无相互作用。
我们的纵向分析表明，社会隔离与痴呆症发病之间的关系可能由海马体萎缩介导；然而，影响方向取决于隔离类型。这些发现有望有助于阐明痴呆症发病的社会机制。
