Hiroshi Ito, Shuichi Okaya, Tatsuya Watanabe, Ying-Fang Zheng, Nobutake Shimojo, Satoru Kawano, Takahiro Tabuchi
Loneliness, but not social isolation, was associated with subsequent reporting of new chronic conditions. Psychological distress may partly account for this association.
BACKGROUND: Loneliness and social isolation are related but distinct dimensions of social disconnection, but their longitudinal associations with chronic condition accumulation remain unclear in non-Western populations.
METHODS: We analyzed 8,721 adults aged 18 years or older who completed the 2021 and 2025 waves of the Japan "COVID-19 and Society" Internet Survey. Loneliness and social isolation were assessed in 2021, during the COVID-19 pandemic, using the UCLA 3-item Loneliness Scale and the 6-item Lubben Social Network Scale. The outcome was the newly reported presence in 2025 of at least one of 14 physician-diagnosed chronic conditions not reported as currently present in 2021. Standardized inverse probability-weighted logistic regression estimated adjusted odds ratios (ORs) per 1-SD higher loneliness score and per 1-SD lower social network score, adjusting for both exposures, sociodemographic factors, and baseline condition count.
RESULTS: Among 8,721 participants, 2,399 (27.5%) reported at least one new condition. Loneliness was associated with the outcome (OR, 1.24; 95% CI, 1.13-1.36), whereas social isolation was not (OR, 1.06; 95% CI, 0.97-1.17). Additional adjustment for baseline psychological distress attenuated the loneliness association (OR, 1.10; 95% CI, 0.98-1.23).
CONCLUSIONS: Loneliness, but not social isolation, was associated with subsequent reporting of new chronic conditions. Psychological distress may partly account for this association.