Adolescent loneliness and social isolation as predictors of 24-h movement guidelines adherence into adulthood: a prospective study

BACKGROUND: Loneliness and social isolation are psychosocial factors linked to adverse health outcomes in adolescence, but their associations with the integrated 24-h movement guidelines, covering physical activity, screen time, and sleep, remain poorly understood, particularly over the life course. The aim of the study was to examine the associations of loneliness and social isolation with adherence to the 24-h movement guidelines during adolescence and in sustained patterns from adolescence into adulthood over a 22-24-year follow-up. METHODS: We analyzed longitudinal data from individuals who participated in Waves I (1994-1995, n = 20,603) and V (2016-2018; n = 10,979) of the Add Health study. Loneliness (single CES-D item) and social isolation (frequency of peer interactions) were assessed in adolescence (ages 12-17). Adherence to movement guidelines was self-reported at both waves. Generalized linear models with Poisson regression estimated relative risks (RR) for cross-sectional and sustained (adolescence-to-adulthood) adherence. RESULTS: At baseline, loneliness was reported by 8.4% and social isolation by 9.4% of adolescents. In women, loneliness was associated with lower adherence to physical activity (RR = 0.87; 95%CI 0.77-0.99), sleep (RR = 0.86; 95%CI 0.79-0.94), and all 24-h movement guidelines (RR = 0.68; 95%CI 0.51-0.90), with associations for sleep (RR = 0.77; 95%CI 0.65-0.91) and all guidelines (RR = 0.37; 95%CI 0.10-0.91) persisting into adulthood. In men, loneliness was associated with lower adherence to sleep (RR = 0.87; 95%CI 0.78-0.97) and all guidelines (RR = 0.78; 95%CI 0.59-0.92), with similar associations observed longitudinally. Social isolation was strongly associated with lower physical activity in both sexes (women: RR = 0.59; 95%CI 0.46-0.75; men: RR = 0.48; 95%CI 0.38-0.61) and with adherence to all guidelines (women: RR = 0.61; 95%CI 0.43-0.87; men: RR = 0.69; 95%CI 0.51-0.93), both cross-sectionally and longitudinally. CONCLUSIONS: Addressing loneliness and social isolation as distinct, yet complementary, correlates of movement behaviors may enhance the effectiveness of strategies aimed at promoting healthier movement patterns and supporting social connectedness.