The interplay between loneliness and health factors from adolescence to midlife: a cohort study

Abstract There is growing evidence of adverse health outcomes among lonely individuals, with health behaviors representing one potential underlying mechanism. However, existing research overlooked the potential gender-specific dynamic interplay of health behaviors and loneliness across the first decades of life. In this Norwegian 28-year prospective cohort study (n = 3,072) from adolescence to midlife, we investigated reciprocal relationships between loneliness and health factors, including alcohol use, body mass index (BMI), smoking status, and physical exercise. Using a structural nested mean modeling approach with G-estimation, we accounted for a comprehensive set of baseline and time-varying confounders. We demonstrated that increased loneliness among adolescent males diminished subsequent physical exercise and elevated loneliness during adolescence and/or young adulthood was linked to a subsequent increase in BMI among both males and females. The remaining loneliness-health behavior relationships were consistent with a null effect. Considering the effect of health factors on loneliness, physical exercise in adolescent males decreased subsequent loneliness, whereas obesity among females during young adulthood was linked to an increase in loneliness. In summary, except for a loneliness-physical exercise interplay in adolescent males and a loneliness-BMI interplay in females, our results provide limited support for gender-specific reciprocal relationships between loneliness and health factors across the first decades of life. Key messages • Loneliness and physical exercises are reciprocally related in adolescent males. • Among females, loneliness and BMI influence each other over the first decades of life.