Association between Loneliness and Suicidal Thoughts and Attempts in Adolescence and Young Adulthood: A Longitudinal Analysis of a Nationally Representative US Sample.

Objective: Previous research has identified loneliness as a risk factor for suicidal ideation and attempt but has lacked studies using representative samples of adolescents. We aimed to address this evidence gap by using a nationally representative sample of US adolescents to investigate whether loneliness is longitudinally associated with suicide-related outcomes.

Method: We analyzed data on 17,751 participants in the National Longitudinal Study of Adolescent to Adult Health (Add Health) aged 11-21 years at baseline. We used multivariable logistic regression to test the longitudinal association between baseline loneliness (1995; aged 11-21 years) and past-year suicidal ideation and suicide attempt measured six years later (2001-2002; aged 18-28 years) and 13 years later (2008-2009; aged 24-34 years) adjusted for socio-demographic and clinical characteristics.

Results: Adolescents with higher levels of loneliness aged 11-21 years were 1.97 times more likely to report suicidal ideation six years later (OR_adj1=1.97, 95% CI [1.45, 2.67], p < 0.001), but this association was no longer significant after adjustment (OR_adj2=1.10, 95% CI [0.75, 1.61], p = 0.62). They were also significantly more likely to report suicidal ideation at 13-year follow-up (OR_adj1=2.22, 95% CI [1.71, 2.89], p < 0.001), even after adjustment (OR_adj2=1.36, 95% CI [1.00, 1.86], p = 0.049). However, there was no association between loneliness and suicide attempt at either follow-up point.

Conclusions: Loneliness aged 11-21 years predicts suicidal ideation (but not suicide attempt) 13 years later, suggesting a need for interventions delivered at the start of adolescence to prevent the onset of distressing suicidal ideation later in adolescence and young adulthood.