Adolescent personality traits, low self-esteem and self-harm hospitalisation: a 15-year follow-up of the Norwegian Young-HUNT1 cohort.

Affective disorders are closely related to self-harm and suicidal behaviours. Less is known about how adolescent personality traits and self-esteem influence the development of later self-harm. We examined associations between personality traits such as neuroticism, psychoticism and extroversion, and self-esteem, in adolescence, and the risk of future self-harm hospitalisation. Baseline information from 13 to 19-year-old participants in the Norwegian Young-HUNT1 study in 1995-97 (n = 8965) was linked to endpoint data recorded from participants' hospital records, describing self-harm hospitalisation episodes within the catchment area. Crude and adjusted hazard ratios (HR) were estimated by Cox regression analyses. A one-unit increase on the 0-6 scale for neuroticism was associated with a HR of 1.29, 95% confidence interval (CI) 1.14-1.47. Corresponding HR for psychoticism was 1.30, 95% CI 1.03-1.63 per unit increase, and for extroversion risk was reduced (HR 0.89, 95% CI 0.77-1.04). Positive perception of self-esteem was more strongly associated with reduced risk of self-harm hospitalisation (HR per unit increase on the 0-12 scale was 0.74, 95% CI 0.68-0.82). Additional adjustment for alcohol use and symptoms of combined anxiety and depression symptoms attenuated effect estimates, in particular for neuroticism (HR 1.13, 95% CI 0.96-1.32) and psychoticism (HR 1.07, 95% CI 0.82-1.40). In contrast, self-esteem associations remained largely the same after adjustment. Our results indicate that brief assessments of personality and self-esteem might add additional relevant information, and could be included as a supplement to standard suicidal risk assessment in adolescents.