Internalizing and externalizing symptoms and suicidal behaviour in young people: a systematic review and meta‐analysis of longitudinal studies

<jats:sec><jats:title>Objective</jats:title><jats:p>To assess internalizing and externalizing symptoms as risk factors for suicidal behaviour and suicide among adolescents and young adults.</jats:p></jats:sec><jats:sec><jats:title>Method</jats:title><jats:p>We conducted a systematic review of articles published until January 2017. We identified 26 883 potential papers; 1701 full‐text articles were assessed for eligibility, of which 1479 were excluded because of methodological reasons. Diverse meta‐analyses were performed for each group of symptoms. Odds ratios (<jats:styled-content style="fixed-case">OR</jats:styled-content>s) and 95% confidence intervals (95% <jats:styled-content style="fixed-case">CI</jats:styled-content>) or beta coefficients for categorical variables, and effect size (<jats:styled-content style="fixed-case">ES</jats:styled-content>) were calculated for continuous variables.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>Finally, 41 studies were included, involving participants aged 12–26 years for a systematic review, and 24 articles were included for meta‐analysis. The meta‐analysis showed that youths with any internalizing (<jats:styled-content style="fixed-case">ES</jats:styled-content> = 0.93) or externalizing symptoms (<jats:styled-content style="fixed-case">ES</jats:styled-content> = 0.76 and <jats:styled-content style="fixed-case">OR</jats:styled-content> = 2.59) were more likely to attempt suicide in future. This effect was also seen in depression symptoms (<jats:styled-content style="fixed-case">OR</jats:styled-content> = 6.58 and <jats:styled-content style="fixed-case">ES</jats:styled-content> = 1.00), legal problems (<jats:styled-content style="fixed-case">OR</jats:styled-content> = 3.36), and anxiety (<jats:styled-content style="fixed-case">ES</jats:styled-content> = 0.65).</jats:p></jats:sec><jats:sec><jats:title>Conclusion</jats:title><jats:p>Reported internalizing and externalizing symptoms are predictors of suicide behaviour in young people; therefore, the detection and management of these symptoms in young populations could be a crucial strategy for preventing suicidality in this group.</jats:p></jats:sec>