Mental health problems in a large representative sample of children and adolescents: Prevalence, associations with problematic substance use and psychometric properties of the Strengths and Difficulties Questionnaire.

Mental health problems are already widespread in childhood and adolescence. The Strengths and Difficulties Questionnaire (SDQ) is an internationally widely used instrument for assessing mental health problems and prosocial behavior in children and adolescents. Particularly, the Total Difficulties score (TDS) from the SDQ (calculated from the sum of all problem scales) is considered a good estimator for mental health problems. Heretofore, there are relatively few estimates for mental health problems based on representative samples that rely on self-assessments by children and adolescents. Although SDQ is frequently used internationally, the findings regarding its psychometric properties are inconsistent. So far, there are no results available from representative samples on the relationships between the TDS and various forms of problematic substance use. A representative sample of 4001 12-17-year-olds from Germany was examined using the SDQ with regard to mental health problems and established standardized instruments for problematic use of alcohol, cigarettes, and cannabis. We calculated relative frequencies, reliability coefficients (Cronbach's alpha and McDonald's omega), correlations, binary logistic regressions, and linear regression analyses. Furthermore, we conducted confirmatory factor analyses. Based on the TDS, 9.6% (95% confidence interval: 8.7%-10.5%) of the representative sample reported severe mental health problems. We observed reliability values for the five SDQ scales between 0.44 (peer problems) and 0.70 (emotional problems), as well as 0.74 and 0.75 for the TDS. In the different confirmatory factor analyses, no model showed a completely satisfactory fit to the data. In bivariate and multivariable analyses, consistent statistically significant associations were found between mental health problems (TDS) and problematic cigarette use and problematic cannabis use, whereas findings for problematic alcohol use were mixed. According to our results, a substantial proportion of German children and adolescents are affected by severe mental health problems, and problematic substance use is a possible source of this.