Associations between academic achievement and internalizing disorders in Swedish students aged 16 years between 1990 and 2018.

Background: Rising rates of internalizing disorders and rising rates of school failure among adolescents are growing concerns. Despite the strong association between academic achievement and internalizing disorders, possible links between these two trends have not been investigated. Thus, the aim of this study was to investigate the development of the cross-sectional associations between academic achievement and internalizing disorders in Swedish students aged 16 years between 1990 and 2018.

Methods: Register data on specialist psychiatric care and prescriptions of psycholeptic and psychotropic drugs were linked to data on students' school grades in the last year of compulsory school. The total sample size was 3,089,674 students. Logistic regression models with internalizing disorders as the dependent variable, and graduation year and academic achievement as independent variables, were estimated.

Results: Throughout the period, there was a strong negative association between academic achievement and internalizing disorders. Low-achieving students had by far the highest risks of internalizing disorders. In absolute terms, the increase in internalizing disorders was clearly largest for low-achieving students. The relative risks for low-achieving compared to higher achieving students increased between 1990 and 2010 and declined after 2010.

Conclusions: This study found consistently large, and at least until 2010 growing, achievement-related inequalities in internalizing disorders among Swedish adolescents between 1990 and 2018, with the lowest achieving students having disproportionally high risks. The increasingly pronounced concentration of internalizing disorders in the lowest rungs of the achievement distribution suggests that preventive interventions should focus on supporting this doubly disadvantaged group of students.