Association between poverty exposure during childhood and adolescence, and drug use disorders and drug-related crimes later in life

Aims: To examine whether poverty exposure in childhood/adolescence increases the risk of later drug use disorder and drug crime conviction.

Design, setting and participants: A national cohort study encompassing 634 284 individuals born between 1985 and 1990, residing in Sweden between 5 and 18 years of age, followed-up from January 2004 to December 2016, starting from the age of 19 years until the first visit to inpatient/outpatient care with a diagnosis of a drug use disorder or a drug crime offence.

Measurements: The exposure variable was 'trajectories of poverty' based on household income, assessed through group-based trajectory analysis. Cox regression analysis was used to obtain hazard ratios for drug use disorders and drug crime convictions using age as the underlying time scale.

Findings: We identified five trajectories of childhood/adolescence poverty: (1) 'moving out of poverty in childhood' (8.7%); (2) 'never poverty' (68.9%); (3) 'moving into poverty in adolescence' (11.0%); (4) 'moving out of poverty in adolescence' (5.4%); and (5) 'chronically poor' (5.9%). Compared with the 'never poor' group, almost all trajectory groups had higher risks for drug use problems. Young males 'moving into poverty in adolescence' had the highest risks of drug use disorder [hazard ratio (HR) = 1.48, 95% confidence interval (CI) = 1.40-1.57] and drug crime conviction (HR = 1.50, 95% CI = 1.38-1.62), after adjusting for calendar year, domicile, origin, psychiatric diagnosis and parental psychiatric diagnosis. The results were similar in females moving into poverty in adolescence (HR = 1.63, 95% CI = 1.52-1.76 and HR = 1.89, 95% CI = 1.74-2.05 for drug use disorders and drug crime, respectively).

Conclusion: In Sweden, poverty exposure early in life seems to increase the risk of drug use problems in adulthood. These associations are not explained fully by domicile, origin or other psychiatric disorders. Young males and females moving into poverty in adolescence are at highest risk.