What predicts illicit drug use versus police-registered drug offending?

Aims To study whether drug offenders differ in childhood and in early adulthood from those who only report using illicit drugs. Design Prospective nationwide birth cohort study. Baseline survey in 1989, follow-up data collection from self-reports, police and military registers in late adolescence and early adulthood. Participants Two-thousand nine hundred and forty six Finnish boys born in 1981. Information about self-reported drug use at age 18 or police-registered drug offending at age 17–20 was available from 79.3% (n = 2,336) of the subjects. Measurements At age 8, psychopathology was assessed using the parent and teacher Rutter scales and child self-reports (Child Depression Inventory). ICD-10 psychiatric diagnoses at early adulthood according to the military register were based on a medical examination. Findings Childhood psychopathology did not predict self-reported drug use at age 18. Both conduct and hyperactivity problems at age 8 predicted drug offences at age 16–20. The predictive association with drug offences was strongest with severe level (over 90th percentile cut-off point) of conduct (OR 5.5, 95% CI 2.9–10.5) and hyperactivity problems (OR 5.0, 95% CI 2.7–9.3). Also moderate level of conduct (OR 2.9, 95% CI 1.7–4.9) and hyperactivity problems (OR 3.1, 95% CI 1.9–5.1) predicted drug offending. Having a psychiatric diagnosis in early adulthood associated with both self-reported use (OR 4.1, 95% CI 2.4–6.8) anddrug offending (OR 13.2, 95% CI 8.3–21.2). Conclusions Drug offending is part of a life-course-persistent deviance, whereas for self-reporters, psychiatric problems arise later in life. Accordingly, the preventive needs, and the age period for intervention are different for boys with divergent illicit drug use involvement