The prevalence of attention deficit-hyperactivity disorder (ADHD) among children in Western countries has been estimated at around 5%. Symptoms may persist into adult life but treatment is often stopped in adolescence or early adulthood. Now Swedish national data (N Engl J Med 2012;367:2006–14) have suggested that continuing medication reduces the likelihood of committing a crime. Data were analysed for 25 656 people with ADHD (16 087 males, 54% of males and 46% of females aged 15–24 years). Criminality included convictions and suspicion of a crime after full investigation. Among males with ADHD, 53.6% had taken medication and 36.6% had been convicted of a crime. Among females the corresponding figures were 62.7% and 15.4%. In matched general population controls, 8.9% of males and 2.2% of females had committed a crime. It was found that during periods on medication (usually methylphenidate or atomoxetine), compared with periods off medication, criminality fell by 32% among males and 41% among females. Treatment for ADHD may reduce criminality rates during periods of medication.

There is uncertainty about …