Childhood symptoms of anxiety and depression are associated with a greater likelihood of using MDMA (ecstasy) in adolescence or young adulthood. In a prospective longitudinal study of 1,580 individuals followed from childhood into adulthood, those whose parents reported deviant-range anxious or depressed behavior in childhood had more than double the risk of later MDMA use (hazard ratio 2.22). The findings suggest that individuals with such symptoms may be particularly susceptible to the drug's euphoric and bonding effects.
Cannabis use is specifically linked to later psychotic symptoms, independent of earlier psychopathology. A 14-year follow-up of 1,580 Dutch children initially aged 4 to 16 found that the association between cannabis use and psychotic symptoms remained after accounting for prior behavioral and emotional problems. The study used survival analyses and suggests cannabis use is a specific risk factor for future psychotic symptoms, not merely a consequence of prior mental health issues. This supports prevention efforts targeting cannabis use to potentially reduce psychotic symptoms in vulnerable individuals.