Wave 4 data collection in 2006–2009 conducted structured psychiatric interviews at an average age of 21.9 (SD 0.8, range 21–26) years, with neuropsychological assessments and collection of DNA & serum samples (for basic biochemistry and metabolomics) from twins of 900+ families most informative for substance abuse/dependence with existing psychiatric interview data (at age 14 for the twins). During this one-day, in-person assessment in Helsinki, we collected information about substance use, abuse and dependence (smoking, alcohol, cannabis and other drug use) based on questionnaires and interviews for DSM-IV diagnoses (alcohol, illicit drugs, depression, eating disorders, suicidal behavior and antisocial behavior), but also about lifestyle (physical exercise, food habits), chemosensory preferences, mood and regulation of emotions [depression (General Behavior Inventory) and mood (General Health Questionnaire-12)], personality (NEO-Five Factor Inventory), schizotypy (Schizotypal Personality Questionnaire), sense of coherence, general health (illnesses, body composition, metabolism, experienced health), cognitive functions (general cognitive capacity, spatial ability, memory, executive functioning, attentiveness, perceptual speed, motor dexterity, and social cognition as measured with ability to recognize emotional facial expressions), and work. The assessments were completed on 1,347 twins (73% of
