Drug use and social integration.
D000293:Adolescent; D002188:Cannabis; D003718:Denmark; D006801:Humans; D007398:Interpersonal Relations; D007857:Leadership; D007899:Leisure Activities; D008019:Life Style; D012917:Social Adjustment; D012963:Sociometric Techniques; D013334:Students; D019966:Substance-Related Disorders / Q000453:epidemiology; D011795:Surveys and Questionnaires