the antisocial prisoners were violent offenders having committed at least one violent crime. The remaining individuals of the ASPD sample were offenders who had been convicted for non-violent crimes, such as house break-ins or crimes against property. The history of substance abuse (alcohol, heroin, buprenorphine, amphetamine, cannabis and/or other) as well as childhood circumstances (for example, good circumstances, indifferent parents or severe maltreatment such as family violence) were screened with a questionnaire. Subjects provided a written informed consent. This study was approved by the Ethics Committee for Pediatrics, Adolescent Medicine and Psychiatry, Hospital District of Helsinki and Uusimaa, and Criminal Sanctions Agency. All the subjects who participated in the study received a voucher of 20 euros for their participation.
