This PhD dissertation originates from The Ministry of Justice, Clinic of Forensic Psychiatry, Copenhagen, Denmark and Institute of Public Health, University of Copenhagen, Denmark.

It is based on a cross-sectional clinical study and a historical follow-up register study.

The aims were 1) to estimate prevalence rates of mental disorders (ICD-10) of remanded 15-17-year old adolescents, 2) to estimate associations between mental disorders and violent crime for remanded adolescents, and 3) to identify predictors of schizophrenia among young criminals.

The clinical study included all 15-17-year old remanded in East Denmark a 12 months period in 1999-2000. 100 boys participated.

The register study included all 780 15-19-year old young criminals who, in 1992 on a given day/month, were in contact with the Danish Prison and Probation Service. All were followed up in 2001 in the Danish Psychiatric Central Register, the Danish Criminal Register, and the Danish National Causes of Death Register.

The clinical study found 71% with a past year ICD-10 mental and behavioural disorder.

For 15-17-year old remanded boys there was found no association between mental disorder and violence.

The register study found that psychiatric admission before age 15-19 predicted later admission to a psychiatric hospital due to schizophrenia (OR = 1.83, [1.32;2.54]). A verdict of violence before 15-19 predicted later admission to a psychiatric hospital due to schizophrenia (OR = 4.59, [1.54;13.74]).

The dissertation recommends that the judicial system in Denmark introduces screening for mental disorders of remanded adolescents and identification of young criminals with previous psychiatric admission and a verdict of violent crime as this increases the risk of future schizophrenia.