Elusive cases in forensic psychiatry? Exploring subgroups of schizophrenia spectrum disorder patients in Germany.

Background: The relationship between schizophrenia spectrum disorders (SSD) and criminal behaviour is a central issue in forensic psychiatry. People with mental illness face some of the same types of criminogenic factors as people without mental illness, albeit more frequently. The research question of this study is the extent to which a framework of early and late offender typology can be empirically reconstructed in a forensic psychiatric population, and whether there are any practical implications.

Method: For N = 733 patients in six different forensic hospitals in Germany, the age at first psychiatric admission and the age at first registered offence were documented, as well as a number of other patient-related characteristics. Two clustering procedures were used to investigate whether forensic psychiatric patients could be classified according to these characteristics.

Results: A k-means cluster analysis using age at first psychiatric admission, age at first recorded offence, sociodemographic, clinical and criminological characteristics supported a 4-cluster solution. MANOVA analyses revealed further differences between the identified types.

Conclusion: This study empirically confirms some of the sub-groups of the early and late starter typology described in the literature. In particular, the "early starters", "late starters" and "first presenters" were identified, but cluster four comprises individuals not previously described in the scientific literature. Each of these classes has group-specific characteristics that may have implications for forensic treatment, post-release aftercare, and the legal system.