Characteristics of forensic psychiatric patients with a neurocognitive disorder

Emotional and behavioural disturbances accompanying neurocognitive disorders may sometimes lead to a criminal offence. Our knowledge of this specific forensic subpopulation is lagging behind the knowledge on, and attention for, 'classic' psychiatric disorders in forensic populations.

To gain knowledge on the prevalence and characteristics of individuals with neurocognitive disorders in the forensic population.

This retrospective database study uses an anonymised data-set of the National Database of penitentiary psychiatric centres (PPC) (N = 8391), which collects data on all patients admitted to one of the four PPCs (mental health clinics within the prison system) in The Netherlands since May 2013. Inclusion criterion for this study was the presence of a Diagnostic and Statistical Manual of Mental Disorders, fourth edition, text revision (DSM-IV-TR) or Diagnostic and Statistical Manual of Mental Disorders, fifth edition (DSM-5) diagnostic code belonging to the category of neurocognitive disorders.

A DSM-IV-TR or DSM-5 diagnostic code of a neurocognitive disorder was classified in 254 out of 8391 unique individuals, resulting in a prevalence of 3.0% in the total PPC population. The most prevalent diagnosis was unspecified neurocognitive disorder (59.1%). The neurocognitive disorder group significantly differed from a random control group from the database (n = 762) on demographic, clinical and criminological variables.

The prevalence of neurocognitive disorders in this real-world clinical sample is remarkably lower than in two earlier studies in similar populations. Also remarkable is the relatively high prevalence of an unspecified neurocognitive disorder. These findings lead us to hypothesise that neurocognitive disorders may be underdiagnosed in this population. Forensic psychiatric settings should evaluate whether they have sufficient expertise available in neuropsychological assessment.