Screening for intellectual disability in Dutch police suspects

The screener for mild intellectual disability (SCIL) was developed to screen for mild intellectual disability (IQ below 85). The aims of this study were (a) to examine the predictive validity of the SCIL in screening for intellectual disability among police suspects and (b) to explore the prevalence of cognitive intellectual disability among suspects in police custody in the Netherlands. An unselected sample of police suspects (N=178) charged with a variety of offences was assessed with the SCIL, a Wechsler Adult Intelligence Scale (WAIS)-III-NL short form, and a malingering measure. The SCIL screened 50.0% of the sample as having mild intellectual disabilities, whereas the short WAIS classified 84.3% of the sample with an IQ below 85. A principal component analysis of the SCIL showed ambiguous results. Furthermore, the short WAIS classified 55.6% of our sample with a borderline IQ (IQ=70-84), 84.3% with an IQ below 85 and 28.7% with an IQ below 70. The prevalence of intellectual disability in this sample of Dutch (police) suspects appears to be higher than prevalence rates found in previous international studies. More exhaustive research is needed to examine the prevalence of intellectual disabilities in police suspects, and the utility of the SCIL to screen for these disabilities.