Research and literature on sex offenders with intellectual and developmental disabilities.
People with intellectual disabilities who commit sex offenses need validated assessment tools and long-term treatment—short classes do little.
01Research in Context
What this study did
Lindsay (2002) read every paper on sex offenders who also have intellectual or developmental disabilities.
The author looked for two things: how many people with ID commit sex crimes, and whether any treatment really works.
No new data were collected; this was a narrative review that maps what was known at the time.
What they found
The review found no solid proof that people with ID are more or less likely to commit sex offenses than anyone else.
Short treatment courses showed little benefit; the author says plan for multi-year, comprehensive programs instead.
Few studies used validated risk or knowledge tests, so clinicians were flying blind.
How this fits with other research
Stancliffe et al. (2007) extends this picture. Their Vermont case-series followed 103 men with ID for six years and recorded a 10.7 % sexual recidivism rate, giving the long-term numbers Lindsay (2002) said were missing.
van Schrojenstein Lantman-de Valk et al. (2006) answers the call for validated tools. They built the GSKQ, a reliable sexual-knowledge test for people with ID, and showed that lower knowledge does not predict offending—useful when you screen risk.
Noordenbos et al. (2012) adds depth. They found that male sex offenders with ID report higher rates of childhood sexual abuse than other offenders. This abuse-history angle was only speculation in Lindsay (2002), so the newer data sharpens your assessment protocol.
Why it matters
You now have three concrete take-aways: use a validated tool like the GSKQ, plan treatment for years not weeks, and screen every client for trauma history. These steps move you from “we don’t know” to evidence-based practice with this high-risk, under-served population.
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02At a glance
03Original abstract
The present paper sets out to review the literature on several aspects of sex offenders with intellectual and developmental disabilities, including the relationship between sex offending and developmental disabilities, the prevalence and characteristics of sex offenders in this client group, assessment, treatment, and outcome of intervention. Several important variables were identified as influencing the disparate results found in different prevalence studies. These include variations in inclusion criteria, differences in the source of the sample, differences in determination of IQ, the impact of deinstitutionalization, and the effect of changing social and penal policies in the area where studies have been conducted. Although some studies have suggested an increasing incidence, there is no clear evidence for the over- or under-representation of people with developmental disabilities amongst sex offenders. One of the main methodological flaws in several reports listing the characteristics of sex offenders is that considerations are based on clinical samples. Therefore, there is no control group to show that these characteristics do not exist in other samples of individuals with intellectual disability (ID). It does appear that sex offenders with ID are more likely to commit offences across categories and to be less discriminating in their victims. There may also be an association with sexual abuse in childhood. The primary issue considered has been assessment of competency, in that people with ID are considered to be disadvantaged by the criminal justice process. While several authors have delineated the important areas for assessment, there are few assessment measures with robust psychometric properties. Pharmacological, behavioural, educational and cognitive treatments are reviewed. Several comprehensive treatments which include all of the aforementioned methods are also considered. Although most studies do not report particularly positive outcomes, several authors have found better outcomes with treatment lasting at least 2 years.
Journal of intellectual disability research : JIDR, 2002 · doi:10.1046/j.1365-2788.2002.00006.x