This article reviews evaluation studies of programs designed to treat sex
offenders with intellectual and developmental disabilities (IDD) published in
peer-reviewed journals between 1994 and 2014. The design of this study is
mirrored after PRISMA (Preferred Reporting of Items for Systematic Reviews and
Meta-Analyses) recommendations for conducting a systematic literature review.
The study design, study setting, characteristics of participants, type of
treatment, and intervention procedures comprise areas of focus for evaluating
the implementation of treatment programs. Therapeutic outcomes include changes
in attitudes consistent with sex offending, victim empathy, sexual knowledge,
cognitive distortions, and problem sexual behaviors. Eighteen treatment
evaluation studies were identified from the United States, the United Kingdom,
Australia, and New Zealand. Cognitive-behavioral treatments were the most
commonly delivered treatment modality to sex offenders with IDD. Other less
common treatments were dialectical behavioral therapy, problem solving therapy,
mindfulness, and relapse prevention. No randomized controlled trials were
identified. The most common designs were multiple case studies and pre- and
post-treatment assessments with no control and repeated measures follow-up.
Small sample sizes, no control groups, and wide variation in treatment length
and follow-up time complicate the qualitative synthesis of study findings. Short
follow-up times introduce the potential for bias in conclusions surrounding
treatment efficacy for many of the studies reviewed in this analysis. The
overall quality of studies examining treatments for sex offenders with IDD is
poor and requires further development before rendering firm conclusions about
the effectiveness of interventions for this population.