Effectiveness of low intensity behavioral treatment for children with autism spectrum disorder and intellectual disability

• Low intensity behavioral treatment in children with ASD and ID was investigated.
• The treatment group received 4–10 h LIBT and regular (pre) school services.
• The treatment group outperformed the control group receiving treatment as usual.

To determine the effectiveness of low intensity behavioral treatment (LIBT) supplementing regular treatment in young children with autism spectrum disorder (ASD) and intellectual disability (ID) standardized tests of cognition, adaptive behavior, interpersonal relations, play, language, characteristics of autism, emotional and behavioral problems, behavioral flexibility, early social communication, and maternal stress were administered in a treatment group (n = 20), receiving 4–10 h LIBT per week and a control group (n = 20) receiving treatment as usual. At baseline, no differences were found between groups (mean chronological age: 5.3 years; mean developmental age: 1.11 years) on several key variables, but after two years of intervention the treatment group outperformed the control group on IQ, developmental age, adaptive behavior, interpersonal relations, play and receptive language, and less autistic symptoms were seen in treatment group. Following intervention, no differences between groups were found on expressive language, behavioral flexibility and maternal stress. Progress in developmental age, adaptive behavior, interpersonal relations, play and receptive and expressive language was clinically and reliably significant for the majority of the LIBT group.