JUNE 2017 – Researchers at the Vanderbilt Kennedy Center believe that prevalence rates of ASD in PWS have been overestimated due to limited data and questionable screening so they conducted a large cohort study of 146 individuals and clinically evaluated the participants using standard ASD measures. They found the rate of ASD and PWS to be 12.3%, much lower than previously thought. They also confirmed that the prevalence rate is higher amongst those with PWS by UPD or imprinting defect, approx. 25% and 28% respectively.
Compared to the PWS-only group, children with PWS + ASD had lower verbal and composite IQ’s and adaptive daily living and socialisation skills, as well as elevated restricted interests and stereotypies (mechanical/rhythmic, persistent movements or utterances.) They found that regardless of ASD diagnosis, the repetitive behaviours of compulsivity and insistence on sameness were seen in 76-100% of their entire study group, particularly in routines, events, timing, repetitive questioning, becoming upset if interrupted, hoarding and ordering and arranging items. These behaviours did not correlate to IQ but clearly impeded adaptive functioning (day to day living skills.) Restricted interests and stereotypies were unusual in the group with a PWS-only diagnosis. They also found that despite being below the threshold for ASD, 45-70% of the PWS-only group had some degree of impairment in sustaining conversations and in the quality and amount of their reciprocal social interactions. No PWS group differences emerged in the self-injurious behaviour domain. Read More >