Deficit in Social Cognitive Abilities Among PWS Children Linked to Genetic Subtype, Study Says

The deficit in social cognitive abilities among young children with Prader-Willi syndrome (PWS) starts at an early age — and varies with the genetic subtype, a study found.

Children with PWS who inherit two chromosomes 15 from their mother showed manifestations similar to those of autism spectrum disorder (ASD), the study showed. In comparison, PWS children with a deletion in chromosome 15 — inherited from the father — seem to have a higher functioning level.

The study, “Early Social Cognitive Ability in Preschoolers with Prader–Willi Syndrome and Autism Spectrum Disorder,” was published in the Journal of Autism and Developmental Disorders.

Children with Prader-Willi syndrome and autism spectrum disorder both have impaired social cognitive abilities, namely in their interaction with parents and peers. Comparing the social ability of children with these conditions is important because alterations in the region 15q11-q13 of chromosome 15 — which is inactive in PWS — have been associated with certain behavioral symptoms in children with ASD.

Most studies on social cognitive abilities in children with PWS are based solely on reports from parents or caregivers. This, however, can lead to inaccurate measures, as parental observation might be biased. Therefore, clinical assessment should complement parental reports, researchers say.

Now, investigators in Cleveland assessed the social cognitive abilities of 50 children ages 3 to 5 years with PWS or ASD. Among the participants were 17 children diagnosed with PWS due to deletion in the father’s chromosome (DEL group), and 13 children with PWS due to inheritance of two chromosomes from the mother (MOTHER group). Also included were 20 children with ASD.

Researchers measured the cognitive adaptative functioning of the children using the Mullen Scales of Early Learning, among others.

Children also underwent a clinical assessment following the Affect in Play Scale—Preschool Version. This standardized play task is designed to measure different aspects of children’s pretend play, such as the organization of the story line, imagination, and comfort while playing.

The team also evaluated parental reports.

“This is the first study to investigate social cognitive ability using direct assessment and parental report in PWS, and in comparison to autism during the preschool years,” the researchers said.

The initial evaluations showed that the DEL group presented higher social cognition than the MOTHER and ASD groups. Further, the clinical assessment showed that the DEL group had the highest scores in all measures, compared with the other two groups, which had similar scores between them.

However, there were some cases in which children in the MOTHER group “performed more poorly than both the DEL and ASD groups, such as, on average, spending twice as much time not engaging with the toys (‘no play’ variable), and expressing a significantly less amount of affect than the other two groups,” the researchers said.

The researchers noted that, in the parental reports, “there was no difference in functioning by PWS subtype.”

“On behavioral assessments, the DEL sample expressed overall higher functioning, and the [MOTHER] group presented with performance more similar to the ASD group across certain measures. However, results from parent report were not consistent with these findings,” the team said.

“Parents reported that both subtypes of PWS were performing at a higher level than the ASD sample across all social cognitive domains,” they said.

These findings suggest that “parent report alone may not be nuanced enough to capture the specific differences between PWS subtypes,” the researchers said.

Overall, the results suggested that impairment in cognitive ability is evident from an early age in children with PWS — the children in this study were ages 3 to 5 — and that the manifestations vary depending on the genetic subtype.

“Behaviorally, the paternal deletion subtype [DEL] expressed overall higher functioning, whereas the maternal uniparental disomy subtype [MOTHER] performed more similarly to the ASD group,” the researchers said.

“These differences may be important in informing early intervention techniques so as to be more specifically tailored to each subtype’s ability level and needs,” they concluded.