PWS Children Struggle to Show Emotions, Study Suggests

Children with Prader-Willi syndrome (PWS) struggle to express adequate facial and bodily emotions, which is linked to difficulties adapting socially, a study suggests.

The study, “Equivocal expression of emotions in children with Prader-Willi syndrome: what are the consequences for emotional abilities and social adjustment?,” was published in the Orphanet Journal of Rare Diseases.

Expressing emotions is an important component for social life. PWS influences neurological development and causes both physical and psychological impairments. Usually, children with PWS present mild-to-moderate intellectual disability (low IQ) together with delayed language and motor development. This also leads to complications in social ability, as people with PWS commonly experience social adjustment problems.

Previous studies suggested that the type of genetic alteration influences the degree of physical and behavior disability. PWS is caused by a genetic defect in a specific region of chromosome 15. This alteration can be either a deletion or a condition called maternal uniparental disomy (mUPD), which refers to when both copies of chromosome 15 are inherited from the mother.

Deletions have been associated with high emotional lability (exaggerated changes in mood). However, it is still not clear how PWS affects emotional skills. In fact, few studies to date have investigated emotional functioning in those with PWS.

Now, researchers at University of Toulouse, in France, investigated the ability that PWS children have to express emotions and how it affects their social adaptation.

Their analysis included 25 children 5.5 to 10.5 years old (average age was 7.6 years). The patients’ mean IQ was 75.7, which corresponds to the average intellectual development of a 5.7-year-old child. Eleven children had a chromosome 15 deletion, 12 had mUPD, and two had unknown genetic subtype.

As controls, researchers recruited children with typical development — 25 children with matched sex and age, and another 25 children with matched sex and intellectual development age.

To analyze facial expressions, participants were asked to complete two tests: watch a humorous video clip likely to induce joy (spontaneous emotional reaction task, or EMOrea) and voluntarily express joy, fear, sadness and anger emotions (voluntary production of emotional expressions task, or EMOmim).

Video material was recorded to analyze facial expressions using FaceReader software. This program breaks down facial expression into individual basic movements, so-called actions units (AUs). For example, when a child experiences joy, the software will look for smiling (raising of lips’ corners) and creasing of the eyes’ corners. The more intense the reaction the higher the AU value, which ranges from zero (emotion not visible) to one (emotion completely detected).

To assess social adaptation, researchers asked parents or educators to answer a socio-affective profile (PSA) questionnaire. It includes sub-scales on social competence, internalized and externalized problems, and general adaptation.

Analysis of facial joy showed that the group with mUPD had significantly lower AU scores on average (0.184) compared to patients with genetic deletion (0.382) and both control groups (0.358 and 0.432). Bodily joy also was lower in the PWS groups compared to controls.

Researchers also found significant differences in facial fear expression. The PWS group with mUPD mobilized fewer AU (0.083) compared to those with genetic deletion (0.242) and to controls (0.257 and 0.333). The same was  seen in the bodily fear.

AU scores for sadness and anger also were lower in PWS patients with mUPD compared to all other groups.

Results showed children with PWS deletion (43.2) and mUPD (42.9) had weaker general adaptation compared to control groups (51.1 and 54). A similar trend was observed for social skills and internalized problems.

When researchers compared facial expression tests with questionnaire results, they observed that voluntary expression performance was significantly correlated with scores in general adaptation, social skills and internalized problems.

Overall, “[t]hese results shed new light on emotional dysfunction in PWS and consequently on the adaptive abilities of those affected in daily life,”  researchers wrote.

These findings support the interest “in promoting and supporting the development of the expressive capacities of these children. Offering an early care program would improve the children’s relationship with their parents, which is fundamental to their development,” they added.