Neurocognitive findings in Prader-Willi syndrome and early-onset morbid obesity

Objectives

To examine whether early-onset morbid obesity is associated with cognitive impairment, neuropathologic changes, and behavioral problems.

Study design

This case-control study compared head MRI scans and cognitive, achievement, and behavioral evaluations of subjects with Prader-Willi syndrome (PWS), early-onset morbid obesity (EMO), and normal-weight sibling control subjects from both groups. Head MRI was done on 17 PWS, 18 EMO, and 21 siblings, and cognitive, achievement, and behavioral evaluations were done on 19 PWS, 17 EMO, and 24 siblings.

Results

The mean General Intellectual Ability score of the EMO group was 77.4 ± 17.8; PWS, 63.3 ± 14.2; and control subjects, 106.4 ± 13.0. Achievement scores for the three groups were EMO, 78.7 ± 18.8; PWS, 71.2 ± 17.0; and control subjects, 104.8 ± 17.0. Significant negative behaviors and poor adaptive skills were found in the EMO group. White matter lesions were noted on brain MRI in 6 subjects with PWS and 5 with EMO. None of the normal-weight control subjects had these findings.

Conclusions

Individuals with EMO have significantly lower cognitive function and more behavioral problems than control subjects with no history of childhood obesity. Both EMO and PWS subjects have white matter lesions on brain MRI that have not previously been described.

Abbreviations:  ANOVA, Analysis of variance , BASC, Behavioral Assessment System for Children , CGH, Comparative genomic hybridization , EMO, Early-onset morbid obesity of unknown cause , GIA, General Intellectual Ability , IBW, Ideal body weight , PKU, Phenylketonuria , PWS, Prader-Willi syndrome , SES, Socioeconomic status , UPD, Uniparental disomy , WJ-III, Woodcock-Johnson Test of Cognitive Ability and Academic Achievement-Third Edition