Abstracts

This abstract has been invited to present during the Broadening Representation Inclusion and Diversity by Growing Equity (BRIDGE) poster session

Rationale: People with Prader Willi Syndrome (PWS) have an increased risk of epilepsy compared to the general population (Verrotti et al, 2014). PWS results from an error in paternally inherited chromosome 15, which is most often due to a deletion of part or all of the PWS imprinted cluster in the q11-13 region of chromosome 15 (deletion subtype), or the inheritance of two maternally marked chromosome 15s and no paternally marked copy (uniparental disomy-UPD). Individuals with the UPD subtype are more likely to exhibit obsessive compulsive behaviors and anxiety symptoms than those with the deletion subtype. Despite differences in the cognitive profiles of the two major genetic subtypes, there is a paucity of literature describing neurophysiologic changes.

Methods: We recorded the electroencephalograms (EEGs) of 50 adults with PWS as they underwent a passive event-related potential (ERP) task and analyzed the EEGs during the inter-stimulus intervals. We computed the following quantitative characteristics: band power in the delta (1-4Hz), theta (4-8 Hz), alpha (8-13 Hz), low beta (13-25 Hz) and high beta (25-40 Hz) ranges; spectral variability in the same frequency ranges, approximate entropy, analytic amplitude and global functional connectivity (as measured by weighted phase lag index). The Wilcoxon rank sum test was used to compare the EEG characteristics by sex and genetic subtype. Spearman’s correlation coefficient was used to examine potential correlations with age.

Results: A total of 34 participants had the deletion subtype, 9 had a UPD subtype, and 7 participants were classified as ‘other’. There were 20 males and 30 females. Ages ranged from 18 to 62 years. We found no significant difference between the major genetic subtypes in spectral band power, spectral variability, approximate entropy or analytic amplitude. Females had higher delta power (mdn 7.11 vs. 5.25, p=0.004), lower alpha power (mdn 0.65 vs. 1.17, p< 0.001), and lower low-beta variability (mdn -0.88 vs 0.41, p=0.0393). We found a significant difference between sexes in relative delta power (female mdn=7.11, male mdn=5.25, p=0.004), relative alpha power (female mdn=0.65, male mdn=1.17, p< 0.0001), spectral variance of the alpha power (female mdn=-0.88, male mdn=0.41 , p=0.011), and spectral variance of the low beta power (female mdn=-0.28, male mdn=-0.24, p=0.050). Age correlated negatively with high beta variability (rho=-0.30, p=0.039). Global delta wPLI was higher in the deletion subtype (0.27 vs. 0.23, p=0.038). There were no sex differences in functional connectivity metrics.