Narcolepsy in children was not the cause of intellectual disabilities; however, cognitive performance could be improved in this population through prompt interventions to manage comorbidities, according to study results published in the Journal of Clinical Medicine.
Study researchers from Hôpital Femme Mere Enfant in France sought to investigate high cognitive functioning in children with narcolepsy, and whether it was a protective factor for school and behavioral difficulties in this population.
This retrospective study included all children with idiopathic narcolepsy (N=74) observed in a national reference center for narcolepsy in France from 2010 to 2019. Patients were evaluated for clinical characteristics and underwent neuropsychological evaluation. Parents of the children responded to 4 questionnaires which assessed their child’s sleepiness and insomnia severity.
The majority of the included children were boys (n=43) with a median age of 11.7 years at the time of their narcolepsy diagnosis. Most of the children were obese (64%) or overweight (10%). All children were positive for the HLA-DR-DQB1*06:02 variant and all but 1 had low hypocretin-1 levels.
Nearly half (48%) of the children had difficulties at school. Sleep difficulties included cataplexies (91%), hypnagogic hallucinations (39%), and sleep paralysis (18%).
According to the polysomnography data, a minimal obstructive apnea hypopnea index (OAHI) was common (minimal saturation value, 93%; range, 30-98%), sleep latency was a median of 4.8 (range, 0-78) minutes, total sleep time was 478 (range, 270-615) minutes, sleep efficiency was 84.1 percent (range, 52.5-95.2%), rapid eye movement (REM) sleep was 22.3% (range, 10.5-39.3%), and total arousal index was 11.8% (range, 0-66.6%).
Stratified by difficulties at school, no demographic, narcolepsy characteristics, polysomnographic measurements, or mental health characteristics differed significantly.
Compared to children with high potential (intelligence quotient [IQ]≥130), those without high potential had lower verbal comprehension (P <.0001), perceptual reasoning (P <.0001), working memory (P <.0001), general abilities (P <.0001), IQ (P <.0001), and processing speed (P =.006).
Results indicated a significant correlation between percentage of REM sleep in children with narcolepsy and IQ (r, 0.25; P =.04), in which the higher the IQ, the more REM sleep a child had. A similar correlation was trending towards significant between REM and IQ among children with (r, 0.37; P =.06) and without (r, 0.29; P =.05) high potential.
For every 1 percent increase in REM, the multivariate regression model indicated an increase in IQ of 0.58 (95% CI, 0.09-1.06; P =.02) points.
This study was limited by its lack of a control group of children without narcolepsy, missing information on parental IQ and educational levels, and its cross-sectional design.
Study researchers concluded that “the present results suggest that narcolepsy in children is unlikely to be a cause of intellectual disability despite their frequent school difficulties. Neuropsychological evaluation could help these children to find adapted support.” They added that “the prompt diagnosis and management of comorbidity such as obesity and OSA could improve cognitive performances and decrease school and behavioral difficulties in these children.”
Thieux M, Zhang M, Marcastel A, et al. Intellectual Abilities of Children with Narcolepsy. J Clin Med. 2020;9(12):E4075. doi:10.3390/jcm9124075