Cohort study of neurocognitive functioning and adaptive behaviour in children and adolescents with Niemann-Pick Disease type C1.

AIM: To describe the neurocognitive and adaptive behavior profile of children and adolescents with Niemann-Pick Disease type C1 (NPC1), a rare genetic disease that frequently presents in childhood, with variable onset and symptom complex involving neurodegeneration.

METHOD: Thirty-eight participants (20 males, 18 females; mean age 8y 10mo, SD 4y 8mo, range 1-18y) with NPC1 were evaluated through a natural history protocol.

RESULTS: NPC1 severity was in the mild to moderate range for most participants. Cognitive scores (n=32) ranged from very low to above average; about half of the participants exhibited a clinically significant advantage of Verbal IQ over Non-verbal IQ. Adaptive behavior scores (n=21) were generally in the borderline to impaired range. Longitudinal cognitive data (n=19) suggested a pattern of decreasing scores over time. However, most participants remained at the same general level of functioning throughout the study.

INTERPRETATION: This study begins to systematically describe the neurocognitive phenotype of children and adolescents with NPC1, identifying heterogeneity and decline, aiding in understanding the natural history of the disease to plan treatment studies.