Narcolepsy type 1 features across the life span: age impact on clinical and polysomnographic phenotype

STUDY OBJECTIVES: Narcolepsy type 1 (NT1) is a chronic neurological disorder typically arising during adolescence and young adulthood. Recent studies demonstrated that NT1 presents with age-specific features, especially in children. With this study we aimed to describe and to compare the clinical pictures of NT1 in different age groups.METHODS: In this cross-sectional, multicenter study, 106 untreated NT1 patients, enrolled at the time of diagnosis, underwent clinical evaluation, a semi-structured interview (including the Epworth Sleepiness Scale - ESS), nocturnal video-polysomnography and the Multiple Sleep Latency Test (MSLT). Patients were enrolled in order to establish five age-balanced groups (childhood, adolescence, adulthood, middle-aged and seniors).RESULTS: The ESS score showed a significant increase with age, while self-reported diurnal total sleep time was lower in elderly and young adults, with the latter also complaining of automatic behaviors in more than 90% of cases. Children reported the cataplexy attacks to be more frequent (>1/day in 95% of cases). "Recalling an emotional event", "meeting someone unexpectedly", "stress" and "anger" were more frequently reported in adult and elderly patients as possible triggers of cataplexy. Neurophysiological data showed a higher number of SOREMPs on the MSLT in adolescents compared to senior patients and an age-progressive decline in sleep efficiency.CONCLUSIONS: Daytime sleepiness, cataplexy features and triggers, and nocturnal sleep structure showed age-related difference in NT1 patients; this variability may contribute to diagnostic delay and misdiagnosis.