Objective: To detect the factors associated with total and subscales impulsivity scores in narcolepsy and further explore the non-linear relationship between these factors and impulsivity score.
Methods: One hundred and fifty-eight narcolepsy type 1 (NT1) patients were involved in this cross-sectional study. Patients completed questionnaires evaluating impulsivity symptoms (Barratt impulse scale-11, BIS-11), depression symptoms (Center for Epidemiologic Studies Depression Scale for Children, CES-DC or Self-Rating Depression Scale, SDS) and sleepiness (Epworth Sleepiness Scale, ESS). Parameters from polysomnography and multiple sleep latency test were also collected. Linear regression analysis was performed to detect the factors associated with total and subscales impulsivity scores. Then, generalized additive models and smooth curve fitting were performed to explore the non-linear relationship between chronological age and impulsivity scores.
Results: Factors associated with higher total impulsivity score were higher ESS, older onset and adolescents. Factors associated with higher attentional impulsivity score were higher ESS, older onset and adolescents. Factors associated with higher motor impulsivity score were higher ESS, younger onset and depression symptoms. Factors associated with higher non-planning impulsivity score were adolescents, older onset and depression symptoms. A non-linear relationship between age and impulsivity scores (total impulsivity score, attentional impulsivity score and non-planning impulsivity score) was detected in NT1 patients.
Conclusion: Not only excessive daytime sleepiness but also onset-age, depression symptoms and chronological age were associated with impulsivity in NT1 patients. The non-linear relationship between age and impulsivity scores suggested brain and mental development alterations in NT1 patients.
Keywords: narcolepsy, impulsivity, excessive daytime sleepiness, depression, smooth curve fitting