Body weight and basal metabolic rate in childhood narcolepsy: a longitudinal study

• Body mass index (BMI) increased rapidly in children with type 1 narcolepsy after disease onset.
• Decreased basal metabolic rate (BMR) is an important underlying cause of rapid weight gain.
• BMI growth and BMR were gradually restored to normal levels with prolonged disease.
• Compensatory metabolic mechanisms may contribute to the restoration of BMI growth and BMR to normal levels.

ObjectivesThe aims of this study were to document the trajectory of weight gain and body mass index (BMI) in children with type 1 narcolepsy, and to analyze basal metabolic rate (BMR).MethodsA total of 65 Chinese children with type 1 narcolepsy with a disease duration ≤12 months were included. In addition, 79 healthy age-matched students were enrolled as controls. Height and body weight were measured every six months for up to 36 months to calculate BMI growth. BMR was measured using COSMED K4b2 indirect calorimetry in 34 patients and 30 healthy controls at six months. At the end of 36 months, the BMR was compared among 18 patients and 16 healthy controls.ResultsThe children with type 1 narcolepsy showed higher BMIs at follow-up assessments. At the end of the study, 38.46% of the patients were obese and an additional 26.15% were overweight. The patients' BMI growth at six, 12, 18, 24 and 30 months of follow-up was significantly higher, but not at month 36. The patients' basal energy expenditure was significantly lower than that of the controls at six months but not at 36 months.ConclusionBMI increased rapidly in children with type 1 narcolepsy after disease onset, but BMI growth decreased gradually with prolonged disease. Decreased BMR is an important cause underlying rapid weight gain. The gradual restoration of BMI growth and BMR in narcolepsy emphasizes the importance of compensatory metabolic mechanisms in this disease.