BACKGROUND: Narcolepsy with cataplexy (NC) differs from narcolepsy without cataplexy (NwoC) in the cerebrospinal fluid levels of hypocretin. Since hypocretin is known to regulate not only wakefulness but also eating behaviour, we decided to compare the two entities for body mass index (BMI) and the presence of obesity.
METHODS: Clinical data on patients with NC and NwoC was studied and examined, including nocturnal polysomnography and the Multiple Sleep Latency Test (MSLT). The results were rated against a group of age- and sex-matched healthy controls.
RESULTS: The BMI in NC (29.1±SD=5.8) was significantly higher than in NwoC (25.4±4.4) or in the controls (25.8±3.9) (p<0.001, F=17.4, df= 323), while no difference in BMI was found between NwoC and the controls. The proportion of patients with BMI >30 was significantly greater in NC (39.0%) than in NwoC (13.8%) or than in the control group (13.0%). A negative correlation of BMI and sleep latency in MSLT (p=0.009) was found in the combined NC and NwoC groups.
CONCLUSION: Unlike NC, NwoC has neither a higher BMI nor a higher incidence of obesity than the general population.