Hypocretin Deficiency in Narcoleptic Humans Is Associated with Abdominal Obesity

Authors

  • Simon W. Kok,

    1. Department of General Internal Medicine, Leiden University Medical Center, Leiden, The Netherlands
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  • Sebastiaan Overeem,

    1. Department of Neurology and Clinical Neurophysiology, Leiden University Medical Center, Leiden, The Netherlands
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  • Tommy L.S. Visscher,

    1. Department for Chronic Diseases Epidemiology and Environmental Epidemiology, National Institute of Public Health and the Environment, Bilthoven, The Netherlands
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  • Gert Jan Lammers,

    1. Department of Neurology and Clinical Neurophysiology, Leiden University Medical Center, Leiden, The Netherlands
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  • Jaap C. Seidell,

    1. Department for Chronic Diseases Epidemiology and Environmental Epidemiology, National Institute of Public Health and the Environment, Bilthoven, The Netherlands
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  • Hanno Pijl,

    Corresponding author
    1. Department of General Internal Medicine, Leiden University Medical Center, Leiden, The Netherlands
      Department of General Internal Medicine, Leiden University Medical Center, C1-R39, P.O. Box 9600, 2300 RC Leiden, The Netherlands. E-mail: h.pijl@LUMC.nl
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  • Arend E. Meinders

    1. Department of General Internal Medicine, Leiden University Medical Center, Leiden, The Netherlands
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Department of General Internal Medicine, Leiden University Medical Center, C1-R39, P.O. Box 9600, 2300 RC Leiden, The Netherlands. E-mail: h.pijl@LUMC.nl

Abstract

Objective: To determine the prevalence of obesity among patients with narcolepsy, to estimate associated long-term health risks on the basis of waist circumference, and to distinguish the impact of hypocretin deficiency from that of increased daytime sleepiness (i.e., reduced physical activity) on these anthropometric measures.

Research Methods and Procedures: A cross-sectional, case-control study was conducted. Patients with narcolepsy (n = 138) or idiopathic hypersomnia (IH) (n = 33) were included. Age-matched, healthy members of the Dutch population (Monitoring Project on Risk Factors for Chronic Diseases and Doetinchem Project; n = 10, 526) were used as controls. BMI and waist circumference were determined.

Results: Obesity (BMI ≥ 30 kg/m2) and overweight (BMI 25 to 30 kg/m2) occurred more often among narcolepsy patients [prevalence: 33% (narcoleptics) vs. 12.5% (controls) and 43% (narcoleptics) vs. 36% (controls), respectively; both p < 0.05]. Narcoleptics had a larger waist circumference (mean difference 5 ± 1.4 cm, p < 0.001). The BMI of patients with IH was significantly lower than that of narcolepsy patients (25.6 ± 3.6 vs. 28.5 ± 5.4 kg/m2; p = 0.004).

Discussion: Overweight and obesity occur frequently in patients with narcolepsy. Moreover, these patients have an increased waist circumference, indicating excess fat storage in abdominal depots. The fact that patients with IH had a lower BMI than narcoleptics supports the notion that excessive daytime sleepiness (i.e., inactivity) cannot account for excess body fat in narcoleptic patients.

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