Narcolepsy is a severe sleep disorder that in most patients is characterized by the deficiency of central orexin. Clinically, narcolepsy is associated with obesity. Currently, there is a literature controversy about the potential alteration of leptin levels in narcoleptic patients. Theoretically, diminished leptin levels could partially contribute to the observed overweight of patients. Two studies have reported decreased leptin levels, whereas a larger, recent study failed to detect differences between patients and controls.
To help settle the controversy, we have measured peripheral leptin levels in 42 narcoleptic patients and in 31 body mass index-matched controls.
No significant differences in leptin levels between the groups were observed. Mean leptin levels were 16.0 +/- 14.9 ng/mL in the narcoleptic men and 30.4 +/- 17.8 ng/mL in the narcoleptic women. The corresponding values for the controls were 21.2 +/- 17.0 ng/mL (P = 0.49, men) and 33.9 +/- 16.9 ng/mL (P = 0.31, women). In addition, no correlation was found between leptin levels and clinical symptomatology in the narcoleptic patients.
Taken together, the data argue against a major deterioration of leptin secretion in narcoleptic patients.
"Because leptin is produced by fat cells as part of a signaling pathway to maintain long term energy balance, the incapacitation of this signaling could indeed contribute to a positive energy balance. However, newer reports have not replicated the finding of lowered leptin levels (Arnulf et al 2006; Dahmen et al 2007). "
[Show abstract][Hide abstract] ABSTRACT: Narcoleptic patients suffer frequently from obesity and type II diabetes. Most patients show a deficit in the energy balance regulating orexinergic system. Nevertheless, it is not known, why narcoleptic patients tend to be obese. We examined 116 narcoleptic patients and 80 controls with the structured interview for anorectic and bulimic eating disorders (SIAB) to test the hypothesis that typical or atypical eating attacks or eating disorders may be more frequent in narcoleptic patients. No difference in the current prevalence of eating disorders bulimia nervosa, binge eating disorder, or anorexia nervosa was found, nor was the frequency of eating attacks higher in the narcolepsy group. We conclude that present eating disorders and eating attacks as defined in DSM IV are not the reason for the observed differences in body composition. Additional factors, such as basal metabolic rates and lifestyle factors need to be considered.
Neuropsychiatric Disease and Treatment 03/2008; 4(1):257-61. · 1.74 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: To contribute to the anthropometric and metabolic phenotyping of orexin-A-deficient narcoleptic patients, and to explore a possible risk of their developing a metabolic syndrome.
We performed a cross-sectional study comparing metabolic alterations in patients with narcolepsy with cataplexy (NC) and patients with idiopathic hypersomnia without long sleep time.
Fourteen patients with narcolepsy with cataplexy and 14 sex and age-matched patients with idiopathic hypersomnia without long sleep time. Interventions: N/A.
Metabolic parameters were evaluated by measuring body mass index (BMI), waist circumference (also with abdominal computed tomography), blood pressure, and daily calorie intake (3-day diary). Chronotypes were assessed through the morningness-eveningness questionnaire. Lumbar puncture for cerebrospinal fluid orexin-A determination and HLA typing were performed. Patients with narcolepsy with cataplexy (all HLA DQB1*0602 positive and with cerebrospinal fluid orexin-A levels < 110 pg/mL) had a higher BMI and BMI-independent metabolic alterations, namely waist circumference, high-density lipoprotein cholesterol, and glucose/insulin ratio (an insulin resistance index), with respect to patients with idiopathic hypersomnia without long sleep time (cerebrospinal fluid orexin-A levels > 300 pg/mL). Despite lower daily food intake, patients with narcolepsy with cataplexy displayed significant alterations in metabolic parameters resulting in a diagnosis of metabolic syndrome in more than half the cases.
BMI-independent metabolic alterations and the relative hypophagia of patients with narcolepsy with cataplexy, as compared with patients with idiopathic hypersomnia without long sleep time, suggest that orexin-A influences the etiology of this phenotype. Moreover, considering that these dysmetabolic alterations are present from a young age, a careful metabolic follow-up of patients diagnosed with narcolepsy with cataplexy is mandatory.
[Show abstract][Hide abstract] ABSTRACT: Patients with narcolepsy may suffer from a host of other comorbid medical and psychiatric conditions. These include eating
disorders and obesity, diabetes, schizophrenia, depression, fibromyalgia, migraine headaches, cognitive dysfunction and psychosocial
impairment. The associations between narcolepsy and many of these comorbid medical problems have not been clearly defined,
and there are often conflicting data in the medical literature. Nevertheless, it is important to be aware of possible associated
medical comorbidities when caring for patients with narcolepsy, to facilitate early diagnosis and treatment of these disorders.
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