Cerebrospinal fluid hypocretin-1 (orexin A) levels in mania compared to unipolar depression and healthy controls

Background: Impairment of sleep-wake cycles and circadian rhythm are found in human narcolepsy which is characterized by deficiency of hypocretin (hcrt) or its receptors. A disturbed electroencephalography (EEG) based vigilance regulation is also found in affective disorders such as major depressive disorder (MDD) and mania. For the first time, in the present study hcrt levels were investigated in patients with a manic episode and compared with age-matched patients with MDD and controls. Methods: 15 subjects were enrolled in the study after admission to hospital: 5 manic (mean YMRS 15.6 ± 2.9) and 5 age- matched patients with MDD (mean HDRS 11.6 ± 8.0), and 5 age-matched controls without any neurological or psychiatric disorder. Cerebrospinal fluid (CSF) hcrt levels were measured in all three groups using a fluorescence immunoassay (FIA). Results: Mean hcrt-1 level in manic patients (77.3 ± 20.7 pg/ml) did not differ significantly compared to patients with MDD (75.6 ± 15.7 pg/ml MDD) or controls (74.9 ± 19.3 pg/ml). Hcrt-levels and severity of disease did not show a significant association. Conclusion: In the present study, for the first time hcrt-1 levels in manic patients were investigated but did not reveal significant differences neither compared to age-matched patients with MDD nor healthy controls without any psychiatric or neurological disorder.

Schmidt FM et al., Neuroscience Letters 2010; 483: 20–22