Normal CSF hypocretin-1 (orexin A) levels in dementia with Lewy bodies associated with excessive daytime sleepiness.

Excessive daytime sleepiness, hallucinations and REM sleep behavior disorder are symptoms reported in both dementia with Lewy bodies (DLB) and narcolepsy. Considering the demonstration of low hypocretin-1/orexin A levels in the cerebrospinal fluid (CSF) of most patients with narcolepsy, we hypothesized the presence of a deficient hypocretinergic transmission in DLB. Hypocretin-1 was tested in the CSF of 10 DLB patients. Levels were found to be in the normal range (mean 521 pg/ml, range 382-667) when compared to controls (n = 20, mean 497 pg/ml, range 350-603) and Alzheimer's disease patients (n = 7, mean 474 pg/ml, range 333-564). In DLB, excessive daytime sleepiness, hallucinations and REM sleep behavior may occur in the absence of a detectable hypocretin deficiency.