Olfactory dysfunction in patients with narcolepsy with cataplexy is restored by intranasal Orexin A (Hypocretin-1)

What Was Tested

Researchers studied Orexin-A in this randomized controlled trial publication.

Until recently, olfactory dysfunction was an unknown feature of narcolepsy.

As hypothalamic orexin-containing neurons project throughout the entire olfactory pathway, from the olfactory mucosa to the olfactory cortex, disturbed orexinergic transmission may crucially be involved in impaired olfactory performance of narcolepsy patients.

Who Took Part

By PubMed's age tags, the people studied were adults, middle-aged adults and older adults, both men and women.

How the Study Was Run

The researchers set it up as a randomized, double-blind, placebo-controlled and crossover study.

Random assignment meant chance, not the researchers, decided who got Orexin-A and who got the comparison, which limits bias.

Blinding on both sides kept the participants and researchers unaware of who received Orexin-A.

The comparison arm used a placebo, so changes seen with Orexin-A could be set against what happens without it.

In the crossover set-up each of the participants took both Orexin-A and the comparison in turn, acting as their own control.

What Was Measured

In their study the researchers analysed the olfactory performance (threshold, discrimination, identification and sum score of these measurements, the TDI score) of narcoleptic patients with cataplexies (n = 10) and of age-, gender-, BMI- and smoker/non-smoker-matched healthy controls (n = 10).

The researchers then in a double-blind, randomized, placebo-controlled cross-over design applied orexin A intranasally to seven of the patients and measured 2-phenyl-ethyl alcohol (PEA) single-staircase odour detection thresholds.

Topics PubMed links to this paper include Case-Control Studies, Cataplexy, Intracellular Signaling Peptides and Proteins, Narcolepsy, Neuropeptides, Olfaction Disorders and Orexins.

What This Means in Plain Language

The paper is a randomized, double-blind and placebo-controlled study of Orexin-A.

The publication is from 2008 (Brain : a journal of neurology), a journal based in England.

More context: the Orexin-A compound page, all human trials.