Data from: Decreased cerebrospinal fluid orexin levels not associated with clinical sleep disturbance in Parkinson’s disease: A retrospective study

Patients with Parkinson’s disease (PD) often suffer from sleep
disturbances, including excessive daytime sleepiness (EDS) and rapid eye
movement sleep behavior disorder (RBD). These symptoms are also
experienced by patients with narcolepsy, which is characterized by orexin
neuronal loss. In PD, a decrease in orexin neurons is observed
pathologically, but the association between sleep disturbance in PD and
cerebrospinal fluid (CSF) orexin levels is still unclear. This study aimed
to clarify the role of orexin as a biomarker in patients with PD. CSF
samples were obtained from a previous cohort study conducted between 2015
and 2020. We cross-sectionally and longitudinally examined the association
between CSF orexin levels, sleep, and clinical characteristics. We
analyzed 78 CSF samples from 58 patients with PD and 21 samples from
controls. CSF orexin levels in patients with PD (median = 272.0
[interquartile range = 221.7–334.5] pg/mL) were lower than those in
controls (352.2 [296.2–399.5] pg/mL, p = 0.007). There were no significant
differences in CSF orexin levels according to EDS, RBD, or the use of
dopamine agonists. Moreover, no significant correlation was observed
between CSF orexin levels and clinical characteristics by multiple linear
regression analysis. Furthermore, the longitudinal changes in orexin
levels were also not correlated with clinical characteristics. This study
showed decreased CSF orexin levels in patients with PD, but these levels
did not show any correlation with any clinical characteristics. Our
results suggest the limited efficacy of CSF orexin levels as a biomarker
for PD, and that sleep disturbances may also be affected by dysfunction of
the nervous system other than orexin, or by dopaminergic treatments in PD.
Understanding the reciprocal role of orexin among other neurotransmitters
may provide a better treatment strategy for sleep disturbance in patients
with PD.