To better understand the clinical potential of the measurement of CSF orexin-A levels in patients with neurocognitive disorders and dementia, and considering the lack of studies in the literature comparing this biomarker in different dementias, in this retrospective study, we compared the orexin-A concentrations in CSF samples obtained from patients with AD, behavioral variant of FTD (bv-FTD), non-fluent primary aphasia (NFPA), and iNPH compared to a group of non-demented older controls. This evidence concerns the gene HCRT and frontotemporal dementia.