HCRT and Alzheimer disease: It has been documented that AD patients showing more BPSD with higher scores for the Neuropsychiatric Inventory (NPI) correlate with lower scores in the Mini-Mental State Examination (MMSE) screening test, together with higher levels of orexins and TAU in cerebrospinal fluid (CSF), a more altered sleep structure and an increased likelihood of nocturnal awakening compared to AD patients not affected by BPSD [42,43].