Cerebrospinal Fluid Amyloid-β Levels are Increased in Patients with Insomnia.

Previous studies demonstrate that patients with sleep disorders are at risk of developing Alzheimer's disease (AD), with the mechanism unknown. It is suggested that acute sleep deprivation induces an increase of amyloid-beta (A beta), the major pathological agent in AD, in the cerebrospinal fluid (CSF). In the present study, we recruited 23 patients with chronic insomnia aged between 46 to 67 years and 23 healthy controls aged between 43 to 67 years. We investigated the CSF levels of A beta and tau, another pathological hallmark in the AD pathogenesis. We found that CSF A beta(42) levels were significantly increased in insomnia patients. However, no significant difference was found in A beta(40), total tau (t-Tau), and phosphorylated tau (p-Tau) between the two groups. Furthermore, we found that CSF A beta(40) and A beta(42) levels are significantly correlated with the sleep quality, as reflected by the Pittsburgh Sleep Quality Index (PSQI) scores. But no significant correlation was found in CSF t-Tau and p-Tau levels with PSQI. Our results indicate that chronic sleep disorders may induce the disruption of A beta metabolism in the brain, thus increase the risk for developing AD.