A preliminary study conducted by researchers at the Washington University School of Medicine in St. Louis has revealed that taking a particular sleeping pill known as suvorexant before bed may help reduce the levels of Alzheimer's disease proteins. However, experts caution that it is too early to determine if the medication is effective in staving off cognitive decline.
The study was designed to determine if suvorexant could reduce amyloid and tau protein levels, which are associated with Alzheimer's disease.
The researchers recruited 38 healthy people aged between 45 and 65 years, with no existing mental impairments, to participate in the study. The participants were given a lower dose of 10 milligrammes (mg) of suvorexant, a higher dose of 20mg of suvorexant, or a placebo. The cerebrospinal fluid of the participants was withdrawn via spinal tap every two hours for 36 hours after the medication or placebo was administered, to measure how amyloid and tau levels changed over time.
The researchers found that amyloid levels dropped by between 10% and 20% in the cerebrospinal fluid of participants who had received the higher dose of suvorexant. Levels of hyperphosphorylated tau, a key form of tau associated with forming tau tangles that kill neurons, dropped by between 10% and 15% in the same group.
No significant difference was found between those who received a lower dose of suvorexant and those who received a placebo.
The study authors caution that this is a small, proof-of-concept study and that it would be premature for people to start taking suvorexant every night to stave off cognitive decline. The long-term effectiveness of the medication in reducing cognitive decline is not yet known, nor is the dose and demographic group that might benefit most from the medication.
Although suvorexant is already available and has been proven safe, more research is needed to determine if it can reduce amyloid and tau protein levels in people who are at higher risk of dementia.
The authors of the study are encouraged by the results and believe that if amyloid levels can be reduced every day, the accumulation of amyloid plaques in the brain will decrease over time. Additionally, if tau phosphorylation is reduced, there may be less tangle formation and less neuronal death. However, ongoing studies are necessary to assess the longer-term effects of orexin inhibitors on people at higher risk of dementia, and to determine the effects of the medication on those who already have amyloid plaques in their brains.
Despite the promising results of this study, senior study author Dr Brendan Lucey, an associate professor of neurology and director of Washington University's Sleep Medicine Centre, cautions that the best advice he can give is to get a good night's sleep and, if experiencing difficulty sleeping, to see a sleep specialist to treat any sleep problems.
While future studies may lead to the development of drugs that take advantage of the link between sleep and Alzheimer's to prevent cognitive decline, more research is necessary before this can be realised.