Taking sleeping pills could reduce the risk of developing Alzheimer's, according to new research. People who popped the drugs before bedtime had fewer rogue brain proteins linked to the disease.
Scientists described results as "very encouraging". Not getting enough shut-eye is linked to cognitive decline. The two-night study hints at a potential treatment to slow or stop progression of dementia.
Participants were given suvorexant - sold under the brand name Belsomra to combat insomnia. Senior author Professor Brendan Lucey, of Washington University in the United States, said: "This is a small, proof-of-concept study.
"It would be premature for people who are worried about developing Alzheimer's to interpret it as a reason to start taking suvorexant every night. We don't yet know whether long-term use is effective in staving off cognitive decline, and if it is, at what dose and for whom."
But he added: "Still, these results are very encouraging. This drug is already available and proven safe, and now we have evidence it affects the levels of proteins that are critical for driving Alzheimer's disease." Disturbed sleep can be an early sign. Many patients start experiencing it years before memory loss and confusion emerge.
It's a vicious cycle - Alzheimer's involves changes to the brain that disrupt sleep and poor sleep accelerates harmful changes to the brain. Suvorexant works by blocking a chemical that promotes wakefulness. Three orexin inhibitors have already been approved by the Food and Drug Administration - and more are in the pipeline.
Alzheimer’s disease begins when plaques of amyloid beta start building up - killing neurons. Years later a second protein called tau also form into toxic tangles. Prof Lucey's team was among the first to discover the link between poor sleep and higher levels of amyloid and tau in the brain.
Experiments on mice given orexin inhibitors have suggested good sleep may have the opposite effect- a reduction in the harmful proteins and prevention of Alzheimer's. In the first study of its kind 38 participants aged 45 to 65 with no cognitive impairments were given a lower or higher dose (10 or 20 mg) of suvorexant - or a placebo - at 9pm - and then went to sleep in a specialist lab.
Researchers withdrew a small amount of cerebrospinal fluid via spinal tap every two hours for 36 hours, starting one hour before the sleeping aid or dummy pill was administered, to measure how amyloid and tau levels changed over the next day and a half.
Amyloid levels dropped ten to 20 percent in those who had received the high dose of suvorexant. A key form of tau, known as hyperphosphorylated, also fell ten to 15 percent. There was not a significant difference between peers who received a low dose and the rest who got the placebo.
By 24 hours after the first dose, tau levels in the high-dose group had risen, while amyloid levels remained low compared to the placebo group. A second dose of suvorexant, administered on the second night, sent the levels of both proteins down again for people in the high-dose group.
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Prof Lucey said: "If we can lower amyloid every day, we think the accumulation of amyloid plaques in the brain will decrease over time. And hyperphosphorylated tau is very important in the development of Alzheimer's disease, because it's associated with forming tau tangles that kill neurons. If you can reduce tau phosphorylation, potentially there would be less tangle formation and less neuronal death."
Prof Lucey has studies underway to assess the longer-term effects of orexin inhibitors in people at higher risk of dementia. The number of cases worldwide will triple to more than 150 million by 2050.
With no cure in sight there is an increasing focus on lifestyle factors that reduce risk such as eating right and getting plenty of exercise - and sleep. Prof Lucey added: "Future studies need to have people taking these drugs for months, at least, and measuring the effect on amyloid and tau over time.
"We are also going to be studying participants who are older and may still be cognitively healthy, but who already have some amyloid plaques in their brains. This study involved healthy middle-aged participants. The results may be different in an older population.
"I am hopeful that we will eventually develop drugs that take advantage of the link between sleep and Alzheimer's to prevent cognitive decline. We are not quite there yet. At this point, the best advice I can give is to get a good night's sleep if you can, and if you can't, to see a sleep specialist and get your sleep problems treated." The study was published in the journal Annals of Neurology.
