Sleep medications help many adults get a full night's sleep, but new research suggests they potentially may increase the risk of Alzheimer's disease.
Zolpidem, the sedative in Ambien and other sleep drugs, may adversely effect a brain function believed to be key in preventing dementia, according to an animal study conducted by scientists at the University of Rochester Medical Center in New York and the University of Copenhagen in Denmark.
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When the body falls asleep, the brain transitions away from processing external information. But even during deep, dreamless sleep — the non REM portion of the sleep cycle —the brain is still active.
During that time, brain oscillations power the glymphatic system that "cleans" the brain of toxins like tau and amyloid. These toxins have been found to build up in the memory sections of the brains of people with Alzheimer's disease, the most common form of dementia.
"We know that one, if you don't sleep well, you have a higher risk of dementia, and two, that if you don't clear well, your brain waste, you have higher accumulation of amyloid and other pathologies in the brain," said Silvia Fossati, director of the Alzheimer's Center at Temple Health, who was not involved in the study. "Therefore, you increase the pathological risk for dementia."
Scientists previously believed that zolpidem – also found in the insomnia drugs Edluar, Intermezzo and Zolpimist — would be beneficial to this brain-cleaning process. The new study found zolpidem helped mice sleep. But it also prevented the oscillations, stopping the brain-cleaning process.
"They found that, yes, sleeping is very important; the non-REM sleep phase is extremely important for brain clearance," Fossati said. "But if you increase sleep by mechanisms that change our neurotransmitters in the brain, you don't really have the positive effects you would expect from increasing sleep, at least not in (these) brain clearance processes."
The researchers said their study raises concerns about using the zolpidem over an extended period of time. It "calls attention to the potentially detrimental effects of certain pharmacological sleep aids on brain health, highlighting the necessity of preserving natural sleep architecture for optimal brain function," Dr. Maiken Nedergaard, co-director of the University of Rochester's Center for Translational Neuromedicine, said in a press release.
However, Fossati said more research is needed to better understand the effects later-in-life, because this is the first study to observe this effect. It also needs to be replicated in humans taking the drug, and with other sleep medications that could interact similarly with the brain. But she thinks it's definitely a space to watch.
"This would be really important to really confirm these effects, but in terms of a preclinical study, I think it's a study that is well done, and so it should have a weight, and I think some other people should look into it, for sure," Fossati said.
Vascular issues such as hypertension and obesity also can inhibit this oscillation process, Fossati said, by making arteries stiff. Improvements in diet, exercise and getting eight hours of sleep each night can help promote brain cleaning.
Maria Carrillo, the Alzheimer’s Association chief science officer, said the study's findings could be a good sign for disease prevention. She pointed to a recent Lancet Commission report that found 40% of global dementia is potentially avoidable with behavioral and lifestyle changes and a recent study that found annual dementia diagnoses in the U.S. will double by 2060.
"This speaks to the fact that people in our country need to hear those messages, and need to make changes, because we can, ourselves, help our communities make those changes so that we don't hit the numbers that this new paper talks about for 2060," Carillo said in an email.