About 9 million Americans rely on sleeping pills or some sort of sedative to doze off at night, and 11% of middle-aged women take anti-anxiety medications. The most common of these include benzodiazapines, and now scientists say the drugs are associated with a higher risk of Alzheimer’s.
In a report published Wednesday in The BMJ, researchers say that among 1,796 people with Alzheimer’s disease and 7,184 controls, those who have used benzodiazepines showed a 51% higher risk of the neurodegenerative disorder. Among people who took the drugs more than 180 days, the risk escalated to about two-fold higher.
Previous studies have linked the drugs to memory and cognitive problems, but primarily in those taking them short term. But in the current study, in which the scientists, led by Sophie Billioti de Gage, a PhD student at INSERM, University of Bordeaux, followed the participants for six years, the connection to dementia appeared strong. The interaction remained even after the scientists adjusted for potential confounding effect on Alzheimer’s rates such as blood pressure, heart disease, depression and insomnia.
In order to rule out the possibility that it was happening the other way around—that Alzheimer’s was causing a rise in insomnia and anxiety—the authors focused on people who had been prescribed sleeping and anxiety meds more than five years before they were diagnosed with Alzheimer’s. “We believe that the likelihood that the results are mainly driven by reverse causation is low,” de Gage said in an email discussion about the results.
It’s not clear why the drugs might increase the risk of Alzheimer’s, although de Gage speculates that the short-term effects on memory and cognitive functions may deplete reserve capacities that might help to offset reduce nerve functions as the disease’s hallmark protein plaques start to build up.
She also said that the study did not find an effect among those who used benzodiazepines for less than three months. That’s how most of the medications are prescribed, so people shouldn’t stop using them to treat anxiety disorders, social phobias and insomnia. But, she added, “It seems crucial to encourage physicians to carefully balance the benefits and risks when initiating or renewing a treatment [with benzodiazepines].”