Greater cumulative doses of antihistamines, tricyclic antidepressants and other drugs that are anticholinergic or block the neurotransmitter acetylcholine are associated with significant increases in dementia and Alzheimer’s, according to a study in JAMA Internal Medicine.
“We have known for some time that even single doses of these medications can cause impairment in cognition, slower reaction time, [and] reduced attention and ability to concentrate,” the study’s lead author Shelley Gray from the University of Washington told LiveScience. Originally, “the thinking was that these cognitive effects were reversible when you stopped taking the medication.” But Gray’s study found a link between heavier use of these medications and increasing, irreversible cognitive impairment.
The researchers identified 3,434 people who were ages 65 and older and were free from dementia at the start of the Adult Changes in Thought study, and followed them for about seven years. “The researchers found that the higher a patient’s cumulative dose of anticholinergic medication over the 10 years before entering the study, the greater his or her risk of dementia,” reported LiveScience. The finding held true even when the researchers attempted to adjust for the possibility that some of the drugs might be being prescribed specifically to treat dementia symptoms.
“Older adults should be aware that many medications – including some available without a prescription, such as over-the-counter sleep aids – have strong anticholinergic effects,” Gray told The Guardian.
Gray SL, Anderson ML, Dublin S, and et al. “Cumulative Use of Strong Anticholinergics and Incident Dementia: A Prospective Cohort Study.” JAMA Internal Medicine, January 26, 2015. doi:10.1001/jamainternmed.2014.7663. (Abstract)
Widely Used Drugs Tied to Greater Dementia Risk for Seniors (LiveScience, January 26, 2015)
Study suggests sleeping drugs can increase risk of Alzheimer’s (The Guardian, January 27, 2015)