HealthDay News — Long-term and/or high-dose use of a class of medications used for hay fever, depression and other ills has been linked in a new study to a higher risk of dementia.
The drugs — called anticholinergics — include nonprescription diphenhydramine (Benadryl) and tricyclic antidepressants like doxepin (Sinequan). This class of medications also includes older antihistamines like chlorpheniramine (Chlor-Trimeton) and “antimuscarinic” drugs for bladder control, such as oxybutynin (Ditropan).
However, the study, published in JAMA Internal Medicine, could only point to an association between long-term or high-dose use of these drugs and a higher risk of dementia, it could not prove cause-and-effect.
The new study was led by Shelly Gray, PharmD, of the Group Health Research Institute-University of Washington. Her team explained that the anticholinergic class of medications work by blocking a neurochemical called acetylcholine, in both the brain and body.
The new study tracked outcomes for more than 3,500 seniors who were followed for more than seven years. Gray’s group found that people who took at least 10 milligrams per day of Sinequan, 4 mg per day of Benadryl, or 5 mg per day of Ditropan for more than three years were at greater risk for developing dementia.
Gray said in an institute news release, “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. And they should tell their health care providers about all their over-the-counter [drug] use.”
However, “no one should stop taking any therapy without consulting their health care provider,” said Gray, director of the geriatric pharmacy program at the University of Washington’s School of Pharmacy.
Instead, “health care providers should regularly review their older patients’ drug regimens — including over-the-counter medications — to look for chances to use fewer anticholinergic medications at lower doses,” she advised.
The study is the first to link higher use of anticholinergic medications to increased risk of dementia, the researchers said. It is also the first to suggest that the dementia risk associated with these drugs may not be reversible even years after people stop taking them.
Gray SL, et al. Cumulative Use of Strong Anticholingergics and Incident Dementia. JAMA Intern Med. 2015; doi:10.1001/jamainternmed.2014.7663.