A higher use of anticholinergic medications has been linked to an increased risk of developing dementia, according to a new study.

“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,” said Shelly Gray, PharmD, MS, the first author of the report. The study tracked nearly 3,600 seniors.

The most commonly used medications in the study were tricyclic antidepressants such as doxepin, first-generation antihistamines like chlorpheniramine (Chlor-Trimeton), and antimuscarinics for bladder control like oxybutynin (Ditropan). Those who took at least 10 mg/day of doxepin, 4 mg/day of diphenhydramine, or 5 mg/day of oxybutynin for more than three years would be at greater risk for developing dementia.

Results were published in JAMA Internal Medicine.