Some OTC drugs linked to increased chance of dementia: study

The risk of dementia is said to be high when the so-called anticholinergic drugs are taken in high doses over several years.

Anticholinergics are a class of drug that blocks the action of the neurotransmitter called acetylcholine in the brain and body.

According to study authors, many older people take these medications, which include nonprescription diphenhydramine (Benadryl).

The most commonly used medications in the study were tricyclic antidepressants such as doxepin (Sinequan), first-generation antihistamines like chlorpheniramine (Chlor-Trimeton), and antimuscarinics for bladder control like oxybutynin (Ditropan).

In the study published in the journal JAMA Internal Medicine, researchers looked at older individuals who have taken at least 10mg/day of doxepin, 4mg/day of chlorpheniramine, or 5mg/day of oxybutynin for three or more years, and found that there is an increased risk of dementia for people taking higher doses of these drugs for a prolonged period of time.

University of Washington professor of pharmacy Shelly Gray is first author of the report, which tracked nearly 3,500 Group Health seniors participating in a long-running joint Group Health-UW study funded by the National Institute on Aging.

Gray said: "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.

"If providers need to prescribe a medication with anticholinergic effects because it is the best therapy for their patient, they should use the lowest effective dose, monitor the therapy regularly to ensure it’s working, and stop the therapy if it’s ineffective.

"No one should stop taking any therapy without consulting their health care provider. Healthcare 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."