A class of drugs often taken for a variety of common medical conditions including insomnia, allergies, or incontinence causes long-term cognitive impairment in older African-Americans, according to a study in the journal Neurology. The class of drugs, known as anticholinergics, blocks the neurotransmitter acetylcholine and includes commonly used medications sold by prescription and over-the counter.

Benadryl, Dramamine, Excedrin PM, Nytol, Sominex, Tylenol PM, and Unisom are among the anticholinergics sold over-the-counter. Other drugs in this group include Paxil, Detrol, Demerol, and Elavil, which are sold by prescription. Older adults most commonly use drugs with anticholinergic effects as sleep aids and to relieve bladder leakage problems.

Researchers from Indiana University School of Medicine, the Regenstrief Institute and Wishard Health Services conducted a six-year study, evaluating 1,652 Indianapolis area African-Americans over the age of 70 who had normal cognitive function when the study began. In addition to monitoring cognition, the researchers tracked all over-the-counter and prescription medications taken by study participants.

“We found that taking one anticholinergic significantly increased an individual's risk of developing mild cognitive impairment and taking two of these drugs doubled this risk,” says Noll Campbell, a clinical pharmacist with Wishard Health Services and first author of the study. “This is very significant in a population–African Americans–already known to be at high risk for developing cognitive impairment.”

Although this study, which was funded by the National Institute on Aging, looked at only African-Americans, the researchers believe future studies will find that the results are generalizable to other races.

“The fact that we found that taking anticholinergics is linked with mild cognitive impairment, involving memory loss without functional disability, but not with Alzheimer’s disease, gives me hope,” says Malaz Boustani, associate professor of medicine at Indiana University School, Regenstrief Institute investigator and IU Center for Aging Research center scientist. “Our research efforts will now focus on whether anticholinergic-induced cognitive impairment may be reversible.”