Commonly Used Medications May Produce Cognitive Impairment In Older Adults

Drugs, such as diphenhydramine, which have an anticholinergic effect, are important medical therapies available by prescription and also are sold over the counter under various brand names such as Benadryl®, Dramamine®, Excederin PM®, Nytol®, Sominex®, Tylenol PM®, and Unisom®. Older adults most commonly use drugs with anticholinergic effects as sleep aids.

While it is known that these medications do have an effect on the brain and in the case of sleeping pills, are prescribed to act on the brain, the study authors suggest the amount of cognitive impairment caused by the drugs in older adults is not well recognized.

"The public, physicians, and even the Food and Drug Administration, need to be made aware of the role of these common medications, and others with anticholinergic effects, in causing cognitive impairment. Patients should write down and tell their doctor which over-the-counter drugs they are taking. Doctors, who often think of these medications simply as antihistamines, antidepressants, antihypertensives, sleep aids or even itching remedies, need to recognize their systemic anticholinergic properties and the fact that they appear to impact brain health negatively. Doing so, and prescribing alternative medications, should improve both the health and quality of life of older adults," said senior study author Malaz Boustani, M.D., Indiana University School of Medicine associate professor of medicine, Regenstrief Institute investigator, and research scientist with the IU Center for Aging Research.

Dr. Boustani and colleagues conducted a systematic evidence-based analysis of 27 peer reviewed studies of the relationship of anticholinergic effect and brain function as well as investigating anecdotal information. They found a strong link between anticholinergic effect and cognitive impairment in older adults.

"One of the goals of our work is to encourage the Food and Drug Administration to expand its safety evaluation process from looking only at the heart, kidney and liver effects of these drugs to include effects of a drug on the most precious organ in human beings, our brain," Dr. Boustani said.

"Many medications used for several common disease states have anticholinergic effects that are often unrecognized by prescribers" said Wishard Health Services pharmacist, Noll Campbell, Pharm.D., first author of the study, noting that these drugs are among the most frequently purchased over the counter products. "In fact, 50 percent of the older adult population use a medication with some degree of anticholinergic effect each day."

"Our main message is that older adults and their physicians should have conversations about the benefits and harms of these drugs in relation to brain health. As the number of older adults suffering from both cognitive impairment and multiple chronic conditions increases, it is very important to recognize the negative impact of certain medications on the aging brain," said Dr. Boustani.

The brain pharmacoepidemiology group of the IU Center for Aging Research currently is conducting a study of 4,000 older adults to determine if the long term use of medications with anticholinergic effects is linked to the irreversible development of cognitive impairment such as Alzheimer disease.

Authors of the JCIA study are Noll Campbell, Pharm.D., Wishard Health Services; Malaz Boustani, M.D., MPH; Tony Limbil, M.D., MPH, of University of Illinois; Carol Ott, Pharm.D. of Wishard and Purdue University; Chris Fox, MRCPsych and Ian Maidment, B.Pharm., of Kent Institute of Medicine and Health Sciences University of Kent and Medway NHS Trust, United Kingdom; Cathy C. Schubert, M.D. of the IU School of Medicine; Stephanie Munger, B.S., of Regenstrief and IUCAR; Donna Fick, R.N., Ph.D., of Pennsylvania State University; David Miller, M.D., of the IU School of Medicine and Rajesh Gulati, M.D., of IU Medical Group – Primary Care.

The study was funded by the John A. Hartford Foundation, the Atlantic Philanthropies, the Starr Foundation, and the National Institute on Aging.