THURSDAY, June 4, 2009 (HealthDay News) --Older people taking common over-the-counter drugs for pain, cold symptoms or help with sleep may increase their risk for cognitive impairment, including delirium, University of Indiana researchers report.
These drugs include Benadryl, Dramamine, Excedrin PM, Nytol, Sominex, Tylenol PM and Unisom.
All of these over-the-counter (OTC) drugs contain benadryl (diphenhydramine), a molecule that blocks the neurotransmitter acetylcholine. Acetylcholine is essential for normal functioning of the central and peripheral nervous systems, the researchers explained.
"Before taking any medication prescribed by your doctor or an OTC medication, make sure there is no negative impact of this medication on your brain," said lead researcher Dr. Malaz Boustani.
His group analyzed data from 27 prior studies on the relationship between anticholinergic effects and brain function, as well as looking into anecdotal data. The team found a consistent link between anticholinergic effects and cognitive impairment in older adults.
"Any OTC medication with the term 'PM' will indicate the presence of benadryl, which is bad for the brain," Boustani concluded.
He noted that the effects of benadryl can add up, so the more medications you take that contain benadryl the worse it may be for cognition. "There is a relationship with the number of medications and the burden on your aging brain," the researcher said.
People aged 65 and older who take these medications also run the risk of developing delirium, Boustani said. Delirium is a decline in attention-focus, perception and cognition, or "acute brain failure," as Boustani calls it. Delirium typically increases the odds of dying or being institutionalized, he said.
In addition, taking these medications for 90 days or more may triple your risk of developing Alzheimer's disease, Boustani said.
Given the risks, older adults should look for drugs that don't contain benadryl, he said.
"A lot of these medications are not recognized for these side effects," he contended. "It's time for the FDA to start taking this negative impact of these medications on the aging brain seriously."
The report is published in the May online issue of the Journal of Clinical Interventions in Aging.
According to Boustani, researchers in brain pharmacoepidemiology at Indiana University's Center for Aging Research is conducting a study of 4,000 older adults to see if the long-term use of medications with anticholinergic effects is associated with the development of severe cognitive impairment, such as Alzheimer's disease.
Dr. Clinton Wright, an associate professor of neurology at the Miller School of Medicine at the University of Miami, agreed that more study is needed to assess the effects of these drugs on the brain.
"These findings don't surprise me at all," Wright said. "People tend not to think of their OTC medications as medication, but any medication that has anticholinergic effects can affect people's cognition."
Wright believes the drugs should carry a warning of this potential side effect.
Deborah G. Bolding, a spokeswoman for GlaxoSmithKline, the maker of Sominex, defended the product and said it complies with all current FDA regulations. However, she would not comment specifically on whether diphenhydramine is associated with an increased risk of delirium in older adults.
"Sominex is a mild sleep aid designed to help individuals through periods of nervous tension or stress, which are accompanied by sleeplessness. It has been proven safe and effective in medical tests when taken as directed, and has been safely used by millions of satisfied customers," Bolding said.
"For all formulations, Sominex's active ingredient is diphenhydramine hydrochloride. This is marketed under a final FDA monograph as an over-the-counter sleep aid," she added.
For more information on benadryl, visit the U.S. National Library of Medicine.