These Common OTC Anticholinergic Drugs Can Damage Your Brain, Says Study

If you have any Benadryl or Dimetapp in your medicine cabinet, a new study released Monday may have you thinking twice the next time you reach for them. These and other common medicines fall into the class of anticholinergic drugs, which may cause brain damage, cognitive impairment, and dementia.

As previously reported by the Inquisitr, scientists have known there was some correlation between anticholinergics and dementia for years. For instance, previous studies found that older adults who take prescription drugs, such as the overactive bladder drug oxybutynin and anti-depressant doxepin, often develop dementia.

Although studies have previously linked dementia and anticholinergics for a long time, those studies simply looked at groups of people with dementia and people who took anticholinergics and found overlap. Until now, the link between the drugs and cognitive problems was not firmly established.

In a new study from Indiana University, researchers were able to physically link many common anticholinergic drugs, including many over-the-counter medicines, to cognitive impairments like dementia. The study used brain scans to identify physical changes, such as smaller brains, associated with taking anticholinergics.

"These findings provide us with a much better understanding of how this class of drugs may act upon the brain in ways that might raise the risk of cognitive impairment and dementia," study author Shannon Risacher said via press release. "Given all the research evidence, physicians might want to consider alternatives to anticholinergic medications if available when working with their older patients."

The average age of the 451 people who participated in the study was 73, and researchers used a combination of memory tests and brain scans to determine cognitive impairment. In addition to reduced brain sizes found by MRI scans, the study also used PET scans to find that participants who were taking at least one anticholinergic exhibited lower brain metabolism.

Cognitive testing found a connection between anticholinergic use and poor short-term memory. The study also found that older adults who use anticholinergics suffer from a loss of executive function, including activities like problem-solving, verbal reasoning, and planning.

Some anticholinergic drugs are only available by prescription, and the set of possible and definite anticholinergics reads like a laundry list of blood thinners, urinary control, anti-depressant, blood pressure, and pain medications commonly prescribed to seniors. However, many other anticholinergics are easily available over the counter, found in most medicine cabinets, and used to treat everything from allergies to motion sickness.

Common medicines covered by this study, which you may already have at home, include Benadryl, Dimetapp, Dramamine, and Unisom. The study also provides a full list of medications that fall into this potentially dangerous class, including both drugs that are possible and definite anticholinergics.

According to CNN, even short-term anticholinergic use can impair cognitive functions. Strong anticholinergics may cause symptoms after just two months of use, while weaker drugs may take three or more months to have an effect. Less frequent or non-continuous use may carry less risk, but more research is required to say for sure.

"These findings might give us clues to the biological basis for the cognitive problems associated with anticholinergic drugs, but additional studies are needed if we are to truly understand the mechanisms involved," Dr. Risacher said via the press release.

Are you less likely to take these anticholinergic drugs knowing that they can cause lower brain metabolism, smaller brains, dementia, and other adverse effects, or will you keep reaching for drugs like Benadryl and Dimetapp?

[Photo by Evan Vucci/AP Images]