A study

A report published online this week in JAMA Internal Medicine offers compelling evidence of a link between long-term use of anticholinergic medications like Benadryl and dementia.

Anticholinergic drugs block the action of acetylcholine.  This chemical messenger is vital to normal nervous system functioning.  In the brain, acetylcholine is involved in learning and memory.  In the rest of the body, it stimulates muscle contractions.  Commonly used Anticholinergic drugs include some antihistamines like Benadryl, tricyclic antidepressants, medications to control overactive bladder, muscle relaxants,  drugs to relieve the symptoms of Parkinson’s disease.

A group of pharmacists at the University of Washington’s School of Pharmacy, tracked nearly 3,500 men and women ages 65 and older who took part in Adult Changes in Thought (ACT), a long-term study conducted by the University of Washington and Group Health, a Seattle healthcare system.  They used Group Health’s pharmacy records to identify all medications, both prescription and over-the-counter, each participant took the 10 years before the study began.

Participants’ health was tracked for an average of seven years.  During that period, 800 of the volunteers developed dementia.  The researchers found people who used anticholinergic drugs were more likely to have developed dementia as those who didn’t use them.  Moreover, dementia risk increased along with the cumulative dose.  Taking an anticholinergic for three years or more was associated with a 54% higher dementia risk than taking the same dose for three months or less.

These findings add to a growing body of evidence that anticholinergics should be taken briefly to protect brain functioning.  The body’s production of acetylcholine diminishes with age, so blocking its effects can deliver a double whammy to older people.  It’s not surprising that problems with short-term memory, reasoning, and confusion lead the list of anticholinergic side effects, which also include drowsiness, dry mouth, urine retention, and constipation.

The University of Washington study is the first to include nonprescription drugs.  It is also the first to eliminate the possibility that people were taking a tricyclic antidepressant to alleviate early symptoms of undiagnosed dementia; the risk associated with bladder medications was just as high.

“This study is another reminder to periodically evaluate all of the drugs you’re taking.  Look at each one to determine if it’s really helping,” says Dr. Sarah Berry, a geriatrician and assistant professor of medicine at Harvard Medical School.  “For instance, I’ve seen people who have been on anticholinergic medications for bladder control for years and they are completely incontinent.  These drugs obviously aren’t helping.”

What should you do?

In 2008, Indiana University School of Medicine geriatrician Malaz Boustani developed the anticholinergic cognitive burden scale, which ranks these drugs according to the severity of their effects on the mind.  It’s a good idea to steer clear of the drugs with high ACB scores, meaning those with scores of 3.  “There are so many alternatives to these drugs,” says Dr. Berry.   For example, selective serotonin re-uptake inhibitors (SSRIs) like citalopram (Celexa) or fluoxetine (Prozac) are good alternatives to tricyclic antidepressants.  Newer antihistamines such as loratadine (Claritin) can replace diphenhydramine or chlorpheniramine (Chlor-Trimeton).  Botox injections and cognitive behavioral training can alleviate urge incontinence.

One of the best ways to make sure you’re taking the most effective drugs is to dump all your medications — prescription and nonprescription — into a bag and bring them to your next appointment with your primary care doctor.