Are the drugs you’re taking putting you at increased risk for dementia? A new study in the journal JAMA Internal Medicine gives good reason to take a second look inside your medicine cabinet.

For some time, scientists have known about the connection between anticholinergic drugs and an increased risk of dementia. Now new research suggests that they could be upping your risk of dementia by as much as 50 percent.

What Are Anticholinergic Drugs?

Anticholinergic drugs are a class of drugs that treat a wide group of conditions, including allergies, colds, high blood pressure, depression, Parkinson’s disease, epilepsy, COPD, urinary incontinence and overactive bladders.

Anticholinergic drugs work by blocking acetylcholine, a neurotransmitter that stimulates the autonomic nerves that regulate contractions in the lungs, airways, blood vessels, cardiovascular system, urinary tract, and GI tract. Anticholinergic drugs help to relax these muscles, which is why they can lead to side effects like dry mouth and constipation.

In the brain, the neurotransmitter acetylcholine is involved in learning and memory, which is why confusion and memory problems are also common side effects of many anticholinergic drugs.

List of Anticholinergic Drugs

Some of the strongest anticholinergic drugs include antihistamines, sleeping pills, tricyclic antidepressants, and drugs to treat an overactive bladder.

Common anticholinergic drugs include Benadryl, Dimetapp, Sinequan (doxepin), Paxil (paroxetine), Desyrel (trazodone), Remeron (mirtazapine), Enablex (darifenacin), Toviaz (fesoterodine), Urispas (flavoxate), Ditropan (oxybutynin).

Anticholinergic Drugs and Dementia Risk

This most recent JAMA study on dementia and anticholinergics found that there was nearly a 50% increase in dementia risk in people who’d taken just over 1,000 daily doses of an anticholinergic drug within a 10-year period, compared to those who’d never taken the drugs. That’s the equivalent of being on a strong anticholinergic prescription for three or more years.

“The study is important because it strengthens a growing body of evidence showing that strong anticholinergic drugs have long-term associations with dementia risk,” said Carol Coupland, lead author of the study and professor of medical statistics at the University of Nottingham.

The researchers looked at data from 284,343 adults age 55 and older over a 12-year period. Using prescription details, they determined each person’s anticholinergic exposure, as well as their exposure to other common classes of drugs, like antihistamines, muscle relaxants, gastrointestinal antispasmodics, antiarrhythmics, and antimuscarinic bronchodilators. They found no increased dementia risk associated with the other types of medication.

The researchers are quick to caution that the association isn’t necessarily causal – meaning, there could be other factors among this group of people that increases the risk. If it is a cause and effect relationship, however, the authors point out that anticholinergic drugs could account for 10% of all dementia diagnoses.

Past research also suggests that long-term use of anticholinergic medications increases the risk of dementia, even as much as 20 years later.

What to Do If You’re Taking Anticholinergics

Keep in mind that this doesn’t mean you have a 50 percent risk of getting dementia if you take anticholinergics. If you have a 20 percent chance of dementia, it would increase your risk to 30 percent. By comparison, smoking and inactivity increase your risk for dementia by 40 to 60 percent.

Before going cold turkey on your medication, talk to your doctor. There may be other suitable medications to treat your condition that don’t have as much of an anticholinergic effect on the body.