Information about the Effects of Digestive Drugs on Memory

Several digestive disorders including gastroesophageal reflux disease (GERD) and irritable bowel syndrome (IBS) are treated with medications from a diverse and widely used group called anticholinergics. Although these drugs can help reduce digestive symptoms, their activity in the brain can lead to unwanted side effects: memory loss and cognitive decline.

That's because anticholinergics block a chemical messenger called acetylcholine, which is involved in an array of biological functions including transmission of nerve impulses in the brain. Acetylcholine also controls heart rate.

Because anticholinergics are very effective, they're found in a wide variety of drugs. Hyoscyamine (Levbid) and dicyclomine (Bentyl) used to treat IBS and diphenoxylate/atropine (Lomotil) for diarrhea are common anticholinergic digestive drugs. Also, anticholinergics are used to treat

  • allergies
  • anxiety
  • asthma
  • depression
  • heart failure
  • overactive bladder
  • pain and inflammation
  • Parkinson's disease

About half of the population uses some type of anticholinergic medication.

Anticholinergics and Older Adults

Anticholinergics are commonly prescribed to older adults. In nursing homes, 30 percentage of elderly residents take more than two of these medications, and 5 percent of them take more than five. Unfortunately, due to neurological changes, older adults are especially vulnerable to the adverse effects of anticholinergics. In addition to confusion and memory problems, other unintended anticholinergic effects include blurred vision, constipation, dry mouth, and lightheadedness.

Older individuals who complain of memory or thinking problems are sometimes diagnosed with early dementia when their symptoms may actually be caused by their medication and might be reversible. The irony is that some people with medication-related mild cognitive impairment may be prescribed a drug like donepezil (Aricept)—a procholinergic Alzheimer's medication—to counteract the effects of the anticholinergic drug causing their cognitive problems. (In Alzheimer's disease, the cholinergic or neurotransmitter system is affected first; that's why several medications considered to be procholinergic improve cognition—by boosting levels of acetylcholine.)

Experts recommend that people with mild cognitive impairment be screened for their use of anticholinergic drugs before being prescribed dementia medications.

Association Between Anticholinergics and Cognitive Decline

Two different studies have confirmed an association between anticholinergic medications and cognitive decline. The first, published in 2008 in Archives of Internal Medicine, looked at the medical records of two groups of adults age 65 and over: a retrospective analysis of records for anticholinergic medication use among 132 men and women at geriatric care clinics and a prospective analysis of records for medication use among 117 men in primary care clinics.

The researchers developed an anticholinergic risk scale to rank commonly prescribed medications based on their anticholinergic potential. Taking medication with a high score on the anticholinergic risk scale was associated with a 30 percent higher risk of adverse effects such as dizziness and confusion in the geriatric care patients. The risk was 90 percent higher in the primary care patients.

A second study from 2008, published in the Journal of the American Geriatrics Society, included 544 men age 65 and older with hypertension. The men took two cognitive function tests at the beginning of the study and again one year later. One test focused on memory, asking the participants to recall a series of 12 words. The other test assessed executive function, which includes tasks such as handling money, using the telephone, and preparing meals.

The researchers found that men who regularly took anticholinergic medications were significantly likely to experience decline in both memory and executive function at the follow-up tests. And the degree of decline increased proportionally with the number of medications taken and their anticholinergic effects.

Memory Loss

Older individuals may attribute any cognitive decline to age, but memory loss is not inevitable. Talk with your doctor if you or a loved one is taking a medication and you notice any decline in memory or executive function. This goes for anticholinergics and any other drugs you are taking. If you think your medications is affecting your memory, do not stop taking it without talking with your doctor. He or she may be able to switch you to another medication or adjust the dosage.

And the good news is that cognitive side effects of anticholinergic medications do not appear to be permanent; they do improve once the medication is stopped.

Publication Review By: H. Franklin Herlong, M.D.

Published: 30 Mar 2011

Last Modified: 11 Sep 2015