Ask the Pharmacist: How medications inadvertently cause memory problems

Suzy Cohen
Memory loss

Several dozen people have died while on vacation at different Caribbean islands including the Dominican Republic. While not totally conclusive for everyone, post-mortem examination suggests organophosphate (insecticide or pesticide) poisoning may have been implicated. The toxic and fatal effects occur due to an imbalance in the cholinergic pathways of the human body. When I say “cholinergic,” I am referring to acetylcholine production and utilization. 

To be clear, the neurotransmitter acetylcholine is a beneficial, memory-enhancing and life-giving compound in the body. It is a natural compound that your nerve cells use to communicate with one another. You can’t think or live without it. But like all good things, poisoning the body with substances that spike acetylcholine levels can be fatal. 

Let’s talk about acetylcholine some more because it is the neurotransmitter that many good medications target in the opposite way. By that I mean some drugs lower levels of acetylcholine as part of their side effect profile. They may do something helpful like ease depression, but in doing so, they have the side effect of reducing acetylcholine a little bit. Reducing acetylcholine function causes memory problems due to the anticholinergic side effect. 

Brain fog, memory loss, difficulty concentrating, and other dementia-like symptoms can be caused by several diseases. Sure, sometimes the real reason behind dead brain cells and loss of gray matter is Alzheimer's. But sometimes, memory loss is the result of a treatable disease or condition, a nutritional deficiency, an unhealthy habit, or another reversible issue. […]

It is that side effect that may cause you to get diagnosed with a memory disorder you don’t really have. For people with new onset memory issues, the first thing I have them do is look in their medicine cabinet! What are you taking that could be causing this?

If a drug raises acetylcholine it is termed a “cholinergic” drug. Medications that slightly increase levels are good for the brain and memory system. Drugs that seek to do this usually work by blocking an enzyme that would otherwise degrade the acetylcholine, so it hangs around longer. Pills that seek to do this are useful, and include donepezil, rivastigmine, and galantamine all used for Alzheimer’s, Parkinson’s or dementia. 

How does the brain respond when you take an anticholinergic drug? You know these medications as drugs that lower acetylcholine as part of their side effect profile. In fact, they are blockbusters big name drugs like diphenhydramine and chlorpheniramine for allergies, scopolamine patches for dizziness, oxybutynin or tolteridine for bladder problems, many older antidepressants, ipratropium inhalers for breathing, dicyclomine for IBS and others.

Just as you would imagine, anticholinergic drugs can harm memory pathways. There was a JAMA study published in 2015, entitled, “Cumulative Use of Strong Anticholinergics and Incident Dementia.” They evaluated data from hundreds of participants over 10 years and essentially, they found that long term use of anticholinergic drugs is bad for the brain!

If you wish you had more brain power, look at the medications you’re currently taking and see if you’re taking an anticholinergic drug.  If you’re worried about brain function, I have a free e-book on the topic available at my website, as well as a longer version of this informative article. 

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Suzy Cohen is a registered pharmacist. The information presented here is not intended to treat, cure or diagnose any condition. Visit Read past columns at