“Avoid them like crazy,” was a recommendation I gave three years ago. We’ve had to wait a while, but the lead author of an important new study now says the same thing.

Okay, she didn’t put it quite as strongly as I did. In sober academic language she said, “The risks of this type of medication should be carefully considered…and alternative treatments should be considered where possible.”

My translation: Avoid, avoid, avoid.

The drugs she’s so concerned about are taken by up to half of older adults every day. If you’re one of them, you need to sit down with your doctor and try to find another solution.

Here’s why. . .

The drugs I’m talking are called anticholinergics. Alert long-time readers have heard us warn about them not just once, but a number of times.

Many types of drug have anticholinergic activity, including antidepressants, bladder medications, anti-psychotics, drugs that treat epilepsy, Parkinson’s and pulmonary diseases, and gastrointestinal antispasmodics.

Negative Short-Term Effects on the Brain

Anticholinergic drugs block the action of acetylcholine, an important central and peripheral nervous system neurotransmitter needed by brain cells to communicate and to stimulate muscles to contract.

A lack of acetylcholine blunts memory and learning and impairs muscle function.

Some of the drugs are available over the counter, such as first-generation antihistamines, motion sickness tablets, sleep aids and anti-diarrhea medication. Well-known brands to avoid include Benadryl, Dimetapp, Dramamine, Unisom and Imodium.

This class of drug is known to cause short-term confusion, cognitive problems and memory loss in older adults, and evidence has been accumulating for over a decade that long-term use increases the risk of dementia.

The evidence against them was not conclusive because previous studies were subject to bias, the population sizes were not large enough, and they didn’t cover a long enough time period to produce dependable results.

So in this new study a research group from the UK tried to cover all the bases. They published their results in JAMA Internal Medicine in June.

Risk of Dementia Rises by Almost Half

They analyzed 12 years’ worth of data collected from 58,769 dementia patients aged 55 or over, and matched them to 225,574 controls without dementia.

Compared to those who didn’t take any of the 56 strong anticholinergic drugs included in the study, patients in the highest category of intake who took these drugs for three years or more had a 49% increased risk of dementia.

That is a horrendous boost in your risk.

The risk for specific categories within the larger group was even higher. Anti-psychotics increased the risk by 70%, and drugs prescribed for an overactive bladder, such as Ditropan, raising the risk by 65%. There was also a strong association between antidepressants and anti-epileptic drugs and the onset of dementia.

While large and well designed, the authors pointed out this type of study can only show an association, not cause and effect.

It isn’t possible to rule out all possible factors that could impact the result, and it’s possible the diseases the drugs were prescribed for affect the brain, rather than the drugs themselves.

“However,” said lead author Carol Coupland, “if the association is proven to be a causal effect, we can estimate from our results that anticholinergic drugs could be responsible for about 10% of new cases of dementia.”

New Trial Will Test Cause and Effect

Dr. James Picket, Head of Research at the Alzheimer’s Society UK, commented on the results: “Our own researchers have already shown a strong link between anticholinergic drugs and risk of dementia. This study builds on this information.”

Dr. Noll Campbell, from Purdue University College of Pharmacy, West Lafayette, Indiana, added, “The suggestion that this effect may be responsible for about 10% of new cases of dementia is new. I have not seen that quantified before.”

“That might not seem like a lot, but in the US there are about 500,000 new cases of dementia every year, so if this relationship is shown to be causal and we can get patients off these drugs, then that could prevent about 50,000 cases of dementia every year just in the US. To me, that’s worth going after.”

Something else I’ve been urging for a long time is for doctors to take patients off drugs where possible and see what happens. They might be pleasantly surprised to see their patients regain mental sharpness.

And in fact — after a long wait – we might get additional evidence for that. The National Institute on Aging has awarded $3.3 million to an American research group to carry out a randomized “deprescribing” trial of anticholinergic drugs.  The aim is to eliminate them and compare the results with a control group of people who continue with the medications.

We should have an answer in about three to four years. In the meantime, if you’ve been prescribed one of these drugs, it’s worth having a word with your physician. In many cases there are safer alternatives that work by a different mechanism.


  1. https://www.medscape.com/viewarticle/915011
  2. https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/2736353

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