Common Cold and Sleep Meds Linked to Higher Dementia Risk

Could the drug you take regularly for insomnia, depression, allergies, bladder problems or even the common cold put you at greater risk for mental decline, or even dementia?

For the past decade, a growing number of studies have raised red flags about a common class of medications — called anticholinergics — that are frequently used by older adults.

These drugs, available both over the counter and by prescription, are used for a range of disorders, from hay fever and sleep problems to overactive bladder and Parkinson’s disease.

There’s a long list of medications included in the anticholinergic group — one estimate put it at 600 drugs — but some of the most common are old-school antihistamines like Benadryl (diphenhydramine); sleep aid drugs like Nytol, Advil PM and Tylenol PM, which all contain diphenhydramine; certain antidepressants like Paxil (paroxetine) and Elavil (amitriptyline); and overactive bladder medications like oxybutynin (brand names include Ditropan XL and Oxytrol).

How these drugs may affect your mind and health

Studies show that regularly taking more than one anticholinergic drug, or taking even the minimum effective dose of one anticholinergic for longer than three years, is linked to a higher likelihood of dementia in older adults.

Anticholinergic drugs work by blocking a natural chemical in the brain, called acetylcholine, which helps different types of cells communicate with each other. It’s important for heart rate and certain muscle contractions, and it’s also vital for memory and learning.

According to these studies, that’s why taking these drugs may interfere with thinking ability, a side effect that doctors thought was reversible once a person stopped taking the medication but that subsequent research suggests can last for many years. In addition, the drugs may have a greater effect in those already at risk for Alzheimer’s.

What worries Shelly Gray, an anticholinergics researcher and director of the Plein Center for Geriatric Pharmacy Research, Education and Outreach at the University of Washington, is that many older adults — an estimated 1 in 3 — take anticholinergic medications, including over-the-counter ones like cold and allergy drugs and sleep aids, and may not be aware of the long-term effects on their brain health.

They also may not even realize they’re taking multiple anticholinergic drugs — both prescription and nonprescription — “which is why it’s important to tell your health care provider about all drugs you take, including the over-the-counter ones, and ask if there are safer alternatives,” she stressed in an interview.

Here’s how the research about the worrisome effects of these drugs stacks up:

• The drugs’ effects may not be reversible. A March 2015 study published in JAMA Internal Medicine was the first to link a higher risk of developing dementia to higher use of these medications “and the first to suggest that dementia risk linked to these drugs may persist and not be reversible even years after people stop using them,” said Gray, the study’s lead researcher.
  
  Gray and her colleagues analyzed 10 years of data from more than 3,400 adults age 65 and older and found that taking the minimum effective dose of anticholinergic medication for longer than three years was linked with a significantly increased risk for dementia and Alzheimer’s.
  
  
• Three years’ use may increase risk. In June 2019, a large British study also published in JAMA Internal Medicine found a 50 percent increased likelihood of dementia linked to older adults taking a single strong anticholinergic medication daily for three years or more.
  
  
• Despite warnings, use of anticholinergics has grown. A July 2020 British study of more than 15,000 adults age 65-plus found that the use of anticholinergics had nearly doubled in Britain over the past 20 years, largely due to greater use of bladder drugs and antidepressants that contained anticholinergics. “This despite guidance suggesting cautious use of these drugs,” researchers wrote in the journal BMC Geriatrics.
  
  
• These drugs may have greater effect on those at risk for Alzheimer’s. A September 2020 study in the journal Neurology found that long-term use of anticholinergics may be linked to a higher risk of cognitive decline in older people who are at greater risk for Alzheimer’s.

Researchers from the University of California, San Diego, followed 688 cognitively normal older adults, average age 74, who were taking at least one anticholinergic drug. Many were taking more than four. The participants were given annual mental skills tests for up to 10 years and the scientists looked at whether they had biomarkers — such as certain types of proteins in their spinal fluid — or genetic risk factors for Alzheimer’s disease.

Researchers found that those at greater risk for Alzheimer’s were 47 percent more likely to develop mild cognitive impairment, often a precursor to dementia, compared to those who did not take these drugs.

What you should know:

Gray, a professor in the School of Pharmacy at the University of Washington who specializes in medication safety for older adults, had these suggestions for avoiding anticholinergics, if possible:

• Do you have a cold or seasonal allergies? Choose a nonprescription medication carefully. “Check the label and check with your doctor. It’s probably OK to take a cold medication that includes diphenhydramine (such as Benadryl) for a runny nose, if it’s only for a day or two,” Gray said. But for seasonal allergies that last for an extended time, “ask your pharmacist to suggest an alternative that doesn’t contain an anticholinergic. There are several newer allergy meds that older adults can take that are safer, such as Claritin.”
  
  
• Read the label on over-the-counter sleep aids. More than half of older adults have sleep problems, and 1 in 3 take sleep medication despite potential health risks like falls, grogginess and confusion. Antihistamines, like doxylamine and diphenhydramine, are often used in nonprescription sleep aids — such as TylenolPM, AdvilPM, Nytol, Unisom and generics — to make people drowsy and help them fall asleep “and should be avoided by older adults,” Gray said. Instead, talk to your health care provider about nondrug therapy for improving sleep.
  
  
• Talk to your health care provider about stopping a medication or finding an alternative. Bladder drugs and antidepressants are among the most used anticholinergics, studies show. There may be alternative drugs you can take, but don’t stop any medical therapy without first talking to your health care provider, Gray cautioned.