Taking medications that relieve pain, depression, allergies or incontinence may be causing another problem: faster memory loss, researchers at the University of Florida have found.

Subjects who took a category of medicine called anticholinergics -- drugs designed to treat a wide range of chronic conditions -- experienced more rapid memory loss than those who didn’t, according to the study published in a recent issue of PLOS ONE.

Among the medications on the list were Benadryl, an over-the-counter antihistamine; Detrol, which treats overactive bladder; Elavil, a common antidepressant, and certain sleep aids, said Dr. Kenneth Heilman, professor of neurology at UF College of Medicine, who co-authored the study.

“We found that if you take these medications, you’re going to have more rapid memory loss and cognitive decline,” he said.

“Brain cells need to be able to communicate with each other for the brain to work correctly,” said Heilman. “Brain cells give off a chemical called acetylcholine, which helps to excite their neighbor neurons. That excitement is necessary to form a memory.”

Anticholinergic medications inhibit that ability.

“Sometimes you don’t have a choice. You need to take these medicines,” said Heilman, who recommends patients ask their doctors or pharmacists how much anticholinergic activity a drug has, or look online.

Then try to find less anticholinergic alternatives, he said.

“There are medications that treat overactive bladder, for instance, that don’t get into the brain,” said Heilman. “Those would be safer.”

Anticholinergics are also commonly used in painkillers, antidepressants and antihistamines.

Although other studies have shown this connection, Heilman and his colleagues wanted to find out whether when a subject started taking the medications made a difference.

They looked at data collected over 10 years from 1,000 participants, who were divided into three groups: those who routinely used one or more anticholinergic medications, those who didn’t report using any, and those who started to take an anticholinergic medication after the study began.

Participants who began using the medications during the study had a steeper cognitive decline than both the other groups. Those who had never used that category of medication had the slowest rate of decline, Heilman said.

“We thought the chronic users would be the most impaired, but they weren’t — it was the people who began using the medications after enrolling in the study,” said Heilman.

He suspects that’s because younger brains are better at compensating, and may actually produce more acetylcholine if it’s blocked. Older brains don’t do that as well.

Although researchers couldn’t say whether patients could recover their memory loss once they stopped taking the medication, stopping would prevent the more accelerated decline from continuing, Heilman said.

Meanwhile, he said, “the healthiest thing to do for your brain is to use it.”

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