The use of anticholinergic drugs may account for 10 percent of the 500,000 dementia cases diagnosed annually in the United States, according to a study published online by the journal JAMA Internal Medicine on June 24. Several previous reports showed similar results.
The current study, involving nearly 59,000 dementia patients, found that middle-age and older adults who took a standard dose of an anticholinergic drug for as a little as three years showed a 50 percent increase in incidents of developing dementia. Antidepressants, medications to treat overactive bladder, antipsychotics, and anti-epileptic drugs exhibited the strongest correlation.
Anticholinergic drugs, a class of more than 56 different medications prescribed for a variety of conditions including chronic obstructive pulmonary disease (COPD), bladder conditions, gastrointestinal disorders, depression, and symptoms of Parkinson’s disease, block the action of the neurotransmitter acetylcholine. Animal studies show that blocking acetylcholine causes an accumulation of certain protein fragments in the brain like those seen in Alzheimer’s disease, Noll Campbell, a professors of pharmacy at Purdue University, told Medscape. Doctors have noted similar changes in the brains of Parkinson’s disease patients treated with this class of drugs, he said.
Other factors could cause people who take anticholinergic drugs to develop dementia. But, because other studies show similar results, Carol Coupland, the lead researcher, urged doctors to use caution in prescribing these medications.
“I would suggest that, from what we know so far, clinicians should weigh up the potential benefits and the potential risks of these drugs for their individual patients and consider alternative treatments if possible,” she told Medscape. “For most of these drugs, there are very reasonable alternatives that can be used.” —J.B.