A new study has found that patients prescribed larger quantities of particular anticholinergic drugs have a higher risk of dementia. The researchers found that people who used certain types of anticholinergics for a year or more had a roughly 30 percent increased risk of developing dementia in the future. For comparison, lifestyle factors, such as smoking, social isolation, and physical inactivity, are associated with a 40 percent to 60 percent increased risk of developing dementia.
Anticholinergic drugs block acetylcholine, a chemical component that carries signals through the nervous system. It has been speculated that some anticholinergic drugs may block the normal activity of acetylcholine in the brain areas associated with memory and cognition, causing Alzheimer’s-like symptoms.
This was the biggest study into the long-term impact of anticholinergic drugs relative to dementia. Researchers reviewed the medical records of 40,770 patients between the ages of 65 and 99 with a diagnosis of dementia between April 2006 and July 2015. The data was compared to that of 283,933 people without dementia. The study also analyzed more than 27 million prescriptions
Anticholinergic drugs are prescribed to 20 percent to 50 percent of older adults in the United States to treat a variety of conditions. Anticholinergic drugs used for depression, Parkinson’s, and urinary incontinence had the highest risk for new-onset dementia. The study found no risk with other anticholinergic medicines used to treat common conditions such as hay fever, asthma, travel sickness, and stomach cramps.
The research was funded by Alzheimer’s Society and published in the British Medical Journal. Experts say the drug’s benefits may outweigh any risk, so patients should not stop taking them. Dr. James Prickett, head of research for the Alzheimer’s Society, was quoted as saying that the risk of an anticholinergic drug contributing to the onset of Alzheimer’s was “quite small”.
Previous studies found that anticholinergics were associated with dementia incidence. A 2015 study found a 54 percent increased risk of dementia among individuals prescribed high levels of anticholinergics over a 10-year period. However, this was the first study that incorporated the class of the drug into the equation.