Millions of people use everyday medicines for allergies, high blood pressure, depression, bladder problems, sleep problems, or motion sickness.
Some of these medicines have what doctors call anticholinergic effects, meaning they reduce the action of acetylcholine, an important chemical messenger in the brain and body.
Acetylcholine helps nerve cells communicate and plays a major role in memory, learning, attention, muscle movement, and other body functions. Medicines that block its action can be useful for treating certain symptoms, but researchers have long wondered whether regular use could have unwanted effects on the aging brain.
A study led by researchers at the University of California, San Diego, adds to those concerns. The research, led by Lisa Delano-Wood, was published in Neurology, the medical journal of the American Academy of Neurology.
The study included 688 adults with an average age of about 74. None had memory or thinking problems when the study began, and researchers followed them with yearly tests for as long as 10 years.
Participants reported whether they had regularly taken medicines with anticholinergic effects at least once a week for more than six months. About one-third of the group used these medicines, and many were taking several different drugs.
During the follow-up period, people taking at least one of these medicines were 47% more likely to develop mild cognitive impairment than people who did not use them. Mild cognitive impairment, often called MCI, involves noticeable problems with memory or thinking that are greater than normal age-related changes but are not severe enough to be dementia.
MCI does not always lead to Alzheimer’s disease, but it can be an early warning sign in some people. This makes it especially important to understand factors that may increase the chance of developing memory problems.
The researchers also found a much stronger link in people who already had biological signs associated with Alzheimer’s disease. Among people with certain changes found in spinal fluid, those taking anticholinergic medicines were about four times more likely to develop MCI.
Genes also appeared to matter. People with genetic factors that increased their Alzheimer’s risk were about 2.5 times more likely to develop memory problems if they used these medicines than similar people who did not.
The findings do not prove that the medicines directly caused memory decline. People who take these drugs may differ in other ways that affect brain health, and the study was observational rather than an experiment designed to prove cause and effect.
Still, the results suggest that medicine use deserves careful review as people get older, particularly for those already at higher risk of Alzheimer’s disease. Doctors may sometimes be able to adjust the dose, replace a medicine with another option, or decide that the benefits of the current treatment are greater than the possible risks.
People should not suddenly stop prescribed medicines because of this research. Anyone concerned about memory changes or the anticholinergic effects of a medicine should speak with a doctor or pharmacist, who can review the full medication list and explain whether safer alternatives are appropriate.
The study adds to growing research showing that medicines can affect the brain in ways that may become more important with age. Regular medication reviews may therefore be one simple way to help older adults balance the benefits of treatment with possible effects on memory and thinking.
If you care about brain health, please read studies about Vitamin B9 deficiency linked to higher dementia risk, and cranberries could help boost memory.
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