Millions of people take medicines every day to manage common health problems such as allergies, high blood pressure, depression, and motion sickness.
These medications are often considered safe because many have been used for years and are prescribed by doctors or sold over the counter.
However, new research suggests that some of these familiar medicines may have unwanted effects on the brain, especially in older adults and people who already have a higher chance of developing Alzheimer’s disease.
The medicines in question belong to a group called anticholinergic drugs. These drugs work by blocking a chemical messenger in the body known as acetylcholine.
This chemical plays many important roles. It helps control muscle movements and influences heart function, but it is also essential for learning, attention, and memory. Because acetylcholine is so important for brain function, scientists have long wondered whether blocking it for long periods could affect memory and thinking abilities.
Researchers from the University of California, San Diego, decided to investigate this question. Their study followed 688 adults whose average age was about 74 years. At the beginning of the research, none of the participants had memory problems or signs of cognitive impairment.
The researchers asked each person whether they had taken anticholinergic medicines at least once a week for six months or longer. The participants then completed memory and thinking tests every year for as long as ten years.
Around one-third of the participants reported taking these medications. On average, they were using almost five different anticholinergic drugs. Some of the commonly used medicines included metoprolol and atenolol for treating high blood pressure, loratadine for allergy symptoms, and bupropion for depression.
As the years passed, the researchers noticed an important pattern. People who used at least one anticholinergic medicine had a 47 percent higher risk of developing mild cognitive impairment compared with people who did not use these drugs.
Mild cognitive impairment, often called MCI, is a condition in which a person develops memory and thinking problems that are greater than what would normally be expected with aging. Some people with MCI remain stable, but others eventually develop dementia or Alzheimer’s disease.
The findings became even more concerning when researchers looked at participants who already showed early biological signs linked to Alzheimer’s disease. Those individuals were four times more likely to develop memory problems if they were taking anticholinergic medications.
The study also found that people who carried genes associated with a greater risk of Alzheimer’s disease were about 2.5 times more likely to experience cognitive decline if they used these medicines.
These results suggest that certain medications may speed up memory decline in people who are already vulnerable. This is particularly important because anticholinergic drugs are widely used and many people may not realize that some medicines can influence brain health as well as treat other medical conditions.
The researchers stress that people should not stop taking prescribed medicines on their own. Instead, they recommend discussing concerns with a doctor or pharmacist.
In some cases, there may be alternative treatments that work well and place less strain on memory and thinking. Regular reviews of medications can be especially helpful for older adults, who often take several medicines at the same time.
The study also highlights a broader lesson about healthy aging. Medicines can provide important benefits, but they may also have effects in other parts of the body that are not immediately obvious. Understanding these possible effects can help doctors and patients make better choices and may help protect brain health later in life.
The research was led by Lisa Delano-Wood of the University of California, San Diego, and was published in the journal Neurology.
If you care about dementia, please read studies about dietary strategies to ward off dementia, and how omega-3 fatty acids fuel your mind.
For more health information, please see recent studies about Choline deficiency linked to Alzheimer’s disease, and what to eat (and avoid) for dementia prevention.
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