Millions of people take medicines every day to manage common health problems such as allergies, high blood pressure, depression, motion sickness, and many other conditions.
These medicines often help people feel better and improve their quality of life.
Because many of them have been available for years, they are often considered safe when used as directed.
However, scientists are continuing to discover that some medicines may have unexpected effects on the body, especially when they are taken for a long time.
A study from the University of California, San Diego suggests that a group of commonly used medicines could affect memory and thinking, particularly in older adults and people who are already at higher risk of developing Alzheimer’s disease.
The medicines studied are known as anticholinergic drugs. They work by blocking a natural chemical in the body called acetylcholine. Acetylcholine is important because it helps nerve cells communicate with each other.
It plays a major role in memory, learning, attention, muscle movement, and many other body functions. Blocking this chemical can be helpful for treating certain illnesses, but it may also reduce normal brain activity if the effect is strong or lasts for a long time.
Many people may not even realize they are taking an anticholinergic medicine because these drugs are found in treatments for several different health conditions.
Some are used for allergies, while others help treat depression, high blood pressure, bladder problems, motion sickness, or stomach disorders. This means many older adults could be taking one or more of these medicines without knowing they belong to the same drug group.
To better understand how these medicines affect brain health, researchers led by Professor Lisa Delano-Wood studied 688 adults with an average age of about 74 years. At the beginning of the study, none of the participants had problems with memory or thinking.
The researchers asked each person whether they had taken anticholinergic medicines at least once a week for more than six months. They then followed the participants every year for as long as 10 years, using tests that measured memory and thinking skills.
About one-third of the participants were taking at least one anticholinergic medicine. On average, they were using almost five different anticholinergic medications. Some commonly used medicines included metoprolol and atenolol for high blood pressure, loratadine for allergies, and bupropion for depression.
The results showed a clear pattern. People who regularly took at least one anticholinergic medicine were 47% more likely to develop mild cognitive impairment, also called MCI.
Mild cognitive impairment is a condition in which memory and thinking become worse than expected for a person’s age, but the symptoms are not yet severe enough to be called dementia. Some people with MCI remain stable, but others eventually develop Alzheimer’s disease or another form of dementia.
The researchers found an even greater risk among people who already showed early biological signs linked to Alzheimer’s disease. Participants with these changes who took anticholinergic medicines were about four times more likely to develop memory problems than similar people who did not use the medicines.
People who carried genes that increased their risk of Alzheimer’s disease were also about two and a half times more likely to experience memory decline if they regularly used these drugs.
These findings suggest that anticholinergic medicines may speed up memory decline in people who are already vulnerable. Because these medicines are so widely used, the researchers believe doctors and patients should carefully consider whether they are truly needed, especially in older adults.
The study does not prove that these medicines directly cause memory loss. It only found a strong link between regular use and a higher risk of developing memory problems. More research is needed to understand exactly why this happens and whether reducing the use of these medicines can lower the risk.
The researchers encourage people not to stop taking prescribed medicines on their own. Instead, anyone who is concerned about memory or who takes several medications should speak with their doctor or pharmacist. In some cases, there may be safer alternatives that have less effect on the brain.
As people live longer, protecting brain health becomes increasingly important. Choosing medicines carefully, reviewing prescriptions regularly, and discussing possible side effects with healthcare professionals may help reduce unnecessary risks while still treating important medical conditions.
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The research was published in the journal Neurology.
