INDIANAPOLIS, April 21 (UPI) -- Drugs that block the neurotransmitter acetylcholine, which is used in many over-the-counter cold medicines and sleep aids, were linked to later cognitive impairments in a recent study.
Researches at Indiana University found that people who use anticholinergic drugs had lower metabolism and reduced brain size, according to a study published in the journal JAMA Neurology.
In addition to over-the-counter drugs, prescription sleep aids and drugs for hypertension, cardiovascular diseases and chronic obstructive pulmonary disease also have anticholinergic effects.
Previous research has shown the drugs can cause cognitive problems in older adults for more than a decade, with impairment possible with as little as 60 to 90 days of continuous use.
"These findings provide us with a much better understanding of how this class of drugs may act upon the brain in ways that might raise the risk of cognitive impairment and dementia," Dr. Shannon Risacher, an assistant professor of radiology and imaging sciences, said in a press release.
For the study, researchers recruited 451 people with a mean age of 73.3 years who were participating in a larger study by the Alzheimer's Disease Neuroimaging Initiative, 60 of whom were taking at least one drug with medium or high anticholinergic effects.
Using PET scans to measure brain metabolism and MRIs to measure brain structure, and all of the participants completed cognitive tests of short-term memory, verbal reasoning, planning and problem solving, among other functions.
Participants taking anticholinergic drugs performed worse on cognitive tests, had lower glucose metabolism in the hippocampus and overall brain and had lower brain volume and larger cavities inside the brain than normal.
While the researchers caution people against changing medication without their doctors' advice, and suggest more research is needed to confirm and understand the link, the new study reinforces previous research, they said.
"Given all the research evidence, physicians might want to consider alternatives to anticholinergic medications if available when working with their older patients," said Risacher.