INDIANA, United States, Thursday April 28, 2016 – A new study published in the journal JAMA Neurology offers the most positive proof yet of what scientists have suspected for at least a decade: that anticholinergic drugs are linked to cognitive impairment and an increased risk of dementia.
Using brain imaging techniques, researchers at Indiana University School of Medicine found lower metabolism and reduced brain sizes among study participants taking drugs known to have an anticholinergic effect, meaning they block acetylcholine, a nervous system neurotransmitter.
Brand name medications containing this class of drug include Benadryl, Demerol, Dimetapp, Dramamine, Paxil, Unisom and VESIcare, according to a CNN report.
They are widely available over the counter, as well as by prescription, as sleep aids and for chronic diseases including hypertension, cardiovascular disease and chronic obstructive pulmonary disease (COPD).
Earlier research found a link between anticholinergic drugs and cognitive impairment and increased risk of dementia.
The new paper, published last week, is believed to be the first to study the potential underlying biology of those clinical links using neuroimaging measurements of brain metabolism and atrophy.
“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,” said Shannon Risacher PhD, assistant professor of radiology and imaging sciences, and first author of the paper.
“Given all the research evidence, physicians might want to consider alternatives to anticholinergic medications if available when working with their older patients,” Dr Risacher said.
The latest research project looked at 451 participants with an average age of 73. Sixty of them were taking at least one medication with medium or high anticholinergic activity.
The participants were drawn from a national Alzheimer’s research project, the Alzheimer’s Disease Neuroimaging Initiative, and the Indiana Memory and Aging Study.
To identify possible physical and physiological changes that could be associated with the reported effects, researchers assessed the results of memory and other cognitive tests, PET scans measuring brain metabolism, and MRI scans to assess brain structure.
The cognitive tests revealed that patients taking anticholinergic drugs performed worse than older adults not taking the drugs on short-term memory and some tests of executive function, which cover a range of activities such as verbal reasoning, planning, and problem solving.
Anticholinergic drug users also showed lower levels of glucose metabolism – a biomarker for brain activity – in both the overall brain and in the hippocampus, a region of the brain associated with memory and which has been identified as affected early by Alzheimer’s disease.
The participants using anticholinergic drugs were also found to have reduced brain volume and larger ventricles, the cavities inside the brain.
“These findings might give us clues to the biological basis for the cognitive problems associated with anticholinergic drugs, but additional studies are needed if we are to truly understand the mechanisms involved,” Risacher noted.