Using a combination of PET and MR images, researchers have linked cognitive impairment to a type of drug used in products such as nighttime cold medicines in a study published online April 18 in JAMA Neurology.
The group found that drugs with an anticholinergic effect, meaning they block the neurotransmitter acetylcholine, could result in lower metabolism and reduced brain sizes, leading to the recommendation that older adults might want to avoid them.
The study evaluated 451 subjects from the Alzheimer's Disease Neuroimaging Initiative and the Indiana Memory and Aging Study. Sixty of the participants were taking at least one medication with medium or high anticholinergic activity.
To identify possible physical and physiological changes, the group led by Shannon Risacher, PhD, from Indiana University used PET scans to measure brain metabolism and 3-tesla MRI to illustrate structure. The researchers also administered memory and other cognitive tests to the participants.
They found significant links between brain structure revealed by the MRI scans and use of anticholinergic drugs; the participants who used anticholinergic drugs had reduced brain volume and larger ventricles, the cavities inside the brain. Those using anticholinergic drugs also had lower glucose metabolism on PET in the brain overall and in the hippocampus.
In addition, cognitive tests revealed that patients who took anticholinergic drugs performed worse than older adults who weren't using the drugs on short-term memory tests, as well as some tests of executive function, which cover a range of activities such as verbal reasoning, planning, and problem solving.
The findings provide some biological insights into cognitive problems associated with anticholinergic drugs; however, more studies are needed to validate the connection, the researchers concluded.
