Over-the-counter anticholinergic medications, such as Benadryl, Tylenol and Advil, are very helpful in relieving pain and discomfort in a short time. However, a new study shows that taking these over-the-counter drugs can be harmful to the brain.

Anticholinergic, according to Health Line, are kind of drugs that block the neurotransmitter acetylcholine in the brain.

The new study, published in the journal JAMA Neurology, suggests that taking anticholinergic medications can reduce brain volume and enlarge ventricles in the brain, which, in turn, causes lesser cognitive function.

"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, assistant professor of radiology and imaging sciences at Indiana University School of Medicine and first author of the new paper.

For the study, researchers analyzed already existing data of 451 people from the Alzheimer's Disease Neuroimaging Initiative (ADNI) and the Indiana Memory and Aging Study (IMAS), aging from 70 to 75 with normal brains. The participants underwent memory and cognition tests, MIR scans, brain structure assesments and PET scans to measure brain metabolism.

The researchers discovered that participants who took at least one anticholinergic medication performed poorer in the short memory test compared to those who did not take over-the-counter cold medicine. Lower brain volumes and less glucose metabolism in the whole brain and the temporal lobe were also observed in the users of anticholinergic medications.

According to CNN, there are already many studies linking anticholinergic medications to dementia and loss of cognitive function. However, the recent study is the first one to take a closer look at the physical changes of the brain that causes cognitive decline.

"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 said.

Other side effects of anticholinergic medications include dry mouth, blurred vision, constipation, drowsiness, sedation, hallucinations, difficulty urinating, confusion, delirium and decrease sweating and saliva.

Researchers then advise everyone, especially adults, to check in with their health care providers before taking any over-the-counter medications to relieve pain or discomfort.