Apr 22, 2016 06:27 AM EDT By Mariel Hemingway, UniversityHerald Reporter

Common allergy drugs used to treat flu, hay fever and colds may increase the risk of dementia. The drugs classified as anticholinergics are popular over-the-counter-medications that could result in side effects that could cause cognitive impairment.

A study conducted by Indiana University School of Medicine scientists looked at popular anticholinergic drugs. These medicines include anti-vertigo drugs, muscle relaxants, sleeping aides, antihistamines, anti-psychotics and cardiovascular and gastrointestinal drugs. CBS News shares that popular allergy drug brands include Paxil, Benadryl, Advil PM, Dimetapp, Unisom, Vesicare, Demerol and Dramamine.

Scientists looked at brain scans and cognitive exam results of more than 400 elderly adults including those who have been taking anticholinergic drugs for 4 weeks. The participants have no cognitive impairment conditions including dementia or Alzheimer's disease.

They found in their study that those who used anticholinergic drugs had lower brain activity in the memory region. Reuters reports that it is the same area that indicates early Alzheimer's disease diagnosis. Researchers also found that their brains had lower brain volume and thickness in parts attributed to cognitive function. Furthermore, the participants who used anticholinergic drugs had lower memory test scores compared to those who did not use the medication. The results of the study are detailed in the journal JAMA Neurology.

According to the researchers, their study provides evidence that health providers should prescribe their elderly patients with alternatives instead of using anticholinergic medication. The popular over-the-counter drugs might increase their risk for cognitive impairment conditions including dementia and Alzheimer's disease.

However, an expert from the Alzheimer's Society says that the findings need more research, Telegraph reports. The full effects of anticholinergic drugs are still unknown. However, those taking the drugs should not stop from using them, but instead, talk to their doctor first.

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