The elderly should not take some over the counter flu, hayfever, allergy and heartburn tablets because they cause short term memory loss and problems in thinking.
Brain scans found the elderly who take anticholinergic drugs which include heart burn medicine Zantac, Night Nurse liquid containing Promethazine and antihistamine Clarinex had slower brain processing and smaller brain sizes.
These calls of drugs block the chemical acetylcholine, which is involved in the transmission of electrical impulses between nerve cells.
They are prescribed for a wide range of conditions, including Parkinson’s disease, overactive bladder, chronic obstructive pulmonary disease, nausea and vomiting, sleeping problems, high blood pressure, depression and psychosis.
Previous studies have linked the drugs with cognitive impairment and increased risk of dementia.
But the new study by Indiana University School of Medicine is the first to explore their impact on brain metabolism and atrophy through brain scans.
Assistant professor of radiology and imaging sciences Dr Shannon Risacher said: “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,”
“Given all the research evidence, physicians might want to consider alternatives to anticholinergic medications if available when working with their older patients.
The impact of these drugs have been know about for over a decade with a 2013 study found drugs with a strong anticholinergic effect cause cognitive problems when taken continuously for as few as 60 days.
Drugs with a weaker effect could cause impairment within 90 days.
The new study involved 451 participants, 60 of whom 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 Ageing 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, positron emission tests (PET) measuring brain metabolism, and magnetic resonance imaging (MRI) scans for brain structure.
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 researchers also found significant links between brain structure revealed by the MRI scans and anticholinergic drug use, with the participants using anticholinergic drugs having reduced brain volume and larger ventricles, the cavities inside the brain.
Prof Risacher added: “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.”
The study was published in the journal JAMA Neurology.