Those planning a bathroom cabinet clear-out following headlines about a range of popular over-the-counter medicines causing brain shrinkage might want to reconsider.
New research has concluded that people regularly taking popular drugs including Clarityn and Piriton for hay fever and other allergies, the sleeping tablet Nytol, and Night Nurse Liquid containing promethazine did worse in cognitive tests and showed signs of loss of brain cells and connections.
It’s the latest study to question the side effects of anticholinergics, a class of drugs widely used to treat conditions including asthma, incontinence, gastrointestinal cramps, depression, muscle spasms and sleep disorders. They work by blocking the action of the neurotransmitting chemical acetylcholine. Research published last year suggested those on anticholinergics were at a 50% greater risk of dementia.
In the new study, published in JAMA Neurology, US researchers carried out brain scans and other tests on 451 adults with an average age of 73 with normal cognitive function, including 60 who were taking at least one anticholinergic. Those taking the drugs had lower cortical volume, which has previously been linked to Alzheimer’s. They also performed worse in tests of immediate recall and executive function, which covers planning, verbal reasoning and problem-solving, and exhibited reduced glucose metabolism, a marker of brain activity.
So far, so bad. However, reports of the findings downplayed the study’s limitations. Most importantly, there is no way of knowing if the lower brain tissue levels and test scores of those taking the anticholinergics were the result of the drugs. They were also more likely to be suffering from depression, anxiety and insomnia, which could also have caused the effects.
“What they were unable to do in the study was to determine cause and effect,” says Dr Ian LeGuillou of the Alzheimer’s Society. “We don’t know whether the drugs themselves are triggering these effects or if they just happen to be correlated.”
Those concerned should speak to their GP before stopping any medication. That’s not to say these drugs are in the clear; far from it. However, bigger, more in-depth studies will be needed before it is possible to properly assess whether the risks associated with anticholinergics outweigh their benefits.
