Some Hay Fever Drugs May Increase Risk Of Dementia In The Elderly

A link between these drugs and neurological problems seems to exist, but it's not yet definitive. VonaUA/Shutterstock

As anyone that suffers from it will know, hay fever is nothing short of profoundly irritating. Fortunately, there are a range of prescription and over-the-counter drugs you can take to remedy the problem, but as a new study shows, some of them may be causing some particularly unfortunate neurological side effects.

As revealed in the journal JAMA Neurology, a class of drugs known as “anticholinergic medication” – which includes treatments for hay fever, colds, and high blood pressure – are linked to shrinkage of the brains of those around retirement age. Although a direct causal link cannot yet be demonstrated, there is some evidence suggesting that these drugs may increase an elderly person’s chance of getting dementia as they age.

“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, in a statement.

In 2015, a study began to make frightening headlines that anticholinergic medications raises the risk of dementia. These drugs are easily obtainable and commonly consumed.

Published in the journal JAMA Internal Medicine, it revealed circumstantial evidence that suggested those over the age of 65, if taking a high dose (one pill a day, every day) for at least three years, have a 54 percent higher risk of developing dementia; 80 percent of these subjects had Alzheimer’s disease.

This new study was designed to find out why this may occur. The researchers observed 451 participants at pensioner age, 60 of whom were taking medication with moderate-to-high anticholinergic activity potency, for nearly a decade. At set intervals throughout observation, they were all given cognitive reasoning tests to assess their mental acuity, along with MRI brain scans.

The precise underlying neurological mechanism for these changes has not yet been found. Juan Gaertner/Shutterstock

Those on higher doses not only showed increasingly impaired mental acuity over time, but their brains showed overall shrinkage. In addition, their brains featured lower levels of glucose metabolism – a proxy for brain activity – throughout, but particularly in the hippocampus, the region associated with memory formation.

These drugs, a list of which can be found here, are known to block acetylcholine, an important nervous system chemical used by neurons to communicate with each other. It may be that this effect is inadvertently having these other observed effects, although this study cannot directly prove this – once again, it’s a circumstantial link.

As with both studies, these links were not investigated for those under 65. As always, if you’re thinking of changing medication based on this study, see a healthcare professional first. Suddenly stopping medication for hay fever may be vexing, but doing the same for high blood pressure tablets may prove dangerous.

“Given all the research evidence, physicians might want to consider alternatives to anticholinergic medications if available when working with their older patients,” Risacher added.

It’s also worth stressing that an increased risk of getting dementia by 54 percent is not the same as having a 54 percent chance of developing dementia. If you are in the U.K., for example, you have about a 7 percent chance of developing dementia if you are 65, which is quite low. This percentage barely changes when the increased risk gained by taking these drugs into account.

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