Some over-the-counter medicines to treat coughs and colds can increase the risk of Alzheimer’s, a study has found.
The findings showed people taking at least four milligrams per day of diphenhydramine (found in some Benylin products, Dozol oral solution and Panadol Nights) or five milligrams per day of oxybutynin (found in Ditropan and Kentera) for more than three years would have an increased risk of developing dementia.
Benylin, Dozol and Panadol Nights can be purchased over the counter in Ireland. Ditropan and Kentera are available on prescription to treat an overactive bladder.
Researchers found the drugs have “anticholinergic” blocking effects on the nervous system that are said to raise the likelihood of developing Alzheimer’s and other forms of dementia significantly at higher doses over several years.
US study leader Professor Shelly Gray, director of the geriatric pharmacy programme at the University of Washington School of Pharmacy, said while “no one should stop taking any therapy without consulting their health-care provider”, doctors should nonetheless regularly review older patients’ drug regimens, including over-the-counter medications — to look for chances to use fewer anticholinergic medications at lower doses.
Many of the medicines highlighted are taken by vulnerable older people, according to the scientists, who say their findings have public health implications.
Anticholinergic drugs block a nervous system chemical transmitter called acetylcholine, leading to side effects that may include drowsiness, blurred vision and poor memory.
People with Alzheimer’s disease are known to lack acetylcholine.
The scientists tracked the health of 3,434 men and women aged 65 and over for around seven years while monitoring their use of anticholinergic drugs.
Of the total, 637 developed Alzheimer’s disease and 160 other forms of dementia.
For those taking the highest doses of anticholinergic drugs over the study period, the relative risk of dementia was increased by a statistically significant 54% compared with no use.
The risk of Alzheimer’s alone was raised by 63%.
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