London - Common over-the-counter hayfever pills could raise your risk of Alzheimer’s, warn researchers.
They found a link between dementia in older people and anticholinergic drugs, which include the antihistamines Benadryl and Piriton, as well as sleep remedy Nytol and some older antidepressants.
These medications affect the brain by blocking a key chemical messenger called acetylcholine, which has a range of functions in the body. The dementia risk is greatest when high doses are taken over several years, the US study found.
Many of the drugs are more commonly taken by older people, with up to half of the UK’s elderly population being prescribed at least one anticholinergic medication.
Study leader Professor Shelly Gray, of the University of Washington School of Pharmacy, said no one should simply stop taking the drugs without speaking to their doctor. But she said: ‘Healthcare providers should regularly review their older patients’ drug regimens, including over-the-counter medications, to look for chances to use fewer anticholinergic medications at lower doses.’
Research last year linked the use of anticholinergic drugs with mental impairment in the elderly. But the new study, in the journal JAMA Internal Medicine, is the first to show that the higher the dose, the higher the risk of dementia.
Researchers tracked 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 and 160 were affected by other forms of dementia.
For those taking the biggest doses of anticholinergic drugs, the risk of dementia was 54 per cent higher than those using none. The risk of Alzheimer’s was 63 per cent higher.
Of the drugs named in the study, an increased risk of dementia was seen in people taking at least 10mg a day of the antidepressant doxepin, 4mg a day of diphenhydramine (which is in Nytol and Benadryl) or 5mg a day of oxybutynin (Ditropan) for an overactive bladder for at least three years.
Many newer drugs to treat these conditions do not have anticholinergic effects, such as the antidepressant Prozac and antihistamines such as loratadine (Claritin).
Anticholinergic drugs block a chemical transmitter called acetylcholine, leading to side effects such as drowsiness and poor memory. People with Alzheimer’s disease are known to lack acetylcholine.
Dr Simon Ridley, of Alzheimer’s Research UK, said more research was needed, adding: ‘This large study adds to some existing evidence linking anticholinergic drugs to a small increased risk of dementia, but the results don’t tell us that these drugs cause the condition.’
Daily Mail