Study: Common drugs used for hay-fever and sleeping aids may increase Alzheimer's risk

A new study released on Monday found that over-the-counter sleeping aids and hay-fever treatments can increase the risk of Alzheimer's.

Researchers found a link between dementia and the antihistamine drugs Piriton and Benadryl, as well as sleep remedy Nytol, and older antidepressants.

The study looked at medications with anticholinergic effects, which work by blocking signals in the nervous system, and include a number of treatments, for a range of conditions, available both on prescription and over-the-counter.

Lead author Dr. Shelly Gray, from the University of Washington, said that older patients should know the risks associated with these medications.

Dr Shelly Gray and colleagues from the University of Washington followed the health of 3,434 people aged 65 and older who had no signs of dementia at the start of the study.

"Older adults should be aware that many medications - including some available without a prescription, such as over-the-counter sleep aids - have strong anticholinergic effects," Gray said in a statement.

"O f course, no one should stop taking any therapy without consulting their health-care provider. Health-care 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."

Of the total, 637 developed Alzheimer's disease and 160 other forms of dementia.

The study estimated that people taking at least 10 mg/day of doxepin (antidepressant), 4 mg/day of diphenhydramine (a sleep aid), or 5 mg/day of oxybutynin (a urinary incontinence drug) for more than three years would be at greater risk of developing dementia.

After about seven years of follow-up, the researchers found that 637 participants (18.5 percent) had developed Alzheimer's disease, and 160 (4.6 percent) had developed other forms of dementia.