Sleeping aids, hay fever cures increase risk of Alzheimer's risk by 63% – study
The study, led by researchers at the University of Washington, published in JAMA International Medicine, monitored 3,434 men and women aged over 65 for seven years while recording their use of the anticholinergic drugs.
The drugs block acetylcholine, a chemical transmitter in the body, which can lead to blurred vision, poor memory and drowsiness.
By the end of the study, around 637 of the participants, almost one-fifth, developed Alzheimer's and 160 were affected by other forms of dementia.
Dr Doug Brown, director of research and development at the Alzheimer's Society UK, said: “There have been concerns that regular use by older people of certain medications with anticholinergic effects, such as sleep aids and hay fever treatments, can increase the risk of dementia in certain circumstances, which this study supports.
“However, it is still unclear whether this is the case and if so, whether the effects seen are a result of long-term use or several episodes of short-term use.
“More robust research is needed to understand what the potential dangers are, and if some drugs are more likely to have this effect than others.”
The sleeping medication Nytol and anti-allergy pills Benadryl and Piriton all belong to a class of drug highlighted in the study.
The study found that for those who had a high intake of anticholinergic drugs over the study period, the risk of dementia was increased by 54 percent compared with no use. The risk of Alzheimer's alone was raised by 63 percent.
The findings showed that people taking at least 10mg per day of doxepin, 4mg per day of diphenhydramine (Nytol, Benadryl) or 5mg per day of oxybutynin (Ditropan) for more than three years were at an increased risk of developing dementia.
It is the first study to show a dose response that links an increased and steady use of the medicines with an increasing risk of dementia.
Two-thirds of people with dementia are women. By 2015, there will be 850,000 people living with dementia in the UK, according to The Alzheimer’s Society UK. There will be 1 million people with dementia in the UK by 2025.
Dr Simon Ridley, at Alzheimer’s Research UK, said: “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.
“Continued research to shed light on these links will be important for helping understand the benefits and potential risks of these drugs. In the meantime, anyone who is worried about the medication they are taking should seek advice from a doctor or pharmacist before stopping a course of treatment.”