The onset of dementia could be promoted by regularly using pills to ward off hay-fever, depression and insomnia.
All types of medication in question are those with an “anticholinergic” effect, although experts say there’s no need to panic, or stop taking the medicines.
Higher doses and prolonged use were linked to higher dementia risk older people, in a study published in the journal JAMA Internal Medicine.
After studying only senior citizens, researchers found levels of dementia risk were increased when people took the drugs every day for three years or more.
Dr Doug Brown from the UK’s Alzheimer’s Society commented.
“We would encourage doctors and pharmacists to be aware of this potential link.”
Together with colleagues from the University of Washington, Dr Shelly Gray followed almost 3,500 people aged 65 and older, with no signs of dementia at the start of the study.
While the US study didn’t name specific brands, it sketched out the types of medication under the microscope. They included Tricyclic antidepressants, Antihistamines used to treat hay-fever and allergies, and Antimuscarinics for urinary incontinence
Findings of the study estimated that taking at least 10 mg/day of doxepin (antidepressant), four mg/day of diphenhydramine (sleep aid), or five mg/day of oxybutynin (for urinary incontinence) over more than three years would increase the risk of dementia.
Researchers have suggested that doctors and pharmacists might be more cautious in their treatments, offering alternatives or giving the lowest dose for the shortest possible period.
Some study participants agreed to have an autopsy after their death, allowing researchers to try and find a biological mechanism to explain the results.
Opinion remains split on the new findings. Dr Simon Ridley, head of research at Alzheimer’s Research UK, said the study was interesting but not definitive. While Dr Doug Brown, from the UK’s Alzheimer’s Society, also commented.
“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.”
Drug company Johnson & Johnson Ltd has said that a number of new hay-fever products contain newer, second generation antihistamines, rather than the type studied in the dementia research.
[Image: NL Group]