A new study has linked the long-term use of certain medications to a higher risk of dementia in older people. The study, which focused on drugs that alter the action of a brain chemical called acetylcholine, is published on Monday 26 January in the journal JAMA Internal Medicine.
Led by researchers at the University of Washington, the team looked at data from 3,434 over-65s who were part of the Adult Changes in Thought study, none of whom had dementia when they were recruited to the study. The researchers looked at pharmacy records to track what medications the participants were using, and a series of memory and thinking tests were carried out every two years. Participants were followed for an average of 7.3 years.
The researchers looked in particular at the use of drugs which have an ‘anticholinergic’ action – meaning they block the action of a brain chemical called acetylcholine, which is used to help nerve cells send signals to one another. Some of the symptomatic treatments for Alzheimer’s disease work by boosting levels of this chemical, and some previous research has linked the use of anticholinergic drugs to an increased risk of dementia.
Some of the treatments in the study, such as certain drugs used to treat muscle spams, were designed to work by targeting acetylcholine. However for other drugs – including some older antihistamines or older antidepressants – the anticholinergic action was a side effect of the treatment. The researchers found that people who had been prescribed anticholinergic drugs for long periods were more likely to develop dementia later on, with the greatest risk of dementia in those were prescribed the drugs for the longest periods.
Dr Simon Ridley, Head of Research at Alzheimer’s Research UK, the UK’s leading dementia research charity, 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. Investment in research is vital if we are to find more effective ways of treating and preventing dementia.”
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