In one of the largest and most detailed study of its kind, researchers from the University of East Anglia (Norwich, UK) have revealed that long-term use of some anticholinergic medications could be associated with an increased risk of dementia – even when taken up to 20 years before a diagnosis.
The research, which was recently published in the BMJ, was funded by the Alzheimer’s Society (London, UK) and indicates that dementia risk is associated with medications prescribed for bladder conditions (e.g., tolterodine, oxybutynin and solifenacin) and Parkinson’s disease (e.g., procyclidine).
Several other anticholinergic medications, including antihistamines and those used for abdominal cramps and travel sickness, were not found to be linked to dementia.
In the study, the research team examined medical records of 40,770 patients above the age of 65 who were diagnosed with dementia and compared them with the records of 283,933 individuals without dementia.
The researchers investigated whether there were links between different classes of anticholinergic medication and incidence of dementia diagnosis. They found that there was a greater incidence of dementia among patients prescribed greater quantities of antidepressants and anticholinergic medication for bladder conditions and Parkinson’s disease.
Although the link between these medications and dementia cannot be classified as causal, the researchers suggest that this work does provide a potential preventative approach to reduce dementia.
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“We studied patients with a new dementia diagnosis and looked at what anticholinergic medications they were prescribed between 4 and 20 years prior to being diagnosed,” explained George Savva (University of East Anglia), the lead researcher of the study.
“We found that people who had been diagnosed with dementia were up to 30% more likely to have been prescribed specific classes of anticholinergic medications. And the association with dementia increases with greater exposure to these types of medication.
“What we don’t know for sure is whether the medication is the cause. It could be that these medications are being prescribed for very early symptoms indicating the onset of dementia. But because our research shows that the link goes back up to 15 or 20 years before someone is eventually diagnosed with dementia, it suggests that reverse causation, or confounding with early dementia symptoms, probably isn’t the case.”
Current guidelines for medical practitioners advise that anticholinergic drugs should be avoided for older individuals due to their impact on memory and thinking, however, the researchers believe that doctors should consider these new findings for all over-65s as long-term use could raise the risk of dementia.
They also believe that safer alternatives to anticholinergic medications should be prioritized long before symptoms of dementia are recognized.
To conclude, lead pharmacist of the study, Ian Maidment (Aston University, Birmingham, UK), commented: “This study shows that some anticholinergics may cause long-term harm in addition to short-term harm. Other research has shown a dramatic increase in polypharmacy – the number of older people taking five or more medications has quadrupled over 20 years to nearly half of all older people.
“With many different medicines having at least some anticholinergic activity, one focus should be de-prescribing. Doctors, nurses and pharmacists need to work with older people and their carers to ensure that they only take medication if the benefits clearly outweigh the harms.”