Certain types of commonly prescribed drugs used to treat bladder conditions, Parkinson’s disease and depression could significantly increase the risk of dementia later in life, according to a recent study.
The research, which has been published in JAMA Internal Medicine, was carried out by researchers from the University of Nottingham (UK). The team identified that there was a nearly 50% increased risk of dementia among patients aged 55 and over who had used strong anticholinergic medication daily for 3 years or more.
Within the nested case-control study, the investigators examined the medical records of 58,769 patients with a diagnosis of dementia and 225,574 patients without a diagnosis of dementia. All participants were aged 55 and over and registered with UK general practitioners contributing data to the QResearch database (between 1 January 2004 and 31 January 2016).
The results of the study suggested increased risks of dementia for anticholinergic drugs overall. Specifically, those that were said to be of risk included anticholinergic antidepressants, antipsychotic drugs, anti-Parkinson’s drugs, bladder drugs and epilepsy drugs, after accounting for other risk factors for dementia.
No increased risks were reported for the other types of anticholinergic drugs studied, such as antihistamines and gastrointestinal drugs.
Of the 58,769 patients with dementia, all had an average age of 82 and 63% were women. Each person with dementia was matched to five control patients of the same age, sex and general practice.
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Anticholinergic drug exposure was assessed using prescription information over a complete period of 10 years from 1–11 years before diagnosis of dementia or the equivalent dates in control patients and was compared between the two patient groups. Further analysis looked at prescriptions for anticholinergic drugs up to 20 years before diagnosis of dementia.
As the research was an observational study, no firm conclusions can be drawn about whether these anticholinergic drugs cause dementia. According to the researchers, it’s possible that the drugs were being prescribed for very early symptoms of dementia.
Carol Coupland (University of Nottingham), lead author of the study, said: “We found a greater risk for people diagnosed with dementia before the age of 80, which indicates that anticholinergic drugs should be prescribed with caution in middle-aged people as well as in older people.”
These results, along with those of a similar study published in 2018, help to clarify which types of anticholinergic drugs are associated with the highest risk of dementia.
In the 1–11 years before the dementia diagnosis date or equivalent in controls, nearly 57% of individuals with dementia and 51% of individuals without were prescribed at least one strong anticholinergic drug, with an average of six prescriptions in cases and four in controls. The most frequently prescribed types of drugs included antidepressants, anti-vertigo and bladder antimuscarinic drugs.
As noted by the researchers, the increased risk associated with these drugs indicates that if the association is causal, then approximately 10% of dementia diagnoses could be attributable to anticholinergic drug exposure, which would equate to around 20,000 of the 209,600 new cases of dementia per year in the UK.
Martin Rossor (NIHR National Director of Dementia Research, London, UK) concluded: “This study gives insight into the potential long-term impacts of the use of anticholinergic drugs. Further research is needed to confirm whether or not the association between these drugs and risk of dementia is causal. These drugs are prescribed for a number of health conditions and any concerns patients might have about them should be discussed with their doctors.”
Sources: Coupland CAC, Hill T, Dening T, Morriss R, Moore M, Hippisley-Cox J. Anticholinergic drug exposure and the risk of dementia: a nested case-control study. JAMA Intern. Med. doi:10.1001/jamainternmed.2019.0677 (2019) (Epub ahead of print); www.nottingham.ac.uk/news/drugs-and-dementia-risk