Study links long-term use of certain anticholinergic drugs with increased dementia risk

A major scientific study has raised concerns about the long-term use of certain commonly prescribed medicines after researchers found they may be associated with a higher risk of dementia among older adults.

The research, carried out by experts at the University of Nottingham and funded by the National Institute for Health Research, examined the potential connection between strong anticholinergic medications and the development of dementia.

Anticholinergic drugs are prescribed for a range of medical conditions, including bladder problems, Parkinson’s disease, depression, epilepsy and chronic obstructive pulmonary disease. These medicines work by blocking acetylcholine, a chemical messenger that helps transmit signals throughout the nervous system.

The study found that adults aged 55 and older who had taken strong anticholinergic medicines daily for three years or longer had almost a 50% increased risk of developing dementia compared with those who had not used the drugs in the same way.

Researchers analysed medical records from 58,769 people diagnosed with dementia and compared them with 225,574 individuals who did not have a dementia diagnosis. The participants were registered with UK GP practices contributing information to the QResearch database between January 2004 and January 2016.

The investigation, which was first reported in 2019 and published in the JAMA Internal Medicine journal, identified increased dementia risks linked to specific groups of anticholinergic medicines.

The strongest associations were found with anticholinergic antidepressants, antipsychotic drugs, anti-Parkinson medicines, bladder treatments and epilepsy medications. Researchers did not identify an increased risk for other types of anticholinergic drugs, including antihistamines and gastrointestinal medicines.

Professor Carol Coupland from the University of Nottingham’s Division of Primary Care, who led the research, said the findings added further evidence of the potential risks linked to strong anticholinergic drugs, particularly certain categories of medication.

The findings have added to an ongoing discussion among scientists and healthcare professionals about the effects of these medicines on brain health.

The Alzheimer’s Society said previous research had already shown a strong link between anticholinergic medicines and dementia risk. The charity stated that the latest findings strengthened concerns that long-term and high-dose use may increase the likelihood of some forms of dementia, particularly vascular dementia.

However, experts also highlighted an important limitation of the research. Because it was an observational study, it could not confirm that the medications directly caused dementia. It remained possible that diseases leading to dementia had already started developing before some patients began taking the medicines.

Current medical guidance already recommends avoiding anticholinergic drugs in frail older adults where possible because of their effects on memory and thinking. The Alzheimer’s Society suggested that doctors should consider the latest evidence when prescribing these medicines to middle-aged and older patients, especially when long-term treatment is required.

Despite the concerns, health experts strongly advise patients not to stop taking prescribed medication without first speaking to a healthcare professional.

Suddenly stopping treatment could worsen existing medical conditions or create additional health problems. Decisions about changing or stopping medication should always involve a discussion with a doctor who can balance the benefits of treatment against any potential risks.

The study highlights the need for continued research into the long-term effects of widely used medicines and their possible impact on cognitive health.

With millions of older adults relying on prescription drugs for chronic conditions, understanding the balance between effective treatment and possible long-term risks remains a major priority for doctors and researchers.

The findings contribute to a growing body of evidence exploring how certain medications may influence dementia risk, but scientists stress that more research is needed to fully understand the relationship.