Anticholinergic drugs help to contract and relax muscles by blocking acetylcholine – a chemical that transmits messages in the nervous system. Doctors prescribe the drugs to treat a variety of conditions, such as chronic obstructive pulmonary disease, bladder conditions, allergies, gastrointestinal disorders and symptoms of Parkinson’s disease.
Confusion and memory loss are short-term side effects of these medicines but it is not certain whether long-term use actually increases the risk of dementia. Which is why experts from the University of Nottingham, backed by funding from the Nottingham Biomedical Research Centre (NIHR) School for Primary Care Research, carried out a study to find out more. They found that there was nearly a 50% increased risk of dementia among patients aged 55 and over who had used strong anticholinergic medication daily for three years or more. The research has been published in the JAMA Internal Medicine journal.
The team, led by Professor Carol Coupland from the University’s Division of Primary Care, looked at the medical records of 58,769 patients with a diagnosis of dementia and 225,574 patients without a diagnosis of dementia, all aged 55 and over and registered with UK GPs contributing data to the QResearch database, between 1 January 2004 and 31 January 2016. The results revealed there was an increased risk of dementia for anticholinergic drugs overall and specifically for the anticholinergic antidepressants, antipsychotic drugs, antiparkinson drugs, bladder drugs, and epilepsy drugs after accounting for other risk factors for dementia. However, there were no increased risks found for the other types of anticholinergic drug studied such as antihistamines and gastrointestinal drugs.
Professor Tom Dening, Head of the Centre for Dementia at the University of Nottingham and a member of the research study team, said:
This study provides further evidence that doctors should be careful when prescribing certain drugs that have anticholinergic properties. However, it’s important that patients taking medications of this kind don’t just stop them abruptly as this may be much more harmful. If patients have concerns, then they should discuss them with their doctor to consider the pros and cons of the treatment they are receiving.
Study Details
The average age of the 58,769 patients with dementia was 82.
63% of the patients were women.
The researchers matched every dementia case with five control patients of the same age, sex, and general practice.
Prescription information over a complete period of 10 years – from 1 to 11 years before the diagnosis of dementia, and the equivalent dates in control patients – was used to assess anticholinergic drug exposure.
Then the information was compared between the two patient groups. The researchers even went on to do further analysis, looking at prescriptions for anticholinergic drugs up to 20 years before the diagnosis of dementia.
Conclusion
This research does not provide firm conclusions about whether these anticholinergic drugs cause dementia because it was purely an observational study. There is the possibility even that the drugs were being prescribed for very early symptoms of dementia.
Professor Coupland said:
Our study adds further evidence of the potential risks associated with strong anticholinergic drugs, particularly antidepressants, bladder antimuscarinic drugs, anti-Parkinson drugs and epilepsy drugs.
The risks of this type of medication should be carefully considered by healthcare professionals alongside the benefits when the drugs are prescribed and alternative treatments should be considered where possible, such as other types of antidepressants or alternative types of treatment for bladder conditions.
These findings also highlight the importance of carrying out regular medication reviews. 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 only help to clarify which types of anticholinergic drug are associated with the highest risks of dementia. The most frequently-prescribed types of drugs were antidepressants, anti-vertigo, and bladder antimuscarinic drugs—which are used to treat an overactive bladder. If the association was found to be causal, that would mean around 10% of dementia cases could be blamed on these drugs. That means about 300,000 of the 3 million diagnoses per year in the US, for example.
Dr. Douglas Scharre, director of the division of cognitive neurology at the Ohio State University Wexner Medical Center in Columbus, who was not involved in the study encourages any patients who might have questions about this association to talk to their physicians. He said:
I spend a lot of my time in the memory disorder clinic seeing geriatric patients and taking people off medications, mostly ones that have anticholinergic properties, and many times there can be another drug out there that has less anticholinergic impact or is non-anticholinergic that may work. Some of the medications that they list in the study may be quite critical and important and are well worth the person taking for their seizures or their psychosis, and so it’s a risk-benefit discussion. So have a conversation with your doctor.
