Taking certain widely prescribed medications over several years may increase the risk of dementia by nearly 50 per cent, researchers have found.
The study identified a significantly higher dementia risk in people aged 55 and over who took strong anticholinergic drugs daily for three years or more.
Anticholinergic drugs block acetylcholine, a chemical messenger involved in transmitting signals through the nervous system.
These medications are used to treat a range of conditions including bladder problems, depression, chronic lung disease, Parkinson’s disease, and digestive disorders.
They affect how muscles contract and relax, and can influence memory and thinking.
Professor Carol Coupland, lead researcher from the University of Nottingham’s Division of Primary Care, 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.”
The research examined medical records from 58,769 people diagnosed with dementia and 225,574 without the condition.
All participants were aged 55 or older and registered with a UK GP between 2004 and 2016. The study was first published in 2019.
The strongest associations were found with anticholinergic antidepressants, antipsychotic drugs, bladder antimuscarinic drugs, anti-Parkinson drugs and epilepsy drugs.
No increased dementia risk was found for anticholinergic antihistamines or gastrointestinal medications.
The Alzheimer’s Society said: “Our own researchers have already shown a strong link between anticholinergic drugs and risk of dementia.
This study builds on this information, showing that long-term, high-dose use increases risk of some dementias, particularly vascular dementia.”
Vascular dementia is caused by reduced blood flow to the brain, which damages brain tissue over time.
The Society added: “A shortcoming of this type of study is that from this information we can’t rule out whether the diseases that cause dementia might have already begun in the brains of people involved before they started taking these drugs.”
Current clinical advice already recommends avoiding anticholinergic drugs in frail older adults due to their known effects on memory and cognitive function.
The researchers suggest these findings should also be considered when prescribing for middle-aged patients.
