Researchers compared how many daily doses of anticholinergic drugs these patients had been prescribed between four and 20 years earlier with a control group of nearly 300,000 matched individuals.
A "robust" link was found between certain anticholinergic drugs, used to treat a variety of conditions, and future incidence of the neurological disorder.
As a general rule, they say, someone with a 10% of developing dementia in the next 15 years would see that increase to 13% if they had been on anticholinergics for a year or more - or a "one in 33 chance of getting dementia you would otherwise not have got".
Patients with concerns should continue taking their medicines until they have consulted their doctor or pharmacist.
"More than 50 million people worldwide are affected by dementia and this number is estimated to be 132 million by 2050", Savva said in a statement.
To try and answer outstanding questions about the link between anticholinergic drug use and dementia risk, the researchers analyzed the anonymized prescribing records of more than 40,000 older adult patients, aged 65-99 years, held in the U.K.'s Clinical Practice Research Datalink (CPRD) who were diagnosed with dementia, and another 283,993 older adults without dementia. The study didn't investigate what might cause this link between anticholinergics and dementia risk, and researchers will need to build on these findings in future studies.
A list of medications with anticholinergic action can be found here.
"Doctors and patients should therefore be vigilant about using anticholinergic medications". The early symptoms of dementia include depression and urinary incontinence, so it is possible the drugs were sometimes being prescribed for people who already had the early stages. In addition, "many studies have linked anticholinergic drug use with concurrent or short term cognitive effects, but few have examined associations of long term anticholinergic exposure; the latter tend to report positive associations".More news: Oh, Yeezus: Trump and Kanye West trade Twitter love
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The clearest effect was associated with anticholinergics used to treat depression - for example, amitriptyline, dosulepin and paroxetine - and bladder conditions, such as tolterodine, oxybutynin and solifenacin.
"This research is really important because there are an estimated 350 million people affected globally by depression, and bladder conditions requiring treatment are estimated to affect over 13 per cent of men and 30 per cent of women in the United Kingdom and US". He had co-authored the study in the BMJ medical journal.
The researchers say that while the associations appear "moderate", they still reflect an "appreciable risk to patients", given the high incidence of dementia.
This means those patients with a new dementia diagnosis had significantly more exposure to anticholinergic medications during the study period than those without dementia, according to Savva.
In a study of 264 people, consumption increased as labels on drinks showed lower alcohol content.
"With many different medicines having at least some anticholinergic activity, one focus should be de-prescribing. But we know from other research that people with long-term health conditions really only take their medication as prescribed around half of the time - the other half, people either take more or less of their medication or not at all".
The research was led by the University of East Anglia in collaboration with Aston University, Birmingham, the University of Aberdeen, the Royal College of Surgeons in Ireland, Dublin, Regenstrief Institute (US), Purdue University (US), Indiana University (US), Newcastle University, and the University of Cambridge.
The study was funded by the Alzheimer's Society.