New evidence shows some anti-depressants can raise dementia risk

Leslie Hanson
April 26, 2018

Many older adults know that long-term use of certain medications can negatively affect cognition and increase one's risk of dementia.

They block acetylcholine, a chemical messenger that carries signals across the nervous system.

They found that there was a greater incidence of dementia among patients prescribed greater quantities of anticholinergic antidepressants, and anticholinergic medication for bladder conditions and Parkinson's. But taking anticholinergics was found to increase the risk to 13 per cent.

The researchers, who report their findings in the British Medical Journal, investigated GP records for more than 40,000 people over the age of 65 with dementia and almost 300,000 without dementia.

Dr George Savva, who led the research at the University of East Anglia's school of health sciences, said: 'We found that people who had been diagnosed with dementia were up to 30 per cent more likely to have been prescribed specific classes of anticholinergic medications.

Alzheimer's Society head of research Dr James Prickett told the BBC that compared with the risk of dementia being caused by an unhealthy lifestyle, the potential risk of an anticholinergic drug contributing to the onset of the disease was "quite small". They looked back at prescribing records for up to 20 years earlier, to find out whether there was a link between the anticholinergic drugs they were given and a later diagnosis of dementia.

"In total, there were 27 million prescription events that we were looking at over that period", Savva said.

The research, funded by Alzheimer's Society and published today in the BMJ, also shows a dementia risk associated with medications prescribed for bladder conditions (for example Tolterodine, Oxybutynin and Solifenacin), and Parkinson's (for example Procyclidine).

'And the association with dementia increases with greater exposure to these types of medication.' Doug Brown of the Alzheimer's Society, which sponsored the research, said: 'Guidelines for doctors say that anticholinergic drugs should be avoided for frail older people due to their impact on memory and thinking, but doctors should consider these new findings for all over-65s as long-term use could raise the risk of dementia'.

But experts said patients should not stop taking them, as their benefits may outweigh any risk. Previous research has suggested anticholinergics, which include hayfever medications, could also increase the risk of dementia.

But the researchers warned that patients should not stop taking the drugs without talking to their doctor first.

Tau and amyloid are proteins found in increased levels in the brains of many dementia patients, particularly those with Alzheimer's, according to the National Institute on Aging.

"This study shows that some anticholinergics may cause long-term harm in addition to short-term harm".

The chance of a random individual developing dementia is roughly 10 per cent.

Rob Howard, professor of old age psychiatry at University College London, said: "It is possible that use of some of these drugs may have actually been to treat the very earliest symptoms of Alzheimer's disease, which can be associated with low mood and lower urinary tract infections, many years before the development of dementia".

"Of particular interest to us is the classes where there is no association".

"It is important to be cautious about associations, as they do not prove causation", Rossor said.

"We don't know exactly how anticholinergics might cause dementia".

One in five people on anti-depressants are prescribed anticholinergics - the most common being amitriptyline.

"When I see patients on these drugs, I now say, 'let's think about other alternatives, ' " Fox said.

"Many medicines have this activity, and I think the key things from our finding is that it probably shifts the balance looking at risks versus benefits", said Ian Maidment, senior lecturer in clinical pharmacy at Aston University and another author on the study.

Other reports by Iphone Fresh

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