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Long-term anticholinergics raise dementia risk, finds study

GPs should consider the risks in prescribing anticholinergic drugs long-term as they may increase the risk of dementia, a study has suggested.

Antidepressants, anti-Parkinson's drugs and urological drugs with anticholinergic modes of action were associated with an increased risk of dementia, the research found.

The study was carried out by researchers from the UK and the USA and looked at data for just under 41,000 patients aged 65-99 with a dementia diagnosis and just under 300,000 controls without dementia, making this the largest study of its kind to date.

The data was pulled from a UK general practice database and looked at patient exposure to different classes of anticholinergic drugs. The researchers found that there was a significant association between dementia and drugs for depression, Parkinson’s and urological conditions with the risk of dementia increasing by 11%, 29% and 18% respectively in patients on anticholinergics.

They also found that the association between drugs with the strongest anticholinergic action and dementia continued for up to 20 years post-exposure, with patients taking these drugs at a 17% increased risk.

The researchers suggested that doctors must take care when prescribing anticholinergic drugs and consider the risks, particularly when prescribing to Parkinson’s patients.

They said in the paper: ‘Patients with Parkinson’s disease have an elevated risk of dementia; anticholinergic antiparkinson drugs have previously been associated with greater cognitive decline. This study provides further evidence that anticholinergic drugs should be avoided when treating patients with Parkinson’s disease.

‘Clinicians should continue to be vigilant with respect to the use of anticholinergic drugs, and should consider the risk of long term cognitive effects, as well as short term effects, associated with specific drug classes when performing their risk-benefit analysis.’

BMJ 2018; available online 25th April

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