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Comment & Response
December 2019

Association of Anticholinergic Drug Exposure With Increased Occurrence of Dementia—Reply

Author Affiliations
  • 1Division of Primary Care, University of Nottingham, Nottingham, United Kingdom
  • 2Primary Care and Population Sciences, University of Southampton Medical School, Aldermoor Health Centre, Southampton, United Kingdom
  • 3Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford, United Kingdom
JAMA Intern Med. 2019;179(12):1730-1731. doi:10.1001/jamainternmed.2019.4908

In Reply We are grateful to Paul for highlighting that we excluded patients with a recorded diagnosis of Parkinson disease from the case patients and controls in our study.1 We agree that this means that our findings of an association of antiparkinson drugs and other anticholinergic drugs with an increased risk of dementia may not apply to people with Parkinson disease but only to people receiving prescriptions for these drugs for other conditions. We decided to exclude people with Parkinson disease to reduce indication bias because people with Parkinson disease have a substantially increased risk of developing dementia2 and are frequently treated with anticholinergic drugs. However, some studies restricted to people with Parkinson disease have found an association of the use of anticholinergic drugs with increased risks of cognitive decline3 and dementia.4 Therefore, in the absence of robust evidence to the contrary, we conclude that careful evaluation and ongoing review of benefits alongside potential harms are still needed when these drugs are prescribed in people with Parkinson disease.

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