Introduction Recent studies have highlighted the accumulated use of anticholinergic drugs is associated with an increased risk of dementia, and many of those are used for symptomatic management in Parkinson’s disease (PD). Unfortunately, the only available post-mortem study investigating the effect of anticholinergic agents on Alzheimer’s pathology burden suffers from several methodological limitations. Therefore, we aimed to validate if cumulative use of anticholinergic medication will increase Alzheimer’s pathologies in the post-mortem PD brains.

Material and methods Retrospective case note analysis was carried out on 54 selected PD cases from the Parkinson’s UK Brain Bank and cases were stratified into no, low and high anticholinergic burden using literature-based anticholinergic scores. Association of anticholinergic burden and Alzheimer’s pathology in post-mortem tissues was analysed with logistic regression modelling.

Results A higher anticholinergic burden is associated with a greater tau burden in entorhinal cortex in PD cases (OR=2.21). Interestingly, a high anticholinergic burden decreases the odds of amyloid-beta presence in the anterior hippocampus (OR=0.127), entorhinal cortex (OR=0.124) and frontal cortex (OR=0.113) of PD cases.

Conclusion We have demonstrated that anticholinergic drugs have varying effect on Alzheimer’s pathology in post-mortem PD brain tissues. Complex mechanism is probably involved and require further studies.