Everyday life, including for patients taking different types of medicine, involves dealing with numbers. Even though Parkinson's disease may ordinarily be thought of as primarily being a motor disorder, there is evidence that numerical abilities decline as Parkinson's disease progresses. Further, the brain areas involved in arithmetic operations overlap with the areas that degenerate in Parkinson's disease.

In this Stage 1 Registered Report, Loenneker et al. (2022) will test healthy  controls, Parkinson disease patients with normal  cognition, and Parkinson disease patients with mild cognitive impairment on general working memory tasks as well as arithmetic performance on the four basic  operations (addition, subtraction, multiplication, division). The study aims to test whether or not there is a deficit in each operation, and the relation of any deficits to general working memory capacity.

The Stage 1 manuscript was evaluated over four rounds of review (including two rounds of in-depth specialist review). Based on comprehensive responses to the reviewers' comments, the recommender judged that the manuscript met the Stage 1 criteria and therefore awarded in-principle acceptance (IPA).

URL to the preregistered Stage 1 protocol: https://osf.io/nb5fj

Level of bias control achieved: Level 6. No part of the data or evidence that will be used to answer the research question yet exists and no part will be generated until after IPA.

List of eligible PCI RR-friendly journals:

• Advances in Cognitive Psychology
• Brain and Neuroscience Advances
• Cortex
• Peer Community Journal
• PeerJ
• Royal Society Open Science
• Swiss Psychology Open

References

Loenneker, H. D., Liepelt-Scarfone, I., Willmes, K., Nuerk, H.-C., & Artemenko, C. (2022). Arithmetic deficits in Parkinson’s Disease? A Registered Report. Stage 1 preregistration, in principle acceptance of version 4 by Peer Community in Registered Reports. https://osf.io/nb5fj