A Rejoinder to Otaiku: Religiosity and Risk of Parkinson's Disease in England and the USA-The Health Determinants of Spirituality, Religiosity and the Need for State of the Art Research.

This rejoinder refers to the research of Otaiku (J Religion Health 1-17, 2022), which concluded that low religiosity in adulthood is associated with an increased risk of developing Parkinson's disease. Although Otaiku points to a number of limitations of their own research and thus clearly qualifies that further work is needed to verify the findings, a number of concerns still need to be raised about this research. Five points are highlighted in this article, namely (1) it is not clear why and how the variables of religiosity and spirituality were combined; (2) it is not reported whether other variables were tested; (3) they refer to the four different groups of how religiosity plays a role, which include extremely small samples of 11, 16, 25, 22 participants, (4) the final conclusion is based only on the two extreme groups with Parkinson's disease, (5) it remains unclear whether all patients had Parkinson's disease. Consequently, we are of opinion that Otaiku's findings and conclusions are questionable, but agree that future studies are warranted that require state-of-the-art research. [Note: A detailed response to this rejoinder has been provided in a subsequent commentary; Koenig (Journal Religion Health 62, 2023)].