Nevertheless, based on a minimal clinically important difference of 4.63 points, our results are still sufficiently precise to exclude any clinically meaningful difference over at least 4 years.27 Future studies with larger sample sizes and additional biomarkers, such as tau or amyloid pathology, may help clarify whether α-syn SAA negative sporadic PD represents a distinct PD subtype or are a result of technical limitations of the assay. Here, MAPT is linked to Parkinson disease.