Slowing Cognitive Decline in Alpha-synucleinopathies by Enhancing Physical Activity

α-Synucleinopathies, including Parkinson's disease and dementia with Lewy bodies, are the second most common neurodegenerative diseases. In addition to progressive motor deterioration, cognitive decline is a key element of the non-motor symptom complex of these diseases. Isolated rapid eye movement (REM) sleep behavior disorder (iRBD) indicates an early stage of α-synucleinopathies, even before relevant motor or cognitive disorders are present. Therapeutic interventions in individuals with iRBD therefore have great preventive potential. In particular, increasing physical activity could have a relevant effect on neurodegenerative processes, including the preservation of cognitive functions. The aim of the study is therefore to investigate the effects of increased physical activity in everyday life on cognitive functions in individuals with iRBD. In this randomized, double-blind, actively controlled study, an increase in physical activity will be implemented over a period of one year with the help of a motivational smartphone application. The intervention and control conditions are the same as those used in the Slow-SPEED trials, making the connection between the trials concrete. The primary outcome parameter is the change in cognitive performance in a neuropsychological test battery over one year. Eighty individuals with iRBD and 50 age- and gender-matched individuals are being recruited at the University Hospital Bonn and the "Deutsches Zentrum für Neurodegenerative Erkrankungen" (DZNE) Bonn (German branch only). In addition to classic neuropsychological tests as the primary endpoint, magnetic resonance imaging (MRI) and blood-based markers of brain aging are being examined as secondary endpoints. This study is in close collaboration with the Slow-SPEED study (https://clinicaltrials.gov/study/NCT06993142). In addition, selected data from three separate trials-Alpha-Fit, Slow-SPEED-NL, and a sister trial in Austria currently in preparation-are planned to be synthesized into a meta-analysis.