Motor and nonmotor features of p.A53T alpha-synuclein PD vs idiopathic PD: longitudinal data from the PPMI study

Background and objectives The phenotype of p.A53T-α-synuclein (SNCA) mutation carriers with Parkinson’s disease (A53T-PD) appears more severe compared to idiopathic PD (iPD), however, information is limited. Here we conducted a comprehensive longitudinal study to investigate the progression of motor and nonmotor features of Α53Τ-PD compared to iPD. Methods Detailed longitudinal 3-year data, concerning both motor and non-motor features, of 16 p.A53T-PD and 48 iPD, matched for age (51–53 years) and disease duration (approximately 4 years) at baseline, were downloaded from the Parkinson's Progression Markers Initiative (PPMI) database and compared between the two groups. Additionally, a cognitive composite score was generated by five cognitive tests, focused more on executive/visuospatial function. Results At baseline, global cognitive function, as assessed by the Montreal Cognitive Assessment (MOCA), was not significantly different between the two groups, in contrast to tests evaluating executive/visuospatial function, including the composite score, which were worse in A53T-PD. There was a significant decline over time in all neuropsychological tests in A53T-PD, while iPD remained stable. A similar pattern was revealed for motor status and function, as well as autonomic function, which were similar between the two groups at baseline, but deteriorated significantly only in A53T-PD over time. Discussion A53T-PD patients present an accelerated decline in both motor and non-motor parameters, with an impairment in executive-visuospatial function occurring early in the disease process. Such data may set the stage for targeted disease-modifying therapies in this particular subtype, while generated data may be widely applicable to iPD, which is largely a sporadic synucleinopathy.