BACKGROUND: The clinical manifestations of multiple system atrophy-Parkinsonian variant (MSA-P) largely overlap with that of Parkinsons disease (PD).Cognitive impairment is well documented in PD, while dementia is a required feature in current consensus diagnostic criteria for MSA.Nevertheless, increasing evidence indicates that cognitive impairment is more common than is recognized, affecting single or multiple cognitive domains and varying from mild cognitive impairment to severe dementia.This study aimed to examine the difference of the cognitive function and clinical characteristics in MSA-P and PD by using systemic assessing scales for cognition in this study.