Progression characteristics of motor symptoms and cognitive function in patients with motor subtype of Parkinson's disease: a 3-year longitudinal study

Objective To explore the characteristics in motor symptoms development and cognitive function change in patients with different motor subtypes in patients with Parkinson's disease (PD) by retrospective longitudinal study. Methods A total of 78 patients with PD subtype and mild cognitive impairment diagnosed in the neurological department of our hospital from 2015 to 2019 were enrolled in this study. They were divided into tremor-dominant (TD) group (n=22), bradykinesia with slowness and impaired dexterity (BSID) group (n=29), and postural instability and gait difficulty (PIGD) group (n=27). Their clinical data were collected in an interval of 3 years. The motor symptoms, activities of daily living, disease stages and changes of cognitive function of these PD patients were assessed by the Unified Parkinson's disease rating scale (UPDRS)-Ⅱ and Ⅲ scores (UPDRS-Ⅱ and UPDRS-Ⅲ), Hoehn-Yahr (H-Y) stage assessment scale, Montreal cognitive assessment (MoCA) and mini-mental state examination (MMSE) scales. Results In the comparison of the baseline and follow-up data among the 3 groups, the UPDRS-Ⅱ and UPDRS-Ⅲ scores of the TD group were significantly decreased (P < 0.05); the H-Y stage, UPDRS-Ⅱ, UPDRS-Ⅲ and MOCA scores of the BSID group were also obviously reduced (P < 0.05, P < 0.01); the H-Y stage, UPDRS-Ⅱ, UPDRS-Ⅲ and MOCA scores and total MMSE score of the PIGD group was notably decreased (P < 0.01). During the follow-up, the motor symptoms and cognitive function were lower in the BSID group and PIGD group than the TD group, with H-Y stage, UPDRS-Ⅱ, UPDRS-Ⅲ and MOCA scores and total MMSE scores significantly decreased (P < 0.05, P < 0.01). The UPDRS-Ⅲ of PIGD group was significantly reduced than the BSID group (P < 0.05). Conclusion With the progression of the disease, the motor symptoms are deteriorated and cognitive functions are declined more rapidly in the PIGD and BSID subtypes, specially in the PIGD subtype.