Metabolic syndrome contributes to cognitive impairment in patients with Parkinson's disease.

INTRODUCTION: Metabolic syndrome (MetS) increases the risk of cognitive impairment in normal aging but this has not been studied in Parkinson's Disease (PD). The purpose of this study was to investigate the impact of MetS on cognitive impairment in PD.

METHODS: This study investigated subjects older than 60 years who were diagnosed with PD. They were enrolled into this study between January 2010 and December 2011, and followed for 5 years. The assessment of cognitive function in subjects with PD was based on the cognitive and neuropsychiatric tests, and MetS was diagnosed according to the National Cholesterol Education Program's Adult Treatment Panel III. The subjects were divided into three groups according to the cognitive function at the end of follow-up: PD with normal cognitive function (PD-NC), mild cognitive impairment in PD (PD-MCI) and PD dementia (PDD).

RESULTS: Of the 787 subjects with PD included in our study, 255 (32.4%) were diagnosed with PD-MCI, and 105 (13.3%) were diagnosed with PDD. MetS was significantly associated with PD-MCI (odds radio [OR]: 1.45, 95% confidence interval [CI]: 1.17-1.72) and PDD (OR: 2.12, 95% CI: 1.57-2.83). The associations between MetS and the main cognition domains of PDD were statistically significant. The treatment of MetS was helpful in reducing the risk of PDD.

CONCLUSIONS: We found that MetS increase the risk of cognitive impairment in patients with PD, and is significantly associated with the severity of cognitive impairment. The results suggest that the intervention against MetS is helpful in managing cognitive impairment in PD.