Metabolic Syndrome and Parkinson's Disease Incidence: A Nationwide Study Using Propensity Score Matching

Background:Metabolic syndrome (MetS) and Parkinson's disease (PD) share common pathophysiological mechanisms. This study aimed to investigate the influence of MetS on PD incidence. Materials and Methods:A propensity score-matched cohort study was conducted using the National Health Insurance Service-National Health Screening Cohort (NHIS-HealS) data (2002-2015) from the Korean National Health Insurance Service. Individuals with MetS were identified from those who underwent a health checkup in 2009-2010 and were 1:1 matched to individuals without MetS (non-MetS) using the propensity score method. Among 314,737 eligible individuals, 85,530 MetS and non-MetS pairs were selected. Results:During a mean follow-up of 7.23 years, 819 (0.48%) PD cases occurred. Individuals with MetS exhibited 1.23 times greater PD incidence (95% confidence interval [CI], 1.06-1.43;P = 0.006). The risk of PD increased with the number of MetS components, with the presence of five MetS components altogether doubling the incidence of PD (odds ratio [OR], 2.00; 95% CI, 1.30-3.04;P = 0.001). High blood pressure, low high-density lipoprotein cholesterol, and high fasting blood glucose increased PD incidence by 1.34 times (95% CI, 1.15-1.58;P < 0.001), 1.31 times (95% CI, 1.13-1.52;P < 0.001), and 1.20 times (95% CI, 1.04-1.38;P = 0.013), respectively. Elevated waist circumference was not associated with PD incidence (OR, 1.11; 95% CI, 0.96-1.28;P = 0.176). High triglycerides exerted a protective effect against PD incidence especially in men (OR, 0.66; 95% CI, 0.54-0.81;P < 0.001). Conclusions:MetS may be a risk factor for PD incidence, and individual components of MetS exert different effects depending on sex.