Association of serum carotenoid, retinol, and tocopherol concentrations with the progression of Parkinson's Disease

BACKGROUND/OBJECTIVES: A pivotal role of oxidative stress has been emphasized in the pathogenesis as well as in the disease progression of Parkinson's disease (PD). We aimed at investigating serum levels of antioxidant vitamins and elucidating whether they could be associated with the pathogenesis and progression of PD. MATERIALS/METHODS: Serum levels of retinol, alpha- and gamma-tocopherols, alpha- and beta-carotenes, lutein, lycopene, zeaxanthin and 13 -cryptoxanthin were measured and compared between 104 patients with idiopathic PD and 52 healthy controls matched for age and gender. In order to examine the relationship between antioxidant vitamins and the disease progression, multiple group comparisons were performed among the early PD (Hoehn and Yahr stage I and II, N = 47), advanced PD (stage III and IV, N = 57) and control groups. Separate correlation analyses were performed between the measured antioxidant vitamins and clinical variables, such as Hoehn and Yahr stage and Unified Parkinson's Disease Rating Scale (UPDRS) motor score. RESULTS: Compared to controls, PD patients had lower levels of alpha- and beta-carotenes and lycopene. alpha-carotene, beta-carotene and lycopene levels were significantly reduced in advanced PD patients relative to early PD patients and were negatively correlated with Hoehn and Yahr stage and UPDRS motor score in PD patients. No significant differences were found in serum levels of retinol, alpha- and gamma-tocopherols, and other carotenoids between PD patients and controls. No significant correlations were found between these vitamin levels and clinical variables in PD patients. CONCLUSTIONS: We found that serum levels of some carotenoids, alpha-carotene, beta-carotene and lycopene, were lower in PD patients, and that these carotenoids inversely correlated with clinical variables representing disease progression. Our findings suggest that decreases in serum alpha-carotene, beta-carotene and lycopene may be associated with the pathogenesis as well as progression of PD.