Clinical correlates of serum insulin-like growth factor-1 in patients with Parkinson's disease, multiple system atrophy and progressive supranuclear palsy

Background: Recently, increased serum insulin-like growth factor-1 (IGF-1) levels have been reported in patients with Parkinson's disease (PD) and multiple system atrophy (MSA). Objective: To assess a correlation between the serum IGF-1 levels and clinical background factors in patients with PD and related disorders such as MSA and progressive supranuclear palsy (PSP). Methods: A total of 79 PD patients, 25 MSA patients, 16 PSP patients and 52 healthy controls were included in this study. The serum IGF-1 and growth hormone (GH) levels were measured in a fasting state. Unified PD Rating Scale (UPDRS) part III was used to evaluate motor function. Unified MSA Rating Scale (UMSARS) part II was also employed for the MSA patients. Results: The serum IGF-1 levels were significantly increased in the MSA patients compared with the PD patients and controls. No significant differences were observed in the serum GH levels among the patients and controls. The serum IGF-1 levels of PD patients with Hoehn and Yahr stage 2 were significantly higher than those of patients with Hoehn and Yahr stages 3-5. In patients with PD and PSP, the serum IGF-1 levels were negatively correlated with UPDRS part III. In contrast, patients with MSA showed a positive correlation of the serum IGF-1 levels with disease duration, UPDRS part III and UMSARS part II. Conclusion: The difference in the serum IGF-1 level and its correlation with clinical variables among these disorders may reflect different ongoing disease processes in each disorder. (C) 2013 Elsevier Ltd. All rights reserved.