Plasma Insulin-Like Growth Factor 1 Is Associated with Cognitive Impairment in Parkinson's Disease

Abstract

Objective: The aim of this study was to test plasma insulin-like growth factor 1 (IGF-1) change in Parkinson's disease (PD) and essential tremor (ET), and assess the association of plasma IGF-1 level with motor and nonmotor symptoms in PD and ET. Methods: Plasma IGF-1 was measured in 100 PD patients, 40 ET patients, and 76 healthy controls. Motor and nonmotor symptoms were assessed by different scales. Spearman correlation test and linear logistic model were used to analyze the correlation of plasma IGF-1 with motor and nonmotor symptoms of PD and ET. Results: The plasma IGF-1 level was significantly increased in PD compared to healthy controls and ET patients. In addition, low plasma IGF-1 was correlated with low Mini-Mental State Examination (MMSE) scores in PD patients. However, no correlation was found between plasma IGF-1 and MMSE scores in ET patients. Conclusion: Plasma IGF-1 increased significantly in PD but remained unchanged in ET. A low plasma IGF-1 level was associated with poor cognitive performance in PD but not in ET patients.