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.

Vascular Remodelling is Impaired in Parkinson Disease

“…A similar finding has been recently reported by another group [12], where the reduced IGF-1 receptor is only associated with Lewy bodies disease, but not PD. Given the PD cases used for current study were not Lewy body disease the changes of IGF-1 function may be the hallmark for PD with dementia [28]. Interestingly, the activation of IGF-1R was in close correlation with cell proliferation in capillaries, in which these proliferating cells were highly associated with the pericytes (Figure 4).…”

“…IGF-1 deficiency has been reported in PD patients by showing increased plasma IGF-1 and IGF binding protein (IGFBP)-3 [28]. While over 75% of circulating IGFBPs are IGFBP-3 [29], the dominant binding protein in the CNS is IGFBP-2 [30].…”

“…The plasma IGF-1 increases in PD patients, but reduces in PD with cognitive decline [28,35]. Although the transport of IGF-1 across the BBB is very restricted, circulating IGF-1 can directly act on IGF-1 receptors located in the luminal side of vessels to promote vascular remodelling [36].…”

Manganese and the Insulin-IGF Signaling Network in Huntington’s Disease and Other Neurodegenerative Disorders

“…However, the majority of recent studies mainly focus on plasma IGF-1 levels as a biomarker for PD progression. Several groups published studies suggesting IGF-1 levels were increased in the sera of PD patients compared to control 188, 189 . Furthermore, studies revealed that increased plasma IGF-1 levels correlate with cognitive decline and motor symptoms 188, 190 .…”

“…Several groups published studies suggesting IGF-1 levels were increased in the sera of PD patients compared to control 188, 189 . Furthermore, studies revealed that increased plasma IGF-1 levels correlate with cognitive decline and motor symptoms 188, 190 . While these studies have great utility as a clinical tool and seem to be quite sensitive, they have added minimal mechanistic insight as to if or why IGF-1/insulin and related signaling may be dysregulated or pathogenic consequences.…”