Serum cortisol and insulin-like growth factor 1 levels in major depressive disorder and schizophrenia

Abstract

The pathophysiology underlying major depressive disorder (MDD) and schizophrenia is related to endocrine system functions and includes changes in the blood levels of cortisol and insulin-like growth factor 1 (IGF-1). However, these hormones have not been investigated simultaneously in patients with MDD and schizophrenia. We investigated the differences in serum cortisol and IGF-1 levels among patients with MDD and schizophrenia and controls. We included 129 patients with MDD, 71 patients with schizophrenia, and 71 healthy volunteers. Blood tests were performed between 6:00 am and 11:00 am after fasting. Serum cortisol levels were significantly higher in patients with schizophrenia than in patients with MDD and controls. Serum cortisol levels were significantly higher in patients with MDD than in controls. Serum IGF-1 levels were higher in both patient groups than in controls, whereas there was no significant difference between patients with MDD and schizophrenia. Both cortisol and IGF-1 levels were positively correlated with the Hamilton Rating Scale for Depression score in patients with MDD, whereas cortisol level was positively correlated and IGF-1 level was negatively correlated with the Brief Psychiatric Rating Scale score in patients with schizophrenia. The differences in the level of these hormones suggest pathophysiological differences between these disorders.

Figure 1

Serum levels of cortisol (A) and insulin-like growth factor 1 (IGF-1) (B) in patients with major depressive disorder (MDD), patients with schizophrenia, and controls. The mean and standard deviation for each group are shown as bar graphs and error bars, respectively. Serum cortisol levels in patients with MDD were higher than in controls (p = 0.02), and those in patients with schizophrenia were higher than in controls and patients with MDD (p < 0.01 and p < 0.01, respectively) (A). Serum IGF-1 levels were higher in patients with MDD and schizophrenia than in controls (p < 0.01 and p < 0.01, respectively). There were no significant differences in serum IGF-1 levels between patients with MDD and schizophrenia (p = 1.0) (B).

Figure 2

Scatterplots of serum cortisol level versus Hamilton Depression Rating Scale (HAM-D) score (A) and serum insulin-like growth factor (IGF)-1 level versus HAM-D score (B) in patients with major depressive disorder. Serum cortisol level was significantly positively correlated with HAM-D score (R = 0.28, p < 0.01) (A), and serum IGF-1 level was significantly positively correlated with HAM-D score (R = 0.24, p < 0.01) (B).

Figure 3

Scatterplots of serum cortisol level versus Brief Psychiatric Rating Scale (BPRS) score (A) and serum insulin-like growth factor (IGF)-1 level versus BPRS score (B) in patients with schizophrenia. Serum cortisol level was significantly positively correlated with BPRS score (R = 0.38, p < 0.01) (A), and serum IGF-1 level was significantly negatively correlated with BPRS score (R = − 0.50, p < 0.01) (B).