Correlation Between the Plasma Cortisol Level and the Characteristics of Magnetic Resonance Spectroscopy of the Prefrontal Cortex and Hippocampus in Depressed Patients

To explore the characteristic changes of magnetic resonance spectroscopy of prefrontal cortex and hippocampus and the correlation with the plasma cortisol level in depressed patients without any therapy. Subjects were divided into groups by the Hamilton depression scale. Blood was taken to detect the plasma cortisol level. Meanwhile, subjects were scanned by MRI and 1H-MRS to test the brain structure and the levels of NAA, Cho, Cr in prefrontal cortex and hippocampus. The level of plasma cortisol, the value of MRS and 1H-MRS of the patients were compared with those of normal control. We found that the level of plasma cortisol in depression group is higher than that in normal control group (P=0.000). A negative correlation between the level of plasma cortisol and the level of NAA in the left prefrontal cortex is observed (r = -0.625, P = 0.041), while in the left hippocampus, the correlation between them is positive (r = 0.647, P = 0.043). The level of NAA in the left prefrontal cortex of depression group is lower than that of normal control (P = 0.006); and the levels of NAA, Cho, Cr in both left and right hippocampus of depression group is lower than those of normal control group (P < 0.05). These data suggest that the changes of energy metabolism may happen before the structural damage of prefrontal cortex and hippocampus, and correlate to the changes of the level of plasma cortisol in depression patients.