Blood-Serum Glutamate in Patients with Depressive Disorders as a Potential Peripheral Marker of the Prognosis of the Effectiveness of Therapy

Depressive disorder is considered as an important medico-social problem due to its severity, chronic nature, and high level of clinical polymorphism. The precise biological mechanism of this pathology is still unknown. The latest data confirms the role of the glutamatergic system in the pathogenesis of depression. Here, 79 patients with depressive disorders (50 diagnosed with a “single depressive episode” and 29 with “recurrent depressive disorder”) who were treated with selective serotonin reuptake inhibitors (SSRIs) and 27 healthy control donors underwent complex clinical and biochemical examinations. The depression severity at the baseline and on the 14th and 28th days of treatment, as well as during remission, was evaluated using the 17-item Hamilton Depression Rating Scale (HDRS-17). The therapy response was evaluated using the CGI-I scale. The blood serum glutamate concentration was measured at the baseline. The concentration of glutamate was significantly higher in the group of patients compared to the controls. No difference in this parameter was observed between groups of patients. A positive correlation between the severity of depression at the 28th day and the glutamate concentration was found in the groups of patients with recurrent depressive disorder. No association between glutamate concentration and the CGI-I scale score, as well as remission, was found. A high glutamate level in blood serum of patients with depressive disorders could be an indicator of glutamatergic system dysregulation. This value in the future may be used as a predictor of the effectiveness of SSRI treatment in patients with recurrent depressive disorder.