Plasma levels of neurotrophic factors are not associated with the severity of depression

Abstract

Depression is one of the most common mental illnesses. Impaired neurogenesis is observed in depression. Studying the concentration of biochemical indicators in the blood that may be involved in the pathogenesis of depression, looking for associations with the severity of depressive symptoms can be useful as an objective diagnosis of the disease and predicting the severity of the pathology. We determined plasma concentrations of the monoamine neurotransmitters serotonin and dopamine, and neurotrophic factors involved in neurogenesis (BDNF, CDNF and neuropeptide Y) in depressed patients and healthy volunteers with the same socio-demographic parameters using enzyme immunoassay and mass spectrometry. All study participants were administered the Hamilton Depression Scale (HAMD), the Generalized Anxiety Disorder Questionnaire (GAD-7), and the Center for Epidemiological Studies (CES-D). The cumulative scores on the three scales examined were significantly higher in depressed patients than in controls. The concentration of serotonin, dopamine, BDNF, CDNF, and neuropeptide Y in plasma did not differ between the subject groups and was not associated with the scores on the scales. Positive correlations were found between the content of neuropeptide Y and serotonin, BDNF and CDNF in blood plasma. Thus, although these markers are related to the pathophysiology of depression, they do not correlate with the severity of symptomatology and possibly in plasma cannot reflect processes occurring in the brain.

Keywords

• depression
• hamd
• ces-d
• gad7
• bdnf
• cdnf
• neuropeptide y