The biological basis of depression in schizophrenia

Posted onMarch 21, 2021

From modern positions, depression is considered as an unfavorable factor in the course of schizophrenia. To a large extent, this is determined by an increased risk of suicide and a deterioration in therapeutic sensitivity. But the question of the influence of depression on the course of the schizophrenic process remains open. In studying this problem, a modern approach is relevant, involving the consideration of schizophrenia and affective disorder from the standpoint of brain degeneration. From this point of view, it is of interest to analyze the level of BDNF, which can act as a marker of this process. BDNF promotes the growth and development of immature neurons, improves adult neuron survival and function, and helps maintain synapse connections. Experimental studies have shown the relationship of BDNF with the main transmitters involved in the development of mental pathology.

Studies of neurotrophic factors, in particular BDNF, were of particular interest and led to the formation of the neurotrophic hypothesis of depression. There is now much less research and more conflicting results regarding the relationship between BDNF levels and schizophrenia. Most of the research is focused on studying the relationship of BDNF with ongoing therapy. In the study of psychiatrists from the Institute. V.M. Ankylosing spondylitis included 25 inpatients. All patients met the ICD-10 diagnostic criteria for schizophrenia (F20) and were hospitalized for exacerbated mental illness. The study did not include patients with organic brain disease (severe trauma, history of stroke, etc.), as well as with severe somatic pathology in the acute stage. Patients were examined twice, at admission and after 4-6 weeks of therapy. The survey was comprehensive and included clinical psychopathological, laboratory and psychometric methods. In schizophrenic patients, the Calgary Depression Scale (CDSS) was used to assess depressive symptoms. The BDNF level was measured using the Rand Dsystems EL ISAs test system (R&D systems , USA) based on the enzyme-linked immunosorbent assay (ELISA). Blood sampling to determine the level of cortisol was carried out strictly in the morning. The quantitative determination of the concentration of cortisol in the serum of patients was carried out on an automatic immunochemical analyzer Access-2 (manufactured by Beckman Coulter , USA) using chemiluminescence immunoassay using paramagnetic particles. On the basis of the CDSS scale, two samples were made – 15 patients at the time of the first examination had depressive symptoms in the structure of a schizophrenic attack and 10 patients without signs of depression. The groups were comparable in age. The BDNF level in patients with depressive symptoms is significantly lower than in patients without depression. In turn, the level of cortisol in depressed patients is significantly higher. The obtained data on a significant decrease in the level of BDNF in the serum in the presence of depression in patients with schizophrenia indicates the severity of neurodegenerative processes in this category of patients. This may be due to the neurotoxic effects of cortisol.

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