Of interest are instrumental methods for diagnosing depression. The use of computed tomography was limited due to the low resolution and artifacts created by the bones of the skull. In some studies, ventricular enlargement has been found in patients suffering from depression, but most often these changes have been observed in patients who have had an episode of psychosis. It should be noted that the expansion of the ventricles of the brain is relatively often combined with a prolonged increase in the level of cortisol in the urine of a patient with depression. Magnetic resonance imaging in patients with bipolar affective disorder and elderly patients revealed the phenomenon of “hyperintensiveness”: the appearance of bright white areas in the white matter surrounding the ventricles of the brain. Similar foci, localized in the left frontal white matter of the brain and in the left shell zone, are especially common in older people who are in a state of depression.
Single photon emission computed tomography – gamma tomography is currently not considered to be a significant instrumental method for the diagnosis of depression (gamma tomography uses computer processing of cross-images of the distribution of a radioactive substance). At the same time, there are some studies that have revealed reduced perfusion, usually recorded after the end of the treatment for depression. Perfusion changes were also found in the frontal and temporal areas, as well as in the caudal nuclei of the brain.
The conditional diagnostic biological markers of severe depression include the altered nature of the bioelectrical activity of the brain. Electroencephalogram is particularly useful in the assessment and differential diagnosis of cognitive impairment in elderly patients. The most informative studies of brain bioelectrical activity during sleep. In the period of depression, it is important to determine the functional capabilities of the autonomic nervous system. As mentioned above, to assess changes in the latter, studies of skin galvanic evoked potentials are carried out, the rate of extinction of the skin galvanic reaction after a significant stressor is presented, and interval cardiometry is performed. It is necessary to emphasize the need for instrumental methods of research in patients suffering from resistant depression or depression with atypical manifestations.