Analysis of the relationships between the content of serotonin and noradrenalinе in the peripheral blood and the suicidal behavior

Abstract

Laboratory blood testing is one of the most promising methods for determining the suicidal risk biomakers because some neurotransmitters and neuropeptides such as norepinephrine and serotonin can penetrate through the bloodbrain barrier. Three groups were formed: the persons who used the highly lethal methods of self-harm (PUHMS); the persons who made a suicidal attempt in different ways (PSA); the persons who experienced psychosocial stress and previously did not commit suicide attempts (comparison group, GS). The content of serotonin and norepinephrine in blood plasma was determined by the enzyme immunoassay on a Stat Fax 2100 spectrophotometer. The depression severity was assessed using the Montgomery‒Asbrega scale, the motivation to commit suicide was assessed using an analog scale. The highest level of serotonin and noradrenaline was observed in the PSA; in half of this group (50 %), depression was not determined, the motivation severity was statistically significantly lower than in the PUHMS, but higher than in the GS where the noradrenaline content in the peripheral blood was significantly higher than in the PUHMS. The lowest norepinephrine level was noted in the GLIVS where the serotonin level was within the physiological norm (the mean value is 60.4 ng/ml, the physiological norm is 50–220 ng/ml). In the GS, the serotonin level was below the physiological norm (36 ng/ml), and the depression severity corresponded to the PUHMS indicators, however, in the PUHMS, persons with severe depressive disorder predominated (PUHMS – 23.1 %, GS –12.3 %). The low levels of serotonin and norepinephrine in the peripheral blood may indicate the risk of committing suicide.