[Mental state and electrodermal activity in depressed patients during acute suicidal period]

Sixty-eight depressive inpatients were subdivided into an acutely suicidal (n = 34) and a non-suicidal control group (n = 34) by means of item I of the Beck Depression Inventory (BDI). The two groups were matched in age and sex. Electrodermal activity (SCL, SFL, SCR, habituation speed) and heart rate (HR) were recorded in a standard habituation experiment. In self-assessment scales, depression (BDI), trait anxiety (STAI-X1) and bodily complaints (B-L') were evaluated. Assuming a correlation between EDA and serotonergic transmission, we expected clear evidence of serotonergic dysfunction in the acutely suicidal group according to the hypothesis of a deficiency in serotonergic transmission in acutely suicidal depressives. Acutely suicidal depressives showed significantly higher depression and anxiety symptoms as well as more physical complaints (compared to the controls). As for the EDA experiments, SCLs and amplitudes of the first EDRs were significantly reduced in the acutely suicidal depressives (in comparison with the controls), whereas their heart rate was increased. Although the subjects of both groups were not selected regarding suicidality or suicidal attempts in their case history before admission to the depression ward but only for suicidality at the time of the experiment, these results are similar to those of depressive patients we examined during inpatient treatment and who later committed violent suicide. Further research on the mechanisms of central serotonergic regulation are necessary to shed light on the question whether acute serotonergic dysfunctions or outlasting deficiencies significantly contribute to results as found in this study.