Elektrodermale Aktivität und ereigniskorrelierte Potentiale bei Depression und Suizidalität

Abstract

Over the past four decades, different authors have examined biological parameters in psychiatric patients, and their relationship to suicidal behaviour. Biochemical studies demonstrated that individuals that attempted or completed suicide, especially those which used violent methods, exhibited reduced central serotonergic neurotransmission, as indicated by cerebrospinal fluid levels of serotonin-metabolites. Psychophysiological studies examining electrodermal activity (EDA) found a relationship between suicidal behaviour and reduced EDA: Patients with a history of attempted suicide, especially those which used violent methods, showed faster habituation of the orienting response (OR), as indicated by skin conductance response (SCR) measurements. The P300 component of event related potentials is also subject to habituation and is, along with SCR, regarded as a useful indicator of the OR. The habituation of the P300 has not been examined in the context of suicidal behaviour. The object of the present study was to examine habituation of both EDA and P300 in three groups of depressed inpatients: patients with a history of violent attempted suicide, patients with a history of nonviolent attempted suicide and a control group with no history of attempted suicide. During EDA and EEG assessments, a single stimulus habituation-paradigm and an oddball-paradigm were carried out to determine the SCR habituation-rate and P300 reduction. Results indicate that faster habituation takes place in both the EDA and the P300 in the groups with attempted suicide when compared to the control group. This was especially pronounced in the group with violent attempted suicide. Besides the faster habituation of the SCR in patients with attempted suicide it could be shown for the first time that the habituation of a second indicator of the OR, the P300, revealed the same intergroup-differences. This provides further evidence for the existence of a biophysiological basis for suicidal behaviour.