Normal prepulse inhibition and habituation of acoustic startle response in suicidal depressive patients without psychotic symptoms

Background: Until now, there is a lack of useful biological markers to predict suicidal behavior in depressive patients. However, it is consistently found that suicidality is associated with a central serotonin deficit. Animal data suggest that prepulse inhibition (PPI) as well as habituation of the acoustic startle response (ASR), which are established as operational measures for sensorimotor gating, decreases after serotonin depletion. Thus, we investigated PPI and habituation of ASR in suicidal patients with depressive disorders as potential biological markers for suicidal behavior. Methods: PPI and habituation of ASR was measured in 20 depressive patients who had at least one suicide attempt within the last three month. Eighteen healthy matched controls were examined likewise. Results: Suicidal depressive patients did not differ from healthy controls in PPI, startle reactivity and habituation of ASR. Subgroup analyses showed that factors such as severity of depression, impulsiveness, gender, smoking, lethality of the last suicide attempt, number of suicide attempts, and medication had no influence on the results. Conclusions: These results suggest that neither PPI nor habituation of ASR could serve as useful markers for suicidality.