Prepulse inhibition in patients with non-psychotic major depressive disorder

Background: Prepulse inhibition (PPI) of the startle response is a measure of sensorimotor gating. PPI deficits have been reported in schizophrenia and in patients characterized by a known dysfunction in the cortico-striato-pallido-thalamic (CSPT) brain substrates that regulate PPI. Patients with Major Depressive Disorder (MDD) are also thought to have impairment in the CSPT circuitry as they are characterized by clinical gating deficits. Therefore, we assessed PPI in non-psychotic MDD patients and compared their results to schizophrenia patients and non-patients. Method: PPI was assessed in 19 non-psychotic hospitalized MDD patients and compared to 14 hospitalized patients with schizophrenia and 13 archival normal comparison subjects. Results: MDD patients had PPI levels that were significantly higher than schizophrenia patients. The MDD subjects had PPI levels that were lower than non-patients but these differences were not statistically significant. Conclusions: MDD patients without psychosis do not exhibit PPI deficits comparable to schizophrenia patients. However, the MDD patients demonstrated a non-significant tendency towards lower PPI than the non-patients. Our results replicate previous findings that PPI deficits are found in acutely hospitalized schizophrenia patients, even when treated with atypical antipsychotic medication. Future studies with psychotic MDD patients are necessary to fully understand the relationship between MDD, psychosis, symptom severity and PPI.