Effects of antipsychotics on prepulse inhibition of the startle response in drug-naïve schizophrenic patients

Haloperidol Differentially Modulates Prepulse Inhibition and P50 Suppression in Healthy Humans Stratified for Low and High Gating Levels

“…Thus, it appears that stratification of normal subjects into low and high PPI performers did not reveal the predicted enhancement of PPI by haloperidol in normal subjects with relatively low PPI levels. This negative finding is in accordance with several studies in schizophrenia patients, which showed that atypical antipsychotic medication had no PPI-enhancing effect (Grillon et al, 1992;Kumari et al, 1999;Oranje et al, 2002b;Duncan et al, 2003a, b;Perry et al, 2002;Mackeprang et al, 2002). It should be noted that the healthy subjects in our earlier study (Vollenweider et al, 2006) had lower PPI levels (mean SOA60 ¼ 8.873.3%) than did the low PPI group in the present study (mean SOA60 ¼ 43.8713.8%).…”

“…However, another study failed to replicate this distinction, finding that typical and atypical medications were equipotent in reversing the PPI deficit in schizophrenia patients (Quednow et al, 2005). On the other hand, several studies have failed to show PPI-enhancing effects of either typical or atypical medication in schizophrenia patients (Duncan et al, 2003a, b;Perry et al, 2002;Mackeprang et al, 2002), even though Duncan et al (2003b) found an improvement of clinical symptoms with atypical medication. In contrast to these negative findings, a recent study showed that an enhancement of PPI is associated with symptom reduction in patients treated for schizophrenia with either typical or atypical antipsychotic treatments (Meincke et al, 2004).…”

The Effects of Increased Central Serotonergic Activity on Prepulse Inhibition and Habituation of the Human Startle Response

“…In addition, in a recent study by Kumari et al (2006), patients treated with olanzapine and risperidone showed levels of PPI that were not significantly different from either healthy controls or from patients treated with typical antipsychotics (who showed significantly less PPI than the healthy controls). Currently, however, there is only one double-blind, randomized longitudinal study in which an atypical antipsychotic (risperidone) was compared with a typical antipsychotic (zuclopenthixol) in drug naïve first-episode schizophrenia patients (Mackeprang et al, 2002). This study failed to show any difference with regards to PPI deficits.…”

“…Habituation is a reduction over time of the amplitude of the ASR, seen after repeated presentation of identical startle eliciting pulses, which is not a result of sensory adaptation or muscle fatigue, and is considered a form of non-associative learning (Christoffersen, 1997). Patients with schizophrenia have frequently been found to show disrupted PPI, when compared with healthy controls (eg Braff et al, 1978Braff et al, , 1992Kumari et al, 2000;Parwani et al, 2000;Mackeprang et al, 2002).…”

“…This is hypothesized to contribute to some of the core symptoms found in schizophrenic patients, such as deficits in information processing, attention, and thought disorder Perry et al, 1999). In longitudinal studies of patients with schizophrenia, reduced PPI has been shown to be consistently present over time, indicating it to be a stable trait of schizophrenia as opposed to a state phenomenon (Mackeprang et al, 2002;Ludewig et al, 2002). Similar gating deficits have been found with a higher prevalence in relatives of schizophrenic patients as well as individuals with schizotypal personality disorder, thereby suggesting that the deficits are vulnerability markers already present before outright symptoms of schizophrenia are observed (Braff, 1993;Cadenhead et al, 2000Cadenhead et al, , 2002.…”