J. Wolstein

Influence of atypical neuroleptics on executive functioning in patients with schizophrenia: a randomized, double-blind comparison of olanzapine vs. clozapine

Accepted clinical evidence suggests superior efficacy of novel antipsychotics in the treatment of cognitive symptoms in schizophrenia. Whether this constitutes a primary drug effect or a secondary effect due to easing extrapyramidal side-effects or improving positive symptoms when converting from a first- to a second-generation neuroleptic is still open to debate. Long-term efficacy as well as differential drug effects on cognitive performance are also poorly documented. We therefore compared cognitive performance of olanzapine vs. clozapine treatment in a controlled, randomized, double-blind trial. Fifty-four patients were assessed following a 2- to 9-day washout and again after 4 and 26 wk of neuroleptic treatment. Patients were rated on the PANSS for psychopathological changes, extrapyramidal side-effects were assessed on the Simpson-Angus Scale, and cognitive performance was assessed with the Stroop, Wisconsin Card Sorting and the Tower of London tests. Schizophrenia symptoms, extrapyramidal side-effects and cognitive performance improved significantly in the course of either drug treatment. Stroop test performance and Tower of London planning time improved significantly over 26 wk compared to baseline and 4-wk follow-up assessment while Wisconsin Card Sorting and Tower of London execution time improved significantly after 4 wk with no further improvement after 26 wk. Improved executive function was not related to improving positive symptoms and easing extrapyramidal side-effects, thus indicative of a primary treatment effect of either antipsychotic. However, Stroop reaction time improved with olanzapine while clozapine had a stronger effect on improving negative symptoms, thus suggestive of a differential drug effect.

Safety and efficacy of combined clozapine–lithium pharmacotherapy

Several case reports described neurotoxic side-effects in the course of a combined clozapine-lithium treatment. Here we report on the safety and efficacy of this combination in a sample of 44 hospital patients. Medical records were retrospectively audited and a subsample of 23 patients was re-assessed. Mean total duration of combined treatment was 23.5 months. The combination (indications: prophylaxis; treatment of affective symptoms or aggression/excitement; augmentation of neuroleptic efficacy) was rated effective in 84% and adverse events were reported in 64% of the patients. Notably, most of the adverse events were benign and transient. However, 8 patients (18%) developed transient neurological adverse events that were genuinely novel in only 3 patients (7%) and coincided with high dosage of medication or high plasma levels or serotonergic (antidepressant) co-medication. Our data suggest that combined clozapine-lithium treatment may appear to be safe and effective when administered within a moderate therapeutic dose range and without serotonergic co-medication or other substances interfering with clozapine metabolism.

A topographic event-related potential follow-up study on `prepulse inhibition' in first and second episode patients with schizophrenia

Dopamine agonists impair and antagonists normalize prepulse inhibition (PPI) of startle and gating of the P50 event-related potential (ERP), but the within-subject effect of treatment on impaired gating in schizophrenia has not been studied. We report the first results of a longitudinal study using PPI of ERPs as a measure of sensory gating in an auditory Go/NoGo discrimination. After admission and approximately 3 months later, at discharge, 15 patients with schizophrenia performed a discrimination between a 1.4 kHz target tone and an 0.8 kHz non-target tone with no prepulse, or with a prepulse at 100 ms or 500 ms before either tone. ERPs were recorded from 19 sites. Healthy subjects were studied twice, with 3 months between sessions. PPI of the P50 peak in the 100-ms condition was reduced in patients on admission. At discharge, decreased negative symptoms correlated with enhanced P50-PPI at frontocentral sites. After treatment increased N100-PPI at centrotemporal sites correlated with fewer positive symptoms. At frontal sites in the 100-ms condition, the initially small difference of non-target minus target P300 amplitudes increased as negative symptoms decreased. It is concluded that weak auditory prepulses interfere with early auditory stimulus processing (P50), channel selection (N100) and selective attention (P300). Gating of these stages of processing is impaired in psychotic patients and treatment tends to normalize gating in tandem with improvements of different types of symptoms.