Is there an interrelationship between the effects of antipsychotics on psychopathology and on metabolism?

Background: Increased body weight and hyperlipidemia caused by antipsychotics may be associated with improved antipsychotic efficacy in schizophrenia. If this association has a causal interrelationship via a genuine pathophysiological mechanism, then body weight loss in antipsychotic-treated patients would be accompanied by worsened psychopathology. This could have clinical implications. Aim: To explore whether the decreased body weight in these patients is associated with a worsened psychopathology. Methods: In our previously published study, a 16 week treatment period with add-on orlistat (but not placebo) resulted in body weight loss in male (but not female) clozapine- or olanzapine-treated overweight or obese patients. In the current study, we investigated whether body weight loss in those male patients could worsen psychosis. Changes in the Positive and Negative Syndrome Scale (PANSS) scores within groups and body weight changes and lipid profiles over the treatment period were analysed by the paired samples t-test. Between-group comparisons were analysed by the independent samples t-test. Results: Over the treatment period body weight decreased by 2.56 +/- 3.25 kg from initial 106.02 +/- 12.61 kg (p = 0.04) for the orlistat group, with no statistically significant changes for the placebo group. Lipid levels did not change in either group. The orlistat-induced weight decrease was not associated with worsening in the PANSS scores. Conclusions: Weight loss was not associated with a worsening of psychosis. The interrelationship between the antipsychotic-induced weigh gain and improved schizophrenia psychopathology observed in earlier studies appears to be indirect. Orlistat treatment in our study did not worsen psychopathology in this population.