Entacapone augmentation of antipsychotic treatment in schizophrenic patients with negative symptoms; a double-blind placebo-controlled study

Negative symptoms in schizophrenia are associated with decreased dopaminergic activity in the prefrontal cortex (PFC). It is hypothesized that increasing dopamine levels would alleviate negative symptoms. Termination of dopamine activity in the PFC is mainly via catechol-O-methyl tranferase (COMT) activity. Hence, inhibition of COMT activity with entacapone should reverse PFC dopaminergic transmission. To assess the efficacy of entacapone addition to antipsychotic treatment in patients with residual schizophrenia, we conducted a double-blind, randomised, placebo-controlled study for 12 wk of treatment with entacapone or placebo. Clinical measures (PANSS, CGI and QLS) were obtained at baseline and at weeks 4, 8 and 12 and cognitive functions were assessed by the RBANSS. Significant improvement over time in PANSS and QLS scores was observed in both groups. However, entacapone did not demonstrate a beneficial effect compared to placebo. Therefore, this study does not support a therapeutic role for entacapone in residual schizophrenia.