Background. Numerous cultural and ethnic factors may directly and indirectly influence treatment outcome in schizophrenia. The present study compared the response to antipsychotic treatment in 3 ethnic groups of patients with schizophrenia. Method: Fifty black, 63 mixed descent, and 79 white patients with DSM-IV-diagnosed schizophrenia or schizophreniform disorder who were participants in multinational clinical drug trials were assessed by means of the Positive and Negative Syndrome Scale (PANSS). Treatment response was measured by the change in PANSS total scores and the change in positive, negative, and general psychopathology subscale scores from baseline to 6 weeks. Also, the percentage of responders (defined as greater than or equal to 40% reduction in PANSS total scores) was calculated for each group. Results: Baseline PANSS scores differed significantly, being higher for black and mixed descent patients. Mixed descent patients showed the greatest mean +/- SD percentage reduction in PANSS total score (29.4 +/- 21.6) followed by black (28.4 +/- 14.7) and white (11.4 +/- 27.6) patients. Analysis of covariance revealed a significant effect of ethnicity on the reduction in PANSS total scores (p < .0001). The numbers of responders were 20 mixed descent (32%), 12 black (24%), and 7 white (9%) patients (p = .002). Conclusion: Significant ethnic differences in acute antipsychotic treatment response are demonstrated by this study. Factors such as diet, nutritional status, body mass, and substance use could be important, as well as genetically determined ethnospecific pharmacokinetic and pharmacodynamic differences. Delayed help-seeking may account for the higher baseline scores in the black and mixed descent patients.
