Schizophrenia, hemodialysis, and the placebo effect. Results and issues

This report presents the results of a double-blind study that examines the impact of hemodialysis on patients with chronic schizophrenia. Twelve patients were randomly assigned to sham and 12 patients to active dialysis. All patients experienced a drug washout period and were then followed up over an eight-week period. A statistically significant condition by weeks interaction was found, with patients in the sham group improving and patients in the active dialysis group decompensating over the last weeks of the trial. This complex finding fails to support the hypothesized efficacy of hemodialysis in the treatment of schizophrenia but also fails to support a simple placebo explanation for positive results reported in earlier open studies. The methodologic complications are reviewed, and a possible direction for future research is presented.