For better or for worse? Outcome variance with psychotherapy and other treatments for schizophrenia.

It has been suggested that psychotherapy makes some persons better and some worse, and that this might account for the findings of some studies that there was no significant difference between the mean improvement scores of psychotherapy and control groups. The results of a controlled study indicate, however, that psychotherapy alone did not significantly increase outcome variance in schizophrenia by comparison to a control group. In fact, there was a nonsignificant tendency to decreased variability. Ataraxic drugs alone, psychotherapy plus ataraxic drugs, and ECT had significant variance-reducing effects. There is no convincing evidence, either in the literature or from the findings of this study, that a greater outcome variability results from psychotherapy than that resulting from hospitalization and nursing care (control). Our findings support the view that by comparison with a control group, a treatment for schizophrenia reduces outcome variance in proportion to its efficacy on the particular criterion under study.