Evaluation of Torrey and Yolken's feline viral zoonosis theory of schizophrenia.

A formal method of evaluation is applied to a theory presented by Drs. Torrey and Yolken, which asserts that cases of viral schizophrenia are due to a zoonosis from house cats. A formal method of theory evaluation is described, and the Torrey and Yolken theory is subjected to analysis by the method. The theory is found to be weak in several areas stemming from inadequate description of both the relevant clinical population and the viral pathogenesis, as well as an incomplete examination of available data bearing on a hypothesized association between schizophrenia and cat ownership. At this point, further work is indicated at the level of theory development before proceeding with research or clinical activity.