Indeterminacy of Heritability of Thought Disorder: Reply to Matthysse and Holzman (1988)

The points raised by Matthysse and Holzman (1988) center around two major issues: (a) how to measure thought disorder and (b) how to think about its relation to schizophrenia and the etiology of that disorder. Some of the limitations that Matthysse and Holzman (1988) note appear to be based on misunderstandings of our (Berenbaum, Oltmanns, & Gottesman, 1985) methods, particularly what we were measuring and why we were measuring it. We, too, were surprised to find no evidence that these fundamental aspects of formal thought disorder are heritable. We do not know whether other anomalies of verbal communication are heritable. The issue must be resolved through further empirical investigation. Finally, some aspects of the model proposed by Matthysse and Holzman are open to serious question. The assumption that there is no relation between severity of illness and the underlying liability that precipitated the illness is most likely incorrect.