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In Reply.— We do not agree that the raters in the study by Berenbaum were able to distinguish normal subjects from schizophrenic patients on the thought disorder scale that Berenbaum used. Berenbaum was able to show differences between hospitalized schizophrenic twins and nonschizophrenic cotwins 1(p12) on three categories of thought disorder on the scale he used: "nonsequitur," "derailment," and "tangential responses." Only one of the nine categories of thought disorder (tangential responses) tested produced differences between nonhospitalized schizophrenic twins and the unaffected cotwins. 1 But one cannot re- gard the unaffected cotwins of schizophrenic patients as a normal control group. Indeed, there was no normal control group in that study, which Berenbaum et al also point out as a "limitation." 1 We previously noted, 2 in response to the initial letter by Berenbaum, 3 several other methodologic problems in his study. First, the thought disorder raters were minimally trained American undergraduate

In Reply.— Dr Berenbaum cites a difference between our study 1 and his. 2 We are not the first to find an aggregation of thought disorder in the relatives of psychotic patients. 3-6 We believe that at least three requirements should be met if one seeks to determine whether thought disorder is present in clinically normal members of families in which there is a psychotic patient. First, evaluating personnel must be well trained and experienced with the instrument in use. Second, the instrument used must be able to detect not only severe instances of thought disorder, present in psychotic populations, but also mild instances of thought slippage, since thought disorder in nonpsychotic relatives tends to be muted. Third, categories of formal thought disorder that occur infrequently in the normal population, but frequently in pathological populations, must be determined. These disorders may occur in relatives of psychotic patients. The study by Berenbaum et al

• Using the Holzman-Johnston Thought Disorder Index, thought disorder was examined in the first-degree relatives of schizophrenic, manic, and schizoaffective patients. In all three groups, there was a tendency for probands with higher thought disorder to have first-degree relatives with higher thought disorder. Furthermore, the quality of thought disorder in the groups of relatives was similar to that in the groups of probands, although it was clear that the relatives of schizoaffective-manic patients showed the highest amount of thought disorder, which was not found in the proband sample. Although based on a small sample, these findings suggest that amount and type of thought disorder differ not only among medicated patient groups but also among their unmedicated relatives.