Results
Product moment correlations between these scales derived in this study are shown in Table 4. The correlations between the scales measuring anxiety and depression are still much too high. They are almost of a magnitude of those supposedly measuring depression alone. The BDI/ZDS correlations with the Hamilton are not as good as one would like. In Table 5 one can see that the correlations of the SCL-90-R in depression and anxiety are very high on all the scales. The dimensions of anxiety and depression in the SCL-90-R are not there-fore reflecting adequately different syndromes. It was found for these established scales that there were striking similarities in the mean scores, ranges, profile of item scores, and factorial structures between
this stydy and other published studies (10). This suggests that earlier studies may be kess homogeneous than the authors understood them to be. The present stud) contains patients who would be designated as suffering from both depressior and anxiety. The correlations shown here between the various scales still pose the questior as how to assess relative validity. Fortunately a review of earlier affective studies in the literature using Principal Component Analysis suggests a uniformity in interpretation. When a geometric rather than an algebraic framework is imposed, two clusters of features can be identified. When loadings on the first two components are examined, two separate clusters of clinical features can be easily dentified, one being clinical anxiety and the other clinical depression (9). These two clusters occur in all relevant studies, irrespective of the subtype designation of the affective group under scrutiny. They occur in (a) consecutive inpatient, outpatient, and day patient depressives; (b) general practice and research group depressives; and (c) anxious neurotic outpatients and even some normal population. Further, the clusters are not simply the artifact of any particular rating system as they occur where the domains sampled have varied and also occur in both self-rated and observer-rated studies. The most novel and salient finding here is that two clusters do not represent neurotic (reactive) and psychotic (endogenous) depression. This mislabeling has greatly complicated interpretation of much of the general affective literature. The two clusters are unequivocally those of anxiety and depression. Appending these new labels induces a radical revision in interpretations placed on clinical psychometric, physiological, sociological, and classificatory studies in depression particularly, but also in anxiety.