In a prior study, we identified factors of psychopathology in the interview, ward behavior and self-report ratings of 124 depressed patients from 9 hospitals. The present study attempts to replicate these findings in a sample of 648 depressed patients from 10 hospitals. The criteria for patient selection and the factor analytic methods employed were identical in both studies. The major factors of psychopathology identified in the first study were replicated in the second study. Further, the loadings of the key items on these factors were highly similar in both studies. However, the factors in the second study encompassed a narrower range of psychopathology than those in the first. As a consequence, more factors were extracted for the same evaluation instruments in the second study.
The 12 major categories of psychopathology discernible from these analyses were: 1) depressive mood, 2) feelings of guilt and worthlessness, 3) hostility, 4) anxiety-tension, 5) cognitive loss and subjective uncertainty, 6) interest and involvement in activities, 7) somatic complaints, 8) sleep disturbance, 9) retardation in speech and behavior, 10) bizarre thoughts and behavior, 11) excitement and 12) denial of illness.
The break-up of some of the larger, global factors from the first study into smaller and more narrowly defined factors in the second study was a distinct asset in later efforts to discern the differential effects of various antidepressant drugs. The results from both studies also highlighted the advantages of using different rating instruments and sources of information about the patient. First, within a particular category of psycho-pathology, such as hostility, nuances of behavior across rating instruments would have been missed had we sampled only one aspect of patient behavior. Second, some categories of psychopathology, such as depressed mood, emerged as strong factors on certain rating instruments and were either poorly represented or absent on others.