In this chapter we continue with the issue of symptom-formation factors and particularly their relation to the class,ic distinction between psychotic and neurotic depression. In collecting material for this chapter we used a traditional psychiatric diagnosis of psychotic and neurotic depression, relying on the clinical judgment of a psychiatric colleague at the Institute of Psychiatry who took into account criteria such as the presence of early morning waking and retardation, which are fairly generally accepted as distinguishing features of the two forms of depression. Since 'psychotic' and 'neurotic' symptoms can occur in both types of depression, a judgment has to be made on the basis of the total clinical picture rather than the presence of particular symptoms. For example, just over half the patients considered psychotic and just over a fifth of the neurotic patients had early morning waking. Using such an overall judgment, sixty-three patients were classified as psychotic and forty-nine as neurotic. (Two with some manic symptoms were excluded from this part of the analysis.)
The psychotic-neurotic distinction was only modestly associated with our measure of overall severity.! It was therefore necessary to explain both features of clinical depression. We should, however, remind the reader that this refers only to severity as defined by our measure, in the choice of which we had had to face certain complex issues already discussed in the last chapter. As the analysis proceeded, in fact, we began to feel that, had we concentrated more on the severity of the patient's hopeless resignation rather than on the intensity and number of the total symptoms, a different picture would have emerged: that there would have been a substantial association between such severity and a psychotic type of depression and that to a large extent this was what underlay the traditional distinction between the two forms of depression. 2
The two-fold diagnostic division was subjected to a number of statistical analyses. One of the most important was a discriminant function analysis. This took account of all the clinical material but excluded consideration of factors such as age, provoking agents, or previous episodes in order to avoid the kind of circularity of argument we earlier outlined in the discussion of unit and quality. We used only clinical material collected about the current episode. The discriminant function analysis derived weights for each symptom according to its association with the psychotic and neurotic groups, those items which were the most important in the distinction having the highest loadings, either positively if they were associated with the psychotic group, or negatively if they were associated with the neurotic group. An overall score was obtained for each woman by adding the weights of her symptoms. Various scores can be allotted in this way according to the level of significance at which one is prepared to accept the initial association of the symptoms with the diagnostic distinction and thus the number of items summated for the score. We elected to use scores based on the seventeen clinical items that differed between the two groups at the 20 per cent level of significance. On the basis of the distribution of the patients' scores using these seventeen items a particular score was chosen to represent the best cut-off point between psychotic and neurotic patients. This gave an overall misclassification rate of 23 per cent; that is, the original psychotic and neurotic groups could be successfully reconstructed on the basis of these scores with only a little more than a fifth of the patients being wrongly allocated. The items and their weights are much what would be expected from the literature. In general, the psychotic patients tend to be more retarded in movement, thought, and emotion and the neurotic group to be more active and to show more emotion.