Grade of Membership (GOM) analysis, a multivariate technique for studying disease, was used to explore depressive typology and relationships between depression and anxiety. One hundred and ninety patients with RDC diagnoses of major or minor depression were assessed by the Hamilton and SCL-90 symptom rating scales, the Newcastle diagnostic indices for endogenous depression and for anxiety and depression. Demographic, family and treatment response information were used as external validators.
Five pure types provided the most satisfactory solution to these data. One group corresponded to classical melancholia, occurring in older, stable, in-patients, who lacked panic-phobic symptoms. All patients with agoraphobia fell into two distinct in-patient and out-patient groups, which differed from each other in several ways. In one group, a link was found between panic attacks, agitated melancholia and familial pure depression. The second group was less symptomatic and had more atypical vegetative symptoms.
Two more groups comprised mildly symptomatic, hypochondriacal, depression, and a highly neurotic, obsessive, anxious, non-phobic depression, which was commonly related to a physical stressor.