Stability of the diagnosis of primary affective disorder. A four-year follow-up study.

Most modern studies on depression use standardized diagnostic approaches, such as the St. Louis Criteria or the RDC. The main aim of these methods is to select reliable samples for research purposes. However, doubts have been raised as to whether the groups derived through these criteria are homogeneous. In order to investigate the stability of the diagnosis of Primary Affective Disorder (PAD), a group of 78 patients meeting the criteria for this disorder were followed for 4 years. During this period 19.2% of patients showed important psychopathological symptoms other than affective. No particular factor, apart from bipolar illness, was found to be significantly predictive of a stable diagnosis. However, the rate of diagnoses would have been greater by taking into account family history and premorbid personality of the patients. The authors conclude that other sources of information, beyond present symptoms, ought to be taken into account in order to reach more homogeneous groupings.