The nature of bipolar depression: implications for the definition of melancholia

To examine if melancholic depression is over-represented in those with 'bipolar depression' and, if confirmed, to use that phenomenon to assist the clinical definition of melancholia.

We contrast 83 bipolar and 904 unipolar depressed patients on three melancholic sub-typing systems (DSM, Clinical and CORE system) and compare representation of their clinical depressive features.

By all three melancholic sub-typing systems, the bipolar patients were more likely to receive diagnoses of 'melancholia' and of psychotic depression. To the extent that this differential prevalence of depressive sub-types was reflected in varying patterns of clinical features, we so indirectly identified a set of items defining 'melancholia'. By such a strategy, melancholia was most clearly distinguished by behaviourally-rated psychomotor disturbance. While a number of 'endogeneity symptoms' were significantly over-represented, logistic regression analyses refined the set to psychomotor disturbance (both as a symptom and as a sign) and pathological guilt. We also established a distinctly higher prevalence of bipolar depression in those where a refined diagnosis of melancholia was made.

Bipolar depression appears to be more likely to be 'melancholic' in type, thus providing an indirect strategy for the clinical definition of melancholia.