Validating Kraepelin's two types of depressive mixed states: "Depression with flight of ideas" and "Excited depression"

Despite a venerable classic tradition going back to at least Kraepelin, depressive mixed states (DMX) are not represented in official diagnostic manuals in psychiatry. We have operationalised this condition as a major depressive episode (MDE) with three or more intra-episode hypomanic signs and symptoms (DMX3). Of 320 consecutive bipolar II outpatients, presenting for MDE treatment and interviewed using the Structured Clinical Interview for DSM-IV, modified to permit the systematic evaluation of hypomanic features during the index MDE, 200 met our criteria for DMX3 (62.5%). When compared with the remaining non-DMX bipolar II, they had significantly earlier age at onset, higher percentage of females, atypical features and bipolar family history. Multivariate logistic regression of intra-MDE hypomanic signs and symptoms found evidence supporting an "excited depression" subtype (defined by the core feature of psychomotor agitation, and further characterised by talkativeness, irritable mood and distractability) and a "depression with flight of ideas" subtype (defined by the core feature of racing/crowded thoughts, and further characterised by risky pleasurable impulses including, among others, those with intense sexual arousal). We thereby documented the existence of two distinct DMX subtypes which testify to the clinical acumen of Kraepelin (and his pupil Weygandt) who in 1899 described these two subforms of depressive mixed states in more severely ill hospitalised patients.