Symptoms and behaviors prior to the first major affective episode of bipolar II disorder. An exploratory study.

Background: Few studies have investigated the initial prodrome of bipolar disorders, and none has explicitly addressed bipolar II disorder (BD-II). We explored symptoms and behaviors preceding the first major affective episode (FMAE) of BD-II to generate hypotheses concerning possible clinical targets for early intervention.

Methods: In-depth interviews of 15 BD-II patients and 22 family informants were carried out. Clinical diagnoses were reassessed. The textual data of transcribed interviews were analyzed utilizing qualitative methodology supplemented by quantitative analyses.

Results: All patients experienced clinically significant symptoms and behaviors at an average of more than a decade before the FMAE. Anxiety and depression-type symptoms were the most common. Two distinct subgroups were identified based on prominent and enduring personal characteristics prior to the FMAE. The individuals in one of the subgroups were described as very well-functioning, whereas the individuals in the other subgroup were characterized by neurocognitive deficits, relatively low academic and social functioning, and pronounced irritability and aggressiveness. Furthermore, it is possible that these individuals experience earlier prodromal symptom onset, earlier FMAEs, and more symptoms than individuals without these characteristics.

Limitations: This is a retrospective and hypothesis-generating qualitative study. The hypotheses generated need to be tested in future studies.

Conclusions: Prodromal clinical phenomenology is too nonspecific to predict the occurrence of the FMAE of BD-II. However, identifiable subgroups may exist. We hypothesize that neurocognitive deficits together with pronounced irritability and aggressiveness may constitute a vulnerability marker for a subgroup of individuals who subsequently develop BD-II. This subgroup may be of potential interest for early identification.