"Mixed hypomania" in children and adolescents: is it a pediatric bipolar phenotype with extreme diurnal variation between depression and hypomania?

Abstract

Background: Although DSM-IV and the literature on pediatric bipolarity recognize mania and mixed phases neither recognizes states of "mixed hypomania." There has been preliminary presentation of the latter phenomenon in the adult bipolar literature. The authors herein describe this phenomenon in a consecutive clinical series of bipolar children and adolescents.

Methods: This exploratory study involved 47 consecutive bipolar patients between the ages of 7 and 17 years presenting to an outpatient clinic. They were evaluated using a structured instrument designed to ascertain the presence of major depressive episodes (MDE), hypomania, mania, psychotic disorders, behavioral disorders such as oppositional defiant disorder and conduct disorder and substance use disorders. We defined mixed hypomania as MDE and hypomania coexisting over at least 2 weeks.

Results: Of 47 patients, 9 girls (42.9%) and 9 boys (34.6%) were bipolar II mixed. This paper focuses on them. The mean ages of the bipolar II girls and boys were 14.3 (1.9) years and 12.0 (3.4) years, respectively (p<0.05, t=2.45, df=17). This mixed subgroup tended to experience rising mood in the evening, often with spikes of euphoria; a history of late afternoon to evening increased talkativeness or pressured speech was common. Some patients exhibited flight of ideas. Psychomotor acceleration, heightened level of energy, and increased goal directed activity between 1900 and 0300 were frequently reported. Retrospectively obtained circadian information revealed, in most cases an age inappropriate phase delay of sleep onset: After falling asleep in the early hours of the morning the patients awoke feeling depressed, lethargic and as if they could sleep throughout much of the day.

Limitation: Cross-sectional, exploratory study based on a relatively small sample size and in need of replication in other clinical settings.

Conclusion: Mixed hypomania was a common phenomenon in pediatric bipolar II patients. It is apt to go unrecognized in cross-sectional assessments done in the morning or in the early or mid-afternoon. Those with this proposed phenotype would appear "depressed" at these times. Alternatively, what we have proposed can also be described as severe diurnal variation between depression and hypomania in the evening. Further study is required combining 24-hour clinical observation and state of the art technologically derived data.