Parsing cyclothymic disorder and other specified bipolar spectrum disorders in youth

Most studies of pediatric bipolar disorder (BP) combine youth who have manic symptoms, but do not meet criteria for BP I/II, into one "not otherwise specified" (NOS) group. Consequently, little is known about how youth with cyclothymic disorder (CycD) differ from youth with BP NOS. The objective of this study was to determine whether youth with a research diagnosis of CycD (RDCyc) differ from youth with operationalized BP NOS.

Participants from the Course and Outcome of Bipolar Youth study were evaluated to determine whether they met RDCyc criteria. Characteristics of RDCyc youth and BP NOS youth were compared at baseline, and over eight-years follow-up.

Of 154 youth (average age 11.96 (3.3), 42% female), 29 met RDCyc criteria. RDCyc youth were younger (p = .04) at baseline. Over follow-up, RDCyc youth were more likely to have a disruptive behavior disorder (p = .01), and were more likely to experience irritability (p = .03), mood reactivity (p = .02), and rejection sensitivity (p = .03). BP NOS youth were more likely to develop hypomania (p = .02), or depression (p = .02), and tended to have mood episodes earlier in the eight-year follow-up period.

RDCyc diagnoses were made retrospectively and followed stringent criteria, which may highlight differences that, under typical clinical conditions and more vague criteria, would not be evident.

There were few differences between RDCyc and BP NOS youth. However, the ways in which the groups diverged could have implications; chronic subsyndromal mood symptoms may portend a severe, but ultimately non-bipolar, course. Longer follow-up is necessary to determine the trajectory and outcomes of CycD symptoms.