Conversion from bipolar disorder not otherwise specified (BP-NOS) to bipolar I or II in youth with family history as a predictor of conversion.

Background: Bipolar disorder-not otherwise specified (BD-NOS) is an imprecise, heterogeneous diagnosis that is unstable in youth. This study reports rates of conversion from BD-NOS to BD-I or II in children aged 8-12, and investigates the impact of family history of bipolar disorder and depression on conversion.

Methods: As part of the Multi-Family Psychoeducational Psychotherapy (MF-PEP) study, 27 children (6-12 years of age) diagnosed with BD-NOS at baseline were reassessed every 6 months over an 18-month period. Family history of bipolar disorder and depression was assessed at baseline.

Results: One-third of the sample converted from BD-NOS to BD-I or II over 18-months. Having a first-degree relative with symptoms of bipolar disorder and having a loaded pedigree for diagnosis of depression each were associated with conversion from BD-NOS to BD-I or II (odds ratio range: 1.09-3.14; relative risk range: 1.06-2.34).

Limitations: This study had very low power (range: 10-45) given the small sample size, precluding statistical significance of non-parametric Fisher's Exact test findings.

Conclusions: This study replicates the previous finding of a high rate of conversion from BD-NOS to BD-I or II among youth, and suggests conversion is related to symptoms of bipolar disorder or depression diagnoses in the family history. Additional research is warranted in a larger sample with a longer follow-up period.