The investigators defined subthreshold bipolar disorder as recurrent hypomania (mild hypomania) without a major depressive episode or with fewer symptoms than required for threshold hypomania.

研究者把轻度躁狂复发而没有严重的抑郁发作或者比轻度躁狂阈值要小得多的症状类型定义为亚型双向精神障碍。