Factorial structure and familial aggregation of the Hypomania Checklist-32 (HCL-32): Results of the NIMH Family Study of Affective Spectrum Disorders.

•The Hypomania Checklist-32 (HCL) identifies subthreshold symptoms of bipolar disorder (BD)•Four factors (Activity/Increased Energy, Distractibility/Irritability, Novelty Seeking/Disinhibition, Substance use) fit the HCL•The Distractibility/Irritability score was transmitted within families•The Distractibility/Irritability factor may detect propensity to BD