Parental but not child reports of affective lability in offspring predict conversion to bipolar disorder in youth at increased genetic risk

BACKGROUND: The identification of clinical risk factors in individuals at genetic risk of developing bipolar disorder (BD), and who subsequently go on to develop BD, may enable targeted early intervention. Affective lability has been reported to be increased in youth at familial risk of psychiatric illness, and to predict onset of BD in prospective studies. However, parent-reported and child self-reports of affective instability may be discrepant. METHODS: We measured affective lability at baseline using both the self- and parent-reported versions of the Children's Affective Lability Scale (CALS) in a multisite (US and Australian) cohort of 315 young unaffected individuals, aged 12-21, at high familial risk of BD (HR), 165 controls, and 13 patients with established BD. New onsets of threshold and subthreshold BD were assessed prospectively. RESULTS: Parental, but not child, reports of affective lability at baseline were significantly higher in HR who later developed first onset of either threshold (N = 12) or subthreshold BD (n = 27); these differences were driven by irritability and anxiety/depression factors but not by the mania factor of the CALS. LIMITATIONS: While our study is well powered for whole group comparisons, the HR subgroup analyses (of threshold and subthreshold BD groups separately) were underpowered. CONCLUSION: Parental reports of affective lability in youth at increased familial risk to BD may assist clinicians in detecting individuals at elevated risk of converting to BD, but they do not constitute a validated clinical prediction tool.