RESUMEN
Shared vulnerability in offspring of individuals with schizophrenia (SzO) and bipolar disorder (BpO) might manifest early during development through common temperament traits. Temperament dimensions in child and adolescent BpO (N = 80), SzO (N = 34) and the offspring of community controls (CcO) (N = 101) were assessed using the Revised Dimensions of Temperament Survey. The association between temperament dimensions and lifetime psychopathology (including threshold and subthreshold DSM-IV-TR diagnoses) and current socio-academic adjustment was assessed using logistic regression. Fully adjusted models showed that both BpO and SzO scored significantly lower in the positive mood dimension and in the adaptability factor than CcO, with small-medium effect sizes (Cohen's d ~ 0.3-0.5). BpO also scored lower in the activity factor and the activity dimensions than CcO (Cohen's d ~ 0.3). Lower scores in the positive mood dimension were associated with increased risk of impaired adjustment both in BpO [OR 2.30, 95% CI (1.18-4.46)] and in SzO [OR 2.87, 95% CI (1.07-7.66)]. In BpO, lower scores in positive mood were also associated with increased likelihood of internalizing [OR 1.84, 95% CI (1.28-2.64)] and externalizing disorders [OR 1.48, 95% CI (1.01-2.18)]; in SzO, higher scores in activity and flexibility were associated with increased likelihood of internalizing [OR 2.31, 95% CI (1.22-4.38)] and externalizing disorders [OR 3.28, 95% CI (1.2-9)], respectively. Early difficulties in emotion regulation might represent a shared vulnerability phenotype in BpO and SzO. The identification of extreme temperament traits could help to characterize subgroups at greater risk of psychopathology and impaired adjustment, in which targeted interventions are warranted.