Children Facing the Unknown: An Italian Study Using the Intolerance of Uncertainty Scale – Parent (IUS-P)

Research on Intolerance of Uncertainty (IU) has predominantly focused on adulthood, with limited attention to children. However, examining IU during childhood is clinically important, as it can shed light on the development of early-emerging psychopathologies. Valid and reliable tools assessing IU in children are therefore essential. This study aimed to investigate the factor structure and psychometric properties of the Intolerance of Uncertainty Scale-Parent (IUS-P), a questionnaire for parents to evaluate IU in their children. 796 Italian parents (88.4% mothers) of children aged 4–10 years (51.3% boys) were involved. Other-report tools assessing IU, psychopathological features, and executive functioning impairments (i.e., cognitive inflexibility, impulsivity, difficulties in planning/organization, and emotion dysregulation) were administered. To investigate the IUS-P factor structure, we compared a one-factor model, a two-factor model, and a bifactor model. Measurement invariance across sex and age groups (i.e., 4–6 vs. 7–8 vs. 9–10 years), reliability, and construct validity were evaluated. The bifactor model outperformed competing factor models. Bifactor model indices suggested using a total score instead of separate subscale scores. Measurement invariance by sex and age groups was fully supported. Additionally, the IUS-P total score exhibited excellent one-month test-retest reliability. The total score also showed positive associations with psychopathological features and executive functioning impairments. These findings highlight the IUS-P as a reliable tool to evaluate IU in Italian children. The relations of IU with psychopathological dimensions and difficulties in executive functioning underscore the transdiagnostic nature of IU during childhood. The practical implications of these results are discussed.