State of the Science: Intolerance of Uncertainty.

Over 30 years ago, a group of researchers at Laval University, Canada, conceptualized the construct of intolerance of uncertainty (IU) and proposed a self-report measure of IU, the Intolerance of Uncertainty Scale (IUS; Freeston et al., 1994). At the time, we were interested in identifying a cognitive vulnerability factor for the development and maintenance of worry and GAD. Initial nonclinical and clinical research by the Laval group suggested that IU, as measured by the IUS, was a sensitive and relatively specific marker of worry and GAD. Subsequent studies by countless other research groups indicate that although IU does show some evidence of specificity to worry and GAD, it is also a transdiagnostic and trans-situational construct. In the current State of the Science paper, we review the research on IU, with a focus on (1) initial studies on the specificity of IU to worry and GAD, (2) the construct and measurement of IU, (3) the transdiagnostic and trans-situational nature of IU, (4) cultural and related considerations, (5) IU and cognitive processing, (6) the neural and psychophysiological correlates of IU, (7) treatment and IU, and (8) future directions. Overall, it can be concluded that the construct of intolerance of uncertainty, despite the fact that its definition and measurement remain actively debated, has established itself as a central construct in the field of mental health and psychopathology. Indeed, research on IU over the past three decades has led to significant improvements in both theory and clinical practice, and to a better understanding of what people think, feel, and do when experiencing uncertainty.