Cognitive-Behavioural Model of Intolerance of Uncertainty and GAD
Hébert & Dugas (2019) · Generalised anxiety disorder
Written by Tarun Vermani, Trainee Clinical Psychologist Last reviewed
The intolerance-of-uncertainty model of generalised anxiety disorder, set out by Dugas and colleagues (1998) and developed by Hébert and Dugas (2019), explains how difficulty bearing not-knowing drives worry, anxiety and safety behaviours.
Cognitive-Behavioural Model of Intolerance of Uncertainty and GAD
Hébert & Dugas (2019)
Trigger
A situation involving novelty, ambiguity or unpredictability — anything where the outcome is not yet known.
Uncertainty
Uncertainty: not knowing how things will turn out. People who are intolerant of uncertainty notice and react to it more readily than others.
Catastrophic Misinterpretation of Uncertainty
Catastrophic beliefs about uncertainty — e.g. 'Uncertainty is unbearable and unfair', 'If I'm unsure, I shouldn't act', 'Not knowing means something bad will happen'. Intolerance of uncertainty runs in the background and colours the whole cycle.
Worry
Worry: repeated 'What if...?' chains, trying to think the uncertainty away. Worry itself generates further possibilities — and so more uncertainty.
Anxiety
Anxiety: apprehension and physical arousal — restlessness, muscle tension, irritability, poor concentration and disturbed sleep.
Safety Behaviours
Safety behaviours: reassurance-seeking, over-preparation, checking, list-making, doing things oneself, or avoiding uncertain situations. They lower anxiety briefly but prevent the person from learning that uncertainty can be tolerated.
The published model, shown for reference. Switch to “Blank” to see the empty template you complete with a client.
Understanding the model
Some people find not knowing how things will turn out especially hard to bear. This model describes a pattern that can keep generalised anxiety going.
It begins with a situation that is new, ambiguous, or unpredictable — anything where the outcome is not yet certain. For someone who finds uncertainty very uncomfortable, that not-knowing gets read as a sign that something bad is likely, or as simply unbearable or unfair.
That reading sparks worry — long chains of 'What if...?' — as the mind tries to think its way to certainty. Worry brings anxiety: feeling on edge, restless, tense, and finding it hard to switch off. To feel safer, people often seek reassurance, over-prepare, double-check, or avoid uncertain situations altogether.
These responses ease the discomfort for a moment, but they get in the way of discovering that uncertainty can be lived with. So the pattern repeats — and worrying, by throwing up ever more possibilities, can actually add to the very sense of uncertainty it was meant to settle.
Questions therapists ask about this model.
Frequently asked questions
What maintains generalised anxiety in this model?
A situation whose outcome is not yet known is read as threatening, or simply as unbearable, because the not-knowing itself is hard to tolerate. Worry follows as an attempt to think a way through to certainty, bringing anxiety and arousal with it. Reassurance-seeking, over-preparation, double-checking and avoidance then settle the discomfort briefly while leaving the belief about uncertainty untested — and worry, by throwing up further possibilities, adds to the uncertainty it was meant to resolve.
How does it differ from the metacognitive model of GAD?
Both models agree that the content of a particular worry is not what keeps the problem going, and differ on where the engine sits. This one puts it in beliefs about uncertainty itself — that not knowing is intolerable, unfair, or a sign something bad will happen. Wells (1995) locates it in beliefs about worry: that worrying helps, and that it is uncontrollable or harmful. Both are formulated for generalised anxiety disorder, which NICE CG113 covers.
Is intolerance of uncertainty specific to generalised anxiety?
The construct was developed to explain worry: Freeston and colleagues (1994) introduced it in asking why people worry, and Dugas and colleagues (1998) built it into this model of generalised anxiety disorder. Carleton (2016) later reviewed a wider set of models in which uncertainty plays a part, and intolerance of uncertainty is now also studied across other anxiety-related presentations. The cycle drawn here, though, is the generalised anxiety version.
Worksheets and reading for this model
Using this model in session — for therapists
How to introduce the model, guided-discovery questions, treatment targets and a behavioural experiment are available to signed-in therapists.
References
- Dugas, M. J., Gagnon, F., Ladouceur, R., & Freeston, M. H. (1998). Generalized anxiety disorder: A preliminary test of a conceptual model. Behaviour Research and Therapy, 36(2), 215–226.
- Hébert, E. A., & Dugas, M. J. (2019). Behavioral experiments for intolerance of uncertainty: Challenging the unknown in the treatment of generalized anxiety disorder. Cognitive and Behavioral Practice, 26(2), 421–436.
- Freeston, M. H., Rhéaume, J., Letarte, H., Dugas, M. J., & Ladouceur, R. (1994). Why do people worry?. Personality and Individual Differences, 17(6), 791–802.
- Carleton, R. N. (2016). Into the unknown: A review and synthesis of contemporary models involving uncertainty. Journal of Anxiety Disorders, 39, 30–43.
This diagram is a reconstruction of the published model for clinical and educational use, grounded in the sources above.
Cite this page (APA 7)
Vermani, T. (2026). Cognitive-Behavioural Model of Intolerance of Uncertainty and GAD. Formulate. https://formulatetools.co.uk/tools/formulation/gad-intolerance-of-uncertainty
For use alongside professional support
Formulate provides educational CBT resources for use with a qualified therapist. They are not a substitute for professional assessment, diagnosis, or crisis care.
If you need urgent help now:
- Emergency services: 999 — if you or someone else is in immediate danger
- Samaritans: 116 123 — free, day or night, 365 days a year
- SANEline: 0800 689 5555 — 4:30pm–10:30pm, every day
Build this formulation with your client
Create a free account to open the interactive formulation builder, complete this model collaboratively, and export it as a PDF or share it with your client.