The investor sends a shorter reply than usual. The quarterly numbers come in below forecast. A key team member asks for a meeting with no context given. In each case, the information available is partial and ambiguous. The catastrophising mind does not sit with the ambiguity. It completes the partial signal toward the worst available outcome — the investor is pulling out, the business is failing, the team member is resigning — and generates the emotional and physiological response appropriate to that outcome, before any evidence for it exists.

This is catastrophising: the systematic overestimation of the severity of potential negative outcomes under uncertainty. Michael Sullivan and colleagues’ formal definition established the precision that matters most for understanding the mechanism. The problem is not that catastrophisers overestimate how often bad things happen. They often have reasonably calibrated probability estimates. The problem is the severity estimate: the belief that if the feared outcome materialises, it will be as bad as the worst-case version of it, and that it will be unmanageable when it arrives. The catastrophic interpretation is not about frequency. It is about magnitude.

The amygdala’s pattern-completion function

Joseph LeDoux’s research on the amygdala’s role in threat processing provides the most mechanically precise account of why catastrophising defaults arise under uncertainty specifically. The amygdala operates as a pattern-completion system: it processes partial threat signals against stored templates from prior threatening experiences and fills in the missing information with whatever prior pattern the partial signal most closely resembles. The function is adaptive in environments where partial signals often precede complete threats and where rapid response is more valuable than accurate assessment.

Under conditions of uncertainty, the pattern-completion function generates worst-case completions because they maximise protective readiness. The ambiguous signal from the investor’s short reply activates the threat template; the template is completed toward the most available negative outcome; the completed pattern is what reaches conscious processing. By the time deliberate thought engages with the situation, the catastrophic interpretation is already present and already generating the physiological and emotional response associated with it.

This is not a failure of rational processing. The pattern-completion mechanism is performing the function it was built for, in circumstances it was not built for.

The somatic confirmation loop

The most self-sustaining feature of catastrophising is the mechanism that maintains it after the initial worst-case completion has been generated. The catastrophic thought produces the physiological activation — cortisol release, increased heart rate, the felt urgency of threat — that a genuinely threatening situation would produce. The catastrophising mind then interprets this physiological response as evidence that the threat is real: the body is responding as if something is wrong, which feels like confirmation that something is wrong.

The loop is self-confirming. The catastrophic interpretation generates the somatic response; the somatic response is read as evidence for the catastrophic interpretation; the confirmed interpretation intensifies the somatic response. The person at three in the morning whose catastrophic thought woke them finds that the physiological state of wakefulness and arousal makes the catastrophic interpretation feel more certain and more urgent than it would in a rested, calm state — because the activated physiology is being interpreted as evidence rather than recognised as a consequence.

Uncertainty intolerance as the underlying driver

Michel Dugas and colleagues’ research on intolerance of uncertainty established that the primary driver of catastrophising is not the objective level of threat but the person’s capacity to sit with not knowing. The catastrophising sequence is in large part the mind’s attempt to resolve the discomfort of uncertainty by generating certainty — even negative certainty — in its place. A defined worst-case outcome, however terrible, is cognitively preferable to the suspended state of not knowing what will happen.

The entrepreneurial environment is structurally high in uncertainty across all its primary domains: revenue, product-market fit, team stability, funding, competition. For the person with high uncertainty intolerance, this chronic environmental uncertainty chronically activates the catastrophising function, independently of the objective threat level at any given moment. The catastrophising is not a response to things being bad. It is a response to things being unknown.

What interrupts it

Aaron Beck’s decatastrophising technique targets the severity overestimation directly rather than the probability estimate. The operative question is not “how likely is this?” but “if this did happen, would it actually be as bad as I believe, and could I manage it?” The second question is the one that reaches the unmanageability belief that sustains the catastrophic severity estimate. Catastrophic outcomes are typically experienced as both maximally bad and maximally unmanageable; the evidence that previous bad outcomes were managed, and that this one would be too, is what the severity calibration requires.

The combination of catastrophising and rumination that Susan Nolen-Hoeksema’s research predicts — the worst-case content generated by catastrophising, then processed repetitively through the ruminative cycle — is the most cognitively impairing configuration because the severity overestimation is not merely generated but elaborated and revisited. Interrupting the combination requires addressing both components: the mode of processing as well as the content it is operating on.

The catastrophising mind will not be argued out of its worst-case interpretation through probability estimates alone. The severity estimate and the unmanageability belief are the actual cognitive targets. Reaching them requires specific questions rather than general reassurance, and the questions need to be applied to the specific feared outcome rather than to the anxiety as a general state.

If the dynamics described here are significantly affecting your wellbeing, speaking with a psychologist is the right next step. UK: Samaritans (116 123, free, 24/7). Mind (0300 123 3393). BACP: bacp.co.uk/search/Therapists. Crisis Text Line — text HOME to 741741 (US, UK, Canada, Ireland). International: internationaltherapistdirectory.com.

This article is for educational and informational purposes only. Sources: Sullivan, M.J.L., Bishop, S.R. & Pivik, J. (1995), The Pain Catastrophizing Scale: Development and Validation, Psychological Assessment, 7(4), 524-532. LeDoux, J.E. (1996), The Emotional Brain, Simon & Schuster. Porges, S.W. (2011), The Polyvagal Theory, W.W. Norton. Arnsten, A.F.T. (1998), The Biology of Being Frazzled, Science, 280(5370), 1711-1712. Nolen-Hoeksema, S., Wisco, B.E. & Lyubomirsky, S. (2008), Rethinking Rumination, Perspectives on Psychological Science, 3(5), 400-424. Dugas, M.J., Buhr, K. & Ladouceur, R. (2004), The Role of Intolerance of Uncertainty in Etiology and Maintenance, in Generalized Anxiety Disorder, Guilford Press. Beck, A.T. (1979), Cognitive Therapy of Depression, Guilford Press. LeDoux, J. (2015), Anxious, Viking. Robson, D. (2022), The Expectation Effect, Canongate.