Thoughts on the Defense Cascade, Freezing and Arousal

Defense Cascade

Kozlowska et al 2015 have written a very impressive review of trauma physiology. This post covers my attempt to make sense of the way they describe responses to threat; ‘the defense cascade’.

The defense cascade is described as a sequence, that feels a little rigid. The authors acknowledge that prior learning means that threat can trigger any one of a number of responses. The venn diagram attempts to show the defense cascade in a non hierarchical way.

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Freeze is defined by Kozlowska et al in a very particular way as ‘flight-or-fight on hold’ or ‘attentive immobility’ or ‘despite being immobilised, the rat remains alert’. They reserve the term ‘tonic immobility’ for last ditch, passive responses to threat. In the past I have often described immobility as dissociation, and, confusingly, freeze (freeze as tonic immobility is fairly common see Levine, van der Kolk and Porges).

The images below on ‘Threat Causes Arousal’ show different types of response that I put under the umbrella term Orientation. I do not feel that ‘freeze’, ‘social engagement’ or ‘tend and befriend’ completely describe the range of responses that are possible as we become aroused. Orientation covers the responses before we go into mobilisation – a full sympathetic response of fight-or-flight.

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Polyvagal Theory

Kozlowska et al 2015 utilise polyvagal theory in their descriptions of the defense cascade, though for me they underplay the importance of social engagement. The images below on polyvagal theory are still my preferred simple overview of the human responses to threat. Some direct Porges quotes are below:

‘Sequence of response strategies: (1) removal of VVC (ventral vagal complex) then, (2) increase in sympathetic tone, and (3) a surge in DVC (dorsal vagal complex DMN) tone.’ Porges (2011 p165).

‘In contrast, defensive behaviors could be categorized into two domains: one related to mobilization including fight and flight behaviors and the other related to immobilization and death feigning that might be associated with dissociative psychological states. Within this dichotomy of defensive strategies, freezing behavior that requires increased muscle tension in the absence of movement, such as stalking or vigilance behaviors, is categorized within mobilization. In contrast, immobilization is associated with a decrease in muscle tension and often with fainting and other features of decreased metabolic activity.’ Porges (2011 p267).

‘When the environment is appraised as being safe, the defensive limbic structures are inhibited enabling social engagement and calm visceral states to emerge. In contrast, some individuals experience a mismatch and the nervous system appraises the environment as being dangerous, even when it is safe. This mismatch results in physiological states that support fight, flight, or freeze behaviors, but not social engagement behaviours.’ Porges (2011 p273).

Bold added, in the second quote from Porges the text supports the ‘freeze’ concept of Kozlowska et al. However in the third quote he also uses ‘freeze’ as something different from social engagement.

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You can download as slide show here: Defense Cascade Steve Haines 2015-11

Kozlowska K, Walker P, McLean L, and Carrive P (2015) Fear and the Defense Cascade: Clinical Implications and Management. Harv Rev Psychiatry. 2015 Jul; 23(4): 263–287.

Porges, S. (2011) The Polyvagal Theory: Neurophysiological Foundations of Emotions, Attachment, Communication, and Self-Regulation. New York: Norton

Taylor SE, Klein LC, Lewis BP, Gruenewald TL, Gurung RA, Updegraff JA (2000) Biobehavioral responses to stress in females: tend-and-befriend, not fight-or-flight. Psychol Rev. 2000 Jul;107(3):411-29.

Want more?

Check for a video with great examples of tonic immobility, freeze and mobilisation in a mouse surviving a cat attack.

Even More?

Buy ‘Trauma Is Really Strange’, a non-scary comic book about trauma by Steve Haines, art by Sophie Standing:


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