Heartbeats and healing

In a previous article, I described two aspects of my PhD.  1) How I came to develop a curriculum of interoceptive awareness opportunities (IAOs) during outdoor education for looked after children (Forster, Maister & Wimpory, 2023).  2) One exemplary interoceptive awareness opportunity was tested in a sports science laboratory, providing evidence to support the concept. 

Underlying theory of interoceptive interventions 

As my foray into the wealth of literature on interoception continued, the complexity of the topic became apparent – it was quite a rabbit hole! There is a spectrum of interoceptive acuity across individuals – even our biological interoceptive systems, operating below conscious awareness, vary between people. Initially, I naively assumed that people with 'good' interoception can notice how their body is feeling and can interpret that as emotion, which helps their emotional regulation and resultant capacity to control their behaviour.   

I needed to revise my terminology because "Good interoception = good mental health" isn't strictly accurate.  'Adaptive' is a more appropriate term than 'good'. It is possible for someone to be very good at feeling their body, but this is unpleasant and excessive, potentially exacerbating the somatic symptoms of mental health disorders. This sensitivity is maladaptive, so it is overly simplistic to think that guidance to notice the body could be helpful for mental health issues associated with trauma. 

Our individual interoceptive systems are now thought to relate directly to our mental health (Khalsa et al., 2018). Everybody has a unique interoceptive system that has been built through personal life experiences from birth to the present day. Interoceptive models using a 'predictive coding' framework suggest that our lifelong experience of sensory input forms an expectation over time (Seth, 2013). This is an unconscious and non-cognitive expectation, where the brain predicts how something will feel according to previous experience. 

If a person has a healthy interoceptive system, then it can adapt; these predictions can be modified and updated according to new sensory experience. Conversely, when interoceptive expectations are not amended in response to new sensory input, this becomes a dysfunctional interoceptive system (Paulus, Feinstein & Khalsa, 2019). To illustrate this with a basic example, a child living in a household where they experience recurrent physical abuse may have a well-tuned threat response, as this is helpful for survival. Their brain may learn to be hypersensitive to signals in the body it associates with imminent danger, such as an increased heartrate. However, this vigilant nervous system response is no longer helpful in later life when they are in a place of safety.  A brain that continues to overreact to visceral sensations communicated by the body, such as a raised heart rate, could perpetuate anxiety symptoms. 

Psychopathology can be modelled using predictive coding principles, to categorise how rigid the interoceptive expectations ('priors') are, as well as the propensity to adapt to new sensory input ('prediction errors'). Generally speaking, hyper-precise priors when combined with underweighted or overweighted prediction errors is often associated with dysfunctional interoception. Encouraging a more adaptive interoceptive system is theoretically possible. 

Mental health interventions designed to address maladaptive interoception aim to 'reprogramme' how the brain interprets visceral signals that were previously associated with negative experience. For example, interoceptive exposure has been utilised for anxiety (Boettcher, Brake & Barlow, 2016; Boswel, Farchione, Sauer-Zavala, Murray, Fortune & Barlow, 2013), consisting of slightly elevating the heart rate to a level that a person can notice but tolerate, until their brain habituates to that sensation. 

Over time their heart rate can be raised further as their sensitivity to anxiety symptoms reduces.  Interoceptive exposure has also been indicated as a treatment modality for trauma (Wilkinson et al., 2017) and PTSD (Krupnik, 2020; Kube et al., 2020; Lyndon & Corlett, 2020).

Interoceptive awareness opportunities

Numerous relevant professionals were consulted during the development phase and instructors received specific training on how to deliver IAOs in a trauma-informed way. There were four main aims of the interoceptive awareness opportunities: 

1) To facilitate children to observe positive or neutral bodily sensations during playful and fun activities, so their body can become a safe place. Professor Lisa Feldman Barrett's popular science metaphor of 'seeding the brain' is relevant here; the IAOs introduce novel sensory input which provides unfamiliar visceral ingredients, enabling new recipes for how to feel inside to become possible. The activities hopefully create some positive experiences, both narratively and viscerally - their brains will be able to 'cook' differently in the future!

2) Training the skill of observing the present moment can help develop dispositional mindfulness (D'Antoni, Feruglio, Matiz, Cantone & Crescentini, 2021; Gibson, 2019; Hanley, Mehling & Garland, 2017). Pure awareness of bodily sensations without judgement or attachment creates some distance between the emotion and the individual. This is a key factor practised within meditative disciplines, where the experiencer is separate from the experience. This reduces the chance of coupling their identity with an adverse mental health experience. Children could be more likely to notice their bodies and emotional responses outside of outdoor education, which could enable them to seek support or try alternative coping strategies.  

3) Numerous recommendations pertaining to predictive coding models of interoception were adhered to. For example, the IAOs enable 'behavioural experiments' (Kube et al., 2020), such as testing how far they need to hike or cycle before they can feel their heartbeat increase. Direct observation of current sensory input can help with updating 'prediction errors' rather than defaulting to 'priors' (Farb et al., 2015; Paulus et al., 2019).  

Interoceptive exposure principles could also be utilised; helping their brains to reassociate a raised heart rate with physical exertion (i.e. cycling up a hill), rather than a traumatic early memory. The IAOs were designed to align with interoceptive exposure recommendations, in accordance with predictive coding models of interoception (Boettcher et al., 2016; Farb et al., 2015; Garfinkel et al., 2016; Krupnik, 2020; Kube et al., 2020; Linson & Friston, 2019; Lyndon & Corlett, 2020; Paulus et al., 2019; Wilkinson et al., 2017).

4) To help children learn self-regulation skills that could be applied outside of outdoor education. Some IAOs encouraged children to try different breathing patterns, for instance to make cycling or hiking on steep terrain more sustainable. They also experimented with inhalation vs exhalation at the point of exertion during rhythmic activities like kayaking and pedalling a bike, or to prepare for dynamic rock-climbing moves. 

The additional mechanistic benefit of altering the breath to encourage a calming parasympathetic nervous system mode could be beneficial, as complex trauma can dysregulate the nervous system (Boullier & Blair, 2018; Corrigan, Fisher & Nutt, 2011). The respiratory IAOs enable a subtle lesson to be learned by the children – that they can have more autonomy over their moods by manipulating their physical state. 

Implications

It is a complex topic to explore and it's not appropriate to make any sweeping conclusions about how attending to the body during exercise can improve mental health outcomes in people with a history of trauma. Even if the IAO in the laboratory setting improved interoceptive accuracy compared to a control task, it doesn't necessarily mean this is beneficial for mental health, especially for people with a history of trauma. Indeed, being overly aware of the heartbeat in a distressed way can be a pathological sign of anxiety. 

As alluded to previously, interoceptive exposure attempts to lower aversive associations to the sense of the heartbeat – so good awareness of the heart is fine, as long as it isn't perpetuating distressing and habituated responses. Within this research protocol, it isn't possible to ascertain whether good awareness equated to benefits for mental health. Also, the research participants were not from a clinical cohort, so extrapolating anything to a different demographic is not feasible. 

Within the residential children's home setting, IAOs were delivered 1:1 to each child, so instructors could dynamically adjust how much physical exertion (raised heartrate) would push a child out of their emotional baseline - and avoid that! Within the laboratory setting, due to the necessity of consistent variables, all participants had to reach an equivalent light and vigorous heartrate. So, some participants might have felt dysregulated at the vigorous level and others would have been fine. 

However, this study is a useful piece of the puzzle contributing to the development of mental health interventions using interoceptive mechanisms. Commissioned from a clinical perspective, this project operated across disciplines of psychology, sports science and psychophysiology. The optimal exercise intensity regarding body-based interoceptive mental health interventions for people with a history of trauma warrants further research.  Interoceptive exposure principles within a predictive coding framework could be relevant when attempting to disentangle which individuals would benefit from greater physiological arousal from exercise. 

We're at an exciting phase in terms of the development of mental health interventions! Technology has become exponentially more sophisticated, enabling a greater understanding of how our minds work, and therefore how they can be helped. I personally feel hopeful that within the next decade, tools will become available for clinical practitioners to assess clients' unique interoceptive systems and design bespoke techniques to help them, alongside (and complementary to) existing evidence-based psychological therapies.   

About the author

Kitty Goldthorpe is currently a psychology postgraduate researcher at Bangor University, focusing on interoception and mental health.