Periodic Reporting for period 1 - ILBAB (The interoceptive link between anxiety and breathing perception)
Reporting period: 2018-06-01 to 2020-05-31
Anxiety is one of the most common mental health issues, and debilitating anxiety symptoms can be present across a spectrum of diseases and disorders. Many symptoms of anxiety manifest in the body (such as a racing heart rate or shortness of breath), and an impaired ability to monitor bodily symptoms is hypothesised to exist across a range of psychiatric illnesses, and in particular within anxiety. Whilst the severity of these symptoms can vary greatly across individuals, this miscommunication between the brain and body is thought to be a key component, where bodily perceptions (termed ‘interoception’) may be under-, over- or mis-interpreted to perpetuate continued anxiety. Therefore, the main aim of this project was to measure specific body perceptions in people with differing levels of anxiety from the general population, before future work moves towards applications in disease or disorder-specific populations. This project took place within the wider framework of the Translational Neuromodeling Unit (TNU), a joint institution of the University of Zurich and ETH Zurich, where the goal is to develop and validate mathematical models that allow us to understand and treat a range of psychiatric conditions.
The body perceptions that were the focus of this project centred around breathing. Whilst altering and evaluating the internal state of our body is challenging, our breathing offers a viable pathway for accessing interoception. While anxiety is known to be related to altered perceptions of breathing, it is not yet known where in this perceptual model anxiety exerts its effect. Therefore, my research developed and utilised novel tasks that specifically measured a number of important aspects of breathing perception, including accuracy detecting small changes in breathing resistance, self-awareness and insight into interoceptive abilities, and how quickly an individual can learn about their breathing within a changing environment. Functional magnetic resonance imaging (fMRI) of the brain was also used in conjunction with a novel breathing learning task, to observe both how the brain dynamically adapts its perception of breathing and how this process may be impaired with anxiety. These rich datasets allowed us to apply state-of-the-art computational models to investigate what, where and how anxiety can interrupt the brain’s processing of internal bodily states.
In this project we found that significant disparities in breathing perceptions exist in individuals with different levels of anxiety. These disparities were apparent in subjective experiences (assessed with questionnaires), meta-cognitive evaluation (characterised with computational models of behavioural responses), and brain activity (measured with fMRI). These results now provide us with a rich characterisation and pointers towards potential mechanisms of how anxiety may change our body perceptions within a healthy population. Future projects that will directly follow on from this research will use this knowledge to investigate how these relationships may further change in individuals with clinically-significant levels of anxiety, and also how current treatments of anxiety (pharmacotherapy and exercise treatment) act on these body perceptions.
The body perceptions that were the focus of this project centred around breathing. Whilst altering and evaluating the internal state of our body is challenging, our breathing offers a viable pathway for accessing interoception. While anxiety is known to be related to altered perceptions of breathing, it is not yet known where in this perceptual model anxiety exerts its effect. Therefore, my research developed and utilised novel tasks that specifically measured a number of important aspects of breathing perception, including accuracy detecting small changes in breathing resistance, self-awareness and insight into interoceptive abilities, and how quickly an individual can learn about their breathing within a changing environment. Functional magnetic resonance imaging (fMRI) of the brain was also used in conjunction with a novel breathing learning task, to observe both how the brain dynamically adapts its perception of breathing and how this process may be impaired with anxiety. These rich datasets allowed us to apply state-of-the-art computational models to investigate what, where and how anxiety can interrupt the brain’s processing of internal bodily states.
In this project we found that significant disparities in breathing perceptions exist in individuals with different levels of anxiety. These disparities were apparent in subjective experiences (assessed with questionnaires), meta-cognitive evaluation (characterised with computational models of behavioural responses), and brain activity (measured with fMRI). These results now provide us with a rich characterisation and pointers towards potential mechanisms of how anxiety may change our body perceptions within a healthy population. Future projects that will directly follow on from this research will use this knowledge to investigate how these relationships may further change in individuals with clinically-significant levels of anxiety, and also how current treatments of anxiety (pharmacotherapy and exercise treatment) act on these body perceptions.
The work performed in this project covered the following topics:
- Project planning, ethical approval and experimental setup.
- Development and open-access publication of two novel breathing tasks to measure different aspects of breathing-related interoception.
- Recruitment and measurement of 60 individuals, 30 of whom had very low levels of anxiety and 30 with moderate levels of anxiety. These groups were matched for both age and sex, with equal numbers of men and women in each group. Each participant completed two separate experimental sessions, one of which was conducted in conjunction with a magnetic resonance imaging scan at high field strength (7 Tesla).
- Planning and implementation of a novel analysis pipeline that combined multiple computational models.
- Ongoing preparation of a third manuscript that details the main results of the study.
- Dissemination and communication via public engagement activities, teaching and supervision of students, and academic publications.
- Successful application for research funding for projects that directly follow on from this work, allowing us to extend our current findings in healthy volunteers to clinical populations and longitudinal studies to better understand interventions for the treatment of anxiety.
The preliminary results from this project have demonstrated a host of differences in breathing and body perception amongst individuals with different levels of anxiety. Notably, people who have higher levels of anxiety have reduced sensitivity to small changes in their breathing, lower confidence in their perceptual decisions, lower self-reported awareness and positivity towards body symptoms, and altered brain activity when predicting upcoming breathing symptoms when they are compared to people with low levels of anxiety. A manuscript that details these results is currently in preparation, and we plan to make the data publicly available on an open-source platform for use in further scientific projects wherever possible.
- Project planning, ethical approval and experimental setup.
- Development and open-access publication of two novel breathing tasks to measure different aspects of breathing-related interoception.
- Recruitment and measurement of 60 individuals, 30 of whom had very low levels of anxiety and 30 with moderate levels of anxiety. These groups were matched for both age and sex, with equal numbers of men and women in each group. Each participant completed two separate experimental sessions, one of which was conducted in conjunction with a magnetic resonance imaging scan at high field strength (7 Tesla).
- Planning and implementation of a novel analysis pipeline that combined multiple computational models.
- Ongoing preparation of a third manuscript that details the main results of the study.
- Dissemination and communication via public engagement activities, teaching and supervision of students, and academic publications.
- Successful application for research funding for projects that directly follow on from this work, allowing us to extend our current findings in healthy volunteers to clinical populations and longitudinal studies to better understand interventions for the treatment of anxiety.
The preliminary results from this project have demonstrated a host of differences in breathing and body perception amongst individuals with different levels of anxiety. Notably, people who have higher levels of anxiety have reduced sensitivity to small changes in their breathing, lower confidence in their perceptual decisions, lower self-reported awareness and positivity towards body symptoms, and altered brain activity when predicting upcoming breathing symptoms when they are compared to people with low levels of anxiety. A manuscript that details these results is currently in preparation, and we plan to make the data publicly available on an open-source platform for use in further scientific projects wherever possible.
To conduct progressive and mechanistic research within the field of breathing-related interoception, in this project we developed and published the methodology for two unique breathing tasks. Firstly, we developed a breathing circuitry that allowed the remote administration of inspiratory resistances within a magnetic resonance imaging environment. The details of this methodology have been made widely available through an open-access publication (https://doi.org/10.3389/fnhum.2020.00161(opens in new window)). Secondly, we developed an algorithm to increase the amount of viable data collected in a breathing perception task, and paired this with an extension of an existing computational model. We have made the code for this task publicly available on an open access repository (https://github.com/ofaull/FDT(opens in new window)) and it will soon also be released as part of the TNU’s software package (TAPAS https://github.com/translationalneuromodeling/tapas(opens in new window)). A manuscript that details the task and analysis methods is currently available as a preprint (https://www.biorxiv.org/content/10.1101/2020.06.29.176941v1(opens in new window)) and is under review at the journal ‘Neuroscience of Consciousness’. Therefore, this project has contributed two novel tasks to the field of interoception research, and these tasks have been taken up by multiple independent groups for use in seven different research projects beyond ILBAB thus far.
Beyond the provision of novel methodology, the results of this project are the first to demonstrate both the dynamic brain activity associated with interoceptive-related predictions and errors, as well as the effect of anxiety on each of the interoceptive measures employed. The results of this project therefore provide an important step forward towards understanding both interoceptive processing and its relationship to psychiatric conditions such as anxiety. Furthermore, the implications of these results will extend beyond our scientific understanding by improving our medical knowledge of these alterations in body perceptions for both patients and physicians, considering the contribution of altered symptom perception towards mental health.
Beyond the provision of novel methodology, the results of this project are the first to demonstrate both the dynamic brain activity associated with interoceptive-related predictions and errors, as well as the effect of anxiety on each of the interoceptive measures employed. The results of this project therefore provide an important step forward towards understanding both interoceptive processing and its relationship to psychiatric conditions such as anxiety. Furthermore, the implications of these results will extend beyond our scientific understanding by improving our medical knowledge of these alterations in body perceptions for both patients and physicians, considering the contribution of altered symptom perception towards mental health.