4. Anorexia Nervosa

What are the main symptoms associated with Anorexia Nervosa?

• low body weight

• restriction

What are the main symptoms associated with Bulimia Nervosa?

• binge episodes

• compensatory action: purging or restriction

What are the main symptoms associated with binge eating disorder?

• binge episodes

• no compensatory actions

What are the 3 key links between interoceptive bodily signals and eating disorders?

• intuitive link through the gastrointestinal system

• failure to detect hunger leading to restriction

• failure to detect fullness leading to binge eating

What are the key links between interoception, emotions and eating disorders?

• patients confuse body sensations with emotions

• find it difficult differentiating between emotions and emotional regulation

• Axlexithymia is quite prevalent with EDs, particularly Anorexia: not being able to match up body feelings and emotions.

What are three 3 behavioural patterns in Anorexia Nervosa?

• extreme overvaluation of shape and weight

• disturbed eating, resulting in clinically significant impairments in health and psychosocial function due to self-starvation

• resistance to treatment, poor prognosis, high mortality

What are the DSM criteria for Anorexia Nervosa?

• restriction of energy intake to be less than what the body needs - leading to significantly low body weight

• intense fear of gaining weight

• disturbance in the way in which one’s body weight or shape is experienced; inaccurate estimation of their own body size

• reduced capacity to soothe oneself or empathise with others

• emotionally inhibited (flattening of affect)

• depression, negative self evaluation

• alexithymia - inability to describe or recognise emotions

What does the Interoceptive Deficits subscale aim to identify with in the eating disorder inventory questionnaire?

• a lack of confidence in recognising and accurately identifying emotions and sensations of hunger or satiety

• confusion and mistrust related to affective and bodily functioning are characteristic of eating disorders

What does the research as a whole suggest about the different types of interoceptions and their role in Anorexia?

• research does not dissociate between different types of interoception that may be impacted

• interoceptive sensibility and interoceptive accuracy were not correlated in patients with AN

• but instead → dysfunctional thoughts and feelings impacting the interpretation of visceral signals

What did Jenkinson et al’s meta analysis across all EDs, using EDI interoceptive scale find regarding AN patients?

• significantly lower scores

• systematic overall effect → AN patients significantly different score lower on interoceptive scales compared to people who don’t have a diagnosis

What did Jenkinson et al’s meta analysis across all EDs, using EDI interoceptive scale find regarding patients with EDs other than AN?

• Bulimia Nervosa had equivalent effects to AN

• Binge earing disorder had a smaller effect size, but still significant and present

• lower interoception in those with higher alexithymia

What might be the conclusions of Jenkinson et al’s meta analysis across all EDs, using EDI interoceptive scale?

• interoceptive sensibility may be a transdiagnostic characteristic of EDs

• it varies across diagnosis

• may be a heritable risk factor and/or important for maintenance and development

• interoceptive sensibility could be a target for therapeutic intervention

What did Pollatos et al (2008) find conducting an interoceptive accuracy task with AN patients?

• heartbeat perception task was performed using four intervals of 25s, 35s, 45s and 100s

• during all trials, ppts were asked to silently count their own heartbeats

• patients with AN exhibit a generally reduced capacity to accurately perceive bodily signals

• have less intense emotional experiences in many everyday situations

• therefore indicating the potential importance of interoception in the pathogenesis of AN

In contrast to the findings of Pollatos et al what do eshkevari and Kinnaird show regarding interoceptive accuracy in AN patients?

• findings are mixed using interoceptive accuracy task

• Eshkevari et al (2014) → no difference between ED and controls (both at chance)

• Kinnaird et al (2020) → no difference between AN and HC in accuracy but confidence was different (interoceptive awareness)

What did Lernia et al (2018) find in a case study of AN vs Healthy controls using:

• heart beat counting task (interoceptive accuracy)

• confidence measure (interoceptive awareness - when compared to accuracy score)

• MAIA (interoceptive sensibility)

• found a trend towards lower interoceptive accuracy but enhanced confidence of interoception (interoceptive awareness)

• patient less able to regulate distress and distract from bodily signals → reduced body trust (interoceptive sensibility)

• patients demonstrated detachment between the ability to perceive the body and the awareness → object reality and experience of the body become detached

What did Lutz et al (2019) find comparing using a heartbeat counting task during EEG-HEP, comparing AN and HC?

• no significant difference in interoceptive accuracy

• but significant differences in interoceptive neural processing

• disturbance of interoceptive signal processing found at the level of cortical representation → difference in the way the brain is processing the heartbeats in AN patients

Affective touch definition

• touch specifically associated with pleasantness sensations

• informs about physiological body state

• some evidence that affective touch can modulate pain (similar mechanism to scratch and itch)

What did Crucianelli et al (2016) find when AN patients were given affective and neutral touch when looking at images of faces with different facial expressions?

• smiling, rejecting and neutral

• measured judgements of pleasantness and anhedonia

• pleasantness of affective touch was lower in AN

• moderated by social context in both groups

• difference more likely to be bottom-up than top-down → the CT pathway

What did Murialdo et al (2007) find investigating regulatory control of heart rate variability in EDs using the tilt table test?

• lie on a table that adjusts your body position from horizontal to vertical to simulate standing up

• monitored changes in heart rate and blood pressure

• patients had lower blood pressure

• sympathetic cardiac activity did not increase in patients after lying to standing as occurs in healthy control

• cardiac abnormalities similar in AN and bulemia even though only AN are emaciated (not linked to BMI)

• illustrates more widespread difficulties → exhibit differences in both heart rate detection/interpretation and regulation, consistent with insular cortex involvement

What did Fischer et al (2016) find conducting CBT with 15 AN patients - paying special attention to maladaptive emotional processes?

• aim of the intervention is a normalisation of the eating behaviour and to reach an adequate body weight - but also targeting aetiology

• tested at the beginning, after 4-6 weeks, and at the end of therapy

• found significant improvements of BMI and depression

• interoceptive accuracy and sensibility - any recovery was small and inconsistent

What do the results of Fischer et al CBT study in which depressive symptoms of AN patients improves but interoceptive accuracy and sensibility did not lead us to conclude?

• interoception processed differently in AN

• does not improve with other symptomology (weight and depression)

• a potential mechanism for development, maintenance and relapse of AN

Most interoceptive differences seem focused on the gastric system → are heartbeat monitoring tasks indicative of all interoception? Should other tasks be used in relation to AN?

What did Kerr et al (2016) find in weight restored (recovered) AN patients who completed an interoceptive attention task which focused on sensations in their heart, stomach and bladder. Followed by anxious rumination phase and exteroceptive trial?

• activity in the dorsal mid-insula was reduced in AN patients during stomach interoception

• activity in the anterior insula was relatively higher in AN patients during heart interoception.

• AN displayed increase activation during anxious rumination in the dorsal mid-insula

• activity in this region during stomach interoception also correlated with measures of anxiety and psychopathology

• different functional activity in the dorsal mid-insula during gastric interoception → contributes to the symptomatology of AN - includes anxiety

What occured in Kerr et al (2016) study when patients were asked to change their attention to stomach?

• little signal change/ facilitation effect

• we can infer that there was higher activity at baseline

• hypervigilance → attending all the time, so don’t see effect when shifting to it

What is involved in the vicious cycle with stomach interoception which might exacerbate gastrointestinal symptoms during weight restoration and inhibit recovery?

gastric discomfort leading to increased anxiety that then leads to greater gastric discomfort

How might interoceptive processing in gastric and cardiac domains influence AN symptomology?

• many AN patients difficulty detecting hunger and satiety

• hypervigilance of gastric symptoms may lead to anxiety over eating and distorted exteroceptive bodily experience (feeling fat)

• reduced ability to detect heart beats → flattening of affect

How might the somatic error hypothesis and other prediction theories relate to AN?

• these theories suggest inaccurate interoceptive predictions in psychiatric disorders

• difference in gastric processing may not be sensory input but interpretation

• unclear mechanisms for how interoception underlies a complex disorder such as AN

What did Khalsa et al (2015) find regarding interoception and eating?

• ppts given drug to make heart rate increase or saline

• measured pre and post meal intensity of heartrate and breathing

• interoceptive detection thresholds and interoceptive accuracy

• patient group reported higher rates of interoception before eating

• AN experienced more intense cardiorespiratory sensations before consuming a meal

• AN more likely to report interoceptive experiences in all conditions, particularly in low arousal conditions

• AN could be anticipating general increases in interoception during a meal

• anticipating food intake (and/or gastric discomfort) could lead to anxiety

How is interoception not an all or nothing measure?

• dependent on modality and environment

• the insular cortex integrates information across modalities with visceral/interoceptive sensation

• supports a prediction error rather than a general issue

What prevents intuitive eating in AN?

• inaccurate mapping of interoceptive signals in AN results in prediction errors about the internal bodily state

• intuitive link between difficulty perceiving hunger and satiety and dysfunctional eating habits

How might interoception underlie restrictive symptoms of AN?

• impaired interoceptive experiences means that AN patients cannot use internal signals to perceive physical changes of weight loss

• also do not recognise satiety or hunger

• AN patients continue to restrict food intake despite emaciation

How might interoception underlie the emotional symptoms of AN?

• AN is associated with high rates of alexitheymia

• AN linked to decreased ability to self-regulate emotions - regaining homeostasis - autonomic control of the insula

• inaccurate perception and interpretation of interoceptive signals → intense fear of gaining weight

What factors might influence AN patient’s disturbance in the way in which one’s body weight or shape is experienced?

• overevaluation of weight and shape

• self-objectification

• inaccurate (overestimation) experience of body size

What is the definition of body image?

How you experience and feel about your body

• mental representation of body in brain

What is involved in Objectification Theory?

• bodies are viewed and evaluated based on appearance

• the body as an object (sexual)

• the body and sexuality are separate from the person

• objectifying others and objectifying the self → the more you self objectify, the more important body appearance and deviations from social ideas is important for self worth

How does the allocation of attention influence interoception and lead to self-objectification?

• competition of cues hypothesis suggests their are finite attentional resources available

• emphasis on body appearance detracts from internal signals and vice versa

• less attention paid to ‘unreliable’ bodily signals - down regulated

• poor interoception in AN → self objectification, only way to learn about body is through vision

How does interoception underlie body image and lead to disturbance in the way in which one’s body weight or shape is experienced?

• failure to update external perception of the body through direct sensory input - don’t realise they have lost weight and continue to feel dissatisfied with their body

• an over-reliance on exteroception (vision) leads to enhanced self objectification and symptoms such as body checking

• Insular cortex is a neural hub connecting interoceptive signals with other modalities including exteroception, cognition and emotions

• potential mechanism in AN of interoception underpinning many of the key symptomology in AN

What might the failure to address it in treatments lead to?

• a high chance of relapse

Interocepetive prediction errors may lead to further errors and negative affect that if unresolved may lead to…

risk of relapse particularly with certain triggers

• both exteroceptive and interoceptive bodily symptoms continue following weight restoration

Weight restored AN patients show differences in insula activity when…

• anticipating food

• decreased response to the taste of food stimuli

What is the current state of AN treatment and what might guide future inventions for treatment?

• interoception abnormalities seems resistant to current treatments

• plasticity of the insula suggests such issues can be targets for treatment

• potential interoceptive treatments need to be tested e.g. interoceptive exposure to increase tolerance to the physical symptoms of anxiety through repeated provocation triggers, and mindfulness