26.11 - Eating Disorders Flashcards
What are the main eating disorders?
- Anorexia nervosa
- Bulimia nervosa
- Binge eating disorder
- (Other conditions that do not fit exactly into these categories)
What is the lifetime prevalence of any eating disorder?
5%
Define eating disorders.
Definite disturbance in eating habits or weight control behaviour with a core psychopathology that leads to disturbed eating and overevaluation of the control of eating and weight. It results in clinically significant impairment in health/psychosocial function and is not secondary to any general medical or psychiatric condition.
What is anorexia nervosa?
- A severely debilitating psychiatric disorder characterised by relentless self-starvation with dramatic physiological and psychological effects.
- It has low rates of recovery (<50%) and the highest mortality rate of any psychiatric disorder.
What is the prevalence of anorexia nervosa?
- 1-4% in women
- 0.3% in men
What is the heritability of anorexia nervosa?
50-60%
When is the onset of anorexia nervosa most common?
Adolescence
What are the outcomes of anorexia nervosa?
- 10-15% mortality rate
- Chronic illness seen in 50% of cases -> No effective therapies for these patients
What are some common features of anorexia nervosa?
- Strict dietary rules, such as counting calories
- Rigidity of eating and ritualistic behaviour
- Body checking and weighing
- Compulsive exercise
- Obsessive preoccupation with (control of ) eating shape and weight
- Parallels with OCD (and a high comorbidity OCPD)
- Body image dysphoria and distortion
What is bulimia nervosa?
- A condition similar to anorexia nervosa, but with lapses of control, such that the person experiences periods of binge eating
- It features extreme weight control behaviour, including self-induced vomiting, laxative misuse, extreme exercise, strict dieting
- However, the diagnostic criteria for anorexia nervosa are not met (usually because the BMI is not low)
When is the onset of bulimia nervosa most common?
Adolescence and young adulthood
What is binge eating disorder?
- A condition characterised by recurrent episodes of binge eating more than weekly for more than 3 months
- It leads to impairment and/or distress
- But there are no compensatory behaviours and no over evaluation of control of eating, weight and shape
When is the onset of binge eating disorder most common?
It has a later onset than anorexia and bulimia.
Can people switch between different types of eating disorder?
Yes, it is relatively common.
What is the common feature in the psychopathology of anorexia nervosa and bulimia nervosa?
Overevaluation of control of eating based on shape and weight. In other words, both conditions involve putting too much importance on body weight when evaluating self-worth.
Experimentally, describe the Minnesota starvation study and its results.
[EXTRA]
(Keys et al, 1950)
Study plan:
- 36 young healthy men
- 3-month baseline
- 6-month period of severe dietary restriction (50% prior intake)
- 3-month re-feeding phase
Results:
- Preoccupation with food and eating
- Eating habits changed
- Eating became planned, ritualistic and prolonged
- Food smuggled out of meals to be consumed later in private
- Increased use of salt and spices; coffee and tea; odd food concoctions
- Overeating
- Some experienced episodic loss of control (resembling binge eating) during the restriction phase, and in a minority this persisted for months
- Many overate “more or less continually” during the refeeding phase
- Changes in mood
- Extreme in 20%-increase in anxiety and depression
- Lability of mood, marked irritability
- Severe dysphoria on refeeding (one man cut fingers off)
- Hoarding, compulsive behaviours
- Decrease in outside interests
- Impaired concentration and alertness
What are some implications about anorexia and bulimia that we can learn from the Minnesota starvation experiment?
- Many features of eating disorders are compounded by starvation, and some are reversed by re-feeding
- Some are likely to maintain the eating disorder
- An essential component of treatment is weight restoration
- Corollary is that other clinical features are not due to starvation; rather, some are responsible for it
- Treatment needs to involve much more than weight regain
Describe the cycle that keeps anorexia nervosa going.
There are two cycles:
- “Starvation syndrome”, where the starvation itself makes you preoccupied with weight, so you exert greater control over eating, etc.
- Perverse rewards, where losing weight leads to social reinforcement and euphoria
Describe the cycle that keeps binge eating disorder going.
Describe how eating disorders are treated in general.
- A transdiagnostic form of CBT , CBT-E developed in Oxford ( Fairburn et al 2012) for the full range of eating disorders
- Based on a transdiagnostic theory of maintenance
- Evidence from controlled evaluation indicates that outcome for ED-NOS exactly the same as for bulimia nervosa
- But all talking treatments of limited efficacy in low weight anorexia nervosa
Describe how anorexia nervosa can be treated.
- In adolescents, there is good evidence for the Maudsley model eating disorder family therapy (for patients will less than 3 years illness)
- In adults, there is moderate evidence for all treatments (less than 50% recover)
- Early intervention is most effective since behavioural patterns get stuck
- Key aspects to management:
- Helping patients to see they need help to fight the ED ‘motivation’
- Helping patients reverse starvation, restore weight
- Addressing over-evaluation of shape, weight and control over eating
- Compulsory treatment only relevant in a few cases
- Drug treatment does not currently have an established role
Describe how bulimia nervosa can be treated.
NICE guidelines:
- Grade A treatment (treatment of choice): A specific form of CBT
- Grade B treatment: Interpersonal psychotherapy
- Grade B treatment: Evidence-based self-help and/or a trial of anti-depressant drugs
What are some risk factors for anorexia/bulimia nervosa?
[IMPORTANT]
There are both genetic and environmental factors -> 50-60% heritability, highest for anorexia nervosa. Cross-transmission between eating disorders.
Some example risk factors:
- Being female
- Adolescence and early adulthood
- Living in western society
- Family history of: Eating disorders of any type, depression, substance abuse and obesity
- Adverse parenting
- Sexual abuse
- Family dieting
- Critical comments about eating, weight and shape from others
- Occupational pressure to be slim
- Obesity
- Early menarche
- Low self-esteem
- Perfectionism
- Anxiety and anxiety disorders
- Altered 5-HT and dopaminergic function that is exacerbated by weight loss
Give some experimental evidence for the genetic component of anorexia nervosa.
[EXTRA]
(Watson, 2019):
- GWAS of 16,992 cases of anorexia nervosa and 55,525 controls
- Identified eight loci significant to anorexia nervosa
Is anorexia nervosa purely an psychiatric disorder?
It has been proposed that it should be considered a metabo-psychiatric disorder, since it shares significant genetic correlations with psychiatric disorders, physical activity, metabolic (including glycemic), lipid and anthropometric traits.
Give some experimental evidence for the relevance of the gut microbiome in anorexia nervosa.
[EXTRA]
(Ghenciulescu, 2021):
- Reviewed research about the gut microbiome in patients with anorexia nervosa
- Studies show considerable low divergence and altered taxonomic abundance of the anorexia nervosa gut microbiome
- It is uncertain whether this is causative of the symptoms of anorexia nervosa or simply a result of the calorific restriction
- Fecal transplants and other therapies show potential for treatment
What are some neuropsychological abnormalities that may explain anorexia nervosa?
[EXTRA]
Imbalance in top-down cortical control and bottom-up striatal control:
- In most people, the sight of food triggers the reward pathways driving the urge to satisfy hunger in the short term
- In people with anorexia nervosa, the sight of food triggers activation of the amygdala and prefrontal cortex, leading to a dominant desire to stay thin in the long-term, rather than satisfy hunger
- In other words, the prefrontal cortex, which is involved in decision making and control, does a lot of work to ensure that the individual does not want to eat the high calorie food by overruling their desires (i.e. the PFC weighs up a lot of evidence against eating high calorie food in order to decide that this outweighs the benefit of eating it)
- Dysfunction of cortico-striatal circuitry can also explain why patients with anorexia nervosa experience aberrant reward upon starvaing themselves -> (Fladung, 2009) showed that patients with anorexia nervosa had higher ventral striatal activity compared to controls when shown a picture of an underweight person
Decreased connectivity in regions associated with somatosensory processing and abnormalities in body/object recognitions areas:
- Explains reduced interoceptive awareness and misperception of body image
Is anorexia nervosa driven by “liking” or “wanting” low calories foods?
[EXTRA?]
- “Liking” is explicit, while wanting is “implicit”
- (Cowdry, 2013):
- “The aberrant responses to food that characterize AN may be driven more by altered motivational salience (“wanting”) than by explicit liking responses.”
