26.11 - Eating Disorders

Question 1

What are the main eating disorders?

Answer 1

• Anorexia nervosa
• Bulimia nervosa
• Binge eating disorder
• (Other conditions that do not fit exactly into these categories)

Question 2

What is the lifetime prevalence of any eating disorder?

Answer 2

5%

Question 3

Define eating disorders.

Answer 3

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.

Question 4

What is anorexia nervosa?

Answer 4

• 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.

Question 5

What is the prevalence of anorexia nervosa?

Answer 5

• 1-4% in women
• 0.3% in men

Question 6

What is the heritability of anorexia nervosa?

Answer 6

50-60%

Question 7

When is the onset of anorexia nervosa most common?

Answer 7

Adolescence

Question 8

What are the outcomes of anorexia nervosa?

Answer 8

• 10-15% mortality rate
• Chronic illness seen in 50% of cases -> No effective therapies for these patients

Question 9

What are some common features of anorexia nervosa?

Answer 9

• 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

Question 10

What is bulimia nervosa?

Answer 10

• Similar to anorexia nervosa, but w/ lapses in control -> periods of binge eating (>weekly >3 months)
  
  • different diagnostic criteria (don’t need low BMI)
• Extreme weight control behaviour including extreme exercise, strict dieting + compensatory behaviours (laxative misuse/ self-induced vomiting)

Question 11

When is the onset of bulimia nervosa most common?

Answer 11

Adolescence and young adulthood

Question 12

What is binge eating disorder?

Answer 12

• Recurrent episodes of binge eating > weekly for > 3 months
• It leads to impairment and/or distress
• NO compensatory behaviours + NO over evaluation of control of eating, weight and shape.

Question 13

When is the onset of binge eating disorder most common?

Answer 13

It has a later onset than anorexia and bulimia.

Question 14

Can people switch between different types of eating disorder?

Answer 14

Yes, it is relatively common.

Question 15

What is the common feature in the psychopathology of anorexia nervosa and bulimia nervosa?

Answer 15

Overevaluation of control of eating based on shape and weight (too much importance placed on body weight when evaluating self-worth).

Question 16

Experimentally, describe the Minnesota starvation study and its results.

[EXTRA]

Answer 16

(Keys et al, 1950)

Study plan:
36 young healthy men
* 3-month - baseline feeding
* 6-month - 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
  Full recovery was not experienced by all after refeeding.

Question 17

What are some implications about anorexia and bulimia that we can learn from the Minnesota starvation experiment?

Answer 17

• 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

Question 18

Describe the cycle that keeps anorexia nervosa going.

Answer 18

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

Question 19

Describe the cycle that keeps binge eating disorder going.

Answer 19

Question 20

Describe how eating disorders are treated in general.

Answer 20

• 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

Question 21

Describe how anorexia nervosa can be treated.

Answer 21

• 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

Question 22

Describe how bulimia nervosa can be treated.

Answer 22

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

Question 23

What are some risk factors for anorexia/bulimia nervosa?

[IMPORTANT]

Answer 23

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

Question 24

Give some experimental evidence for the genetic component of anorexia nervosa.

[EXTRA]

Answer 24

(Watson, 2019):

• GWAS of 16,992 cases of anorexia nervosa and 55,525 controls
• Identified eight loci significant to anorexia nervosa

Question 25

Is anorexia nervosa purely an psychiatric disorder?

Answer 25

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.

Question 26

Give some experimental evidence for the relevance of the gut microbiome in anorexia nervosa.

[EXTRA]

Answer 26

(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

Question 27

What are some neuropsychological abnormalities that may explain anorexia nervosa?

[EXTRA]

Answer 27

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

Question 28

Is anorexia nervosa driven by “liking” or “wanting” low calories foods?

[EXTRA?]

Answer 28

• “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.”