L7: Eating Disorders I

What percentage of people were obese in England and Wales in 2021

26%

What figure is there to show there’s a growing rate of dieters

42.2% of adolescents trying to lose weight in 2015, compared to 28.6% in 2005

Solmi et al. (2015): Changes in the Prevalence and Correlates of Weight-Control Behaviours and Weight Perception in Adolescents in the UK, 1986-2015 RESULTS

• Increase in weight-control behaviour over time

• Higher in girls BUT a steeper increase in boys

What is over-estimation of weight associated with

Higher depression scores

Fardouly et al: Appearance Comparisons

• In person comparisons the most common context

• Upward comparisons most common across contexts

• Upward comparisons on social media were associated with the greatest negative outcomes

What are two key clinical features of ED’s

1. Persistent disturbance of eating, or eating-related behaviour

2. Impaired physical health and psychological wellbeing

Pica ED

Eating non-nutritive or nonfood substances

Rumination disorder

Repeated regurgitation of food

Anorexia Nervosa (AN): Characteristics and Subtypes

Characteristics

• Restriction of energy intake relative to requirements, leading to significantly low body weight

• Intense fear of gaining weight

• Disturbance in the way one’s body weight or shape is experienced

Subtypes

• Restricting

• Binge-eating/purging

What is AN mortality rate compared to peers

AN has 5 times higher mortality rate than peers

Bulimia Nervosa (BN): Characteristics and Subtypes

Characteristics

• Recurrent episodes of binge eating

• Recurrent, inappropriate compensatory behaviours to prevent weight gain

• Self-evaluation unduly influenced by body shape and weight

• Not experiencing AN

Subtypes

• Purging

• Non-purging

How often should binge eating and compensatory behaviours occur on average to be clinically significant

1 per week for 3 weeks

If someone reaches the criteria threshold for both a AN and BN diagnosis, what will they be diagnosed and treated for?

AN due to higher mortality rates

What distinguishes Binge Eating Disoder (BED) from AN and BN

No compensatory behaviour

What is the frequency criteria for a BED diagnosis

At least once a week for three months

What are some common comorbidities of ED’s

• Depression

• OCD

• Substance Use Disorders

• Personality Disorders

• ASD

Diagnositc crossovers (transitions) between AN, BN, and BED

• Quite common in ED’s

• Transition between two AN subtypes (AN-R and AN-BP) are common

• AN and BED appear quite distinct (low transition)

• Criticism that the diagnostic system is not doing a good job at categorizing these disorders

  • An argument behind moving to a trans-diagnositc approach

Using DSM-IV diagnostic criteria, what percentage of treatment seeking adolescents and adults are diagnosed with ‘EDNOS’ or Eating Disorder Not Otherwise Specified

60%

Who might be diagnosed with EDNOS?

• Individuals who display quite severe symptoms but don’t quite meet the criteria for a diagnosis but still has a severe impact on their life

• People may display symptoms across different diagnosis

What diagnosis supports a trans-diagnostic criteria?

EDNOS

Transdiagnostic CBT-Model

• Developed to account for the high degree of movement between the different diagnosis 

• Useful model for individuals who fall under the EDNOS diagnosis

• All of these might not apply to individual with ED, but useful for personalised understanding and treatment approach

Prevalence of ED’s: BED, BN, AN, ENDOS

• Binge Eating Disorder: 2%

• Bulimia Nervosa: 1%

• Anorexia Nervosa: 0.9% women, 0.3% men

• Other specified/unspecified ED’s: most common

Prevalence of AN over time

AN stable for the past decades, incidence among those under 15 years old has increased

Prevalence of BN over time

BN increased in the 1970s-1990s, now declining

In Bassett and Ewart (2023) study looking at media depictions of ED’s, what was the most commonly depicted demographic (sexuality, ethnicity, gender, age)

Heterosexual, White, Women, Under 30 years of age

Average age of onset: AN, BN, BED

• AN

  • Age 16 to 20

• BN

  • Age 21 to 24

• BED

  • Age 30 to 50

Gender and ED disorders

• Gender ratio previously thought to be 10:1, now estimated 3:1

• Higher prevalence in gay and bisexual men than straight men

Biological Factors in EDs

• Genetics

• Hormones

• Neurological factors

Biological Factors in EDs: Genetics through family

• ED’s seem to run in families

• Strober (2000) found ED’s at least 3x more common among relatives of individuals with AN or BN than among relatives of individuals without AN or BN

  • AN over 10 x more common in relatives of AN sufferers

• BUT looking at families doesn’t allow us to separate potential genetic and environmental factors

AN Diagnosis in MZ vs. DZ Twins (Genetic Factor)

• MZ twins show 58% concordance comapred to DZ twins (5%)

• Conclusion

  • Some genetic contribution

  • If there is a genetic mechanism underlying the familial patterns, it is more consistent with increased susceptibility as opposed to an all-or-nothing mechanism

How is the genetic influence mediated

• Three underlying mechanisms:

  • Via the determination of body weight/shape/size

  • Via the determination of brain chemistry

  • Via the determination of personality traits (including neurocognitive and socio-emotional profile)

• Not necessarily mutually exclusive

What brain structures are involved with ED’s

Hypothalamus

• Ventromedial and lateral hypothalamus are involved in satiety and appetite

Frontal Cortex

• Temporal cortex is involved in body image perception

• Orbitofrontal cortex is involved in monitoring the stimuli pleasantness (smell and taste)

• Linked to development of AN and sometimes BN

Hypothalamus: Animal studies

• Animal studies have found that lesions to the ventromedial hypothalamus increase hunger and the inability to regulate intake WHEREAS stimulating stops eating 

• Animal studies had found the opposite effects in the lateral hypothalamus (lesions stop eating and visa versa)

• HOWEVER, there’s not a lot of clear evidence of abnormalities in the hypothalamus of individuals with ED’s, but still rationale to say it was a role in weight recognition 

  • Maybe it is the network of this brain area to others (such as the amygdala) which is important

Neurotransmitters that have a role in ED’s

Serotonin and Dopamine

Neurotransmitters role in ED’s: Serotonin

• Most popular neurotransmitter in AN research given its involvement in mood, obsessions, appetite regulation and impulse control

• Patients with AN have low levels of serotonin metabolites (5-HIAA)

• Following recovery, patients with previous AN or BN have higher levels of 5-HIAA than controls

  • Might experience over activity

Neurotransmitters role in ED’s: Dopamine

• Recent interest given its role in reward systems

• Foods high in sugar and fat usually what individuals engage with when binge eating

• Also being less sensitive to food reward might ‘help’ individuals with restricting food intake

What is Set Point Theory

States there is a biological control method in humans that actively regulates weight towards a predetermined set weight for each individual

• Body tries to keep us at this set weight, hormones may be used to regulate this 

What are the Hormones involved in appetite and weight regulation: Set Point Theory

• Leptin

  • Satiety hormone

  • Reduces food intake

  • Profoundly disturbed in AN

• Grehlin

  • Hunger hormone

  • Increases food intake

Puberty and the Role of Sex Hormones

• Puberty key risk period of ED onset

• Before puberty, genetic influences account for ~0% of the variability in disordered eating, where as genetic factors account for over 50% during and after puberty

What is the hormone thought to “activate” genetic risk for disordered eating in girls during puberty

• Ovarian hormones

  • Oestradiol is potent regulator of gene transcription in CNS, thought to activate genetic risk in girls during puberty

Fordouly et al. (2023): Social media mirco-interventions to improve young women’s body image and mood

• A Facebook ‘micro-intervention’ to improve body image

• Randomly assigned one of:

  1. Body positive Facebook group

  2. Appearance neutral Facebook group

  3. Facebook as usual

• Results

  • Body positive and neutral groups experienced decreased body dissatisfaction

  • Body positive group experienced decreased appearance comparisons

  • Small to medium effects