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Aetiology of Eating Disorders, Limitation: Spanos et al (2010)
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- Aetiology of Eating Disorders
Experiential (Learning)
- Raffi et al (2000): Aversive life experiences may act as a vulnerability for AN + BN
- Jacobi et al (2004): Childhood sexual abuse has been implicated in the development of EDs
- EDs may be coping mechanisms for other disorders + traumatic events
- AN restriction of intake = increased control
- BN binge/purge cycle = emotional relief
Limitation: Smolak + Muren (2002)
- Meta-analysed studies
Weak positive link for child sexual abuse leading to development of EDs
Biological
Genetics
- Wade (2010): EDs run in families
- Steinhausen et al (2015): Family history of AN = 4x higher risk compared to general population
- BN + BED run in families - Hudson et al (2006); Strober et al (2000)
Genetics
- Twin studies (Yilmaz et al (2015):
:check: 48-74% of total variance in liability to AN
:check: 55-62% of total variance in liability to BN
:check: 39-45% of total variance in liability to BED
- Schaumberg et al (2017): Epigenetic effects on neurotransmitter receptors may be risk factor for EDs
Neurobiology - Hypothalamus
:warning: Ventral medial hypothalamus - Lesions = overeating, stimulation = starvation
:warning: Lateral hypothalamus - Lesions = starvation, stimulation = eating
Limitation: No evidence of hypothalamus disruption in ED
- Where there is evidence, hypothalamus disruption is likely to be a consequence rather than cause of ED
Neurobiology
:warning: Titova et al (2013): AN associated with decreased grey matter volumes in regions related to appetite, somatosensory processing (body perception), reward processing
:warning: Frank (2013): AN + BN linked to structural + functional changes to reward processing regions (e.g. insula, orbito-frontal cortex + anterior cingulate)
Limitation: Causation not established
- Brain changes cause ED/ED causes brain changes
Neurobiology - Serotonin
:warning: Bailer + Kaye (2011): Low levels of 5HIAA in AN + BN
:warning: Chandler-Laney et al (2007): Low levels of serotonin may be caused by prior dieting
:warning: Starvation in AN increases endogenous opioids, feelings of euphoria, reinforces starving
:warning: BN decreases opioids, generates cravings
Limitation: Causation for opioids in BN
- Decrease in opioids = cravings/cravings = decrease in opioids
Neurobiology - Dopamine
:warning: AN + BN increase dopamine - More susceptible to rewarding properties of food
:warning: BN = Low HVA (Dopamine metabolite)
- May be caused by downregulation of dopamine systems that has become overstimulated due to recurrent binges
:warning: BN = Low D2 receptor density, may result in increased release of dopamine (so increased food reward)
Sociocultural
Media
:red_cross: Spypeck et al (2004): Increasingly thinner cover stars on magazines
:red_cross: Media images negatively influence body image
- Grabe et al (2008) - Evidence for females
- Bartlett et al (2008) - Evidence for males
:red_cross: Cohen + Blaszczynski (2015): Social media may have greater influence on body dissatisfaction
- Body dissatisfaction = Gap between ideal + actual weight + body shape
:red_cross: Jett et al (2010): Evidence of causal link between pro-ED websites + ED
Limitation: Huasenblas et al (2013)
- Meta-analysis of 33 studies on media and EDs
- Effects are small + influence is modest
Peers
:red_cross: Meyer + Waller (2001): Attitudes converge of what is socially valued in peer groups
:red_cross: Eisenberg et al (2005): Behaviour of close friends significantly influenced unhealthy weight control methods (e.g. vomiting)
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Family
:red_cross: Eusler (1995): Family is context in which ED is embedded, not cause
:red_cross: Tozzi et al (2003); Hoste et al (2008): AN + BN patients cite family dysfunction
:red_cross: Psychosomatic family model (Minuchin et al, 1975): Enmeshment, overprotection, rigidity, poor conflict resolution associated with AN
:red_cross: Whecan + Cooper (2000): Link between mother's attitudes/behaviours + children's disordered eating
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Limitation: Spanos et al (2010)
- Dysfunctional families may be caused by member having ED
- Unhealthy attitudes to food often predate parent-child conflict
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