PSYC 210 Chapter Notes - Chapter 11.2: Binge Eating Disorder, Etiology, Twin Study
30 Apr 2018
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11.2$Etiology$of$Eating$Disorders$
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Genetic'Factors!
• Eating!disorders!run!in!families!
• Twin!studies!of!anorexia!and!bulimia!report!higher!MZ!than!DZ!concordance!rates!
• Environmental!factors!such!as!parents!or!peers!can!contribute!to!the!development!
• Genetics!may!account!for!the!relationship!between!personality!characteristics!like!negative!
emotionality!and!constraint!present!in!EDs!
• Genes!and!environment!interactions!are!the!biggest!indicators!
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Neurobiological'Factors!
The!hypothalamus!is!a!key!brain!center!for!regulating!hunger!and!eating!
• Hypothalamus:!in!the!subcortical!region!of!the!brain,!the!structure!that!regulates!many!visceral!
processes,!including!metabolism,!temperature,!perspiration,!blood!pressure,!sleeping,!and!
appetite!
• Does%not%seem%a%likely%factor%for%anorexia!
• Hypothalamus!controls!hormones!like!cortisol!
o Hormone!differences!in!anorexia!occur!as!a!result!of!self-starvation!and!return!to!normal!
after!weight!gain!
• This!model!is!not!fully!accurate!
o Animals!with!hypothalamus!lesions!appear!to!have!no!hunger!and!be!indifferent!to!food,!
whereas!people!with!anorexia!starve!themselves!despite!being!hungry!and!having!interest!in!
food!
o Does!not!account!for!body-image!disturbances!or!becoming!fat!
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Opioids!are!released!during!starvation!and!have!been!hypothesized!to!play!a!role!in!anorexia,!bulimia,!
and!binge!eating!disorder!
• Endorphins'(endogenous'opioids):!opiates!produced!within!the!body;!may!have!an!important!role!
in!the!processes!by!which!the!body!builds!up!tolerance!to!drugs!and!is!distressed!by!their!
withdrawal!
• Starvation!may!increase!the!levels!of!endorphins,!resulting!in!a!positively!reinforcing!positive!
mood!state!
• Excessive!exercise!releases!endorphins,!which!could!be!reinforcing!
• Studies!show!bulimia!is!associated!with!low!levels!of!beta-endorphins!
o Not!sure!if!this!occurs!before!the!disorder!or!in!response!to!the!disorder!
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Neurotransmitters:!serotonin!and!dopamine!
• Serotonin!is!related!to!eating!and!satiety!(feeling!full)!
o Serotonin:!a!neurotransmitter!of!the!central!nervous!system!whose!disturbances!are!
thought!to!figure!in!depression!
o Serotonin!deficit!may!cause!those!with!bulimia!or!binge!eating!disorder!to!not!feel!full!after!
they!eat!
o Food!restriction!in!anorexia!interferes!with!serotonin!synthesis!in!the!brain!
• Low!levels!of!serotonin!metabolites!found!in!those!with!anorexia,!indicating!serotonin!
is!underactive!
o More!likely!linked!to!the!comorbid!depression!often!found!in!people!with!EDs!
Document Summary
Twin studies of anorexia and bulimia report higher mz than dz concordance rates. Environmental factors such as parents or peers can contribute to the development: genetics may account for the relationship between personality characteristics like negative emotionality and constraint present in eds, genes and environment interactions are the biggest indicators. Opioids are released during starvation and have been hypothesized to play a role in anorexia, bulimia, and binge eating disorder. Endorphins (endogenous opioids): opiates produced within the body; may have an important role in the processes by which the body builds up tolerance to drugs and is distressed by their withdrawal. Starvation may increase the levels of endorphins, resulting in a positively reinforcing positive mood state. Excessive exercise releases endorphins, which could be reinforcing. Studies show bulimia is associated with low levels of beta-endorphins: not sure if this occurs before the disorder or in response to the disorder.
