Biological Explanations for Anorexia Nervosa Flashcards
Neural Explanations
Neurotransmitters = Serotonin +Dopamine
Neurodevelopment = Pregnancy + birth complications + seasons of birth
Serotonin
Bailer et al = compared serotonin activity in women recovering from restricting type + binge eating-purging type
Sig higher serotonin activity in women recovering from binge-eating/purging type
Highest levels of serotonin activity in women who showed most anxiety = suggesting persistent disruption of sero levels may lead to increased anxiety, which may trigger AN
Dopamine
Kaye et al
Found overactivity in dopa receptors in part of brain where dopa plays part in interpretation of harm + pleasure
Increased dopa activity in this area = alter the way people interpret rewards
Indis with AN = hard to associate good feelings with things people find pleasurable
Pregnancy + birth complications
Birth complications may lead to brain damage caused by hypoxia = impairing the neurodevelopment of child
AN mums = double disadvantage =transmission of genetic vulnerability to AN + inadequate nutrition during pregnancy
Season of birth
AN’s = more likely to been born in spring months
Explanation = intrauterine infections during pregnancy + temp at time of conception
Among p’s with AN in equatorial regions of the world (constantly hot) no seasonality effect in development of AN
Evolutionary Explanations
Reproductive suppression hypothesis
Adapted to flee hypothesis:
Adaptive response to famine conditions
Migratory restlessness
Reproductive suppression hypothesis
Ancestral girls delayed the onset of sexual maturation in response to cues about probability of poor reproductive success
Ability to delay reproduction = adaptive because enables a female to avoid giving birth at time when conditions are no conducive of her offspring’s survival
Model is based on observation that a number of species puberty is is delayed in females when subjected to stress or poor physical condition
An adaptive response to famine conditions
AFFH proposes typical AN symptoms of food restriction, hyperactivity + denial of starvation reflect operation of adaptive mechanisms that once caused migration in response to local famine conditions
Increases indis chance of survival by migrating to a more favourable environment
Migratory restlessness
Hyperactivity in AN’s = may be form of migratory restlessness
Many species increase activity in times of food shortage + prior to migration
EEA = starving foragers who deceived themselves about physical condition would have been more confident about moving on to more favourable environment = more likely to survive
Modern= losing weight may trigger ancestral mechs
Real-World Application
US: treatment for AN is restricted under insurance plans because not considered biologically based
Biological explanations create a case for insurance companies to consider AN in same way as other psychiatric conditions
Problems with SSRIs
Are ineffective when used with AN patients
Kaye et al: drugs were effective in preventing relapse
Malnutrition-related changes in Sero = negate action of SSRIs = only become effective when weight returns to more normal level
Dopamine Evalutation
Adolescent girls with AN = higher levels of waste product of dopa
Improvement in weight levels = associated with normalisation of levels of waste product of dopa
Lower than normal levels of dopa receptors in brain in obese people
Levels of dopa = inversely related to body weight = not sure if consequence or cause
Obstetric complications
Research = perinatal (immediately before or after birth) complications significantly associated with risk of developing AN were placental infarction, early eating difficulties + low birth weight
Support for seasons of birth
Found: AN’s are later in birth order
The more elder siblings a child had whilst in womb = mother exposed to infections = passed onto unborn child
Critical period for brain development = second trimester… so a spring birth = second trimester would occur at the time when infections are more likely
Treatment implications
Biological explanations offer promise of range of treatment possibilities e.g. drug therapies to normalise neurotransmitter levels
People realise they are dealing with a dysfunctional biology (treatable) not dysfunctional family (not treatable)
Reduces guilt generated by view that it is the parents who cause the development of eating disorders in their children
