Biological Explanations For Anorexia Flashcards
Define anorexia.
A refusal to maintain expected body weight.
What are some symptoms of AN?
Weigh 15% less than expected body weight Amenhorrhea Preoccupation w food Distorted body perception Denial Periods of hyperactivity
What is the genetic explanation for AN?
Anorexia is Inherited.
First degree relatives have a 10 food increase in developing it.
When looking at MZ and DZ, heritability rate was 60% - some people more likely to develop it than others.
Some specific candidate genes have been found - Ephx2 involved in cholesterol metabolism. People w anorexia have abnormally high cholesterol.
Evaluate the genetic explanation for AN.
S - 45 pairs of twins. Found a concordance rate of 56% in MZ and 5% in DZ. findings not reliable as another study later on found 65/32.
C - difficult to draw conclusions from twin studies as not 100% concordance and they’re raised similarly
I - too simplistic - many physical and psychological characteristics not due to one gene. Multiple genes involved so polygenic disorder. Doesn’t explain why more common in females or why it’s raised in recent years.
What is the serotonin neural explanation for AN?
Research suggests people with AN have lower serotonin. Based on reduced levels of byproduct of serotonin breakdown (5-HIAA) in cerebrospinal fluid of people w AN. levels return to normal after short term weight gain and increase to above normal levels after long term recovery.
Evaluate serotonin as a neural explanation of AN.
S - face validity. Practical applications w SSRIs.
C - SSRIs have varied outcomes. Don’t help all patients - no difference in SSRI and control group. Some research found high levels of serotonin in anorexic patients. Also different subtypes - FMRI scans showed higher levels of serotonin in women recovering from binging/purging type AN than those who had been restricting.
Describe dopamine as a neural explanation for AN.
Research has shown raised levels of dopamine in those recovering from AN compared to control. Dopamine involved in perceptions of rewards and pleasurable feelings but doesn’t create this feeling in those w AN.
Evaluate dopamine as a neural explanation for AN.
S - study gave amphetamines to people w AN and control, which encourage release of dopamine. Made control feel euphoric but AN anxious. So they might not eat food bc increased dopamine = anxiety. Also 10 recovering anorexic women had overactivity in dopamine receptors compared to 12 healthy women. Also increased dopamine = increases blinking and study found increased blinking in AN patients // control.
Generally evaluate neural explanations.
I/D - overly simplistic. Serotonin can’t explain difference between those w AN and those without. AN better understood by looking at interaction of serotonin, noradrenaline and GABA. serotonin and dopamine secondary to noradrenaline. Role of neurotransmitters complex. Better exp= diathesis stress model.
