15% of people at one time in their life(1988),
most common in women, young adults, and those
in lower socio-economic conditions
Symptoms
ABCS
Affective: e.g. feelings of guilt
Behavioural: e.g. passivity
Cognitive: e.g.
suicidal thoughts
Somatic: e.g. hyper/insomnia
Define Bulimia
Prevalence
2-3% women,
0.02-0,03% men
in the US
Symptoms
Somatic: e.g. swollen
salivary glands
Cognitive: e.g. poor
body image
Behavioural: e.g.recurrent episodes
of binge eating/purging
Affective: e.g. guilt or shame
Biological etiologies of MDD
as an example of abnormality
Bio-Chemistry
Combination
Faulty gene coding for 5-HTT
Faulty MAOA gene
Monoamine oxidase
Both play roles in the metabolism of serotonin. If
too much is removed, it can lead to low moods
Abnormal levels of neurotransmitters and hormones
Cortisol
Major hormone in the stress system
RESEARCH: meta-analysis to see cortisols influence on MDD.
Results showed a difference in reactivity to stress between
depressed and non-depressed people: when non-depressed
people are put under stress, cortisol levels rise and fall rapidly but
depressed people have a more blunt reaction and remain under
stress for longer
Serotonin
Burns (2003) cannot ever find
definitive evidence as you can
never measure the levels of
neurotransmitter activity in a
living brain
Linked to happy moods, low levels linked to MDD
Link to successful treatment-SSRIs
Genetics
Twin studies
Monozygotic (Mz) twins develop from the same
egg, and share 100% of the same DNA
Dizygotic (Dz) twins develop from two eggs
and share only 50% of the same DNA
Concordance rate (CR): The rate of which if one twin
has the illness, the other does.
RESEARCH: Meta-analysis of 7 twin studies that investigate the
influence of genetic on MDD. CR Mz twins=65% Dz twins = 36%
Meta-analysis = reliable
If it was fully genetic, then the concordance rate would be
100%, there must be other factors influencing abnormality
REDUCTIONIST
Cause and effect: We are unsure if these
symptoms (e.g. low serotonin levels) are a
cause of MDD or just an effect of MDD
Biological etiologies of bulimia as
an example of abnormality
Genetics
Twin studies
Kendler et al. 1991. 2000 female twins. CR in Mz twins:
23% and Dz twins: 9%
Relatives
Strober 2000, females with first degree relatives with bulimia
are 10 times more likely to develop the abnormality
This could show the influence of genetics, but it could also be a result of the
females environment. SLT as the first degree relative could be a role model.
Bio-chemistry
Abnormal levels of neurotransmitter
Serotonin
High levels of serotonin stimulate the
hypothalamus and decrease food intake
Carraso, 2000, there are lower level
of serotonin in bulimic patients
Nitric Oxide
Regulates how much food we intake,
therefore controls eating behaviour
Vannacci et al. Of 62 female participants, the plasma nitrate and
cgnp were higher in bulimia and was linked to binge eating.
Conclusion
Looking only at biological influences is too
reductionist. It is important too look at different
ideas that intergrate cognitive and sociocultural psychology.
Bio-social approach
Diathesis stress model
Furnald and Gunnar studied mexican families
in lower socio-economic conditions