Eating Disorders Flashcards
Characteristics of Anorexia Nervosa
- Excessive fear of gaining weight
- Body weight below normal (<85%)
- Amenorrhea (cessation of menstruation)
- Disturbed body image
- May involve
- restricted intake
- purging
- Excessive exercise
Characteristics of Bulimia Nervosa
Binge eating
- eating in a discrete period an unusual amount of food
- a sense of lack of control over eating during episode
- usual negative affect after binge Followed by weight compensatory behaviour - purging - diuretics
Time frame - at least 1x p/wk for 3 months
Self-evaluation strongly influenced by shape
Characteristics of Binge-eating disorder
o Binge eating
o No (or little) compensation
o Usually put on weight
o At least 1x/week for 3 months
Prevalence of Eating Disorders
o Relatively infrequent but severe
o Data hard to collect – need high risk samples, covering both adolescence & adulthood
o Overall prevalence – around 2-3% total eating disorders
o Anorexia less common – 0.5% lifetime
o Bulimia – 1.3% lifetime
Sex distribution
o Primarily female disorders
o Overall 6-8 times more females than males with eating disorders
o Anorexia most dramatic – 95% female
o Male “equivalents”??
Body builders, runners
Onset
o Tend to occur early – disorders of adolescence/early adulthood
o Most cases begin during 10-20
o Anorexia – mean – 16 yrs. Almost no cases after mid 20’s
o Bulimia – mean – 18yrs, first cases a little earlier, but a few initial cases seen into middle age
o BED similar to BN
Course
o Discrepancy between lifetime and point prevalence – suggests temporary disorders
o Binge disorders often short-lived or episodic
o Anorexia longer – several years
o Long-tern data – 75%+ of women no longer have disorder after a decade or so – but often still show symptoms
Common co-morbidity
o Mood disorders
o Anxiety disorders
OCD
Social Phobia
o Substance Use
o Personality Disorders
OCPD
Borderline PD Narrated
o Higher risk for a lot of mental illnesses then the general population
o Higher risk with bulimia than anorexia for anxiety disorder, mood disorder, substance abuse disorder up to 9x.
Anorexia still about 2x more likely than general pop for some but also evidence that anorexia is more of a unitary disorder.
Medical complications
o Often severe complications – up to 3% with anorexia will die from complications, less from bulimia
o Menstrual irregularity (BN, cessation (AN)
o Cardiac arrhythmias and damge
o Complications from low weight (starvation)
Low body temperature
Low blood pressure and HR
Lanugo growth • This layer of hair covering body
Osteoporosis
o Complications from weight shifts and purging (BN)
Receding gums, tooth decay, and loss
Gastrointestinal disorders (e.g. IBS, Crohn’s disease)
Kidney disease
Internal damage and bleeding
Mortality in hospitalised with eating disorders – Rosling et al., 2011
o 10% of those hospitalised had died after 10yrs
o BMI > 17.5 – 4x than gen pop
o BMI < 10.5 – 44x
Heritability in eating disorders
o Strong familial component
Increased risk in relatives – 4x for BN & 11x for AN
o Twin studies suggest around 50% variance
Large study of AN heritability .48 - .76 depending on definition
Similar variation for BN - .28 - .88
o Heritability shows overlap with depression and anxiety
o Concordance for MZ higher than concordance for DZ showing clear genetic links.
Brain regions o Three components to explain in biology of eating – Treasure, 2010
Homeostatic system involved in regulation of weight and hunger. Involves lower order brain areas
Drive systems involved in triggers and motivations to eat/or restrict weight and include links with memory and learning.
Higher order mental processes involved in meaning of weight and conscious control over energy
Brain regions o Homeostatic system
Major input from hypothalamus. Involved in several basic functions including hunger and eating
Regulates body’s set point
Damage to lateral hypothalamus leads rats to restrict eating
Damage to ventromedial hypothalamus leads rats to continue eating and not to stop (often till death)
Brain regions o Cause or effect
Brain is markedly affected by low weight and starvation
Structural differences very likely to be a result of starvation or prolonged dieting
Difficult to determine whether these differences precede the disorder due to early onset and low prevalence
Biochemical factors o Kaye et al. (2009) argue that biochemical processes may fall into two groups
Those associated with traits that precede the disorder (causal)
Those caused by dieting that might maintain the disorder (maintaining)
Trait risk factors are general to many disorders (e.g. neuroticism)
Therefore, most eating disorder research has focussed on the latter
Biochemical factors o Serotonin
Many studies have shown abnormalities in 5HT function in people with AN.
Evidence that 5HT is involved in satiety and also impulse control and mood
Reduced levels of 5HIAA in cerebro-spinal fluid (CSF)
Complex relationship - increased binding of 5HT1A and reduced binding of 5HT2A receptors. Still found after recovery.
Biochemical factors o Dopamine
DA thought to be involved in reward learning and sensation-seeking c.f. substance abuse and also excessive exercise and impulsivity in some eating disorders
Low levels of DA metabolites in CSF
Polymorphism of DRD2 gene (control of DA D2 receptor) in anorexia
Some evidence for increased D2 & D3 receptor binding in ventral striatum in AN.
Narrated Transmitter metabolites Receptor binding
• Transmitter metabolites
o Studies show higher levels of serotonin and DA in recovered AN patients relative to controls
• Receptor binding
o Recovered AN patients had abnormal levels of 5HT2A binding at various at parts of the brain compared to controls and these appear to be independent of the effects of starvation.
Psychological risk factors for eating disorders symptoms in females
o Body image dissatisfaction
Strong concern over body weight and shape characterises all eating disorders
Excessive importance placed on weight (e.g. weight as central to self esteem
Includes perceptual/cognitive distortions (e.g. perceiving self as overweight
o Over concern with weight and shape
o Perfectionism
o General negative affectivity
o Low self esteem
o Early menarche
Affective factors
o Involvement of depression, anxiety and obsession
o Importance of sense of order and control
o Low self-esteem and tendency to equate body size with self-worth
o Fear of weight gain
Personality factors
o Internalisation of thin ideal
o Negative affectivity one of the key predictors
o Perfectionism
Restriction and control
o Impulsivity
Binging, purging
Family factors
o Not a main cause, but likely to play some role in onset and maintenance
o As in most disorders, evidence is mixed and effects are small
o Nonspecific factors such as parent criticism and over protection – Criticism and focus on weight may be more specific
Perception of body shape in eating disorders Eye gaze to body areas
o Tendency for controls to underestimate weight, eating disorders and obese to overweight
o 80% of controls to be accurate
o More overestimating and underestimating by eating disorder groups, less accurate
o Tovee et al
Found results that their estimates were accurate.
Greater discrepancy (5 BMI points) between BN estimates and ideals whereas AN were accurate and close to ideal. i.e. they want to be that thin.
Eye gaze
o Controls fairly equal share across body
o AN focussed more on fatty areas.
Social attitudes to thinness
o Change in conception of attractiveness on Western society
o 1960’s Twiggy – reflection of move to thinner ideals of beauty
o Coincides with apparent increase in eating disorders
Cultural influences on eating disorders
o Suggestion that eating disorders may be “culture-bound”
o Some evidence that AN not seen in some societies until recently – mixed evidence
o More evidence for culture restriction in BN - appears more common in West
o Possible increases in eating disorders with stronger Western influence
Socio-economic status
o Some suggestion that eating disorders are more common among more affluent
o Stronger drive for thinness among more affluent
Popular media and eating disorders
o Common tendency to “blame” media
o Many popular examples of super-thin models, pressure to be thin, negative connotations of overweight, etc
o Lots of anecdotal and circumstantial evidence
o But correlation is not causation
Does the media “cause” eating disorders
o Theory – exposure to thin ideal -> body dissatisfaction -> eating disorder
o Several longitudinal studies provide some support
o Experimental studies – exposure to thin media images produces greater dissatisfaction and negative affect
Average weight of playboy centrefolds
o From 90kg in 1960 to 86.5kg in 66, then to 84kg in 78.
Lifetime risk for bulimia in females
o Risk spikes for those born after 1960+
o Methodological shortcomings in study.
Eating disordered behaviour following introduction of TV in Fiji
o Traditional Fiji culture promotes eating to build a robust figure
o Looked at 63 adolescent girls in 95 (pre-TV) and 65 girls in 98
o BMI stayed the same
o Bingeing decreased
o Disordered eating behaviours doubled
o Vomiting to control weight from 0-11.3%
Prediction of weight control from magazine reading
o Chance of weight control behaviours doubles by simply by having read weight control related magazines. Triples once you get to those who read often. Similar but weaker results with bingeing behaviour
Body dissatisfaction in young girls after exposure to barbie
o Girls shown pictures of barbie, emme (plus sized model (16) who has a doll and control (animals)
o Body dissatisfaction lower for those who played with barbie and higher for those who played with emme. By 8 (year 3), effect is lost because girls find the dolls childish.
Exposure to magazine models on body satisfaction in women high and low self esteem
o Teenage girls 14-18.
o Girls shown pictures of thin size models, average size women or control (fonts/colours)
o Divided girls into high self-esteem vs. low self-esteem
o Then measured perceived vs. ideal body size.
o Those with low self-esteem had a greater body dissatisfaction, girls with high SE may be positively affected and motivated.
Classification of eating disorders
risk factors for eating disorders - textbook
being overweight
high social class
acculturation to the majority
ethnic differences in the US
white males prefer thinner women than african american males and this may contribuite to lower rates of eating disorders amongst AA women.
those who diet are in fact at a greater risk of
bingeing
interesting finding of the study on dietary restraint during WWII
the male subjects became obessed with food and eating.
this is also seen in AN patients becoming chefs for family and hoarding food.
may be a result of dieting or starvation alone
