Explanations for Anorexia Nervosa and Obesity

• affects 1/250 women
• affects 1/2000 men
• usually occurs between 16-17 years of age
• dramatic weight loss, huge reduction of food intake, increase in exercise
• DSM has 3 main characteristics:
  • restriction of energy intake
  • intense fear of gaining weight 
  • body image distortion
• loss of menstruation in females

Genetics

• families
• candidate genes
• Genome-Wide Association Studies (GWAS)

Neural

• neurotransmitters
  • serotonin
  • dopamine

Families

• first degree relatives of anorexia sufferers are 10x more likely to be at risk than non
• monozygotic twins have higher concordance rates of AN than dizygotic twins
• never 100%

Candidate Genes

• Zeeland did a gene association study, comparing 152 genes
• found that epoxide hydrolase Ephx2 gene
• Ephx2 codes for an enzyme involved with cholesterol metabolism
  • people with AN often have abnormal levels of cholesteerol 

Genome-Wide Association Studies

• look at genes collectively, rather than individually
• Boraska found that there were no particular genetic variations that were significantly related to AN

Against

• no one gene can be solely responsible for AN as it is such a complex problem
• GWAS shows no relationship of genes to AN
• concordance rates are never 100%
• AN can be cured, but genes are unchangeable
• diathesis-stress model suggests that genes only create vulnerability

Serotonin

• people with AN tend to initially have high levels of serotonin 
• serotonin causes obsessions and anxiety, which is not helped by SSRIs
  • SSRIs block the reuptake of serotonin, making more available to re-stimulate the post-synaptic neuron)
  • Bailer and Kaye suggest  low levels of serotonin metabolites (e.g 5-HIAA) (for the breakdown of serotonin) are associated with AN - leads tto high serotonin levels
• malnutrition-related serotonin changes may decrease anxiety, which in turn leads to anorexia nervosa

Dopamine

• low levels are associated with anorexia nervosa
• dopamine metabolite HVA (homovallic acid) in low levels is associated with AN patients
• high levels are associated with anxiety, so food is avoided to lower dopamine (eating-assocaited dopamine) levels

For

• Bailer - found high serotonin levels in binge/purge anorexia patients, as well as having high anxiety
• Balier - administered chemical into patients to increase dopamine; controls experienced euphoria and AN patients experiences anxiety
• Kaye - found that HVA levels were lower in anorexia patients than in controls

Against

• anorexia is complex, and so just serotonin or dopamine is reductionist
• cause and effect debates of hormones
• Nunn - GABA and noradrenaline are also significant, possibly more so than serotonin and dopamine

Family Systems Theory

• Minuchin
  • Enmeshment, Overprotectiveness, Rigidity and Conflict Avoidance
• Bruch
  • autonomy and control

Social Learning Theory

• modelling and vicarious reinforcement
• media
• Dittmar

Cognitive Theory

• bad cognitions and irrational beliefs lead to misinterpretation and overestimation
• silhouette research
• cognitive inflexibility

Minuchin - the family systems theory (specifically between mother and daughter)

• Enmeshment - overly involved with each other; no privacy and lacks boundaries
• Overprotectiveness - family is controlling and the child feels they will never be autonomous 
• Rigidity - strict beliefs and loyalty leading to lack of flexibility to adapt to new situations
• Conflict Avoidance - low tolerance for conflict and difficulty resolving problems

Bruch - mother-daughter relationship

• mother is intrusive and overbearing 
• daughter feels that she will never achieve autonomy
• daughter's control over her own food makes her feel more autonomous and in control, in general (the thinner she is, the more percieved control she has)
• the outcome is a distorted body image and lack of hunger

For

• Robin - found that 6/11 AN patients recovered with Behavioural Family Systems Therapy (BFST)
• Latzer - daughters with AN had more difficulty discussing topics of disagreement 
• explains why anorexia usually emerges during adolescence and is significantly more common in females

Against

• cause and effect - parents become more overprotective as patients lose weight, out of concern
• anorexia occurs outside of families
• does not cover the role of the father or siblings
• reductionist - does not cover men/boys who have anorexia

Social Learning Theory (SLT)

Modelling

• imitating behaviour of a model (real or symbolic)
• identification to internalisation
• template modifies the social norms in their environment, establishing what is acceptable

Vicarious Reinforcement

• model is rewarded positively (e.g compliments/fame)
• model is critisised negatively (e.g body shaming)

Media

• transmitter of unrealistic cultural ideals (e.g size 0)
• identification with celebrities (the wanting to be glamorous)

Dittmar

• 162 British girls (5-8 years old)
• split into 3 groups, each shown a storybook of photos 
  • either of Barbie, Emme or stock-photos
• Barbie group had the highest rates of body dissatisfaction and lowest self-esteems
  • assessed via silhouette colouring-in
  • they identified with Barbie because of the glamour associated with her body
  • they internalised the 'perfect' proportions of Barbie and began comparing themselves

For

• Chisuwa and O'Dea - increased AN in Japan over 40 years from Western cultural influences
• explains bigorexia in men - male dolls are equally unrealistic and muscular
• westernised ideals spread in China after Britain gave back Hong Kong
• can be used for treatment - counter-vicarious reinforcement

Against

• diathesis-stress model - genes play a role and there may be other stressors, as not all media-users have AN
• methodology issues with Dittmar's study (only young girls observed)

Cognitive Disorders

• disturbed perceptions of body image (core pathology)
• Murphy - cognitions and behaviours leading to overestimation and misinterpretation of emotions as feeling fat, low self-esteem
• Williamson - AN patients were significantly less accurate in estimating their silhouettes

Irrational Beliefs

• defy logic, automatic negative thoughts (Beck)
• perfectionism: critical, increasingly high standards that are never reached because they are always raised (Hewitt), record keeping

Cognitive Inflexibility

• (Treasure and Schmidt) - Cognitive Interpersonal Maintenance Model
  • AN patients have problems set-shifting and stay in the same mindset for all tasks
  • use the same cognitions, that are useless in new tasks
  • after dieting, anorexia forms as the patient can not switch thinking to 'I have reached a good weight' - they continue to see themselves as needing to lose weight

For

• application to CBT treatment
  • Dalle Grave = enhanced CBT lead to weight gain and better body image
• Sachdev - did fMRIs on AN patients and controls and found that AN patients had little activity in the parts of their brains associated with attention when shown images of their own bodies - suggests that AN is based on distortions and not reality
• Halmi - found that childhood perfectionism was a predictor for anorexia nervosa

Against

• high drive for perfectionism may be genetically determined (predisposition)
• causation issue of whether bad cognitions cause AN or whether AN causes bad cognitions

• excessive body fat
• long-term imbalance between energy intake and energy output
• most common estimate is BMI (Body Mass Intake) = kg/m2
• BMI of over 20 is obese
• premature death an diability is caused by obesity

Genetics

• genetic models
• twin studies
• adoption studies
• polygenic determinism

Neural

• hypothalamus
• leptin
• serotonin
• dopamine

Genetic Models

• predict probability of obesity heritability in children
• 0 obese parents = 7% chance
• 1 obese parent = 40% chance
• 2 obese parents = 80% chance

Twin Studies

• monozygotic twins raised apart compared to dizygotic twins raised together
• Maes - monozygotic twins is 74% and dizygotic twins is 32%

Adoption Studies

• heriability comparison of biological and adoptee parents (biological vs. environmental)
• Stunkard - correlation of weight of child and birth parents (none with adoptee parents)

Polygenic Determinism

• Locke - 97 genes account for only 2.7% of BMI variation 

Against

• BMI of body builders is usually over 30 - doesn't account for muscle mass
• probability rates change considerably over time and place 
  • much higher chance of obesity in the city than in the countryside
  • in 1993, the general chance was 13% and in 2013 it was 36%
• Elks - genetic influence on BMI varies with age
• Paracchini - found no relationship between obesity and the LEPR gene that affects the release of Leptin
• twin studies never have a 100% concordance rate, so there must be other influences

Hypothalamus

• damage to the arcuate nucleus or the LH/VMH leads to overeating

Leptin

• secreted by fat cells (warns when full), and disruption to its secretion leads to obesity

Serotonin

• normal serotonin levels regulate eating behaviour via hypothalamus inhibition
• low levels of serotonin cause inaccurate satiety signals
• dysfunctions can be caused by stress or by co-morbid disorders
• low levels = cravings for high-energy food via disinhibition of eating

Dopamine

• Wang: obese individuals had fewer dopamine receptors (hypothalamus, hippocampi, etc)
• lower dopamine stimulation means it can not perform eating-associated pleasure
• to compensate, sufferers overeat to activate reward centre (compensate)

For

• treatment application to neurotransmitter/hormone injections to help obesity
• Baylis - lesions on the hypothalamus lead to obesity in rats
• Ohia - mice with 2C serotonin receptors had late-onset obesity

Restraint Theory

• Herman and Polivy
• consciously limiting and categorising food
• results in a paradoxical outcome: abnormally more preoccupied with food

Disinhibition

• actively ignore physiological indicators of hunger
• restraints are vulnerable to internal and external cues = disinhibitors = binge
• going against their plan once leads them to disinhibit totally and lose control

The Boundary Model

• Herman and Polivy
• restraints have lower biological hunger boundary and higher biological satiety boundary
• greater space on the continuum for social and cultural influence
• self-imposed boundaries are easily broken = the 'hell effect' = all or nothing thinking = binge

For

• useful info for diet schemes = focus on slow, healthy eating (not restrained)
• Wardle and Beales: restrained dieters ate more calories (and disinhibited) more under observation than the non-diet and exercise controls
• Boyce and Kuijer: restrained dieters shown images of (media) models binged the most out of all groups due to these being external cues of disinhibition

Against

• Savage: found women who went on restricted diets in a longitudinal study lost weight
• different types of restraint: felxible and regid (flexible is less likely to cause disinhibition)
• deterministic: not all restraints may be vulnerable to internal/external cues; depends on their locus of control
• a huge proportion of restrained dieters are anorexic - this does not lead to disinhition, and when it does, it heads to purging (not covered)
• only explains obesity in a form of extreme dieting - obesity has therefore occured before diet (causal issues)

Psychological Factors

Success can only occur if:

• dieter has a model of obesity on the basis of behaviour
• dieter avoid denial
• dieter does not use food for reward
• dieter gives themself a new 'identity' as a slim/healthy person

Attention to Detail

Proposed by Redden

• make healthy food less boring by adding colour and variety
• found that people made to eat 22 jellybeans became bored more quickly when the jellybeans were labelled with just numbers, as opposed to a number and a flavour description

Spiral Model

• Heatherton and Polivy
• dissatisfaction = low esteem = restriction = disinhibition = weight gain = link to deficiency
• harder restriction = distress = vulnerable to cues  = metabolic changes = downward spiral

Ironic Processes Model

• Wegner (research: 'don't think of a white bear')
• dieters become more preoccupied with food (forbidden food stands out)
• distraction takes up cognitive capacity and energy = obessessive and exhausted = disinhibit

Restraint, Disinhibition and the Boundary Model

• beaviour is under congtive control = susceptible to cognitive biases and distortions
• vulnerable to cues which leads to all-or-nothing thinking
• do not regulate eating on biological indicators = suppass personal boundaries = disinhibtion = the hell effect

For

• application to dieting schemes: eat healthily, slowly, and with variety
• diets can be successful if they are designed for weight maintenance, not weight loss
• Adriannse: dieters shown dieting intentions ("I will NOT eat chocolate when I am sad) linked the "sad" with "chocolate" and ate more calories under observation than controls

Against

• minimal effects of ironic processes - the research is not directly generalisable
• ability to stick to diets may be based on the locus of control
• attention to detail gives way to adding more unhealthy substances such as sauces and cheese
• uncertainty over where anorexia fits in terms of dieting - it is not explaned by dieting success or failure