CLP 4110 Eating Disorders FSU - Exam 1

Sociocultural Influences

- Eating disorders are more common in industrialized nations and are more common in women than men

- Eating disorder incidence has increased during the 20th century

Cultural Influences

- The emergence of the thin ideal in industrialized nations in the 20th century particularly influenced women

Changing Beauty Ideals

- Miss America contestants were smaller than most women in the US and were not representative of average body weight

- Winners of the pageant after 1970 all had weights lower than other contestants

- Being thin gave more of a competitive image for being seen as more beautiful

- Starting in 1970, all of the winners were medically underweight

Thin Ideal in History

- Not new to the latter half of the 20th century - i.e. the "flapper" in the 1920's

- Dip in incidence of AN during the 1950's (era of Marilyn Monroe)

- times in which women are more likely to work outside the home are associated with dinner ideals of beauty

- Financial prosperity and abundance of food linked ti associating beauty with thinness

- If there was a lack of food, only the poor would be skinny

- BMI associated with socioeconomic status (more money and higher education associated with weighing less)

Thinness is a commodity

- In order to be successful, you need to be thin

- Created market for all the dieting and detox products

- Get people to spend more money on being thin to help the economy

Body Image

- Women faced discrepancy between their current weight/shape and ideal weight/shape

- Ideal weight is underweight, and current weight is overweight for average US women

- Body dissatisfaction makes sense in the current climate

Rodgers et al. - Background

- The extreme thin ideal promoted by the fashion industry implicated in etiology of eating disorders

- Extreme thin ideal is also a health risk for models in the fashion industry

- Following the deaths of several models, several countries have passed laws requiring minimum BMI's or clothing sizes to reduce mortality

- Effective policy change requires involvement of key stakeholders

Rodgers et al. - Objective

- Use triggers to action framework to effect change by asking models about:

1. Pressure to lose weight

2. Use of unhealthy weight control behaviors

3. Impact and feasibility of specific policy proposals aimed to improve working conditions and health of models

4. Exploratory questions to examine the association between model characteristics (age, type of modeling, BMI, race/ethnicity) and perception of policy change

Rodgers et al. - Hypotheses/Methods

+ Hypotheses

- Models would endorse pressures from agents/industry to lose weight

- Models who received pressure to lose weight would be more likely to use unhealthy weight control behaviors

- Factors that increase work insecurity may influence perceived impact/feasibility

+ Methods

- participants: 85 female fashion models, 18 years and older

- Completed online surveys

Rodgers et al. - Results

+ BMI

- Mean = 17.41, range 14.5-26.5

+ Majority endorsed pressures to lose weight in the last year

- 62.4% were asked to lose weight or change body shape/size

- 63.1% were told they would not get work unless they lost weight

- Unhealthy weight control behaviors were common in models and all but vomiting were associated with pressures to lose weight for work

Rodgers et al. - Impact and Feasibility

- Being given food and a break was the only thing that was rated as both positive and feasible

- Nothing else was rated as very feasible

+ Correlates of impact and feasibility

- Impact: higher BMI associated with higher ratings for setting minimum BMI, regular medical check-ups, and preventing firing due to weight changes

Rodgers et al. - Discussion

- Models who were most likely to be helped by policy changes evaluate them least positively

- Internalization of the thin ideal

- Eliminate factor that increases success fir for naturally thin women in industry

- Minimum BMI may be undermined by last minute extreme efforts to lose weight prior to fashion shows

Stigma against obesity

- Not only is it good to be thin, its bad to be fat; this cultural belief goes beyond issues of medical health

- Belief that people can control their weight contributes to blaming overweight people for being overweight

- Overweight people thought to be lazy, stupid, lonely, weak, and dependent

Weight Stigma

- Preferred playmate in elementary school (ranking):

1. Normal healthy child

2. Child in a wheelchair

3. Child with leg brace and crutches

4. Child missing a left hand

5. Child with left side of face disfigured

6. Obese child

- Social denigration of obesity begins at a young age

Obesity and socioeconomic status

- Obesity is more common among individuals of low SES (lower education, lower occupational attainment, lower income)

- May be driven in part by increased density of fast food restaurants/mini marts in poor neighborhoods

- Employers are less likely to hire someone that is overweight

- People who are overweight also receive worse care in health settings

Implicit association test

- Implicit views of weight

- Do you implicitly identify yourself with being light or heavy?

- Implicit self-esteem measured as well

Grover, Keel, and Mitchell (2013) - Participants

- 22 normal weight women

- 20 normal weight men

- 20 overweight/obese women and 21 overweight/obese men

Grover, Keel, and Mitchell (2013) - Methods

- Height and weight were objectively measured

- Completed IAT to assess: implicit weight attitudes, implicit weight identity, and implicit self esteem

- Completed self report (explicit) measures of weight attitudes and weight identity

Grover, Keel, and Mitchell (2013) - Results

- Men and women, regardless of their own weight, endorsed explicit negative attitudes about overweight and demonstrated implicit association between "bad" and heavy

- Men and women provided accurate explicit descriptions of their own weight

+ On implicit measures:

- Heavy women associated self with heavy and normal weight women associated with light

- Men associated self with light regardless of actual weight

- In women, implicit weight identity was associated with implicit self-esteem

Negative implicit attitudes about fat

- Automatic: often outside conscious awareness

- Universal: also help by health professionals

- Difficult to change for the better

- Easy to change for the worse

- Can influence our behavior without our awareness (ex. how close or far you sit from another person)

Dieting and disordered eating

- In Rodgers et al. dieting was considered an unhealthy weight control behavior

- Girls who diet are 8 times more likely to develop an eating disorder than girls who do not at prospective follow-up

- 70-80% of women with BN report that dieting preceded binge eating (vs. 9-17% who reported that binge eating came first)

- Prospective association between dieting and binge eating found in numerous longitudinal studies

- Dieting leads to binge eating

MN Starvation study Keys and colleagues (1950) - Methods

- Evalluated men physically and psychologically at baseline (all determined to be physically healthy and free of psychopathology)

- Placed men on a diet to reduce weight to 75% of previous weight

- Most men were coming back from war very malnourished and starved as a result of being prisoners of war

- It could be unsafe to just reintroduce them to all the food they could want

- Trying to understand metabolism and learn about healthy ways to reseed these men

MN Starvation study Keys and colleagues (1950) - Physical findings

- Initial weight loss occurred rapidly

- Continued weight loss slowed dramatically

- Men's bodies were resisting additional weight loss through reduced basal metabolic rate including:

1. slower pulse

2. decreased respiration

3. decreased blood pressure 4. decreased temperature

- BMR accounts for 70-75% of body's energy expenditure

MN Starvation study Keys and colleagues (1950) - Behavioral findings

- With weight loss, men experienced increased depression and apathy, food related rituals and obsessions, and onset of binge eating episodes in 29% of men after study

Set-point Theory

- To withstand periods of famine, humans and other animals have evolved both physiological and behavioral weight defending mechanisms

- We are designed to not let ourselves starve to death

- Weight suppression ( difference between adult highest and current weight) predicts bulimic disorders/symptoms in several studies

Caveats

- Dieting does not precede binge eating in 8-17% of women with BN

- Dieting does not lead to binge eating in AN restricting subtype (though majority who don't gain weight do start binge eating)

- Dieting does not lead to eating disorders in most individuals (starvation didn't even lead to binge eating in most participants of the MN starvation study)

Psychoanalytic Theory and Anorexia Nervosa

- The tern nervosa reflects psychoanalytic understanding of underlying causes of An as a form of neurotic anxiety; when term was first introduced in 1874, not now

- Symptoms are defenses to reduce neurotic anxiety over conflict between ego and id

- Developed during the pre-oedipal stage where primary gratification is through oral drives (ages 0-1)

- Self starvation interpreted as fear of oral impregnation which is interpreted as a rejection of the feminine role

- Evidence: maturity fears measured on the EDI predicts onset of an eating disorder at 10 year follow u and a lower likelihood of recovery from AN during treatment

What parents did wrong according to psychoanalytic theory

- Mom is aggressive/castrating (poor role for femininity)

- Dad is kind/passive (good model for femininity except for being a guy)

- Conflict emerges in adolescence when girls are supposed to adopt more adult and sex specific roles

- Maturity fears drive self-starvation, attempt to revert to a prepubertal state

- Cant grow up to be like mom or dad, so would rather not grow up at all

Feminist psychodynamic theory

- Parents are still partially to blame

- Mom is controlling because she is powerless outside her home

- Dad is distant/passive

- Child defines her self-worth based on how she perceives others reactions to her and learns that power can only be achieved by attaining a relationship with a man

- Problems emerge in adolescence because the girl doesn't know how to socialize with men and enters a vicious cycle of attempting to literally fit in by changing her weight

- Fear is that they are not ready to become women or mothers

Bruch's psychodynamic theory

- Mothers still suffer blame

- During daughters infancy, mother did not respond appropriately to daughters cues for hunger, fatigue, distress

- Because daughter was unable to change mothers behavior, infant adapts to accept what mother offers

1. apparent perfection

2. profound sense of ineffectiveness

3. fundamental inability to distinguish among drive states, known as alexithymia (inability to read emotions) or poor interceptive awareness

- When adolescence places pressures on girls to develop autonomy, they feel overwhelmed and rebel against source of maternal nurturance, which is food

Bruch's psychodynamic theory - evidence

- Cross-sectional studies of patients with eating disorders show greater perfectionism ineffectiveness, and poorer interoceptive awareness and greater perfectionism predict eating pathology

- Moms who have had eating disorders are less responsive to infant cues, and infants respond by disengaging to reduce conflict, resulting in lower infant body weight compared ti infants to control moms

- Longitudinal follow up of these infants when they were 5 and 10 years old supports that meal related conflict at 5 year follow up predicted disordered eating at 10 year follow up

Family Systems

- Adolescents withAn is the "identified patient" but illness is systematic (problem with family not individual)

1. AN families are enmeshed, overprotective, rigid, and conflict avoidant

2. This created problems when child enters adolescence because family is unable to adjust to child's need to develop autonomy

3. Because family conflict cannot be expressed openly, it is expressed bodily, through self starvation in AN

Family systems - evidence

- Retrospective follow back design supported that mothers of daughters with AN were more protective compared to mothers of controls

- AN mom were more likely to:

1. Provide near exclusive care

2. Express greater distress at first separation

3. A later age for letting their daughter sleep over at another house

Learning

- Eating disorders run in families

- Due to family environment or genetics?

- Children learn disorders eating attitudes and behaviors from their parents

- Social learning through modeling (ex. mom is constantly dieting)

- Direct instruction (e. mom tells girl she is too fat and puts her on a diet

20 year prospective follow up of college students (Klein et al. 2017) - Methods

- College students (N= 799, 71% female)

- Completed surveys in college and at 20 year follow up

- Reported on their own drive for thinness at both time points as well as baseline reports of frequency of mother dieting, father dieting, mother commenting on student's weight/eating, and father commenting on weight/eating

- Examine prospective association between modeling (dieting frequency) vs. direct comments on changes in drive for thinness

20 year prospective follow up of college students (Klein et al. 2017) - Results

+ At baseline

- Men and women did not differ in reports of parental dieting, and both reported that moms dieted more than dads

- Women reported getting more comments from both their moms and dads on their own weight and eating

+ At 20 year follow up

- Moms dieting frequency and dad's comments predicted increased drive for thinness in women

- No association found in men

Social learning and peers

- During adolescence peers gain increasing importance as role models in social learning

- 93%of college women report engaging in "fat-talk"

- Having a college roommate who dieted frequently doubled risk of using self induced vomiting to control weight 10 years after college

Social contagion theory

- Crandall (1988) study of similarity among sorority sisters for binge eating in 2 sororities at the beginning and end of academic year

- The sorority sisters converged on levels of binge eating

- Popularity was associated with how close you were to the mean level of binge eating in your sorority

Peer selection and socialization

- Zalta and Keel (2006) study of similarity among selected peers, unselected peers, and non-peers on self esteem, perfectionism, and bulimic symptoms as a consequence of duration of contact and period of separation over summer break between spring and fall of a calendar year

- One became like the people you chose to be with

- After Sumer break, went back to your own level of bulimic symptoms

Mabe, Forney, and Keel (2014) - Background

- With more than a billion users, Facebook represents a ubiquitous merging of two known social influences, media, and peers

- Prior research established correlation between FB users and disordered eating

Mabe, Forney, and Keel (2014) - Why?

+ Social comparison theory

- Upward social comparisons contribute to body dissatisfaction and are more powerful when made to peers

+ Objectification theory

- Women who come to view their bodies as objects rather than agents experience increased pressure to conform to the thin ideal

- Or maybe women with higher levels of disordered eating are drawn to using FB more often

Mabe, Forney, and Keel (2014) - Methods

+ Study 1:

- Self repot survey of 960 women regarding FB use and disorders eating

- Fall semester 626 women

- Spring semester 224 women

+ Study 2:

- Experiment in which 84 women who endorsed using FB on a weekly basis randomly assigned to one of two conditions:

1. Use FB account for 20 min as they normally would

2. read about the ocelot on wikipedia and watch a brief youtube video on it

- Complete surveys about FB use

Mabe, Forney, and Keel (2014) - Results

+ Is there a link between frequency of FB use and disordered eating?

- Yes, both semesters more frequent FB use was significantly correlated with higher levels of eating pathology

+ Does FB use influence risk factors for eating disorders?

- Yes, preoccupation with weight and shape maintained in FB condition compared to controls and anxiety increased in FB condition to controls

+ Facebook use patterns

- Greater than 95% of college women use FB weekly

1. Mean frequency is 6.5 days a week

2. 76 min a day broken into 3-4 20 min sessions

3. 87% use FB application on their smart phones

4. 67% prefer to look at photos when using Fb

+ Correlated of disordered eating

- Participants with highest levels of disordered eating endorsed greater importance of receiving comments on photos, comments on status, and likes

+ Facebook did not cause eating disorders, and eating disorders do (or do not) influence likelihood of teaser FB use

Mabe, Forney, and Keel (2014) - Conclusions

- FB use is associated with eating pathology in college women

- FB influences greater risk factor for eating disorders

1. reinforces weight and shape preoccupation

2. increases anxiety

- Specific patterns of FB use appear particularly problematic

1. Social comparison to peers (comparing photos)

2. Self-objectification (the quest for likes)

Learning - Final Thoughts

- Peer influence does not have to be a bad influence

- Concluding that peers grow more similar to one another on bulimic symptoms over time means that sine peer groups become more similar for lower scored

- Concluding that girls who spend more time un-tagging heir own photos have higher disordered eating means that girls who allow fewer flattering photos to remain posted and tagged have lowered disordered eating

- Peers can create a positive social environment to protect one another from eating disorders

Psychological factors

+ In a modern, Western context where thinness is idealized and fatness is denigrated, why do only some people develop eating disorders?

- social spheres of influence magnify cultural messages (family, peer, group, extracurricular activities)

- There are individual differences in vulnerability to these social risk factors

+ Temperament and personality

+ Cognitive and affective processes

- Learning, attention, perceptual and cognitive distortions

Personality traits

- Enduring patterns of perceiving, relating to, and thinking about the environment and oneself that are exhibited in a wide range of social and personal contexts

- Lens through which cultural messages could be magnified and impact behaviors, including seeking out environment that further reinforce disordered eating behaviors

Five factor model of personality

1. Neuroticism: negative emotionality (anxious vs. calm)

2. Extraversion: positive emotionality (socially outgoing vs. reserved)

3. Openness to experience: flexible vs. conservative/conventional

4. Agreeableness: altruistic vs. self-oriented

5. Conscientiousness: self-disciplined/hard working vs. freewheeling/lazy

- Neuroticism and extraversion are the two big ones

- Where you fall for one factor does not indicate where you will fall for another

Temperament

- We are born with this biologically based orientation to our environment

1. Neuroticism: harm avoidance

2. Openness to experience: novelty seeking

- Harm avoidance: behavioral inhibition system (BIS)

Novelty seeking: behavioral activation system (BAS)

- Reward dependence: tendency to continue rewarded behaviors even when cost of behaviors increase

- Persistence: tendency to continue behavior despite frustration or fatigue

Temperament and personality findings in eating disorders - AN

- High harm avoidance

- Low novelty seeking

- High persistence

- High negative emotionality

- Low positive emotionality

- High constraint

Temperament and personality findings in eating disorders - BN

- High harm avoidance

- High novelty seeking

- Low positive emotionality

- Low constraint (compared to AN)

Eating behaviors vs. eating disorders

- Differences between AN and BN also seen in comparisons of AN-restricting and AN-binge/purge subtype

-Constricted/overcontrolled personality particularly true for AN -restricting

- Impulsive/emotionality dysregulated personality found in AN-binge/purge and BN

- High perfectionism present across eating disorder diagnoses

Personality and eating disorders: Western and Harden-Fischer (2001) - Methods

- Participants were 103 therapists (psychiatrists and psychologists)

- Described a current ED patient or one treated in the past 6 months

- 1/3 asked to describe female patient with AN

- 2/3 asked to describe female patient with BN

- Give info about themselves and patient's ED symptoms

- Perform Shedler-Western Assessment Procedure Q-Sort (SWAP-200); 200 cards with descriptive statements ('tends to be passive and unassertive"); sort cards into one of 8 piles

Personality and eating disorders: Western and Harden-Fischer (2001) - Results

- People wit AN were high on high function perfectionist and contracted/overcontrolled

- People with BN were highest in high functioning perfectionist and then also showed contracted/overcontrolled and emotion being dysregulated/under controlled

- AN/BN (AN-binge/purge subtype) people were high in constricted/overcontrolled but also showed two other traits

- High function perfectionism is present and high across the board for all three groups

Personality and eating disorders: Western and Harden-Fischer (2001) - Conslusion

- Each diagnostic group includes a mix of personality gestures

- Personality features provide important information for understanding etiology, course, and treatment

- SWAP-200 cluster was more predictive of history of abuse, current level of impairment, and history of psychiatry hospitalization than was diagnosis

- Perfectionism present across all

Learning processes

- From personality to learned behaviors

- Perfectionism may contribute to increased body dissatisfaction, specifically at the gap between current body weight and desire to have a perfect (thin) body

- Body dissatisfaction leads to dieting

- Dieting may be the gateway to all eating disorders through learning

What's wrong with dieting?

- Dieting may lead to initial weight loss which may attract compliments and positive attention (positively reinforcing restricted food intake and weight loss)

- Most diets ultimately fail to produce lasting weight loss

- Fear of weight gain may negatively reinforce restricted food intake or use of more extreme methods to produce weight loss

- Dieting is a prospective risk factor

What's wrong with dieting? - operant conditioning

- Behavior leads to consequence and then the consequence has a feed back on if that behavior will occur again

- Positive reinforcement increases behavior

- Punishment decreases behavior

- Negative reinforcement increases behavior

What's wrong with dieting? - Restrain theory

- In order to follow dietary rules, learn to ignore physiological cues designed to signal when we should start eating and when we should stop eating

- Increases vulnerability for disinhibition (where you lose control over your eating and you eat more that you would have if you never went on a diet in the first place)

- Cognitive disinhibition: thinking about how the diet affects how much you eat

- Affective disinhibition: emotional eating

- Pharmacological disinhibition: you'll eat a lot more after consuming a certain substance, such as smoking or drinking

What's wrong with dieting? - Vicious cycle

- Loss of control overeating, fear of weight gain, dieting (repeats)

- Fear of weight gain, purging, dieting, binge eating (repeats)

- Cycle is maintained through negative reinforcement

Ecological Momentary Assessment (EMA) studies of affect and behavior

- Ecological: during the course of participant's day to day lives

- Momentary: ratings made for that moment (no retrospective recall bias)

- Longitudinal: time frame of weeks not years

- Made momentary ratings (8 times a day for 2 weeks)

- Negative affect was higher on a day that purging occurred than on a day it did not

- When it comes to positive affect, there was a gradual increase on a non-purge day

- Purging early in the day led to a decrease in negative affect later in the day

- Positive affect doesn't increase after purging

- Significant decrease in negative affect after purge, which leads to negative reinforcement for purging

- Increases in positive affect seem to protect people from purging

The power of negative reinforcement

- Negative reinforcement is self-perpetuating even if dreaded consequences would not have occurred (even if eating a donut would not have caused weight gain)

Cognitive dis-inhibitors

- The dis-inhibitor represents an event that caused someone to do the opposite of what they were supposed to be doing

- Perfectionism may contribute to cognitive distortions that increase likelihood of cognitive dis-inhibitor triggering a binge

Dichotomous thinking

- Seeing everything in black and white, if something isn't a success, its a failure

Selective abstraction

- Taking one piece of something and having it stand for the whole

- Ex. most people with AN recognize they are thin but they are able to find one spot on their body that has a little bit of fat, and they use that to represent their whole body

Cognitive factors

- Attention

- Perception

- Evaluation: preferring one thing over another, assigning a positive or negative view of something

- Any of these can influence the development of an eating disorder

Blechert et al. (2010) Study of visual attention in AN and BN - Attentional biases

- All things are not created equal in their ability to capture our attention

- As humans we are inclined to attend more to some things such as money on a sidewalk

- In addition, people differ in what attracts their attention and these differences might contribute to differences in risk for eating disorders

Blechert et al. (2010) Study of visual attention in AN and BN - Background

- Prior research suggests that individuals with eating disorders show attentional biases to words and images that are related to the body

- Individuals with eating disorders show different attentional patterns when viewing their own body vs another's body (negative self-bias) than do individuals without eating disorders (positive self-bias)

Blechert et al. (2010) Study of visual attention in AN and BN - Questions

- Do ED patients show a specific bias towards attending to images of their own body?

- Do attentional biases differ between AN and BN?

- Hypothesized yes to both of these questions

Blechert et al. (2010) Study of visual attention in AN and BN - Methods

- Participants were 19 women with AN, 18 with BN, and 21 healthy controls

- 3 tasks (2 are just to ensure group differences in ability to do the main test of attentional bias, meaning there are not group effects in ability to look at blue or green frame and no differences in ability to recognize own vs. another body)

+ Main test was dot-probe task

- Supposed to look at middle cross, and when they see a blue frame, shift attention to that image

- Are you faster when the target frame is over your own body or a body that is not yours?

+ Dependent variable: latency (delay) between seeing the target (blue) frame

1. Faster when covertly (in peripheral) attending to the body (self vs. other) that cues the target frame

2. So, if participant has no attentional bias, no difference in saccade latency between trials in which self-body cues target (self-target) and trials in which other body cues target

3. If attentional bias is the self, faster on trials where self cues target then when other cues target

4. if attentional bias is to the other (or avoiding the self) faster on trials where self-cues target when other cues target

Blechert et al. (2010) Study of visual attention in AN and BN - Results

- There are significant differences between An, BN, and controls for saccade latency

- AN participants are significantly faster when self-cues target then when other cues target, supporting attentional bias towards self-body not seen in BN or controls

- BN has the opposite trend than AN and controls

Blechert et al. (2010) Study of visual attention in AN and BN - Conclusion

- The more negatively AN patients view their bodies, the more attention they give to their bodies

- Limit opportunities to correct misperception by not using environmental cues of what other people really look like

Molbert et al. (2018) - Background

- AN is characterized by body image disturbance, but prior studies have produced contradictory findings on the nature of this disturbance

1. Several studies support that AN patients overestimate their body size

2. Influenced by instruction

3. May reflect demand characteristics

- Research needed to disentangle visual sensory perceptual distortion (I look fat) from cognitive-affective disturbances (I feel fat)

Molbert et al. (2018) - Methods

- Participants were 24 patients with AN and 24 healthy control women

+ 3 experiments (3rd optional)

1. Accuracy of visual perception of own body and desired size of own body using 3D virtual reality avatar based on body scan of participant's body

a. shown your body and then increased and decreased up to 20%

b. had to choose which one of those is your body (one alternative forced choice)

c. can then adjust body to what your body looks like (method of manipulation

2. Accuracy of visual perception of "other" body and desired size of "other" body using 3D virtual reality avatar based on body scan of participant's body but with altered hair/face/skin color

3. Accuracy of visual perception of own body and desired size of own body using 2D presentation on avatar from experiment 1 on computer screen

Molbert et al. (2018) - Results

1. Actual bodies

- AN = 15.17 BMI

- Controls = 22.07 BMI

2. Estimated body

- AN = 14.26 BMI

- Controls = 21.36 BMI

3. Desired body

- AN = 14.67 BMI

- Controls = 19.97 BMI

+ Difference between actual bMI and estimated BMI represents distortion

+ Difference between estimated bMI and desired BMI represents desired change

+ Actual body compared to desired body represents desired vs. actual discrepancy

Molbert et al. (2018) - Conclusion

- Treatment should emphasize helping AN patients desire a healthy weight

Psychological factors summary

- In a culture that emphasizes thinness and denigrates fastness, individual differences may increase (or protect against) risk for development of eating disorders

- Negative emotionality and perfectionism

- Behavioral traps

- Cognitive processes that emphasize sociocultural risk factors

Biological factors

+ The three C's

- Causes (biological bases)

- Correlations

- Consequences

- Disturbances in eating cause disturbances in biological function, making it difficult to discern causes from consequences

Biology of appetite and weight

- In addition to disturbances of body image, eating disorders involve disturbances in appetite and weight

- Experimental data from animal studies support important biological contributions to appetite and weight regulation

- When ethically feasible, studies of humans support these same biological influences

The hypothalamus

- Very small, 1/300 of total brain weight and only the size of a pea

- Functions include body temperature, emotions, hunger, thirst, circadian rhythms, and controlling pituitary in HPA and HPG axes

Ventral medial hypothalamus

- Helps you know when you are full

- Lesions cause overeating and obesity

- Stimulation or overstimulation causes starvation

Lateral hypothalamus

- Helps you know when you are hungry

- Lesions cause starvation

- Stimulation or overstimulation causes overeating and obesity

Brain activity and neurotransmitters

- Within brain cells, signals are carried electrically

- Between neurons, signals are transmitted by chemicals (neurotransmitters)

- Serotonin (5-HT)

- Dopamine

- Norepinephrine

5-HT and eating disorders

- 5-HT is involved in regulation of appetite, mood, and impulse control

- 5-HT used by neurons in the paraventricular nucleus (PVN) and the medial hypothalamus

- Decreases food intake and weight

Serotonin hypothesis of ED

- AN is caused by over function of 5-HT

- BN is caused by under-function of 5-HT

5-HT and AN

- Study conducted comparing AN patients who are ill and healthy control participants does not support the serotonin hypothesis for AN

- AN ill patients had less 5-HIAA in cerebrospinal fluid, platelet 5-HT receptor binding, 5-HT mediatedprolactim response to fenfluramine than controls did

- Could be a consequence of starvation

- The job the cerebral spinal fluid is to clean out and flush the body

- 5-HIAA in cerebral spinal fluid was a measure of how much serotonin was being used in the brain

- Fenfluramine is used to increase serotonin function in your brain

- If anything, serotonin may be under functioning (but may be cause of starvation)

5-HT and BN

- Studies conducted comparing BN patients who are ill, BN patients who are recovered, and control participants does support serotonin hypothesis for BN

1. Within BN ill: High binge frequency associated with low CSF 5-HIAA

2. BN ill < controls: platelet 5-HT receptor binding and 5-HT mediated prolactin response to fenfluramine

3. BN recovered < controls: Reduced 5-HT2a receptor function

- Could be scar effect (lasting from eating disorder)

- An important maintenance factor possibly, even though we may not be Abe to prove that its a cause

Peripheral control of food intake - body is designed to respond to feedback about nutritional status

+ Body weight

- Ob/ob gene in fat tissue produces leptin

- Higher concentration of fat in body = high concentration of leptin in blood

- Leptin inhibits food intake

+ Gut peptide responses to food intake

- CCK

- PPY

- Ghrelin

Peripheral control of food intake - Leptin

- Genetic mutation makes mice unable to make leptin, and these mice end up overeating, having low metabolism, and they get obese

- Development of diabetes in adulthood

- Daily injections of leptin can help with this

Peripheral control of food intake - Leptin and AN

- Leptin reduces food intake

- AN ill < controls (consequence of low weight)

- An recovered = controls: AN reach normal levels before reaching normal weight

- Any differences seem to reflect consequences of starvation and should not promote weight loss of self-starvation, most should combat this effect

Peripheral control of food intake - Leptin and BN

- BN ill < controls: consequence of dietary restraint

- BN recovered is less than or equal to controls

- Most differences during illness may be consequences of ED, they could maintain illness

Peripheral control of food intake - Gut peptide response

- Participants consume a standardized test meal of 900 kcal in 600g of commercially available liquid meal (ensure plus) after an overnight fast

+ Blood draws

1. Ghrelin: hunger hormone

- Ghrelin levels drop significantly after you eat, and then gradually come back after 2/3 hours after a meal

- Each peak gets lower and lower

2. Cholecystokinin (CCK): satiation signal

- We sometimes eat too much and feel overly full. because we get too much food in before satiation signal kicks in

3. Glucagon-like peptide 1 (GLP-1): satiation signal

4. Peptide tyrosine tyrosine (PYY): satiety peptide, controls time between end of one meal and star of another and delays when you are going to eat again

Genetic influences

- Unlike neurotransmitters or neuropeptides, a persons genetic makeup is not influences by their eating or weight

- Twin studies support significant influence on risk for eating disorders

- Heritability for AN - up to 76%

- Heritability for BN - up to 83%

Twin studies - types of twins

+ Identical (monozygotic)

- Come from one fertilized egg that splits

- Genetically identical (share 100% of genes)

+ Fraternal (dizygotic)

- Come from two operate eggs that are fertilized at the same time

- Genetically similar as siblings (share on average 50% of genes)

Twin studies - study design

+ Compared similarity (concordance) between co-twins for characteristic

- If genes contribute to characteristic, then MZ c-twins will be more similar to each other than DZ co-twins

+ Examples for each factor:

- A: genetics (ex. genotype for the Bcl 1 gene)

- C: shared environment (ex. parents modeling of dieting behaviors)

- E: non-shared environment (ex. sexual abuse at work)

Twin studies - how each factor would influence similarity between siblings (A)

- When genes influence outcome, degree of genetic similarity will be associated with degree of similarity in outcome

- Eye color is 100% genetic, just considering blue vs. brown eye, single genetic locus with brown as the dominant allele

- MZ twins show 100% similarity for eye color (identical twins always have same eye color)

- Regular biological siblings show less than 100% similarity for eye color

- Adopted siblings are no more similar to each other in eye color than to random person from general population

Twin studies - how each factor would influence similarity between siblings (C)

- When shared common environment influences outcome, degree of similarity will be associated with amount of environment the is shared

- Mom insisting on low-fat meals represents 100% shared environmental influence

- MZ twins show 100% similarity for moms low-fat meals

- Z twins show 100% similarity for moms low fat meals

- Adopted siblings and regular siblings show 100% similarity

- members of the general population only show random similarity

Twin studies - how each factor would influence similarity between siblings (E)

- When non shared environment influences outcome, this makes individuals dissimilar to one another

- Within MZ twin pair, if twin A experiences sexual abuse, this makes them feel out of control and impacts er eating and weight

- However, this could not influence twin B

- Same patterns play out at different levels, only individuals who experience the specific environmental stressor demonstrate outcome, and this does not show any association with genetic factors or shared environmental factors

Eating disorders and twins

- Concordance for eating disorders is higher in MZ compared to DZ twins post-puberty

- Twins are not at increased risk for eating disorders

- Supports representatives assumption

- Eating disorder prevalence is not high in MZ compared to DZ twins

- You could conclude that genes contribute to the development of bulimia nervosa if concordance rates were 70% in MZ twins and 40% in DZ twins

Klump et al. (2009) - Used an adoption study to examine:

- Influence of genetic factors on disordered eating (A = additive genetic factors)

- Influence of shared environmental factors on disordered eating (C = shared or common factors)

- Influences of nonshared environmental factors on disordered eating (E = non shared factors)