information processing biases in muscle dysmorphia and anorexia nervosa
TRANSCRIPT
INFORMATION PROCESSING BIASES IN MUSCLE DYSMORPHIA AND ANOREXIA NERVOSA
SCOTT GRIFFITHS
PROF STEPHEN TOUYZ
DR STUART MURRAY
PROF DAVID ALAIS
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Men are no longer “immune” to eating disorders
› Men no longer "immune" to eating and body image disorders
- 15-30% of anorexia and bulimia diagnoses (Hoek & Hueken, 2003; Hudson et al. 2007)
- 30-40% of binge eating disorders (Muise et al. 2003)
- 25% of early onset eating disorders (Madden et al. 2009)
- 100% increase in binge eating, purging and strict dieting from 1995 to 2005 (Hay et al. 2008)
- Young Australian males rate body image as their most significant concern (Mission Australia, 2007, 2010)
- Men with EDs feel that society believes EDs to be a "female issue" (Robinson et al. 2012)
- "Overlooked, understudied and underreported" (p464, Greenberg & Schoen, 2008).
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Men want to be lean and muscular, not “thin”
› The ideal Western male body (as desired by most men)
- V-shaped torso (Pope et al. 2000)
- Broad shoulders, narrow waist
- Well-developed, visible musculature
- Especially in the upper body (chest, arms, shoulders)
- Big biceps especially important (McCreary et al. 2006)
- 6-pack (Nikellen et al. 2012)
› Men pursue a muscular ideal, not a thin ideal (Bergeron & Tylka, 2007)
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What’s causing all this?
› The media is probably at fault.
- Action figures have gone from regular-guy to jacked (Baghurst et al. 2006; Pope et al. 1999)
- Male analogue for barbie dolls getting thinner and bustier.
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What’s causing all this?
› The media is probably at fault.
- Video game characters promulgate the hypermuscular male ideal (Barlett & Harris, 2008)
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What’s causing all this?
› On campus at the University of Sydney
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Not yet classified an eating disorder.
Muscle dysmorphia (Pope et al. 1997)
› Originally named "reverse anorexia" (Pope, Katz & Hudson, 1993)
› Criteria
- Preoccupation with being lean and muscular
- At least 2 of the following:
- Giving up important actities due to a compulsive need to work out and diet
- Avoiding body exposure/enduring body exposure with intense anxiety and distress
- The preoccupation with body size/musculature causes impairments in important activities
- Continuing to work out, diet or use steroids/PEDs despite knowledge of adverse physical or psychological outcomes
- Not better accounted for by anorexia nervosa or body dysmorphic disorder.
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The drive for thinness taken to the extreme
Anorexia nervosa
› Criteria
- A refusal to maintain body weight at or above a minimally normal weight for age and height (BMI <= 17.5)
- Intense fear of gaining weight or becoming fat, even though underweight
- Disturbance in the way in which one's body weight or shape is experienced, undue influence of body weight or shape on self-evaluation, or denial of the seriousness of the current low body weight.
- In post-puberty females, amennorrhea (no period for at least 3 conseuctive menstrual cycles
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› Set shifting difficulties (Danner et al. 2012; Darcy et al. 2012; Oldershaw et al. 2011; Roberts, Tchanturia & Treasure, 2012; Tchanturia et al. 2012)
- An inability to adapt to changins to situational demands
› Weak central coherence (Danner et al. 2012; Harrison et al. 2011; Lopez et al. 2009; Oldershaw et al. 2011; Southgate et al. 2008).
- A preferential bias for processing detail at the expense of global processing
› Thought to be traits, not states (Kanakam et al. 2012; Danner et al. 2012; Roberts, Tchanturia & Treasure, 2012; Tenconi et al. 2010).
› Incorporated into recent aetiological, maintenance and treatment models of eating disorders (Baldock & Tchanturia, 2007; Schmidt & Treasure, 2006; Southgate & Tchanturia, 2005).
Information processing biases in the eating disorders
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› Studies of information processing biases almost always performed on women, using measures that are oriented toward the thin-ideal.
› No study has investigated information processing biases in men with anorexia, or men with muscle dysmorphia.
› Furthermore, no study has investigated information processing biases as they relate to the predominant male experience of body dissatisfaction
- I.e., Insufficient muscularity and muscularity-oriented disordered eating.
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› Study 1
- "Information processing biases in muscle dysmorphia and anorexia nervosa"
› Clinical population
› Participants
- 25 men diagnosed with AN
- 25 men with MD
- 25 controls
Two studies on set shifting difficulties and weak central coherence
› Study 2
› "The drive for muscularity and muscularity-oriented disordered eating in men: The role of set shifting difficulties and weak central coherence
› Non-clinical population
› Participants
- 91 male undergraduates
- Fluent in English
- No current or previous diagnosis of depression, OCD,
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› Participants
- 91 male undergraduates
- All fluent in English
- Mean age of 20
- Mean BMI of 23
- Mean predicted IQ of 109
- No current or previous history of an eating disorder
- No current diagnosis of depression or obsessive-compulsive disorder
- No history of a serious head injury involving ongoing complications
Study 1: “Set shifting difficulties and weak central coherence predict drive for muscularity and disordered eating in men”
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› Participants connect the dots as fast as possible:
- Trail A (1-2-3-4-5-6 etc.)
- Trail B (1-A-2-B-3-C-4 etc.)
The Trail Making Task (Reitain, 1959)
Tests of set shifting
Wisconsin Card Sort Test (WCST; Heaton et al. 1993)
› Stimulus card is matched to 1 of the 4 category cards (according to a categorisation rule (colour, shape or number).
› Rule changes after 3 consecutive correct responses
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Rey-Osterrieth Complex Figure (ROFC; Osterrieth, 1944).
› Participants copy the figure and then recall it from memory without warning after a delay period.
› Figure contains both local and global elements.
› Coherence index (Booth, 2006)
Tests of central coherence
Matching Familiar Figures Test (MFFT; Kagan, 1964)
› "I will be recording both your speed and your accuracy" (word order is counterbalanced).
› Performance based on latency to first response and total number of errors.
› Calculate "efficiency index" (Southgate, Tchanturia & Treasure, 2008)
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Hierarchichal multiple regression analyses
Results from Study 1: Set shifting and central coherence in male undergraduates
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› Evident in the instruments used to measure disordered eating
- EDE-Q (Fairburn & Beglin, 1984)
- "Have you been deliberately trying to limit the amount of food that you eat?"
- "Have you wanted your stomach to be empty?"
- "Have you gone for long periods of time (8 hours or more) without eating anything in order to influence your shape or weight?"
- "Have you had a definite fear that you might gain weight or become fat?"
- "Have you definitely wanted your stomach to be flat?"
- "Have you had a strong desire to lose weight?"
- "Have you felt fat?"
- "Have you taken diuretics to control your shape or weight?"
- "Have you taken laxatives to control your shape or weight?"
The current conceptualisation of disordered eating is synonymous with body fat, fat loss, weight loss and calorie restriction.
Study limitation: The dilemma of disordered eating
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- Macronutrient targets, with heavy emphasis on high protein consumption.
- Consumption of meal replacement shakes and protein shakes to increase calorie/protein intake
- Interrupting important activities to accommodate frequent eating (often every 3 hours)
- Importance placed on the functionality of food as opposed to the taste.
- Cooking meals for days (or weeks) in advance.
- Refusal to eat food for which calorie information is unknown (e.g. at restaraunts)
- Forcing food down when not hungry,
- Liquifying/blending food for easier food intake
- Restrictive food choices ("the chicken, brown rice and brocolli diet") or total elimination of carbohydrates or fats (Higher in MD than in AN [Murray et al. 2012])
- Use of steroids, "testosterone boosters" and other supplements
Eating behaviours motivated by the desire to gain muscle are not captured by existing measures, but can be extremely disordered.
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› Researchers have reversed problematic items on the EDE-Q (Murray et al. 2012).
- E.g. "Have you gone for long periods of time (8 hours or more) without eating to influence your shape or weight?"
-> "Have you gone for short periods of time (3 hours or less) whilst eating to influence your shape or weight?"
› The ideal male body is high in muscularity + low in body fat.
- Constant balance between eating behaviours aimed at shed body fat and eating behaviours to gain muscle.
› What makes eating disordered is the rule underlying the behaviour, not the direction.
- "Do you eat meals based on time intervals, rather than based on feeling hungry?"
We need to revisit our conceptualisation of disordered eating
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› 3 hypothetical factors:
- Behaviours
- "I eat meals throughout the day based on time intervals rather than based on feeling hungry"
- Attitudes
- "The taste of the food is more important than the functionality" (reverse coded)
- Concerns/Anxiety
- "I would feel anxious eating food that I had not prepared myself"
The Muscularity-Oriented Eating Test (MOET)
Future research: Beyond information processing biases in muscle dysmorphia and anorexia nervosa