L11 Obesity and eating disorders
13 important questions on L11 Obesity and eating disorders
What are the brain characteristics associated with over- and underconsumption? --> Overweight/obetiy and anorexia
- Homeostasis
- Reward processing
- Self control
- Food choice
Leptin is primarily produced by
Serum leptin varies with % body fat / BMI
What are the basics of obesity
- 'abnormal or excessive fat accumulation that may impair health' --> metabolic syndrome
- BMI >= 30 kg/m2 (overweight: 25-29/9 kg/m2)
- Worldwide obesity has nearly tripled since 1975
- 39% of adults were overweight in 2016, and 13% were obese
- In 2016, more than 1.9 billion overweight adults (>18 y). Of these over 650 million were obese
- High relapse; dieting often unsuccessful on the longer term
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Alterations in (food) reward related brain responses
- Altered reward processing in many disorders
- One ‘core’ reward system; common neural currency for different reward types
- ‘General’ reward system alterations in obesity and eating disorders, i.e. altered brain response to both primary (food) and secondary (money) rewards
There are several theories about obesity and reward processing, among which:
- Reward deficit
- lower sensitivity of dopamine-based reward regions --> overeating to compensate for this 'reward deficiency'
- Reward surfeit (=beloning teveel)
- Incentive sensitisation
- --> craving and overeating
- Inhibitory control deficit
What is incentive sensitization
--> leads to cravings and overeating
google translate vertaling:
Herhaalde inname van calorierijk voedsel resulteert in een verhoogde responsiviteit van regio's die betrokken zijn bij incentive-waardering op signalen die verband houden met hedonische beloning van inname van dit voedsel via conditionering, wat leidt tot verlangen en te veel eten wanneer deze signalen worden aangetroffen.
What is the Food cue reactivity in people who are overweight/obese and people who have healthy weight [incentive sensitisation]
- Hyper-responsivity in reward-related regions (striatum, PFC) --> incentive-sensitization
Healthy weight
- Higher response in inhibitory control region --> inhibitory control deficit theory of obesity
What is DSM-5 anorexia nervosa
- Restriction of energy intake relative to requirements --> low body weight
- Intense fear of gaining weight or becoming fat or persistent behavior that interferes with weight gain
- Disturbed by one's body weight or shape, self-worth influenced by body weight or shape, or persistent lack of recognition of seriousness of low bodyweight
- (hyperactivity)
The basics of anorexia nervosa
- Affects ± 1-4% of women and 0.4% of men
- twin-based heritability estimates of 50-60%
- Highest mortality rate among mental disorders
- 5.1 deaths per 1000 person-years
- High relapse
- Limited treatment options --> poor outcome
What are the DSM-5 Feeding and Eating Disorders
- Anorexia nervosa (AN)
- Restricting type
- Binge-eating/purging type
- Bulimia nervosa (BN)
- Binge eating disorder (BED)
- 'rest categories' (OSFED/UFED)
What are the reward processing theories of Anorexia nervosa (AN)?
- Anhedonia: anhedonic state due to a reduced dopaminergic activation of the reward system
- Top-down control: reduction of reward activation secondary to hypertrophic 'top-down' cognitive control mediated by dorsal brain structures, leading to strong/wrong habits
- Reward contamination; specific behaviours, such as eating restraint or purging, become rewarding, because of a supposed devlopemtn of inappropriate overlapping neural pathways, which simultaneously process reward and punishment
No single 'best' theory; not easy to differentiate, work in progress...
Where can be looked at when doing a structural neuroimaging in ED
- Grey matter, white matter, CSF volumes
- Cortical thickness
- Regional GM volumes (Morphometery; VBM)
Where can be looked at when doing a functional neuroimaging in ED
- Resting state fMRI -> resting state functional connectivity
reward-related:
- (food) cue reactivity
- reward
- food choice
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