Causal Factors for Eating Disorders

 There is no single cause of eating disorders. They are likely caused by a complex interaction of genetic and environmental factors. Genetic factors: Eating disorders may be partly caused by genes. People who have a family history of eating disorders are more likely to develop them themselves.

Environmental factors

 Eating disorders may also be partly caused by environmental factors. These include cultural pressures to be thin, exposure to dieting and weight loss programs, and traumatic life events.

 

Specific environmental factors (Hooley et al., 2019):

1. Cultural pressure to be thin
2. Exposure to dieting and weight loss programs
3. Traumatic life events
4. Family history of eating disorders
5. History of other mental health conditions, such as anxiety or depression

 The diathesis–stress model helps explain how genetic and environmental factors interact to cause eating disorders.

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The diathesis-stress model (Hooley et al, 2019):

•  Genes make some people more susceptible to environmental pressures, which can then lead to the development of problematic eating attitudes and behaviors.
• the diathesis -  people who are genetically predisposed to a certain condition 
• When the above meets the right stressor, an eating disorder can develop
• This model is only a theory.

Genetics

• Family studies: Family studies have shown that people with eating disorders are more likely to have relatives with eating disorders or other mental health conditions.
• Twin studies: Twin studies have shown that eating disorders are more likely to be shared by identical twins than fraternal twins. This suggests that genes play a role in the development of eating disorders.

Genome-wide association studies:

•   Genome-wide association studies have identified several genes that are associated with eating disorders. These genes are involved in a variety of biological processes, including
•  metabolism
•  mood regulation
•  development.
• These genes alone do not guarantee an eating disorder will develop.

Brain abnormalities 

 

Hypothalamus:

     The hypothalamus is a part of the brain that plays an important role in regulating eating behavior. Animal studies have shown that lesions to the hypothalamus can lead to overeating or undereating.

 Frontal and temporal cortex:

 The frontal and temporal cortex are also involved in eating behavior. Damage to these areas has been linked to the development of anorexia nervosa and bulimia nervosa.

Network of brain areas:

 Animal research suggests that a network of brain areas, including the hypothalamus, the frontal cortex, and the amygdala, may be involved in the development of eating disorders.

Set point

• Set point theory is a theory that suggests that our bodies have a natural weight range that they try to maintain.
• Hunger is one way that our bodies try to maintain our set point. When we lose weight, our hunger increases in an attempt to get us back to our set point.
• Influenced by a variety of factors, including genetics, metabolism, and environment.

Serotonin

• 
   Serotonin is a neurotransmitter that has been implicated in obsessionality, mood disorders, and impulsivity. It also modulates appetite and feeding behavior.
• Many patients with eating disorders respond well to treatment with antidepressants (which target serotonin), leading some researchers to conclude that eating disorders involve a disruption in the serotonergic system.
• Serotonin is made from an essential amino acid called tryptophan, which can only be obtained from food.

5-HIAA

Product of serotonin metabolism(5 HIAA, n.d.). 

• People with anorexia nervosa have low levels
• People with bulimia nervosa have normal levels.

Serotonin overactivity

It has been suggested that people with may use dieting as a way to regulate this by decreasing the amount of tryptophan available to make serotonin (Hooley et al, 2019).

•  Neurotransmitters like serotonin do not work in isolation and changes in the serotonin system will have implications for other neurotransmitter systems too

 

Reward Sensitivity

• A new direction in eating disorders research centers on the brain pathways and neurotransmitters (such as dopamine) that are involved in reward processing.
• Patients with anorexia nervosa show more activity in brain reward areas when they view pictures of thin rather than healthy models, while controls show the opposite pattern
  
• Reward and punishment systems get contaminated; normally rewarding stimuli such as food become aversive, and stimuli associated with self-starvation become valued.

References

 5 HIAA. (n.d.). TheFreeDictionary.com. Retrieved August 27, 2023, from https://medical-dictionary.thefreedictionary.com/5+HIAA

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