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.

.

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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 Anorexia Nervosa

With anorexia, the patient thrives on being thin at any cost and this causes the patient's abnormal behaviors that result in a low body weight regardless of the consequences. Amenorrhea is no longer required for someone to be diagnosed with anorexia nervosa. Significantly low weight is defined as a weight that is less than minimally normal for children and adolescents and less than that is minimally expected. The patient has an intense fear of gaining weight or becoming and persistent behavior that interferes with gaining weight, even though they are significantly underweight

    The patient experiences disturbance in the way that they view their body shape and also a persistent lack of recognition of the seriousness of the current low body weight.

There are two types of Anorexia Nervosa

1. The restricting type
1. Patients restrict food intake to maintain their low weight
2. They do not like to eat in front of other people 
2.  Binge-eating/purging type
1. The restrict calories
2. They binge eat and purge

Some example of how patients suffering from anorexia suffer from distorted thinking (Hooley, et al, 2019).

• “I have a rule when I weigh myself. If I’ve gained then I starve the rest of the day. But if I’ve lost, then I starve too.”
• “Bones define who we really are, let them show.”
• “An imperfect body reflects an imperfect person.”
• “Anorexia is not a self-inflicted disease, it’s a self-controlled lifestyle.”
• “It’s not deprivation, it’s liberation.”

Here are some ways someone suffering from anorexia nervosa might try to conceal their weight loss especially if they know that they are about to be weighed.

•  wearing baggy clothes 
•  carrying hidden bulky objects so that they will weigh more when measured by others
• drinking large amounts of water to increase their weight temporarily.

DSM-5 Criteria for. . .

Anorexia Nervosa

1. Restriction of energy intake relative to requirements, leading to a significantly low body weight in the context of age, sex, developmental trajectory, and physical health. Significantly low weight is defined as a weight that is less than minimally normal or, for children and adolescents, less than that minimally expected.
2. Intense fear of gaining weight or of becoming fat, or persistent behavior that interferes with weight gain, even though at a significantly low weight.
3. 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 persistent lack of recognition of the seriousness of the current low body weight (Hooley et al, 2019).

• Anorexia is centuries old.
• Religious literature tells of cases of extreme cases of fasting (Hooley, et al., 2019).
• 1689
• Richard Morton - wrote about the first documented cases of anorexia nervosa. An 18-year-old girl and a 16-year-old boy both suffered from what they called at the time "nervous consumption" ( Hooley, et al., 2019).
• The girl died eventually because she refused the treatment.
• 1873
• Charles Lasègue in Paris and Sir William Gull in London
• Both wrote about two different cases and described the same symptoms. 
• One case was a 14-year-old girl who was starving herself. They treated her by getting her to eat light food every few hours.
  

References

Hooley, J. M., Nock, M. K., & Butcher, J. N. (2019). Abnormal Psychology (18th ed.).

Pearson Education (US). https://bookshelf.vitalsource.com/books/9780135191033