Biological Basis

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Eating DisordersPresented by :I.Vidya Sree1225612104M.Sc. Applied PsychologyGITAM Institute of Management

Introduction to Eating Disorders

• Eating disorders are one of the unspoken secrets that affect many families.

• Rarely talked about, an eating disorder can affect up to 5 percent of the population of teenage girls because during this period women are more likely to diet to try and keep a slim figure and try stringent dieting.

Classified into 3 types:

There are three main types of eating disorders:

• Anorexia

• Bulimia

• Binge Eating

Anorexia

• Anorexia (also known as anorexia nervosa) is the name for simply starving self because you are convinced you are overweight.

• If you are at least 15 percent under your normal body weight and you are losing weight through not eating, you may be suffering from this disorder.

Bulimia

• Bulimia also known as bulimia nervosa is characterized by excessive eating, and then ridding yourself of the food by vomiting, abusing laxatives or diuretics, taking enemas, or exercising obsessively. This behavior of ridding yourself of the calories from consumed food is often called "purging."

Binge Eating

• A person who suffers from this disorder can have it go undetected for years, because the person's body weight will often remain normal.

• "Binging" and "purging" behavior is often done in secret and with a great deal of shame attached to the behavior. It is also the more common eating disorder.

Biological Causes of Eating DisorderResearch supports that there are complexinteractions accountable for one’s predispositionto develop an eating disorder, certain factors

which play an important role are:• Heritability • Hypothalamic activity • Serotonin• Estrogen• Neurotransmitters

Heritability

• A study found that genetic linkage on chromosome 1 might play a role in having a genetic predisposition for anorexia nervosa.

• It is likely that several genes are responsible for predisposing one to anorexia as well as bulimia nervosa.

Contd..

• Having a mother or a sister with anorexia nervosa makes one twelve times more likely to develop anorexia and four times more likely to develop bulimia nervosa than individuals without a family history of anorexia nervosa.

Hypothalamic activity

• Hypothalamus is responsible for regulating hunger.

• Research indicates that the hypothalamus found in bulimic individuals may not trigger a satiation response after eating a meal, thus induce a binge-eating episode .

Serotonin

• Irregular levels of serotonin may play an important role in binge-eating episodes.

• The body converts carbohydrates into sugars, which are then converted into tryptophan.

• Tryptophan in turn is used to produce serotonin, which plays an important role in the regulation of mood and appetite.

Contd..

• Bulimic individuals often crave foods rich in carbohydrates, suggesting low levels of serotonin in the brain.

• A decrease in bing-eating episodes has been seen in bulimic individuals taking anti-depressants that specifically target serotonin.

Contd..

• The relationship between serotonin and anorexia nervosa remains unclear.

• Some anorexic individuals have been found to have abnormally high levels of serotonin, which induces stress and anxiety.

• Minimal eating would allow for a decrease in anxiety by decreasing levels of serotonin in the brain. However, SSRIs such as Zoloft and Prozac—causing an increase in serotonin levels—have effectively treated anorexic individuals.

Contd..

• Abnormal eating patterns and associated body changes can alter serotonin levels, thus contributing to preexisting abnormal levels. Abnormal serotonin levels can also lead to depression and anxiety disorders.

Estrogen - estradiol

• Scientists have discovered a possible biological culprit in the development of eating disorders during puberty: a type of estrogen called estradiol.

• Estradiol is the predominant form of estrogen in females.

• It is responsible for the growth of reproductive organs and also influences other organs including bones.

Contd..

• Kelly Klump, associate professor of psychology at Michigan State University, and colleagues found that genetic influence on eating disorder symptoms was much greater in pubertal girls with higher levels of estradiol than pubertal girls with lower levels of the hormone.

• The study examined the estradiol levels of nearly 200 sets of female twins, ages 10-15, from the MSU Twin Registry, which includes more than 5,000 pairs of twins in Michigan.

Contd..

The reason in an increase in genetic influences during puberty is that the genes for disordered eating are essentially getting switched on during that time and it was found that increases in estradiol apparently are activating genetic risk for eating disorders.

Neurotransmitters

• Irregular levels of dopamine have been found in women with anorexia nervosa.

• Dopamine is responsible for feelings of pleasure and provides feelings of reward associated with certain tasks, in turn motivating us to perform these tasks.

• Thus, anorexic women’s drive to lose weight but lack of satisfaction after loosing weight may be a result of irregular dopamine levels.

Contd..• High levels of cortisol have been found in

bulimic and anorexic individuals. • Levels of cortisol increase as a response to

stress in order to prepare the body to respond to a threat. Release of cortisol also decreases appetite.

• However, cortisol levels have been shown to increase after the development of an eating disorder, so whether it plays a causal role or is a consequence of an eating disorder is unclear.

Contd..

• Eating disorders may result in a drop in leptin levels due to the loss of large amounts of fat.

• Leptin tells the brain how much energy is available for use and plays a role in regulating “reproduction, appetite, metabolism, and bone formation.”

• Drops in leptin levels can stop a woman’s menstrual cycle, result in bone loss or impaired metabolism.

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