Biological Explanations for Anorexia Nervosa

Neurotransmitters

A01 - Serotonin - disturbances in levels of the neurotransmitter serotonin, are a characteristic of individuals with eating disorders.

Bailer et al (2007) compared serotonin activity in women recovering from anorexia and binge eating, with heathy contols. found higher serotonin activity in the women recovering from the bing eating type. they found the highest level of serotonin levels may lead to increased anxiety, which may then trigger Anorexia Nervosa.

A02  - SSRI's, alter levels of available brain serotonin are ineffective when used with AN patients.

Kaye et al (2001) found that when used with recovering AN patients, these drugs were effective in preventing relapse. malnutrition related changes in serotonin function may stop the action of SSRI's - only become effective when weight goes back to normal.

Neurotransmitters

A01 - Dopamine -

Kaye et al (2005) used a PET scan to compare dopamine activity in the brains of 10 women recovering from AN and 12 healthy women. AN women they found overactivity in dopamine receptors in a part of the brain :basal ganglia - interpretation of harm or pleasure. Alters the way we interpret rewards. AN find it difficult to associate good feelings with the things that most people find pleasurable (food).

A02 - Dopamine -

Castro-Fornieles et al (2006) - adolescent girls with AN had higher levels of Homovianillic acid (waste product of dopamine). Weight gain associated with normalisation of these levels.

Wang et al (2001) - lower than normal levels of dopamine receptors in the brains of obese individuals.

Neurodevelopment

A01 - Pregnancy and birth complications -

Lindberg and Hjern (2003) significant association between premature birth and development of AN. Birth complications could lead to brain damage (lack of oxygen). Nutritional factors may be implicated if mothers have an eating disorder.

Buik et al (2005) - AN mothers expose offspring to 'double disadvantage' inadequate nutrition and genetic vulnerability.

A02 - Obstetic complications -

Favero et al (2006) placental infaraction with AN mother (restricted food supply in to placenta) assosciated with development of AN. Early eating difficulties and a low birth weight.

Neurodevelopment

A01 - Season of Birth -

Eagles et al (2001) indiividuals with AN are more likely to have been born during the spring months. - temperature at time of conception and infections during pregnancy.

 Willoughby et al (2005) found that among patients with AN in regions in the world where it is constantly hot, there was no seasonality effect on the development of AN.

A02 - Eagles et al (2005) AN's later in birth order. The more elder siblings a child has while they are still in the womb, the more likely that the mother will be more exposed to common infections, more likely to be passed to the unborn child. Brain Development critical period is 2nd trimester, spring baby's 2nd trimester happens during period where infections are more likely to be around.