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Chapter 10

PSYB32-Chapter 10 Notes.doc

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Konstantine Zakzanis

Chapter 10 – Eating Disorders • Eating disorder not otherwise specified (EDNOS): The most common eating disorder diagnosis characterize by heterogeneous symptoms and associated features that do not fit the symptoms of other eating disorders. This diagnosis is applied to between approximately 40 and 70% of diagnosed patients. • There is also newly proposed variations known as purging disorder, which is a form of bulimia that involves self-induced vomiting or laxative use at least once a week for a minimum of six months. • Once clear feature of purging disorder is high impulsivity. • Co-twins of patients diagnosed with anorexia nervosa, for example, are themselves more likely than average to have bulimia nervosa. Anorexia Nervosa • Anorexia nervosa (AN). Anorexia refers to loss of appetite, and nervosa indicates that this is for emotional reasons. The term is something of a misnomer because most patients with anorexia nervosa actually do not lose their appetite or interest in food. Most patients with the disorder become preoccupied with food; they may read cookbooks constantly and prepare gourmet meals for their families. • The person must refuse to maintain a normal body weight • The person has an intense fear of gaining weight, and the fear is not reduced by weight loss. • Patients with AN have a distorted sense of their body shape. The tendency to link self-esteem and self-evaluation with thinness is known as “overevaluation of appearance. • In females, the extreme emaciation causes amenorrhea, the loss of the menstrual period. Of the four existing diagnostic criteria, amenorrhea seems least important. Physical Changes in Anorexia Nervosa • Blood pressure often falls, heart rate slows, kidney and gastrointestinal problems develop, bone mass declines, the skins dries out, nails become brittle, hormone levels change, and mild anemia may occur. Some patients lose hair from the scalp, and they may develop laguna, a fine, soft hair, on their bodies. Levels of electrolytes such as potassium and sodium are altered. • Deficits in white-matter volumes in the brain are restored upon- recovery from anorexia nervosa, but deficits in grey-matter volumes appear irreversible. • Anorexia is associated with a 25 year reduction in life expectancy. Bulimia Nervosa • Bulimia nervousa (BN). Bulimia is from a Greek word meaning “ox hunger”. This disorder involves episodes of rapid consumptions of a large amount of food, followed by compensatory behaviours, such as vomiting, fasting, or excessive exercise, to prevent weight gain. The DSM defines a binge as eating an excessive amount of food within less tan two hours. • They report that they lose control during a binge, even to the point of experiencing something skin to a dissociative state, perhaps losing awareness of what they are doing or feeling that it is not really they who are bingering. • As with anorexia, two subtypes of bulimia nervosa are distinguished: a purging type and a non-purging type in which the compensatory behaviours are fasting or excessive exercise. Binge Eating Disorder • DSM-IV-TR includes binge eating disorder (BED) as a diagnosis in need of further study rather than a formal diagnosis but BED will be included in DSM-V • Binge eating disorder appears to be more prevalent than either AN or BN. Biological Factors Genetics • As possible role for genetics is suggested by the fact that both anorexia nervosa and bulimia nervosa run in families. First- degree relatives of young women with anorexia nervosa are about four times more likely than average to have the disorder themselves. Eating Disorders and The Brain • The hypothalamus is a key brain centre in regulating hunger and eating. Research on animals with lesions to the lateral hypothalamus indicates that they lose weight and have no appetite. • A dysfunctional hypothalamus dos not seem a highly likely factor in anorexia nervosa however. • Endogenous optoids are substances produced by the body that reduce pain sensations, enhance mood, and suppress appetite, at least among those wih low body weight. Opioids are released during starvation and have been viewed as playing a role in both anorexia and bulimia. Starvation among patients with anorexia may increase the levels of endogenous opioids, resulting in a positively reinforcing euphoric state that has been characterized as powerfully reinforcing. Furthermore, the excessive exercise seen among some patients with eating disorders would increase opioids and thus be reinforcing. • Bulimia is mediated by low levels of endogenous opioids, which are thought to promote craving; a
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