??????? to the Study of Human Disorders in ??? Ingestion and Body Weight Maintenance
by Paul R. McHugh, Timothy H. Moran and Marie Killilea

Taken from The Annals of the New York Academy of the Sciences, The Psychobiology of Human Eating Disorders: Preclinical and Clinical Perspectives, Volume 575, 1989.

Introduction

Human disorders of food intake fall into two groups: "Proximate causes" or conditions caused by pathology within the individual that disrupts the normal physiology controlling behaviour and "Ultimate causes" or disorders encompassing distortions/deviations in food intake and weight control that emerge with development and its capacity to direct, reinforce or hinder behaviour.

PROXIMATE OR IMMEDIATE FACTOR DISORDERS

• Conditions caused by a factor suddenly appearing.

Hypothalamic Hyperphagia

• Injury to hypothalamus causing obesity due to overeating.

Cancer Anorexia

• Anorexia due to a cancer growth. Patient reduces food intake. Not enough, however, to account for weight loss.
   
• The proteins "tumor necrosis factor" (TNF) and cachectin, homologues of the protein TNF/cachectin, is crucial in weight loss.
   
• TNF/cachectin is produced by hematopoietic mononuclear cells including macrophages and helps to kill a variety of human tumor cells.
   
• TNF/cachectin supresses anabolic enzymes allowing it to deplete body lipid stores and provoke peripheral protein wasting irrespective of caloric intake. This leads to weight loss. TNF/C also leads to reduced food intake.
   

ULTIMATE OR DISTAL FACTOR DISORDERS

Obesity

• Midtown Manhattan Study of mental disorders showed a clear relationship between social class and obesity. In developed societies, obesity seems to be a condition of the lower/middle classes while the upper class seems to avoid it. Conversely, in underdeveloped countries, upper class tend toward obesity and poor are thin. These observations held up in many studies.
   
• Possible reasoning in evolition. Those who survived famine in prehistory now living in a calorie-rich world tend toward obesity. Possibly because of a "thrifty genetype" or genetic endowment for fat storage that had survival value of reducing energy expenditure during times of shortage and overstore as fat during plentiful times.
   
• Appears to be a familial trait with genetic basis.
   
• Using monozygotic and dizygotic twins, Stunkard showed as much as 80% of weight variance can be attributed to genetics. Extrordinary compared to genetic diseases such as hypertension (57%) and epilepsy (50%).
   
• Explanation tries to combine nature-nurture and look at the interaction of two forces.
   
• People have different genetic perceptions of sweetness as well as many other things that may affect calorie intake.
   

Anorexia Nervosa

• Still little is known about causes of AN
   
• All physiological anolamies studied in AN cases appear to be results of AN behaviour rather than causes. Anolamies disappear when normal behaviour is resumed.
   
• In treatment of AN, reduced gastric emptying ???? an early sense of fullness. ????? during refeedingh must be overcome.
   

SYMPTOMS: Russel Criteria for AN & BN

Anorexia Nervosa:

1. Self-induced loss of weight (resulting mainly from studied avoidance of food considered by patient to be fattening).
    
2. Characteristic psychopathology consisting of overvalued idea that fatness is a dreadful state.
    
3. Specific endocrine disorder that in postpubetal girl causes cessation of menstruation or delay of events of puberty in prepubetal or early pubertal female.
    
4. Possible ovarian atrophy.
    

Bulimia Nervosa:

1. Powerful and intractible urge to overeat resulting in episodes of overeating.
    
2. Avoidance of "fattening" effects of food by inducing vomiting or abusing purgatives.
    
3. A morbid fear of becoming fat.
    

PRIMARY AFFECTS

• Youthful females of the upper classes in developed nations in the contemporary era.
   
• Variations: Females outnumber males 10 to 1.
  • High incidence of homosexuality among males.
  • Increasing in incidence: modern day disease.
  • Spread outside 14-25 target range. Initial cases even seen in 30s. Lower classes, poor blacks and upper class, and Third World people.
  • Increase in AN in males.

• Genetic contribution secure. Higher incidence in monozygotic than dizygotic twins. Higher ????
   

PERSONALITY

• Personality may be part of genetics.
   
• AN personality is introverted and self-reflecting with possible obsessional characteristics.
   
• BN personality is extroverted with histronic features, impulsivity is higher than in AN temperment.
   
• AN also have controlling tendencies.
   
• Weight loss in BN is less than AN.
   
• Pressures causing disorder may not be what substains it. (Once thinner, disorder continues). For instance, flabby thighs, no longer.
   

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