Research on eating disorders has revealed a greater incidence of substance use and/or misuse in women with eating disorders than in the general population. Most of the research agrees that substance misuse is more common in patients with bulimia nervosa and the binge eating/purging subtype of patients with anorexia than in women with the restricting subtype of anorexia nervosa. Researchers and specialists have proposed a range of theories to account for the strong association between substance misuse and bulimia nervosa. Experiments have not provided evidence to conclusively support any one theory. However, studies conducted in the past decade have enabled researchers to refine their hypotheses and accumulate more accurate information about eating disorders and substance use. Researchers have examined personality characteristics, family history, and biological and environmental factors common to persons with both substance use problems and eating disorders. In addition, the onset of eating disorders in relation to the beginning of substance abuse are examined to determine if one disorder drives the other. Differences in characteristics of patients with anorexia nervosa and patients with bulimia nervosa are examined to determine differences in rates of comorbidity with substance abuse. While continued research is necessary to assess the validity of proposed theories, the current knowledge proposes some interesting ideas about the relationship between substance abuse and eating disorders.
In the literature on eating disorders and substance abuse there is general agreement on two factors: patients with eating disorders display higher rates of substance abuse problems and patients who binge and purge are more likely than restricting anorexics to engage in substance abuse (Krahn et. al., 1996, Bulik et.al, 1994, Welch et. al., 1996 ). The agreement ends here. While some studies maintain that eating disorders drive substance abuse, many researchers assert that personality characteristics or environmental and biological factors that make individuals more prone to eating disorders also make these persons more likely to use/abuse substances. Thus, an eating disorder and substance abuse may provide a similar appeal to individuals with specific characteristics. Experiments to determine the factors that make patients vulnerable to both eating disorders and substance abuse focus on personality traits, such as behavior undercontrol and novelty seeking, environmental factors, like culture and family, and biological factors such as hormone levels.
The most accepted theory asserts that behavioral undercontrol and high Novelty Seeking propensity are characteristics common to patients that are prone to eating disorders and substance abuse problems. Bulimic women with substance abuse problems have higher scores on Novelty Seeking for Cloninger's Tridimensional Personality Questionaire than normals and than women with bulimia who do not also report problems with substance abuse (Kaye, 1994, Bulik et. al.1994). High scores on novelty seeking are accompanied by personality characteristics such as emotionality, unstable mood states and behavioral undercontrol. It is believed that these characteristics make bulimic, substance abusing women more permissive and more likely to act impulsively. Women with impaired impulse control are thought to be more prone to engage in behavior without weighing the consequences of their actions. Thus, women may binge, then later feel guilty and feel the need to purge. Kaye asserts that thoughts about bingeing and purging resemble addiction-like behavior similar to substance abuse. Patients with high novelty seeking propensity may experience a lack of control over cravings for food and alcohol or drugs, leading them to self destructive behavior. Girls who start dieting in sixth grade are more likely to engage in alcohol or substance abuse later, a finding that indicates problem eaters may have the greatest difficulty constraining their behavior (Krahn et. al,1996 ). Girls who are unable to control eating behavior at a young age may also be more prone to undercontrol when confronted with drugs and alcohol later in life. Both of these behaviors represent a defective ability to control cravings.
In addition, the unstable mood and high irritability of women with high Novelty Seeking scores may necessitate a need to regulate fluctuations in mood. Women may look to drugs and alcohol or food to relieve tension and protect themselves from emotional distress (Goldbloom et. al. 1992 ). Bingeing and substance abuse are self soothing methods to control the uneven temperament characteristic of novelty seekers.
The impulsivity and high Novelty Seeking characteristics of bulimics are not shared by patients with the restricting subtype of anorexia nervosa. Anorexia is associated with significantly lower incidence of substance abuse problems. Anorexic women have not scored high on novelty seeking and do not display behavioral undercontrol. Instead, anorexics display behavior of the opposite extreme; women with anorexia are concerned with perfection, symmetry and exactness (Kaye, 1994). Restricting anorexics are obsessed with control and planning. The lack of control that accompanies substance abuse and binge eating is repulsive to anorexic individuals. Anorexic women avoid bingeing and intoxication in order to maintain the control that they derive from their disease. In addition, anorexics would be reluctant to consume alcohol because of its high calorie content. Thus, anorexic women preoccupied with control and perfection are unlikely to engage in behavior that deprives them of that control. Women with bulimia, however, are prone to irritability and impulsivity that makes them inclined to behave without regard for consequence.
There is a school of thought that uses a genetic model to explain the exaggerated incidence of substance abuse among women with eating disorders. Many theories implicate genetics as a factor that may predispose individuals to alcoholism and eating disorders (Goldbloom, 1992 , Bushnell, 1996, Kaye, 1994). Reviews of family history in patients with eating disorders led to a significant prevalence rate for alcoholism in male first degree relatives. Many individuals with substance abuse problems have a family history of substance abuse, therefore it is difficult to determine whether the comorbidity of substance abuse and eating disorders is due to a genetic predisposition. Kaye asserts that the family history of drug and alcohol dependence may have created an environment of instability that would drive an individual to self medicate through bingeing or substance abuse. Sinha et. al. proposes the idea of an addictive personality type in which individuals are prone to addiction to various substances, which may include food, and drugs or alcohol. Evidence of a genetic link for alcoholism may in reality be evidence of a genetic link for this addictive personality type. This would explain a greater incidence of alcohol abuse among families and the strong association between substance abuse and eating disorders. The genetic passing of characteristics that make one more prone to addiction may manifest itself in some families in the form of alcohol addiction only. Whereas, in some genetic lines both substance abuse problems and eating disorders would be expressed.
The genetic theory does not provide reasons for greater incidence of substance abuse in bulimic individuals than in anorexic individuals. If substance abuse problems are passed genetically they would be inherited by both bulimic and anorexic individuals with the same incidence. In addition, if there is genetic transmission of an addictive personality, both bulimics and anorexics would be equally at risk for substance use problems. Anorexic individuals would be addicted to an obsession with not eating and fear of fat, while bulimics would be preoccupied with food to the point of a loss of control resembling addiction. More research needs to be done to determine the genetic transmission of bulimia and anorexia separate from alcohol addiction. In addition, the addictive personality theory must be further examined. Studies should be conducted to determine whether bulimic and anorexic individuals are more likely to engage in addictive behaviors other than substance abuse.
Finally, there is an environmental theory that examines the cultural influence on substance abuse and eating disorders. Researchers have sought to determine whether cultural forces make certain individuals more prone to eating disorders and substance misuse. In a well supported study Krahn asserts that girls who diet in sixth grade are more likely to use and/or misuse alcohol in ninth grade. On explanation of this phenomenon is that adolescents who are more likely to fall victim to cultural pressures to be thin, will also fall victim to peer pressure to drink alcohol and experiment with drugs (Striegel-Moore, 1993). Girls who begin diets with more frequency in sixth grade drink more heavily and do more drugs in ninth grade than girls who do not diet. Thus, girls who try harder to impress their peers with appearance in sixth grade will try harder to fit in through substance abuse in ninth grade.
Cultural pressure may have a detrimental effect on self esteem that maintains disordered eating and substance misuse problems. Both Krahn and Singha have found lower self esteem among alcoholic women and women with eating disorders. In addition, Striegel-Moore found a positive correlation between body image concern and the propensity to engage in alcohol use. Media and culture place an emphasis on thinness that are may produce body image concern for women. Striegel-Moore believes that the stress produced by body image concerns may lead women to engage in substance use and have eating disorders. Substance use may relieve tension about body image. Women with body image concerns are more likely to diet in order to maintain the cultural ideal that promotes thinness. Women unable to diet successfully may engage in binges to relieve stress, then compensate for their overeating by purgeing.
There is much speculation as to whether eating disorders drive substance use, substance use drives eating disorders, or the co-occurrence is purely coincidental. Theoretically, each model seems acceptable. Bulimia may be an impetus for substance use because feelings of guilt over bingeing and purging may force bulimics to seek other methods of tension reduction. Kaye cites a study of alcoholics that admitted alcohol was the only thing that could make them sleep after binge-purge cycles. Bulimic patients have also described using alcohol to numb hunger and craving for food (Kaye, 1994). While anorexics are not as likely to become alcoholics, they may engage in substance use to numb hunger.
Substance use seems less likely to motivate eating disorders, however, persons who feel guilty about the calories consumed during a drinking binge may engage in compensatory behavior such as restricting food intake or purging. An individual with substance use problems may feel the need to take control over one aspect of her life and use the restriction of food intake to gain this sense of control.
Finally, there is the possibility of overlap between people with eating disorders and people with substance use problems. A given percent of the population has each disorder. There is the possibility that some persons with eating disorders also happen to be prone to substance use problems. It seems unlikely however, that the number of people with bulimia who also have substance use problems acquire both disorders by mere chance. If bulimia and eating disorders do not drive one another it is more likely that an individual is prone to factors common in both disorders.
Although researchers have uncovered information that indicates possible causation for the common co-occurrence of eating disorders and substance use, there is still much work to be done. Many of the studies that researchers have conducted fail to adequately separate causation from correlation. Studies must assess what motivates substance misuse in the absence of bulimia, while matching subjects on age, family environment and genetic predisposition. In addition, studies about the perceived effects of alcohol and drugs to determine what motivates substance misuse must be conducted. In order to determine genetic predisposition to substance use and eating disorders twin and adoption studies would be helpful to determine whether perceptions of genetic links are due in part to environmental factors. The impact of culture on women with and without eating disorders should be researched to find whether women with eating disorders are more influenced by cultural pressures and are less able to deal appropriately with these pressures. There is a long list of factors that must be examined in order to discover the cause of increased incidence of substance misuse among women with eating disorders. Once researchers have found the cause for high rates of comorbidity of substance misuse and eating disorders it will be easier to treat these disorders.
Bulik, C.M., Sullivan, P.F, &McKee, M., Weltzin, T., Kaye, W. (1994). Characteristics of Bulimic Women With and Without Alcohol Abuse. The American Journal of Drug and Alcohol Abuse, 20, 273-283.
Bushnell, J.A., Wells, J.E. and Oakley-Browne, M.A. (1996). Impulsivity in Disordered Eating, Affective Disorder and Substance Use Disorder. British Journal of Psychaitry. 169, 329-33.
Goldbloom, David, Naranjo, C., Bremner, K., &Hicks, L. (1992). Eating Disorders and Alcohol Abuse in Women. British Journal of Addiction. 87, 913-9.
Kaye, W., and Wisniewski, L. 1996. Vulnerability to Substance Abuse in Eating Disorders. NIDA.159, 269-311.
Krahn, D., Piper, D., King, M., Olson, L., Kurth, C., Moberg, D.P. (1996). Dieting in Sixth Grade Predicts Alcohol Use in Ninth Grade. Journal of Substance Abuse. 8, 293-301.
Sinha, R., Robinson, J., Merikangas, K., Wilson, G.T., Rodin, J.,& O'Malley, S. (1996). Eating Pathology among Women with Alcoholism and/or Anxiety Disorders. Alcoholism: Clinical and Experimental Research. 20, 1184-91.
Striegel-Moore, R., and Huydic, E. (1993). Problem Drinking and Symptoms of Disordered Eating in Female High School Students. International Journal of Eating Disorders. 14, 417-25.
Welch, S. and Fairburn, C. (1996). Impulsivity or Comorbidity in Bulimia Nervosa. A Controlled Study of Deliberate Self Harm and Alcohol and Drug Misuse in a Community Sample. British Journal of Psychiatry. 169, 451-8.
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