Eating disorders are characterized by severe disturbances in eating behavior. This section includes two specific diagnoses: anorexia nervosa (AN) and bulimia nervosa (BN). AN is characterized by the refusal to maintain a minimally normal body weight. There are two subtypes: the restricting type (RAN) and the binge-eating/purging type (BPAN). BN is characterized by repeated episodes of binge eating followed by inappropriate compensatory behaviors such as self-induced vomiting; misuse of laxatives, diuretics or other medications; fasting, or excessive exercise. Disturbances in body shape and weight perception are an essential feature of both diagnoses. Studies of AN among females in late adolescence and early adulthood have found a prevalence rate between 0.5%-1.0% in the general population. In recent decades, the incidence appears to increase. The prevalence of BN among adolescent and young adult females is approximately 1%-3%; the rate of occurrence of this disorder in males is approximately one-tenth of that in females. The argument for the study of the personality in the eating disorders is based in the observation of specific patterns of behaviors: in BN, a low tolerance for frustration and a peer impulse control; on AN, inflexibility and the need for having a severe control. Psychometric studies have consistently linked AN to a cluster of moderately heritable personality and temperamental traits, specifically: obsessionality, perfectionism, and harm avoidance. In this regard, it has been speculated that phenotype similarities between these traits of the anorexic's dietary restrain may be based upon shared genetic and environmental factors. While such traits may be exaggerated by starvation, their persistence after recovery supports the speculation that such traits may be risk factors for AN, rather than merely consequences of the disorder. Several analogies between eating disorders and depression, borderline personality, and obsessive-compulsive personality traits have been found. Nevertheless, it is very difficult to detect a single personality disturbance related to eating disorders. The presence of personality disorders in patients with eating disorders goes from 53% to 93%, and it has been observed that the presence of one or more personality disorders is more frequent in eating disorders than in the general population, but still more present in BN patients with a previous history of AN. Different studies in eating disorders patients had shown the presence of obsessive traits in approximately 27% to 61%, shy and dependence in 21% to 48%, and anxiety in 51% to 64% of the cases. Several studies had concluded that the predominant personality traits in eating disorders (69% to 87%) are a combination of obsessive traits, inhibition, and conformism. It has been described that almost 30% of the patients present obsessive personality traits and it has been demonstrated that the RAN presents a lower psychiatry comorbidity compared to any other eating disorder, even though these patients are more isolated and do not accept hunger sensations or distress. The Minnesota Multiphasic Personality Inventory (MMPI), Eysenck Personality Questionnaire (Eysenck) and Temperament and Character Inventory (TCI) had been used to rate personality traits of patients diagnosed with eating disorders. It has been found that social phobia disorder was more frequent in AN patients (14%-16%), followed by the dependent disorder (5%-10%), and finally, the obsessive-compulsive disorder (6% to 7%). It has been described that 30% of the patients have an obsessive personality. In fact, there are clinical similitudes between obsessive personality and eating disorders with restrictive behaviors. It is more common to detect several personality disorders in patients with BPAN while patients with RAN suffer of more anxiety and isolation. Typically, individuals with BN are within the normal weight range, although some may be slightly under or overweight. The disorder is uncommon among moderately and morbidly obese individuals. There is an increased frequency of depressive symptoms or mood disorders (43.5%), particularly dysthymic disorder and major depressive disorder. There may be also an increased frequency of anxiety symptoms or anxiety disorders (69%). Substance abuse, or dependence (18.5%), particularly involving alcohol and stimulants, occurs in about one-third of the individuals with BN. Probably between one-third and one-half of the individuals with BN also have personality features that meet the criteria for one or more personality disorders, specially the borderline personality disorder. Several clinical personality instruments agree to characterize BN patients as impulsive persons with a high sensibility toward interpersonal relationships with low self-esteem, unpredictable behaviors, aggressiveness, and poor impulse control. In conclusion, there are several personality risk factors for anorexia nervosa and bulimia nervosa, some of which are shared with other psychiatric disorders. Factors that increase the likelihood of impulsivity seem to have more influence for bulimia nervosa than for anorexia nervosa. perfectionism and negative self-evaluation appear to be particularly common and characteristic of both caring disorders. However, while anorexia nervosa patients might have a higher persistence, bulimia nervosa patients seem to have an impulsive temperament. According to the conceptual model proposed by Cloninger, both anorexia and bulimia present lower scores in the self-directness dimension.
