The difficulty in treating eating disorders may stem from not only these diseases being intractable and fatal, but also from the psychological characteristics of the patients in that they do not easily accept therapy and deny the severity of the disease. Therefore, it is essential to take their personality into consideration when treating eating disorders. Social cognitive science studies revealed that patients with eating disorders often have interpersonal problems and limited social interaction, and it is difficult for them to accept social support. Furthermore, personality disorders often coexist with eating disorders, and eating disorder patients commonly use primary defense mechanisms, such as "autistic fantasy", "denial", and "omnipotent control", which are specific to personality disorders, in stressful situations. Some eating disorder patients may have developed personality disorders during adolescence, and their personality from adolescence may be reinforced and become chronic after the onset of eating disorders. One recent study on social cognitive functioning in eating disorders suggested that fragmented perseveration and social―emotional difficulties are stronger in patients with eating disorders than in healthy controls, whereas global flexibility is weaker than in healthy controls. Based on our previous brain functional imaging study using functional magnetic resonance imaging, the brain areas related to reward systems were activated by the stimulation of loss anticipation, but the same areas were not activated by the stimulation of gain anticipation. These findings from recent social cognitive studies are consistent with reports of eating disorder patients by clinicians. Eating disorders can be classified into three types by personality tendency, "reactive/conflictive type", "impulsive type", and "persistent type". The reactive/conflictive type is an eating disorder that occurs as a reaction to some psychological stress or from psychological conflict. The impulsive type is an eating disorder that is one of many impulsive symptoms and often coexists with borderline personality disorder. The persistent type is an eating disorder exhibited by patients obsessed with having a thin body, which is intractable. We should select therapeutic approaches that are appropriate for each type of eating disorder. In the future, social cognitive science and brain functional imaging studies will be developed, and the social cognitive and behavioral patterns specific to patients with eating disorders, regardless of the existing personality characteristics, may be clarified. Improved therapeutic approaches and methods of social support are also expected.
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