Key components of the mental capacity assessment of patients with anorexia nervosa: a study of three countries

BACKGROUND: Patients with anorexia nervosa (AN) often refuse treatment despite their extremely low nutritional status. This study investigated the methods of assessing the mental capacity of patients with anorexia nervosa (AN) who refuse treatment by physicians in Japan, the United Kingdom (UK), and the United States (USA). It also identified the key points of the assessment. METHODS: A questionnaire survey using a case vignette was conducted among physicians (Japan, n = 53; UK, n = 85; USA, n = 85) who treat eating disorders. RESULTS: A total of 23% of physicians in Japan, 32% in the UK, and 35% in the USA reported that they believe patients with AN lack the capacity to make appropriate decisions. Physicians who considered patients with AN to have an impaired mental capacity placed significantly more emphasis on the level of psychopathological values, which are values caused by AN (and can be changed by recovery) that affect the ability to be rational, when assessing the mental capacity of these patients. Conversely, physicians who considered patients with AN to have full mental capacity placed significantly more weight on the ability to express a choice or preference. CONCLUSIONS: It may be necessary to add the level of psychopathological values to the assessment of the mental capacity in relation to obesity fears and emotional disturbances of Patients with AN because emotions caused by psychopathological values strongly influence decision-making. By considering the level of psychopathological values, it may be feasible to reflect the actual situation during the assessment of the mental capacity of those who refuse AN treatment, thus making it more likely to overcome ethical dilemmas. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s40337-022-00633-7.