Psychopharmacology as a Tool for Understanding the Pathophysiology of Anorexia Nervosa

Anorexia nervosa (AN) is a body image disorder that manifests itself in the feeling that one is obese, even though the objective reality shows otherwise. People with AN resort to preventive behavior (restriction of food intake) or processes that encourage weight loss (use of medications such as diuretics and laxatives or obsessive engagement in vigorous physical activity). Among the mental disorders, AN is characterized by a high percentage of suicidal rate. Drug treatment began with the antihistamine drug Cyproheptadine. As expected, it increased the appetite of AN patients. However, it did not treat the body dysmorphic disorder accompanied by a concomitant depressive disorder and irrational thinking. After that, the treatment was changed to Tri-Cyclic Antidepressants (TCAs). The TCAs exposed the patients to cardiac arrhythmias (due to electrolyte imbalance). Serotonin reuptake inhibitors (SSRIs) slightly improved mood, while Serotonin and Norepinephrine Reuptake Inhibitors (SNRIs) increased metabolic rate (which is not desirable). The drug Bupropion, as a representative of Dopamine and Noradrenaline Reuptake Inhibitors (DNRIs), pointed to the imbalance in Dopamine levels in different brain regions as one of the main contributors to the pathophysiology of AN disease. This discovery led to the use of the second-generation antipsychotic drugs as very beneficial strategy.