"Although the precise causes of bulimia nervosa are unknown, scientists agree that it is caused by a combination of genetic and environmental factors. People with a family history of eating disorders or a personal history of mental illness, including depression, anxiety, substance abuse and other illnesses, are more likely to develop bulimia nervosa. Traumatic events (e.g., physical or sexual abuse) as well as life-stressors (including being bullied at school) can also increase the risk of developing bulimia nervosa. While no specific region of the brain has been directly connected with bulimia nervosa, certain chemicals in the brain (e.g., the neurotransmitter serotonin) have been shown to have a relationship with binging and purging behaviors."