Mental illness and drug addiction may co-occur due to disturbance in part of the brain

Why do mental illness and drug addiction so often go together? New research reveals that this type of dual diagnosis may stem from a common cause: developmental changes in the amygdala, a walnut-shaped part of the brain linked to fear, anxiety and other emotions. A full report on why these “comorbid” disorders may develop appears in the December Behavioral Neuroscience, published by the American Psychological Association (APA).