Learn how addiction to alcohol or other drugs hijacks the brain and why people in active addiction continue drinking or using substances despite devastating effects. Recovery expert Marvin D. Seppala, MD, joins host William C. Moyers to discuss the disease of addiction in easily understandable terms: the role of dopamine in the brain's reward center; effects of alcohol and other drugs on the brain, liver, heart and mental health; genetic and other risk factors for addiction.