In 'Dopamine Nation,' Overabundance Keeps Us Craving More

'Human beings are programmed to approach pleasure and avoid pain. It's an instinct that dates back millions of years, to a time when people needed to actively seek food, clothing and shelter every day, or risk death. But psychiatrist Anna Lembke tells Fresh Air that in today's world, such basic needs are often readily available — which changes the equation. Lembke is the medical director of addiction medicine at Stanford University and chief of the Stanford Addiction Medicine Dual Diagnosis Clinic. Her new book, Dopamine Nation, explores the interconnection of pleasure and pain in the brain and helps explain addictive behaviors — not just to drugs and alcohol, but also to food, sex and smart phones.'