Ask Dr. Nandi: The five most addictive substances in the world

A panel of experts have listed off the top five most addictive substances in the world. And several of these substances are legal. What are they and how can they affect your life? This list was created by chemists, psychiatrists and pharmacologists. Of the top five addictive drugs they ranked, the first on their list is heroin. Animal research has shown this opiate can increase dopamine levels in the brain by up to 200%. Heroin use has risen sharply here in the US, and unfortunately, so has heroin-related overdose deaths.