Addiction is a complex disease of the brain that encourages the compulsive use of drugs. Continued use of drugs leads to changes in the structure and function of the brain. Most people begin taking drugs for pleasure, or peer pressure. Finally, it becomes a habit, the addict is unable to abstain from drug use. Gender, ethnicity, friends and environmental factors cause addiction. The most difficult task for the drug rehab center is to help patients recover without relapse. Addiction can affect your health and mind of a person.