More than 40 million people are living with HIV worldwide, including 5 million new cases in 2005 alone. For the United States, the latest numbers indicate that by 2004, 1 million Americans were living with HIV – and one in four of them did not know it. Behaviors associated with drug abuse are among the main factors in the spread of HIV infection in the United States. Drugs can change the way the brain works, disrupting the parts of the brain that people use to weigh risks and benefits when making decisions. hiv.drugabuse.gov Comments on this video are allowed in accordance with our comment policy: www.newmedia.hhs.gov