  Early Pot Smokers Become Addicts, U.S. Study Says WASHINGTON (Reuters) - The younger someone is when first trying marijuana, the more likely he or she is to become dependent on illegal drugs later in life, U.S. government researchers said on Wednesday. They found that 62 percent of adults aged 26 or older who first started using marijuana before they were 15 had also tried cocaine at some point. More than 9 percent reported they had used heroin and more than half had used prescription drugs for recreational purposes. Less than 1 percent of those who said they had never tried marijuana reported having tried cocaine or heroin and just 5 percent had abused prescription drugs, the report, by the Substance Abuse and Mental Health Services Administration, found. "These findings are of grave concern because studies show smoking marijuana leads to changes in the brain similar to those caused by cocaine, heroin and alcohol," SAMHSA administrator Charles Curie said in a statement. "Heavy marijuana abuse impairs the ability of young people to retain information during their peak learning years when their brains are still developing," Curie added.
"Every day in this country, more than 3,000 people -- most of them under the age of 18 -- use marijuana for the first time. Their early marijuana use exposes them to risks of drug dependencies, long-term physical and cognitive consequences, and social problems," White House Office of National Drug Control Policy Director John Walters said in a statement.
The report, based on National Household Survey data, found that 18 percent of adults who said they first tried pot before the age of 15 met the criteria for either dependence or abuse of alcohol or illicit drugs, compared to 2.1 percent of adults who said they had never used marijuana. The survey also found that an estimated 2 million Americans 12 or older said they had used marijuana for the first time in 1999, down from 2.5 million in 1998. Other researchers have found that teenagers who start smoking are more likely to become addicted to nicotine than people who wait to try cigarettes when they are adults. 
