Researchers in the U.S. say more than 10 percent of American adults at some point in their lives, abuse or become addicted to drugs.
The most common drugs used are marijuana, cocaine and amphetamines and only a fraction of those addicted seek help.
The researchers found that almost twice as many men abuse drugs than women.
The National Institutes of Health (NIH) researchers say the study presents the most comprehensive picture of U.S. adult drug abuse since the early 1990s and was based on interviews with as many as 43,093 people in 2001 and 2002.
The researchers estimate that 10.3 percent of U.S. adults abuse drugs during their lifetimes, including 2.6 percent who become addicted.
The researchers said 2 percent reported symptoms of abuse or addiction in the previous year which was defined as an intense desire to use drugs to the exclusion of other activities, and addiction as a physical dependence on a drug.
The study found 13.8 percent of men and 7.1 percent of women were likely to abuse drugs at some stage and drug problems were more common among younger people, and as a rule appeared most often at around age 20.
The researchers also found that whites were more likely than blacks or Hispanics to report they had drug problems at some point and there was a higher rate than expected among American Indians.
Dr. Wilson Compton of the NIH's National Institute on Drug Abuse (NIDA), who led the study, says drug addiction and abuse are common problems among adults in the United States and the myth that drugs are mostly a problem of minorities is just not true.
The study found that only 8.1 percent of drug abusers and 37.9 percent of those who became addicted said they received treatment.
NIDA Director Dr. Nora Volkow says it is a concern that treatment rates are so low despite the availability of effective interventions.
Dr. Volkow says the public must be encouraged to view addiction as a brain disease that needs to be treated like any other chronic disease and programs need to be developed which destigmatize the disorders.
The study also looked at the abuse of other drugs such as heroin, opioids, hallucinogens, PCP, inhalants, tranquilizers and sedatives, but did not track alcohol or tobacco use.
Dr. Compton says there appeared to be a strong relationship between drug problems and mental illness, particularly in people with depression, bipolar disorders and anxiety disorders.
Compton suggests that people who come forward for treatment of a serious mental illness should be screened for drug abuse, and drug abusers should be screened for mental illness.
The researchers say the findings indicate that common factors underlie both drug abuse and other psychiatric conditions and drug abuse and dependence are also associated with mental, social and emotional disability.
According to Dr. Compton drug abuse is costly to society in terms of crime, illness and family discord, and also affects work productivity.
The study is published in the current issue of the Archives of General Psychiatry.