FRIDAY, Jan. 6, 2012 (HealthDay News) -- About 200 million people worldwide use illicit drugs each year, and use is highest in wealthier nations, a new study shows.
The researchers also found that the burden of health problems caused by illicit drug use in developed countries is similar to that caused by alcohol, but much less than that caused by tobacco.
Experts in the United States weren't surprised by the numbers, and said that more needs to be done to reduce Americans' dependence on illegal drugs.
The study "serves to confirm something addiction experts have known for some time -- that the extent of illicit drug use and abuse in developed countries like the United States has reached epidemic proportions," said Dr. Jeffrey T. Parsons, a professor in the department of psychology at Hunter College, in New York City.
The analysis of available data from a team of Australian researchers estimates that there are up to 203 million marijuana users, anywhere from 14 million to 56 million amphetamine users, 14 million to 21 million cocaine users, and 12 million to 21 million opioid users around the world.
The researchers also estimate that there are 15 million to 39 million "problematic users" of opioids (which include prescription painkillers such as Oxycontin or Vicodin), amphetamines or cocaine, and 11 million to 21 million people who inject drugs worldwide.
Marijuana use appears to be highest in Oceania (Australia/New Zealand), with up to 15 percent of those aged 15 to 64 using the drug, according to estimates made by the UN Office on Drugs and Crime. Amphetamine use was also highest in Oceania (2.8 percent of this age group), while use of heroin and other opioids was highest in the Near and Middle East (up to 1.4 percent). Cocaine use was highest in North America (1.9 percent).
There is no gold-standard method for estimating the true number of illicit drug users and no one method is ideal for all drugs or all countries, said Louisa Degenhardt, of the National Drug and Alcohol Research Centre at University of New South Wales, Sydney, and the Burnet Institute in Melbourne, and colleague Wayne Hall of the University of Queensland Centre for Clinical Research in Brisbane.
Lack of data also means there are no estimates of the extent of use, or the health effects, of Ecstasy; hallucinogenic drugs; inhalants; or non-medical use of benzodiazepines such as valium or anabolic steroids.
The study, published Jan. 6, is the first in an addiction series appearing in The Lancet.
The toll on human health from illicit drug use is enormous. According to the investigators, the most recent (2004) data from the World Health Organization suggest that illicit drugs caused 250,000 deaths that year, compared with 2.25 million deaths from alcohol and 5.1 million deaths due to tobacco.
Years of life lost because of illicit drug use were 2.1 million, compared with 1.5 million for alcohol. That's likely because drug deaths generally affect younger people while deaths from alcohol (and tobacco) tend to affect middle-aged and elderly people, the researchers said.
Illicit drug use also caused 13 million years lost to disability (disability-adjusted life years, or DALYs).
Wealthy nations, including the United States, are lagging in efforts to beat back the scourge of drug abuse, experts said.
"Unfortunately, the U.S. has made little progress in the prevention and treatment of drug abuse in the past decade," Parsons said. "More research is needed on effective educational and prevention programs designed to reach young people before they begin to use/abuse illicit drugs," he added.
And expert Dr. Marc Galanter said that "it is important that we call attention to very serious drug abuse problems that still exist in the United States. For example, we are seeing recent increases in abuse of painkillers in the United States, as well as the abuse of MDMA [Ecstasy] by adolescents and young adults. Abuse of these particular drugs is not prevalent in less industrialized countries."
Galanter is director of the division of alcoholism and substance abuse at NYU Langone Medical Center/Bellevue, and a professor of psychiatry at the NYU School of Medicine, in New York City. He said that while drug abuse remains at serious levels, "we have made great progress in treatment in many areas, particularly, in the early recognition of alcohol abuse and alcoholism by the general public. This has led to people seeking help before problems become much more serious."
Still, Galanter said, "much more, however, needs to be done."
The new study also "puts substance use in a societal context," noted Dr. Bruce Goldman, director of Substance Abuse Services at the Zucker Hillside Hospital of the North Shore-LIJ Health System, in Glen Oaks, N.Y. "Social norms have a very powerful impact on drug use patterns," he said, and "we need to create norms where substance use and availability, especially for young people is not acceptable."
The U.S. National Institute on Drug Abuse has more about drug abuse and addiction.