One-third of the U.S. population was born during the Baby Boom -- the years 1946 to 1964 -- and many Boomers grew up using drugs and may be continuing to do so, Scientific American reported May 16.

Researchers from the National Institute on Drug Abuse (NIDA) cast doubt on the theory that these lifelong recreational drug users will "age out" of use of marijuana or other substances as they get older. For example, hospitals reported that cocaine mentions at emergency rooms rose 240 percent among people ages 55 and older between 1995 and 2002, while heroin mentions rose 160 percent, marijuana mentions rose 467 percent, and amphetamine mentions rose 700 percent.

Moreover, the National Survey on Drug Use and Health found that illicit drug use among people ages 50-59 rose from 2.7 percent in 2002 to 4.4 percent in 2005.

Experts say that the trends may be related to the fact that people are living longer but also holding on to the drug-use habits of their youth. They worry, however, that drug use could have serious effects on brain function among older Americans and that drug users could face other health consequences as their metabolism slows with age. Interaction with prescription drugs also is a hazard.

The NIDA research appears in the journal Neuropsychopharmacology.