BAKERSFIELD, Calif. -- The baby boomer generation came of age in the 1960s, a time when many young people experimented with illegal drug use.

But for some boomers, the drug abuse turned into a lifelong habit -- one that is now showing its effects in an older population.

Rates of abuse among those 50 and older nearly doubled between 2002 and 2007, according to a new report from the government's Substance Abuse and Mental Health Services Administration. That's 4.3 million users in this age group alone.

In a throwback to their youth, the majority of older drug users opt for marijuana. But a third abuse prescription drugs such as painkillers and sleeping pills -- medications that doctors may be more willing to give to older patients.

The government is concerned that there will not be enough treatment centers to meet the needs of elderly patients.

They suggested that substance abuse programs may have to double in capacity by 2020 as the boomer generation continues to age.