WEDNESDAY, June 16 (HealthDay News) -- Among Americans aged 50 and older, admissions for drug abuse treatment have nearly doubled between 1992 and 2008, a new study reveals.

Admissions for cocaine, heroin, prescription drugs, and/or marijuana abuse among men and women aged 50 and older rose from 6.6 percent in 1992 to just over 12 percent by 2008, according to researchers from the U.S. Department of Health and Human Service's Substance Abuse and Mental Health Services Administration (SAMHSA).

Even though alcohol abuse remains today's number one cause of substance treatment admissions among older Americans, the group's rate of admission for illegal drug abuse increased dramatically over the course of the study.

"These findings show the changing scope of substance abuse problems in America," SAMHSA administrator Pamela S. Hyde said in a news release. "The graying of drug users in America is an issue for any programs and communities providing health or social services for seniors."

The observed trends stem from an analysis of information collected by SAMHSA's ongoing treatment facility reporting system. Among the findings:

Admissions for alcohol abuse among people 50 and older dropped during the course of the study period, from a high of nearly 85 percent to just under 60 percent.

Heroin abuse more than doubled, accounting for 16 percent of all admission for people aged 50 and over in 2008, in contrast to just over 7 percent in 1992.

Cocaine abuse admissions among older Americans quadrupled, from just under 3 percent to more than 11 percent, while marijuana-related admissions rose from less than 1 percent to nearly 3 percent.

Prescription drug abuse also experienced an uptick, rising from less than 1 percent to 3.5 percent.

Abuse of more than one drug at a time also jumped among older Americans, with the proportion of admissions due to multiple substance disorders nearly tripling, from nearly 14 percent in 1992 to almost 40 percent by 2008.

Researchers found that 75 percent of the admissions of people aged 50 and older occurred among people who had first abused drugs before they reached the age of 25. Nevertheless, they noted that older Americans were increasingly coming in due to the abuse of a substance they had only first begun using the five years before treatment admission.

In people who had used drugs they sought treatment for less than five years, cocaine led the list, accounting for 26.2 percent of all such cases. Prescription drug abuse lagged just behind, at 25.8 percent.

"The Administration on Aging supports healthy aging," Kathy Greenlee, the agency's assistant secretary, said in the same release. "A critical aspect of senior health is the ability to be free of alcohol and drug addiction. It is troubling, therefore, to see an increasing number of older Americans struggling with substance abuse. This is a trend we must address for the benefit of each individual now as well as a generation of baby boomers on the doorstep of old age."

More information

For more on substance abuse state by state, visit SAMSHA.