WEDNESDAY, March 20 (HealthDay News) -- Adults with a mental illness or a substance-abuse disorder represent about 25 percent of the U.S. population but account for nearly 40 percent of all cigarettes smoked in the country, according to a new study.

The researchers also said that the smoking rate among adults aged 18 and older with a mental illness or substance-abuse disorder is about 38 percent, compared with just under 20 percent for those without these conditions.

This means that the current rate of smoking among adults with a mental illness or a substance-abuse disorder is 94 percent higher than among adults without the disorders, according to the U.S. Substance Abuse and Mental Health Services Administration (SAMHSA) report.

Adults with substance-abuse disorders but not mental illness represent about 5 percent of the population, but smoke nearly 9 percent of all cigarettes. Those with both a mental illness and a substance-use disorder represent roughly 4 percent of the population, but smoke 9.5 percent of all cigarettes.

"It has long been a public-health priority to develop effective smoking prevention and cessation programs," SAMHSA Administrator Pamela Hyde said in a government news release.

"This report highlights a clear disparity. It shows that people dealing with mental illness or substance-abuse issues smoke more and are less likely to quit," she said. "We need to continue to strengthen efforts to figure out what works to reduce and prevent smoking for people with mental-health conditions."

The report findings are based on data from SAMHSA's 2009 to 2011 National Survey on Drug Use and Health.

SAMHSA and the Smoking Cessation Leadership Center have launched the 100 Pioneers for Smoking Cessation Program, which provides support for mental-health and substance-abuse treatment groups and facilities to help patients quit smoking.

More information

The American Cancer Society offers a guide to quitting smoking.