A new survey predicts that the number of Americans age 50 or older who are addicted to alcohol or other drugs will double by 2020.

Researchers predict that there will be 5 million people age 50 or older with addictions by 2020, up from 2.5 million in 1999. Misuse of alcohol and prescription drugs play a huge role in the trend; so is the willingness of Baby Boomers to take a wide range of drugs to deal with physical and mental health problems.

"There is a huge concern that what we're going to be seeing is a tidal wave of seriously affected substance abusers in later life," said Frederic Blow, of the University of Michigan Medical School.

"Late onset" addiction problems are often related to health problems and emotional trauma associated with aging. Alcohol is the leading drug of abuse among older Americans, followed by prescription drugs. A study of emergency-room admissions for drug-related problems found that a significant percentage involved patients over age 50.

"We are beginning to see an increase in heroin and cocaine addiction at the front-end of the baby boom wave," said Carol Colleran of the Hanley Center, the author of Aging and Addiction. "The increase is slight yet, but it begs the question as to whether that figure is going to increase dramatically if the baby boomers revert back in retirement to the drugs they tended to use in their college years."