Houston’s representative told People Magazine, “Whitney voluntarily entered the program to support her longstanding recovery process.”

No official word has been released as to where Houston will be treated, or for how long.

Houston first went into rehab back in 2004, again in 2005 and declared herself ‘clean’ in 2009, the Guardian reported.

Why do so many addicts have trouble getting clean – and staying clean?

In an interview with CBS News, Dr. Omar Manejwala  the medical director of the Hazelden Foundation substance abuse treatment facility explained, “Addiction is a chronic disease,” He went on to explain that relapses are very common. “Relapse is very common. Evidence suggests that the majority of the people need repeated treatment. If the initial treatment is only partially effective, we don’t call that a failure.”

“Only about 10 percent of the people who need treatment for substance abuse get it,” he said.

About 25 million Americans have a substance abuse problem, including about 19 million alcoholics.

The National Institute on Drug Abuse has more on the substance abuse and rehab.

(Parts of  this article were incorporated from cbsnews.com)