Dr. Adam Bisaga in Cincinnati Enquirer

 Given time off drugs – an estimated one to two years – the brain can approach normal or near-normal activity, a concept known as plasticity, said Dr. Adam Bisaga, a professor of psychiatry at Columbia University Medical Center's Department of Psychiatry Division on Substance Abuse, who calls abstinence programs for opioid and heroin addicts "radical" despite their routine use, even seeming preference, in the United States.
Read more:  http://www.cincinnati.com/story/news/2014/05/17/way-heroin-addicts-trapped-deadly-maze/2235508/