A study by the U.K.'s National Treatment Agency (NTA) finds that two-thirds of heroin and crack-cocaine users who get addiction treatment are either abstinent or have significantly cut back on their drug use six months later, the Guardian reported Oct. 1.

The study found that 42 percent of the study subjects had stopped using heroin, while 29 percent had reduced their use. Among crack users, 57 percent were abstinent and 9 percent had cut back.

"Drug treatment has been greatly expanded in the last few years and so it is very encouraging that this study of the most commonly available treatments in England shows that even those with entrenched addiction to heroin and crack cocaine respond well to treatment," said Colin Bradbury, head of delivery for NTA. "Whilst users are in treatment, we know that their drug use declines and that crime significantly reduces, which is positive for their health and for communities which suffer from the harms caused by drug addiction. The goal of all drug treatment is for the user to overcome their addiction, and this study shows that although that may take time, it is possible to tackle the harms caused by drugs by investing in drug treatment."

Researchers tracked 14,656 addicts who recieved community-based treatment services. The programs aimed to stabilize the lives of patients with medication so they could work toward long-term sobriety, but did not offer any findings on more extended outcomes.

NTA officials said the report demonstrated that treatment is cost-effective.

The findings appear online in the journal The Lancet.