A mix of cognitive-behavioral therapy (CBT) and motivational incentives appears to be effective in treating patients with a primary diagnosis of marijuana dependence, according to the National Institute on Drug Abuse.

Researchers from the University of Arkansas and the University of Vermont studied 90 adults over a 14-week period and compared three groups: those who received vouchers for submitting drug-free urines, those who only received CBT, and those who received CBT and vouchers. 

At the end of the three-month treatment period, 43 percent of the CBT-plus-vouchers group had stopped using marijuana, compared to 40 percent of the voucher-only group and 30 percent of the CBT-only group. At 12 months post-treatment, 37 percent of the CBT-plus group was still abstinent, compared to 17 percent of the vouchers-only group and 23 percent of the CBT-only group.

"This suggests that CBT helps maintain the initial positive effect of using vouchers to initiate abstinence during treatment," said lead researcher Alan Budney of the University of Arkansas.

The research was published in the April 2006 issue of the Journal of Clinical and Consulting Psychology.