Comparing the Spanish Version of CANreduce With or Without Psychological Support and Treatment as Usual, Reducing Cannabis Use.

Cannabis is the most widely used psychoactive substance around the world after alcohol and tobacco. Although approximately one in ten users develop serious problems of dependency, only a small number attend outpatient addiction counseling centers. CANreduce is an adherence-focused guidance enhanced web-based self-help program with promising results in German and other languages. It also reaches those users who hesitate to approach such treatment centers and help them to reduce their cannabis use. This study will test the effectiveness of the Spanish version of the enhanced web-based self-help intervention with psychological support, an enhanced web-based self-help intervention (without psychological support) and a waiting list control in reducing cannabis use in problematic users.