This can last as long as two or more years after drug cessation. Often a strong family history of chemical dependency or alcohol dependency. Usage of THC not hereditary but the addiction development probably is. NOT a drug that explores feelings. Treatment must explore feelings and teach its vocabulary.
Group therapy can help.
Must set rules and limits. Must address the amotivational syndrome in the treatment program. Remember the immaturity and the age level caused by the drug when making assignments. Treat the denial. You have school failures, family dysfunctions etc.