Additionally, three severity levels have been defined: mild (two or three criteria), moderate (four or five criteria) and severe (six or more criteria) cannabis use disorder.Cannabis use disorder is also recognized in the eleventh revision of the International Classification of Diseases (ICD-11), adding more subdivisions including time intervals of pattern of use (episodic, continuous, or unspecified) and dependence (current, early full remission, sustained partial remission, sustained full remission, or unspecified) compared to the 10th revision.A 2019 meta-analysis found that 34% of people with cannabis-induced psychosis transitioned to schizophrenia. This was found to be comparatively higher than hallucinogens (26%) and amphetamines (22%).To screen for cannabis-related problems, several methods are used. Scales specific to cannabis, which provides the benefit of being cost efficient compared to extensive diagnostic interviews, include the Cannabis Abuse Screening Test (CAST), Cannabis Use Identification Test (CUDIT), and Cannabis Use Problems Identification Test (CUPIT). Scales for general drug use disorders are also used, including the Severity Dependence Scale (SDS), Drug Use Disorder Identification Test (DUDIT), and Alcohol, Smoking, and Substance Involvement Screening Test (ASSIST). However, there are no gold standard and both older and newer scales are still in use. To quantify cannabis use, methods such as Timeline Follow-Back (TLFB) and Cannabis Use Daily (CUD) are used. These methods measure general consumption and not grams of psychoactive substance as the concentration of THC may vary among drug users. Treatment
Clinicians differentiate between casual users who have difficulty with drug screens, and daily heavy users, to a chronic user who uses multiple times a day.
Risk factors
Certain factors are considered to heighten the risk of developing cannabis dependence and longitudinal studies over a number of years have enabled researchers to track aspects of social and psychological development concurrently with cannabis use. Increasing evidence is being shown for the elevation of associated problems by the frequency and age at which cannabis is used, with young and frequent users being at most risk.The main factors in Australia, for example, related to a heightened risk for developing problems with cannabis use include frequent use at a young age; personal maladjustment; emotional distress; poor parenting; school drop-out; affiliation with drug-using peers; moving away from home at an early age; daily cigarette smoking; and ready access to cannabis. The researchers concluded there is emerging evidence that positive experiences to early cannabis use are a significant predictor of late dependence and that genetic predisposition plays a role in the development of problematic use. High risk groups
A number of groups have been identified as being at greater risk of developing cannabis dependence and, in Australia, for example, have been found to include adolescent populations, Aboriginal and Torres Strait Islanders and people with mental health conditions. Adolescents
The endocannabinoid system is directly involved in adolescent brain development. Adolescent cannabis users are therefore particularly vulnerable to the potential adverse effects of cannabis use.