The blind men and the elephant: Systematic review of systematic reviews of cannabis use related health harms.

Cannabis is the third most used psychoactive substance worldwide. The legal status of cannabis is changing in many Western countries, while we have very limited knowledge of the public health impact of cannabis-related harms. There is a need for a summary of the evidence of harms and risks attributed to cannabis use, in order to inform the definition of cannabis risky use. We have conducted a systematic review of systematic reviews, aiming to define cannabis-related harms. We included systematic reviews published until July 2018 from six different databases and following the PRISMA guidelines. To assess study quality we applied the AMSTAR 2 tool. A total of 44 systematic reviews, including 1,053 different studies, were eligible for inclusion. Harm was categorized in three dimensions: mental health, somatic harm and physical injury (including mortality). Evidence shows a clear association between cannabis use and psychosis, affective disorders, anxiety, sleep disorders, cognitive failures, respiratory adverse events, cancer, cardiovascular outcomes, and gastrointestinal disorders. Moreover, cannabis use is a risk factor for motor vehicle collision, suicidal behavior and partner and child violence. Cannabis use is a risk factor for several medical conditions and negative social consequences. There is still little data on the dose-dependency of these effects; evidence that is essential in order to define, from a public health perspective, what can be considered risky use of cannabis. This definition should be based on quantitative and qualitative criteria that informs and permits the evaluation of current approaches to a regulated cannabis market.

Motivation for change and barriers to treatment among young cannabis users.

BACKGROUND/AIMS: Despite cannabis use among adolescents has shown to be related to psychosocial and mental health problems, the demand from adolescents for professional help is very low, and determinants of motivation for change among nonclinical populations remain unknown. The purpose of this study was to assess motivation for change among young cannabis users and to identify determinants of intention to change and self-change, as well as perceived barriers to seeking professional help. METHODS: 261 cannabis users aged 16-21 participated in a computerized survey in Spain. RESULTS: Data from this cross-sectional study indicated that few users intend to stop taking the drug. Determining factors of intention to change were the following: having more drug-related problems, paranoid symptomatology and greater concern about the consequences of use. Self-change was facilitated by lower use of cannabis, and could be hindered by tobacco smoking and cannabis dependence. Lack of awareness of the problems and the desire to solve one's problems alone constitute the main barriers to seeking professional help. CONCLUSIONS: Adolescent cannabis users show low motivation for change though experiencing more problems associated with its use emerges as a determinant of increased motivation. Several barriers impede this motivation from turning into treatment demand.