Chunk #16 — 2. Method — 2.1 Background information – twin studies and cannabis phenotypes — 2.1.2 Phenotypes: initiation of cannabis use and problematic use
In the present analysis, problematic use is operationally defined as having one or more of the symptoms of abuse or dependence during lifetime. We did not limit our focus to studies that use full abuse or dependence diagnosis only, because we are interested in vulnerability to problematic cannabis use or addiction. Because of this broad definition we incorporated studies using phenotypes like ‘abuse or dependence’, ‘one or more abuse or dependence symptoms’ and ‘abuse’. All studies incorporated in the meta-analyses have analysed problematic use as a dichotomous measure.
