Chunk #24 — 3. Common liability to addiction — 3.2. Mechanisms of variation in CLA — 3.2.1. Empirical support for the common addiction liability concept
Drug- or drug-class-specific mechanisms of metabolism and pharmacologic action notwithstanding, a wealth of evidence indicates substantial commonality among the different substance use disorder categories. This commonality mitigates the possibility that the addictions each represent a discrete disorder. Both the plausibility of a single common (non-drug specific) liability dimension and the feasibility of measurement of this latent trait are supported by clinical, neurobiological, genetic and statistical findings (Vanyukov et al., 2009, 2003a,b). Thus, statistical modeling suggests that correlations of marijuana and other drug use are accounted for by common liability to and opportunities for consumption (Morral et al., 2002). Further support for the CLA concept is provided by the findings showing location of diagnoses and symptoms of SUD related to different drugs on the same dimension (Agrawal et al., 2004; Kendler et al., 2007; Kirisci et al., 2006, 2002; Wu et al., 2009). Key support for the CLA concept comes from the high genetic correlations between liabilities to specific drug addictions (correlations between the genetic components of the liability variance) determined in biometrical genetic studies. Virtually no specific genetic variance is
