An open bi-centric association study was conducted in two French Addiction Centres. Caucasian patients diagnosed with isolated cannabis dependence were compared with healthy age-matched controls for socio-demographic, clinical and genetic data using chi-square test, Fisher's exact test, or Mann–Whitney U test. Independent association between ABCB1 C3435T SNP marker and cannabis dependence was evaluated using multiple logistic regression analysis.
Versus controls (n = 40), patients with cannabis dependence (n = 40) had a significantly higher 3435C allele frequency (62.5 % versus 43.8 % respectively, P = 0.017) and CC genotype (50 % versus 20 % , P = 0.005, OR = 4.00 [1.50–10.60]). Multiple logistic regression analysis of the C3435T SNP and variables identified in univariate analyses indicated that the CC genotype was independently associated with cannabis dependence (P = 0.045, OR = 6.61 [1.05–46.58]).
This is the first time a significant specific genetic marker has been shown in cannabis dependence. ABCB1 polymorphisms may alter Δ9THC distribution, its psychoactive effects and individual vulnerability to dependence. These results pave the way to a new pharmacogenetic hypothesis in cannabis dependence.