Fig. 4. Bi-variate association between NR3C1 methylation levels at baseline and duration of substance use (per year increase) assessed over three years in adolescent participants of the KUPOL study.

The results should be interpreted in terms of risk ratio (RRs) with 1 as a null value. Methylation level 0% was considered as the reference category. Low methylation group: methylation levels below the median of detectable methylation and high methylation group: methylation levels above the median. RRs were not estimated for the CpG1 CpG5 and CpG1–5 sites with low methylation for cannabis use given no cases in these groups.