Pairs concordant for not using cannabis early were at significantly reduced risk of drug abuse/dependence compared to all other groups (see Table 1). For 5 of the 8 drug abuse/dependence diagnoses, the pairs concordant for early cannabis use were at significantly increased risk compared to all other groups. Although the early-users from the discordant pairs had somewhat higher drug abuse/dependence rates than the later/never-users from discordant pairs, the differences were only significant for only 3 of the 8 drug abuse/dependence diagnoses.
