age at onset of psychotic disorder in lifetime cannabis users whereas the reverse was noted (decreasing age at onset with decreasing copies of Val allele) for lifetime nonusers (68). In addition, a recent study (N=533) posits that the predictive effect of the interaction between cannabis use and COMT genotype on psychosis is only exerted in those with a history of childhood abuse (69). Finally, contradictory evidence from a recent study (N=748 patients) of COMT haplotypes in two Spanish samples indicates a higher degree of association between lifetime cannabis use and schizophrenia in Met (not Val) carriers (70).
