ADHD PRS were associated with nicotine and cannabis involvement, even after controlling for GENSUB. These findings are markedly consistent with an expansive epidemiological and clinical literature documenting higher rates of cigarette smoking in individuals with ADHD, even after accounting for comorbid conduct problems (e.g., Elkins et al., 2007; Chang et al., 2012). Consistent with prior studies showing risk effects of ADHD on both smoking initiation and dependence (e.g., Elkins et al., 2007; Sibley et al., 2014), ADHD PRS related to all levels of nicotine involvement. However, these associations were all of a similar magnitude, allowing us to conclude that the relationship was not dose-dependent with respect to severity of involvement. In contrast, we noted a negative relationship between ADHD PRS and non-problem cannabis use. The evidence supporting the role of ADHD in the use of cannabis is stronger than support for its role in the onset of cannabis use disorders (e.g., Elkins et al., 2007; Lee et al., 2011). However, we are not aware of any studies that have examined non-problem use specifically. It is possible that individuals at high
