4,385 individuals (60.2% of the sample) reported having used all three substances. Of these individuals, the most common sequence of initiation was tobacco prior to alcohol prior to cannabis (46.6%), and 2.7% of individuals reported first using all three substances at the same age. The ages of initiation of all three substances were modestly correlated (men: rs=0.25–0.34, women: rs=0.25–0.29), as were the symptom counts (men: rs=0.32–0.33, women: rs=0.28–0.35). Modest relations were also observed between the ages of first use and symptom counts (men: rs=−0.10 – −0.31, women: rs=−0.12 – −0.28).
