Our measure of rVUS is unique in that it involves repeated non-use of standardized methods of birth control, a behavior less subject to “spur of the moment” sexual activity which is often related to concomitant substance use. Thus, we did not expect indices of impulsivity to be the sole common feature underlying adolescent cannabis use and rVUS – correspondingly, adjustment for early sexual debut or conduct problems, both aspects of disinhibited behavior, did not alter the significance of the relationship. Other indices of impulsive sensation-seeking, such as low conscientiousness, have been reliably related to sexual risk-taking and promiscuity (31) as well as to substance use (32). Secondary analyses suggested that while rVUS was strongly associated with lower conscientiousness (from the NEO-PI-R(33)) in our data as well (mean score of 2.78 vs. 2.65; p<.0001), the addition of a measure of low conscientiousness (bottom quartile of scores) did not account for the association between adolescent cannabis use and rVUS (results available upon request).
