“…Likewise, the association of an early drug use debut and later risk behavior appears to be multidirectional, as subsequent risky substance use practices (e.g., needle sharing), sexual practices (e.g., multiple partners, transactional sex, lack of condom use), and substance use in general have all been linked. This crossover of risk behavior domains, thus, suggests that early initiation of either type of risk behavior can be associated with the other [ 6 , 24 , 25 , 27 , 31 , 37 , 49 , 63 – 65 , 76 , 78 – 80 , 89 , 98 , 103 , 104 ], and both might operate synergistically (e.g., drinking or illicit drug use coupled with unprotected sex [ 105 ]) as part of a tendency toward a generally riskier lifestyle.…”