With regards to questions such as: Can the presence of suicidal or impulsive behaviors lead to or worsen substance use; and, can substance use lead to increased levels of impulsivity or suicidal behaviors, we recognize that interactions in developmental-transactional models are often bidirectional (Bridge et al. 2006) and not orthogonal (Bridge et al. 2006; Dahl, 2004; Pratt, 2002; Steinberg, 2005). Therefore, both of these outcomes are theoretically possible. For example, suicidal or impulsive behaviors in early adolescence may increase the likelihood of developing substance abuse and related psychiatric comorbidity in later adolescence. In contrast, early substance use may exacerbate impulsive-aggression in early adolescence, leading to suicidal behavior later in adolescence.
