The research is unique in that it covers a wide developmental span from early adolescence to adulthood and studies the comorbidities in the understudied population of Puerto Ricans and Blacks. Furthermore, the psychosocial variables associated with pairs of comorbid trajectories of tobacco and marijuana use are related to five important domains in an individual��s life, including sellckchem the individual��s personality attributes and social network. Understanding the relationship of these domains to pairs of comorbid trajectories of use is essential to improve treatment programs. A small number of studies have focused on the relationship between trajectories of use of different substances (e.g., Flory, Lynam, Milich, Leukefeld, & Clayton, 2004; Orlando, Tucker, Ellickson, & Klein, 2005).

Jackson, Sher, and Schulenberg (2008), using a large national sample, followed individuals from late adolescence to adulthood and identified five trajectories of tobacco use and four trajectories of marijuana use. Among 20 possible pairs of trajectories of comorbid tobacco and marijuana use, 7 occurred more frequently than expected. In order to isolate predictors of pairs of such comorbid trajectories of tobacco and marijuana use, Jackson et al. first identified factors that were common to trajectories of use of both substances. A number of important influences on trajectories of substance use have been described in Family Interactional Theory (FIT). FIT (Brook, Brook, Gordon, Whiteman, & Cohen, 1990) is a multidimensional theory of the developmental pathways to substance use and other problem behaviors.

The model incorporates interrelated domains, which function as proximal and distal influences on the individual��s behavior, namely components of the individual��s personality (e.g., Ego Integration, Depressive Mood, Risk Taking, Rebellion, Delinquency), social influences (e.g., Religious Attendance, Peer Deviance, Peer Substance Use), parent personality and parenting, and ecology. These domains are linked to substance use and other problem behaviors via three primary mechanisms: social modeling, parent�Cchild attachment, and identification with values and behaviors as a result of the attachment relationship between parents and child. Studies have found that psychosocial variables such as Sensation Seeking, Depressive Symptoms, Delinquency, Religious Attendance, and Peer Substance Use are significantly related to trajectories of use of a single substance (Brown, Flory, Lynam, Leukefeld, & Clayton, 2004; Windle & Wiesner, 2004). We add to this line of research by examining the associations of many Cilengitide such factors from the personality and social influence domains of FIT with pairs of comorbid trajectories of tobacco and marijuana use.