Trajectories of impulsivity by sex predict substance use and heavy drinking.

Although impulsivity and sensation seeking have been consistently associated with substance use, few studies have analyzed the relationship between changes in these variables and substance use in early adolescents. The aim of this study was to identify trajectories of impulsivity and sensation seeking and explore their relationship with substance use and heavy drinking. A total of 1342 non-user adolescents (53.6% males; mean age = 12.98, SD = 0.50) annually completed the Barratt Impulsiveness Scale, the Zuckerman's Impulsive Sensation Seeking scale and a delay discounting task, over a total period of three years. Past alcohol, tobacco and cannabis use, drunkenness episodes (DE) and problem drinking were also assessed. Impulsivity trajectories were explored using latent class mixed modelling. To study their predictive power binary logistic regressions were used. Two trajectories of impulsivity were found in males and five were found in females. Males with an increasing impulsivity trajectory were more likely to report tobacco [odds ratio (OR) = 1.84] and cannabis (OR = 3.01) use, DE (OR = 2.44) and problem drinking (OR = 3.12). The early increasing trajectory in females predicted tobacco use (OR = 3.71), cannabis use (OR = 5.87) and DE (OR = 3.64). Lack of premeditation and delay discounting were the most relevant facets in high-risk trajectories. Selective intervention and more intense and tailored treatment might help these adolescents to reduce early increases in impulsivity and prevent escalation of substance use.