Longitudinal Analysis of ADHD Symptoms, Impulsivity, and Substance Use in a College Sample

Introduction: Impulsivity is a multidimensional construct related to increased problematic substance use, including earlier onset of dependence (Verdejo-García, Lawrence, & Clark, 2008). Impulsivity is also one of the defining factors of those with Attention-Deficit/Hyperactivity Disorder (ADHD), a population with high levels of comorbid substance use. Previous research using the UPPS model of impulsivity found that the facets of negative urgency, sensation seeking, and lack of premeditation were all significant mediators between ADHD symptoms and substance use in an undergraduate sample (Roberts et al., 2014). The current study extends this prior work by examining whether these mediation models hold across time in the prediction of substance use one year later.

Methods: 296 undergraduates (54% female, 77% Caucasian, M = 19.96 years, SD = 0.86) from a Southern, Midwestern university completed an initial assessment during which they reported symptom severity of ADHD using the Conners’ Adult ADHD Rating Scale-Self Report: Long Version and endorsed different facets of impulsivity on the UPPS Impulsive Behavior scale. One year later, alcohol and tobacco use was assessed using the Life History Calendar and the Alcohol Use Disorder Identification Test.

Results: Indirect effects were calculated in Mplus7 using robust maximum likelihood estimation. As expected, negative urgency and lack of premeditation were each significant mediators between both hyperactive/impulsive and inattentive symptoms and later alcohol use (indirect effects: 0.08-0.14, p<0.05). Sensation seeking was a significant mediator only between hyperactive/impulsive symptoms and later alcohol use (indirect effects: 0.07, p<0.01, 95%CI: 0.03-0.12). Negative urgency significantly mediated the relationship between hyperactive/impulsive symptoms and later frequency of tobacco use (indirect effects: 0.16, p<0.001, 95%CI: 0.07-0.25). Multiple mediation models computed using bootstrapped estimates indicated that lack of premeditation and sensation seeking were significant multiple mediators of the association between ADHD symptoms and alcohol use (indirect effects: 0.03-0.06, p<0.001), but negative urgency was not.

Conclusions: Different aspects of impulsivity appear to mediate ADHD comorbidity with different types of substance use. Study results are consistent with the idea that individuals with ADHD may engage in increased alcohol use without planning. Those individuals with increased hyperactive/impulsive symptoms may additionally use alcohol because of a drive for novelty. Further, tobacco use in these individuals may be motivated by the experience of high negative emotionality. Understanding factors that help explain comorbidity between ADHD and substance use may help tailor future interventions which could be targeted to impulsivity, specifically planning and emotionality (O’Leary-Barrett et al., 2013).