UC San Diego

Although use of both alcohol and tobacco is common among college-attending young adults, little is known about the stability of co-use over time. Difficulties in studying change in these behaviors may reflect inconsistencies in how smoking in particular is categorized. This study used longitudinal data, gathered at three time points three months apart, to examine cigarette and alcohol use profiles and the stability of profile structure and membership. Undergraduate student smokers' (N=320) past 30-day alcohol and cigarette use was assessed using the timeline followback procedure. Smoking (number of cigarettes and number of smoking days) and drinking (number of drinks and number of binges) were entered into a latent transition analysis (LTA) to identify the latent taxonomic structure within the sample, and determine the probability of movement between groups over time. A three-profile solution emerged at each time point. The LTA probabilities highlighted both progression and reduction in the lower-use groups. Overall, findings revealed notable changes in tobacco and alcohol use behaviors over the span of six months, affecting both profile structures and individual membership status. This suggests that among young adults both tobacco and alcohol use are temporally unstable behaviors, particularly among those using at lower levels. © 2014 Informa UK Ltd.