Changes in the trajectories of drug-free friendships and substance use among a cohort of individuals with multiple substance use disorders

<b>Aims:</b> We used reports (<i>n</i> = 208) of drug-free friendships and alcohol and drug use by people diagnosed with substance use disorder in order to investigate their annual change trajectories across 4 years after treatment and the association between these trajectories and debut age and gender. <b>Methods:</b> The participants were recruited from the Stavanger region, Norway. Using cross-sectional analysis, we first examined the relationship between "alcohol and drug use" and "drug-free friendships" across the five follow-ups. We tested whether these associations were significant using chisquare chi-squared tests. Second, we developed three latent growth curve models examining the association between "alcohol and drug use" and "drug-free friendships". <b>Results:</b> Our analysis displays a stable drug-free friendships pattern across follow-ups. Only in the fourth follow-up was there a significant association between lower "alcohol and drug use" and having "drug-free friendships" (χ² = 18.27, df = 8, <i>p</i> < .05). In model 1, we found no association between gender, debut age, and alcohol and drug use; model 2 had significant variance on intercept but not on slope; model 3 had good fit (χ² = 44.33, df = 39, comparative fit index = 0.98, root mean square error of approximation = 0.027). However, we did not find any significant regression path between the "alcohol and drug use" and "drug-free friendships" slopes. <b>Conclusions:</b> Drug-free relationships were in the studied cohort group found to have little influence on reducing alcohol and drug use, while debut age and gender were unrelated to use trajectories across 4 years. We suggest that future research should focus on the frequency and quality of drug-free friendships and participants' friendship assessments because previous research has found such relationships to facilitate recovery.