Change in alcohol demand following a brief intervention predicts change in alcohol use: A latent growth curve analysis

Abstract

Background: The association between behavioral economic demand and various alcohol use outcomes is well established. However, few studies have examined whether changes in demand occur following a brief alcohol intervention (BAI), and whether this change predicts alcohol outcomes over the long term.

Methods: Parallel process piecewise latent growth curve models were examined in a sample of 393 heavy drinking emerging adults (60.8% women; 85.2% white; M_age = 18.77). In these models, two linear slopes represented rates of change in alcohol use, heavy drinking episodes, alcohol-related problems, and demand (intensity and highest expenditure across all price points or O_max ) from baseline to 1 month (slope 1) and 1 month to 16 months (slope 2). Mediation analyses were conducted to estimate the effect of a BAI on 16-month alcohol outcomes through slope 1 demand.

Results: A two-session BAI predicted significant reductions in all five outcomes from baseline to 1-month follow-up. Although no further reduction was observed from the 1-month to the 16-month follow-up, there was no regression to baseline levels. Slope 1 demand intensity, but not O_max , significantly mediated the association between BAI and both outcomes-heavy drinking episodes (Est. = -0.23, SE = 0.08, p < 0.01) and alcohol-related problems (Est. = -0.15, SE = 0.07, p < 0.05)-at the 16-month follow-up.

Conclusions: Reducing high valuation of alcohol among heavy drinking emerging adults within the first month following BAI is critical for the long-term efficacy of the intervention. A two-session BAI was associated with enduring reductions in alcohol demand, and the change in demand intensity, but not O_max , was associated with sustained reductions in heavy drinking and alcohol-related problems.

Keywords: alcohol; behavioral economics; brief motivational intervention; demand; emerging adults.

Figure 1.. Conceptual Model of Demand-Mediated BMI Effects on Alcohol Use at 16-Month Follow-up (Model 4).

Note. “Alcohol Outcomes” is a placeholder for drinks per week (DPW), heavy drinking episodes (HDE), and alcohol-related problems (ARP) outcome models. Bold paths are mediated pathways: (1) Intervention condition intensity slope 1 DPW/HDE/ARP at 16-month follow-up, and (2) Intervention condition O_max slope 1 DPW/HDE/ARP at 16-month follow-up. Ovals indicate latent growth variables. Rectangles indicate time-invariant observed variables defined at baseline.

Figure 2.

Mean Scores for Demand and Alcohol Outcomes Variables at Baseline and Across all Follow-up Assessments by Study Condition. AO = Assessment only. BAI = Brief Alcohol Intervention. BL = baseline, F1 = 1-month follow-up, F6 = 6-month follow-up, F12 = 12-month follow-up, F16 = 16-month follow-up.