Outcome and process evaluation of a social norms approach intervention on nonmedical use of prescription stimulants for study performance among Flemish university students: a quasi-experimental study

Background Students are increasingly engaging in the nonmedical use of prescription stimulants (NMUPS) to enhance their study performance. However, little research has been conducted on the effectiveness of interventions to reduce NMUPS. This study assessed the effect of a social norms approach (SNA) intervention on NMUPS and the perception of NMUPS for study performance among Flemish students. Additionally, a process evaluation of the intervention was performed. Methods A social media campaign, containing social norm messages based on data from 'Head in the Clouds?' (HITC) survey edition 2021, ran from December 2022 to April 2023 at the University of Antwerp. Data from the HITC survey was also used as baseline measurement (Antwerp: n = 2,963, Ghent: n = 8,598). Afterward, a post-intervention survey was conducted among the students of the University of Antwerp (n = 1,827) and Ghent University (n = 3,333), the latter serving as the control group. A quantitative process evaluation among the intervention group was conducted according to the guidance of the Medical Research Council for process evaluation of complex interventions. Results A difference-in-difference approach showed that students of the intervention group at endline estimated NMUPS for study performance among peers significantly lower (P < .0001; Est. = -3.792; SE = 0.805)-and thus closer to the real social norm. There was no significant influence (P = 0.421; OR = 1.10; 95% CI = 0.87 to -1.39) of the intervention on NMUPS for study performance. The process analysis showed that 18.7% of the intervention group had seen the campaign. Most of them found the campaign credible (83.6%) and clear (website: 90.8%; videos 94.7%; images: 92.4%). The overall satisfaction was 6.38 (SD 1.68) out of 10. Very few students (3.1%) had seen the campaign via TikTok, compared to Facebook (64.0%) and Instagram (53.3%), although 35.7% of the total budget had been spent on TikTok. Conclusions The results of this study confirm that an SNA intervention could reduce the misperceptions of NMUPS among students. However, the hypothesis that the behavior of NMUPS for study performance would be reduced subsequently could not be demonstrated. Follow-up research is needed to investigate long-term effects. The implementation of the intervention might be improved by making more optimal use of the campaign budget.