Purpose: Few studies include peers in brief motivational interventions (BMIs) for substance misuse. This study tested a peer-enhanced BMI, where friends in emerging adults’ (EAs) social networks attended interventions. Method: Dyads were randomized to Peer-Enhanced Motivational Interviewing (PMI) or waitlist control (WC) conditions (NCT03264872). Seventy-four dyads (n = 188) enrolled, completing surveys at baseline and then biweekly for 12 weeks. Primary outcomes included cannabis and alcohol problem indices. Supplemental measures were peer supportive behaviors, days of binge drinking, and alcohol-related problems. Linear, quadratic, and piecewise growth models tested differences in trends through 12 weeks. Results: For target clients, most results favored the PMI group with significant differences and moderate effects at select time points. However, these no significant between group differences in trends were observed between conditions through 12 weeks. Peer supportive behaviors increased significantly at 2 weeks among peers receiving PMI, but this effect faded through 12 weeks. Discussion: PMI is a promising dyadic-based treatment for EA substance misuse that should be studied further with larger samples.
BarnettN. P.LightJ. M.ClarkM. A.OttM. Q.DiGuiseppiG. T.MeiselM. K. (2024). Dynamic social network analysis of a brief alcohol intervention trial in heavy-drinking college students shows spillover effects. Alcohol: Clinical and Experimental Research, 48(2), 375–388. https://doi.org/10.1111/acer.15237
2.
BennettK. M.ClaryK. L.SmithD. C.LeeC. (2020). Usability and acceptability of a mobile app to help emerging adults address their friend’s substance use: Quantitative study. Journal of Medical Internet Research, 22(11), Article e16632. https://doi.org/10.2196/16632
3.
BergC. J.StrattonE.SchauerG. L.LewisM.WangY.WindleM.KeglerM. (2015). Perceived harm, addictiveness, and social acceptability of tobacco products and marijuana among young adults: Marijuana, hookah, and electronic cigarettes win. Substance Use & Misuse, 50(1), 79–89. https://doi.org/10.3109/10826084.2014.958857
4.
BorsariB.CareyK. B. (2001). Peer influences on college drinking: A review of the research. Journal of Substance Abuse, 13(4), 391–424. https://doi.org/10.1016/S0899-3289(01)00098-0
5.
CareyK. B.LustS. A.ReidA. E.KalichmanS. C.CareyM. P. (2016a). How mandated college students talk about alcohol: Peer communication factors associated with drinking. Health Communication, 31(9), 1127–1134. https://doi.org/10.1080/10410236.2015.1045238
6.
CareyK. B.Scott-SheldonL. A.GareyL.ElliottJ. C.CareyM. P. (2016b). Alcohol interventions for mandated college students: A meta-analytic review. Journal of Consulting and Clinical Psychology, 84(7), 619–632. https://doi.org/10.1037/a0040275
7.
CuttlerC.SpradlinA. (2017). Measuring cannabis consumption: Psychometric properties of the daily sessions, frequency, age of onset, and quantity of cannabis use inventory (DFAQ-CU). PLoS One, 12(5), Article e0178194. https://doi.org/10.1371/journal.pone.0178194
8.
DennisM.GodleyS. H.DiamondG.TimsF. M.BaborT.DonaldsonJ.LiddleH.TitusJ. C.KaminerY.WebbC.HamiltonN.FunkR. (2004). The cannabis youth treatment (CYT) study: Main findings from two randomized trials. Journal of Substance Abuse Treatment, 27(3), 197–213. https://doi.org/10.1016/j.jsat.2003.09.005
9.
DennisM. L.TitusJ. C.WhiteM. K.UnsickerJ. I.HodgkinsD. (2003). Global appraisal of individual needs: Administration guide for the GAIN and related measures. Chestnut Health Systems. https://chestnut.app.box.com/v/GAIN-I-Materials
10.
GarnerB. R.HunterB. D.SmithD. C.SmithJ. E.GodleyM. D. (2014). The relationship between child maltreatment and substance abuse treatment outcomes among emerging adults and adolescents. Child Maltreatment, 19(3-4), 261–269. https://doi.org/10.1177/1077559514547264
11.
HallW. D.PattonG.StockingsE.WeierM.LynskeyM.MorleyK. I.DegenhardtL. (2016). Why young people's substance use matters for global health. The Lancet Psychiatry, 3(3), 265–279. https://doi.org/10.1016/S2215-0366(16)00013-4
12.
HayakiJ.AndersonB. J.SteinM. D. (2018). Dual use of alcohol and marijuana and condomless sex in young adult men and women: A within-subject day-level analysis. The American Journal on Addictions, 27(5), 413–418. https://doi.org/10.1111/ajad.12738
13.
HidesL.CarrollS.ScottR.CottonS.BakerA.LubmanD. (2013). Quik fix: A randomized controlled trial of an enhanced brief motivational interviewing intervention for alcohol/cannabis and psychological distress in young people [Letter to the Editor]. Psychotherapy and Psychosomatics, 82(2), 122–124. https://doi.org/10.1159/000341921
14.
HingsonR.WhiteA. (2014). New research findings since the 2007 surgeon general’s call to action to prevent and reduce underage drinking: A review. Journal of Studies on Alcohol and Drugs, 75(1), 158–169. https://doi.org/10.15288/jsad.2014.75.158
LeeC. M.NeighborsC.LewisM. A.KaysenD.MittmannA.GeisnerI. M.AtkinsD. C.ZhengC.GarbersonL. A.KilmerJ. R.LarimerM. E. (2014). Randomized controlled trial of a Spring Break intervention to reduce high-risk drinking. Journal of Consulting and Clinical Psychology, 82(2), 189–201. https://doi.org/10.1037/a0035743
17.
LoveC. T.LongabaughR.CliffordP. R.BeattieM.PeasleeC. F. (1993). The Significant-other Behavior Questionnaire (SBQ): An instrument for measuring the behavior of significant others towards a person's drinking and abstinence. Addiction, 88(9), 1267–1279. https://doi.org/10.1111/j.1360-0443.1993.tb02149.x
18.
MagillM.MastroleoN. R.ApodacaT. R.BarnettN. P.ColbyS. M.MontiP. M. (2010). Motivational interviewing with significant other participation: Assessing therapeutic alliance and patient satisfaction and engagement. Journal of Substance Abuse Treatment, 39(4), 391–398. https://doi.org/10.1016/j.jsat.2010.07.006
19.
MartensM. P.NeighborsC.Dams-O'ConnorK.LeeC. M.LarimerM. E. (2007). The factor structure of a dichotomously scored Rutgers Alcohol Problem Index. Journal of Studies on Alcohol and Drugs, 68(4), 597–606. https://doi.org/10.15288/jsad.2007.68.597
20.
McCambridgeJ.StrangJ. (2004). The efficacy of single-session motivational interviewing in reducing drug consumption and perceptions of drug-related risk and harm among young people: Results from a multi-site cluster randomized trial. Addiction, 99(1), 39–52. https://doi.org/10.1111/j.1360-0443.2004.00564.x
21.
MillerW. R.RollnickS. (2023). Motivational interviewing: Helping people change and grow (4th ed.). Guilford Press.
22.
MoyersT. B.RowellL. N.ManuelJ. K.ErnstD.HouckJ. M. (2016). The motivational interviewing treatment integrity code (MITI 4): Rationale, preliminary reliability and validity. Journal of Substance Abuse Treatment, 65, 36–42. https://doi.org/10.1016/j.jsat.2016.01.001
NeighborsC.LeeC. M.AtkinsD. C.LewisM. A.KaysenD.MittmannA.FossosN.GeisnerI. M.ZhengC.LarimerM. E. (2012). A randomized controlled trial of event-specific prevention strategies for reducing problematic drinking associated with 21st birthday celebrations. Journal of Consulting and Clinical Psychology, 80(5), 850–862. https://doi.org/10.1037/a0029480
25.
PocucaN.London-NadeauK.GeoffroyM. C.ChadiN.SéguinJ. R.ParentS.BoivinM.TremblayR. E.CôtéS. M.Castellanos-RyanN. (2022). Changes in emerging adults’ alcohol and cannabis use from before to during the COVID-19 pandemic: Evidence from a prospective birth cohort. Psychology of Addictive Behaviors, 36(7), 786–797. https://doi.org/10.1037/adb0000826
26.
RennyM. H.StecherY.Vargas-TorresC.ZebrowskiA. M.MerchantR. C. (2025). Trends in substance use-related emergency department visits by youth, 2018–2023. The American Journal of Emergency Medicine, 92, 1–9. https://doi.org/10.1016/j.ajem.2025.02.035
27.
SchwartzS. J.PetrovaM. (2019). Prevention science in emerging adulthood: A field coming of age. Prevention Science, 20(3), 305–309. https://doi.org/10.1007/s11121-019-0975-0
28.
SmithD. C.BennettK. M.DennisM. L.FunkR. R. (2017). Screening, assessment and diagnosis of substance use disorders among emerging adults. In Smith’sD. C. (Ed.), Emerging adults and substance use disorder treatment: Developmental considerations and innovative approaches (pp. 38–70). Oxford University Press.
29.
SmithD. C.CleelandC.MiddletonA.GodleyM. D. (2013). Willingness and appropriateness of peers participating in emerging adults’ substance misuse treatment. Journal of Substance Abuse Treatment, 45(1), 148–154, NIHMS# 449291. PMID: 23462152. https://doi.org/10.1016/j.jsat.2013.01.008
30.
SmithD. C.DavisJ. P.DumasT.UrecheD. J. (2016). Six month outcomes of a peer enhanced community reinforcement approach for emerging adults with substance misuse: A preliminary study. Journal of Substance Abuse Treatment, 61, 66–73. https://doi.org/10.1016/j.jsat.2015.09.002
31.
SmithD. C.GodleyS. H.GodleyM. D.DennisM. L. (2011). Adolescent community reinforcement approach outcomes differ among emerging adults and adolescents. Journal of Substance Abuse Treatment, 41(4), 422–430. https://doi.org/10.1016/j.jsat.2011.06.003
32.
SmithD. C.NeighborsC.LemboJ. (2017). What is the state of the art in preventing and treating substance use disorders among emerging adults? In Smiths’D. C. (Ed.), Emerging adults and substance use disorder treatment: Developmental considerations and innovative approaches (pp. 71–95). Oxford University Press.
33.
SmithD. C.SchwebelF.LarimerM. (2017). Facilitators, friends, or the formerly afflicted: Integrating peers into emerging adults substance use interventions. In Smiths’D. C. (Ed.), Emerging adults and substance use disorder treatment: Developmental considerations and innovative approaches.(pp. 147-166). Oxford University Press.
34.
SmithJ. E.MeyersR. J. (2007). Motivating substance abusers to enter treatment: Working with family members. Guilford Press.
35.
Substance Abuse and Mental Health Services Administration. (2020). Key substance use and mental health indicators in the United States: Results from the 2019 National Survey on Drug Use and Health (HHS Publication No. PEP20-07-01-001, NSDUH Series H-55). Center for Behavioral Health Statistics and Quality, Substance Abuse and Mental Health Services Administration. https://www.samhsa.gov/data/
36.
SureshK. P. (2011). An overview of randomization techniques: An unbiased assessment of outcome in clinical research. Journal of Human Reproductive Sciences, 4(1), 8–11. https://doi.org/10.4103/0974-1208.82352
37.
TevyawT. O. L.BorsariB.ColbyS. M.MontiP. M. (2007). Peer enhancement of a brief motivational intervention with mandated college students. Psychology of Addictive Behaviors, 21(1), 114–119. https://doi.org/10.1037/0893-164X.21.1.114
38.
VaderA. M.WaltersS. T.PrabhuG. C.HouckJ. M.FieldC. A. (2010). The language of motivational interviewing and feedback: Counselor language, client language, and client drinking outcomes. Psychology of Addictive Behaviors, 24(2), 190–197. https://doi.org/10.1037/a0018749
39.
VillarosaM.KisonS.MadsonM.Zeigler-HillV. (2016). Everyone else is doing it: Examining the role of peer influence on the relationship between social anxiety and alcohol use behaviours. Addiction Research & Theory, 24(2), 124–134. https://doi.org/10.3109/16066359.2015.1086758
