Brian H. Calhoun’s research while affiliated with University of Washington and other places

Background High‐risk drinking among college students is common, and alcohol expectancies and experienced consequences are proximal predictors of use. This study tested short‐ and long‐term efficacy of a personalized just‐in‐time adaptive intervention with daily messages about alcohol use, alcohol expectancies, and consequences delivered via mobile app. Methods Participants were 408 students enrolled at a 2‐ or 4‐year college (75% 4‐year; 64% female) who completed twice‐daily assessments for 21 days and follow‐up surveys at 1‐, 6‐, and 12‐months. Data collection spanned January 2020 through April 2022. Participants were randomized to either an intervention condition receiving daily intervention messages and other related alcohol and expectancy‐focused content via the app or an assessment‐only control condition. Both conditions were administered daily surveys through the app. Results Poisson multilevel models were conducted to examine intervention effects on alcohol outcomes (i.e., drinks per week, heavy episodic drinking frequency, peak estimated blood alcohol concentration, and alcohol‐related consequences, as well as positive and negative alcohol expectancies) at each follow‐up assessment. On average, participants in both conditions reported decreased alcohol use outcomes, consequences, and expectancies at 1‐, 6‐, and 12‐month follow‐up compared to baseline. A single statistically significant difference between participants in the intervention and control conditions was observed at 1‐month follow‐up. Specifically, participants in the intervention condition reported a 17% greater decrease in heavy episodic drinking frequency than participants in the control condition, on average. Conclusions Findings highlight the complexities of developing, implementing, and testing adaptive interventions, particularly within the context of the COVID‐19 pandemic.

The current study examined age-varying patterns of cannabis use, cannabis-specific risk factors, and their associations across young adulthood. We used repeated cross-sectional data from young adults (N = 15,251; Mage = 22.02 years, SDage = 2.22; 68% female) who enrolled in the annual, statewide Washington Young Adult Health Survey between 2015 and 2022. Logistic time-varying effect models showed that cannabis use increased from ages 18–22 and remained relatively stable through age 26. Most cannabis-specific risk factors increased gradually across young adulthood, although perceptions of cannabis use acceptability (injunctive norms) increased substantially through age 23 followed by decreases. Ease of obtaining cannabis, perceptions about others’ use (descriptive norms), and low perceived physical harm were generally associated with any past-month cannabis use with stronger associations around age 18. Injunctive norms and low perceived psychological harm were consistently associated with past-month use across young adulthood. Ease of obtaining cannabis, injunctive norms, descriptive norms, and low psychological harm were associated with frequent cannabis use across young adulthood with associations strongest prior to age 21. Low perceived physical harm was associated with frequent use across young adulthood with associations getting somewhat stronger across ages. Findings underscore the importance of focusing on cannabis-specific risk factors in preventive intervention efforts over the course of young adulthood, including focus on young adults in their mid- 20 s in the context of legalized cannabis.

Background: There is a robust body of work demonstrating that certain drinking practices, such as pregaming or playing drinking games, are linked to heavier, riskier patterns of drinking among college students. However, less attention has been paid to other drinking practices that are relatively common among undergraduates, such as daytime drinking (i.e., drinking before 4:00 PM). Method: Using data from an intensive longitudinal study (bursts of daily data over the course of 12 months; 6,842 total days of data) collected from a high-risk sample of college students (N=403), the present study tested daytime drinking as both a proximal (daily level drinking outcomes) and distal (AUD symptoms) risk factor for hazardous drinking. Results: Daytime drinking was reported by over 70% of the sample and on approximately 15% of drinking days. Daily-level findings indicated that compared to non-daytime drinking days, daytime drinking days were significantly associated with more drinks consumed, more high-risk drinking practices (i.e., heavy episodic or high intensity drinking), and greater subjective intoxication. Longitudinal analyses identified frequent daytime drinking as a risk factor for increased hazardous drinking behavior, particularly among individuals who were younger or reported lower hazardous drinking at baseline. Conclusions: Findings add to a sparse literature supporting daytime drinking as a risky drinking practice among college students. Future work should aim to further characterize contextual and psychosocial factors associated with daytime drinking practices.

Objectives. To examine trends in young adult self-reported driving under the influence of alcohol (DUI-A), cannabis (DUI-C), and simultaneous alcohol and cannabis use (DUI-AC) in a state with legalized nonmedical cannabis use from before to during the COVID-19 pandemic. Methods. We used logistic regression and annual statewide data from the Washington Young Adult Health Survey to assess DUI behaviors from 2016 to 2021. Results. Both prepandemic yearly changes in prevalence and deviations from those trends during the pandemic years were small and not statistically significant. However, prevalence estimates were alarming: 12.0% of participants reported DUI-A, 12.5% reported DUI-C, and 2.7% reported DUI-AC. Exploratory moderation analyses indicated a relative increase in DUI-A during 2020 among 4-year college students relative to young adults not attending 4-year colleges. Conclusions. Young adults in Washington State continued to engage in risky DUI behaviors during the pandemic. College students may have increased their likelihood of DUI-A during COVID-19. Public Health Implications. Young adults, for whom vehicle crashes remain a leading cause of death, showed little change in DUI behaviors during the COVID-19 pandemic. There is continued need for young adult DUI prevention efforts. ( Am J Public Health. 2024;114(S8):S698–S701. https://doi.org/10.2105/AJPH.2024.307767 )

Objective: It is unknown whether age-related decreases in substance use (maturing out) are observed in the legalized cannabis context. This study evaluated age-related changes in past-month alcohol use frequency, cannabis use frequency, and any simultaneous alcohol and marijuana/cannabis (SAM) use among young adults who engaged in the respective substance use behavior. Method: Young adults, residing in Washington State at enrollment (N=6,509; 68.3% female; ages 18-25), provided 3-5 years of annual data in a longitudinal, cohort-sequential design from 2015 to 2019, a period after nonmedical cannabis was legalized and implemented. Multilevel growth models were conducted; post-stratification weights were applied to make the sample more similar to the Washington young adult general population in demographic characteristics. Results: Among those who reported alcohol use at 1+ timepoints, days of alcohol use increased from age 18 to approximately age 25 and then decreased until age 30. Among those who reported cannabis use at 1+ timepoints, days of cannabis use increased from age 18 until approximately age 23 and then decreased until age 30. Among those who reported SAM use at 1+ timepoints, the probability of SAM use increased from age 18 until approximately age 24 and then decreased until age 30. Age-related changes in SAM use were largely explained by concurrent changes in alcohol and cannabis use frequency. Conclusions: Maturing out was observed for alcohol, cannabis, and SAM use among those who used each respective substance, with evidence that age-related changes in SAM use were tied to alcohol and cannabis use frequency.

Most young adults naturally mature out of high-risk substance use patterns, but it is important to identify factors that may impede normative declines. Use of alcohol and cannabis simultaneously (i.e., simultaneous alcohol and marijuana/cannabis [SAM]) is cross-sectionally associated with alcohol and cannabis concerns, and SAM use increases acute risks at the daily level. However, less is known about long-term risks of SAM use and, specifically, how SAM use relates to maturing out of alcohol and cannabis use. Using four consecutive years of survey data from young adults who reported SAM use (N=409; 1636 responses; aged 18–25 at baseline), we first estimated age-related changes in symptoms of alcohol and cannabis use disorder (AUD/CUD) using multilevel growth modeling. Findings supported a maturing out process, as both AUD and CUD symptom severity significantly declined across young adulthood, on average (4 % and 5 % per year respectively, with significant acceleration). Cross-level interactions tested whether participants’ mean SAM use frequency across all four timepoints moderated age-related trajectories in AUD/CUD symptom severity. Significant interactions indicated that, relative to less-frequent SAM use, participants with more frequent SAM use showed less steep declines in AUD (1 % decrease per year vs. 6 % per year) and CUD symptoms (0 % decrease per year vs. 7 % per year); thus, SAM frequency was associated with slower/delayed maturing out of hazardous alcohol and cannabis use. Findings highlight that SAM use may be a correlate or risk-factor for prolonged high-risk substance use during young adulthood that relates to deviations from maturing out processes.

Motor vehicle crashes are a leading cause of death for young adults (YA) in the USA, and driving under the influence of alcohol (DUIA), cannabis (DUIC), and simultaneous use of both substances (DUIAC) are prominent risk factors. Trends in YA impaired driving behaviors after opening of cannabis retail stores have been understudied. We examined YA trends in DUIA, DUIC, and DUIAC from immediately prior through 5 years following the opening of cannabis retail outlets in Washington State (2014–2019). Differences in trends were assessed across age, sex, and urbanicity. Weighted logistic regressions assessed yearly change in prevalence of DUIA, DUIC, and DUIAC from 2014 to 2019, using annual statewide data from the Washington Young Adult Health Survey (n = 12,963; ages 18–25). Moderation of trends by age, sex, and urbanicity was assessed. Prevalence of DUIA decreased overall (AOR = 0.93, 95% CI 0.90, 0.97) and among drinkers (AOR = 0.95, 95% CI 0.91, 0.99) but remained at concerning levels in 2019 (10% overall; 16% among drinkers). Overall DUIC did not change significantly (AOR = 0.99, 95% CI 0.96, 1.03; 11% by 2019) but decreased among those who used cannabis (AOR = 0.91, 95% CI 0.86, 0.96; 33% by 2019). DUIAC decreased but not significantly (overall: AOR = 0.89, 95% CI 0.78, 1.01; those who used alcohol and cannabis: AOR = 0.84, 95% CI 0.74, 1.04). Prevalence of YA DUI remained concerning. Trends may reflect some success in reducing DUI, but additional detection and prevention are needed.

Young adulthood is a developmental period during which individuals experience shifts in their social roles in various domains, which coincides with a period of time that is also high risk for lifetime peaks in alcohol use. The current study examined age‐related changes in heavy episodic drinking (HED) and high‐intensity drinking (HID) and associations with short‐term (i.e., monthly) variation in young adults' social roles over a 2.5‐year period in a community sample of young adults who reported past‐year alcohol use ( N = 778, baseline age range 18–23). Results showed probabilities of past‐month HED and HID changed in a nonlinear fashion across ages 18–26 with greater probabilities of use at younger ages. Most participants did not report being in the same social role status every sampled month, underscoring the presence of short‐term role variation. Living with parents and being in a serious romantic relationship in a given month were negatively associated with past‐month HED. Living with parents in a given month was also negatively associated with past‐month HID. Being a 4‐year college student and being employed full‐time in a given month were not significantly related to either outcome. Findings provided partial evidence that monthly statuses were associated with heavy drinking. Several avenues for future research are described in light of the findings.

Objective: Alcohol expectancies are beliefs people have about the likelihood of experiencing various positive or negative consequences related to alcohol use. Expectancies have most commonly been treated as trait-like characteristics of individuals, but some researchers have assessed expectancies as state-level characteristics that vary within-persons across days. Previous work developed a 13-item daily alcohol expectancies measure. This study evaluated an expanded version of that measure that includes 10 additional expectancy items. Method: Participants were 2- and 4-year college students (N=201; 63.7% female; 55.2% White Non-Hispanic; 75.1% 4-year students) randomized to the control group of a longitudinal study designed to test the efficacy of a just-in-time adaptive intervention delivered via mobile app to reduce high-risk alcohol use. Multilevel exploratory factor analysis was used to determine the factor structure at the daily and person levels. Multilevel models were used to evaluate the convergent validity of the resulting subscales. Results: Two factors, broadly representing positive and negative alcohol expectancies, were retained at the daily and person levels. Composite reliability (ω) estimates ranged from 0.85 to 0.96 and suggested that the reliability of the resulting subscales was good to strong. Associations between the daily expectancy subscales and baseline scores on an established expectancies measure provided preliminary evidence of convergent validity. Conclusions: Findings indicate that this expanded 23-item daily alcohol expectancies measure is psychometrically sound. This measure is appropriate for use in daily or just-in-time expectancy challenge interventions and is suitable for use among 2- and 4-year college students who drink alcohol regularly and occasionally in heavy quantities and who experience alcohol-related negative consequences.