Decline in cannabis use observed for students in county of Washington state

From 2008 to 2021, a decline in cannabis use among students in grades 8, 10, and 12 in King County, Washington, was observed, and for the first time, current-use prevalence was lower among male students compared to female students.

These results were recently published in the Centers for Disease Control and Prevention’s (CDC) Morbidity and Mortality Weekly Report (MMWR).

Associated with poor outcomes such as impaired driving and cognitive impairment, cannabis use among adolescents “has been declining, but less is known about sex-specific trends,” the study authors stated.

In an effort to shine a light on these trends, investigators used the Washington State Department of Health-administered Healthy Youth Survey to examine specific trends.

Generally, the prevalence of cannabis use has been higher among male youths compared to females, though "recent national data indicate a shift, with prevalence now higher among female youths compared with male youths.”

The Healthy Youth Survey is a representative, biennial, cross-sectional survey administered to public school students in Washington in grades 6, 8, 10, and 12.

Anonymous, self-administered questionnaires are completed by students during structured classroom time. Public Health — Seattle & King County (PHSKC) used data from 7 survey cycles completed from 2008 to 2021, using analyses from students in grades 8, 10, and 12.

To analyze the data, “Current (≥1 day during the previous 30 days) and frequent (≥6 days during the previous 30 days) cannabis use prevalence estimates by sex assigned at birth were generated, and patterns were described. Crude prevalence differences (PDs) and 95% CIs by sex were assessed using separate generalized linear models for each outcome containing a quasibinomial distribution and identity link,” the investigative team wrote.

P values less than 0.05 were considered statistically significant, corresponding to estimates for which 95% Cis exclude 0. These analyses were replicated and stratified by grade.

The prevalence of current cannabis use was stable during 2008, 2010, and 2012 among both male students (19.2%, 20.4%, and 20.3%, respectively) and female students (14.4%, 14.9%, and 15.5%, respectively).

A decline in current use for male students was observed in 2014 compared to 2012 (16.4% vs 20.3%), though, among females, current use remained consistent (15.5% in 2012 vs 15.2% in 2014). Current use prevalence was the lowest during the 2021 cycle for males (7.7%) and females (9.0%).

Between the 2008 (PD = 4.8%, 95% CI = 3.8%–5.8%) and 2014 (PD = 1.2%, 95% CI = 0.4%–2.0%) cycles, cannabis use prevalence among male students was significantly higher compared to females, though during the 2016 and 2018 cycles, sex-specific current-use prevalences were not significantly different.

That changed in the 2021 cycle, when current-use prevalence among males was significantly lower than their female counterparts, “representing a reversal of previous sex-specific differences (PD = −1.3%, 95% CI = −2.1% to −0.5%),” the study authors reported.

In this cycle, the highest prevalence of cannabis use was demonstrated among 12th-grade students, followed by 10th grade, and 8th grade, respectively.

The investigators pointed out limitations to the study published in MMWR, including the potential underreporting of cannabis use, noting use was self-reported.

The report also relied on self-reported assigned sex at birth to categorize students by sex and did not include students who identify as transgender or nonbinary.

The investigators concluded that “Although downward trends in cannabis use among King County students in grades 8, 10, and 12 are encouraging, continued monitoring is necessary to better understand longer-term effects of social phenomena, including cannabis legalization and pandemic-related disruptions, and to assess whether observed decreases are sustained.”

Reference:

Cannabis use among students in grades 8, 10, and 12, by sex — King County, Washington, 2008–2021. Morbidity and Mortality Weekly Report. Centers for Disease Control and Prevention. Press release. January 18, 2024. Accessed January 24, 2024.