1. Gender Differences in Marijuana Use Initiation and Academic
Performance among US High School Students
Faith Ihongbe; Arthur Harralson, PharmD, BCPS
Bernard J. Dunn School of Pharmacy, Shenandoah University, Ashburn, Virginia
Introduction
Methods
Results
References
Background
o Marijuana use among adolescents is a major healthcare
concern in the US.
o In 2013, 8.6% of high school students had tried marijuana for
the first time before age 13 years.1
o National estimates for male and female high school students
in 2013 were 11.1% and 6.2%, respectively.1
o There are limited studies that examined gender differences on
the effect of early marijuana use initiation on academic
performance in male and female high school students.
Objectives
o To estimate the percentage distribution of marijuana use
initiation in high school students in the US.
o To examine sex-differences in the association between
marijuana use initiation and academic performance in US
high school students.
Study Population
o Data from the 2009 national Youth Risk Behavior Survey was
analyzed.
o Students who gave valid responses to survey questions on
marijuana use initiation and academic grade (N=9,745).
Exposure
o Marijuana use initiation: Age at first marijuana use; cate-
gorized into 4 levels: never used, ≤12, 13-14 and ≥15 years.
Outcome
o Academic performance was dichotomized as satisfactory (A,
B, C) or unsatisfactory (D, F) based on letter grades of
students in the past 12 months.
Statistical Analysis
o Descriptive statistics were generated to assess the
characteristics of the study population and determine the
percentage distribution of marijuana use initiation.
o Adjusted OR and 95% confidence intervals were calculated
using multiple logistic regression stratified by gender.
o Analyses were conducted using survey procedures in SAS 9.3
(SAS Institute, Cary, NC), utilizing appropriate analysis
weights to account for the complex survey design.
Study population characteristics
1. Kann L, Kinchen S, Shanklin SL, Flint KH, Kawkins J,
Harris WA,…& Zaza S; Youth risk behavior surveillance
- United States, 2013 MMWR Surveill Summ. 2014 Jun
13;63 Suppl 4:1-168.
2. Wagner FA, Anthony JC. Male-female differences in the
risk of progression from first use to dependence upon
cannabis, cocaine, and alcohol. Drug Alcohol Depend.
2007; 86(2–3):191–198
Discussion
o A larger percentage of male students reported initiating
marijuana use at an early age than females.
o Male high school students with early marijuana use initiation
are more likely to have poor academic performance in the past
12 months than females.
o The increased risk of unsatisfactory academic performance in
male students may be explained by findings from a previous
study which show that males appear to be more likely than
females to become marijuana dependent in the first few years
following initiation along with its attendant complications.2
Figure 1. Percent distribution of Marijuana use initiation in the past 12 months by
Gender
Table 1. Odds ratios for the association between Marijuana use initiation and Academic
performance among US High School Students
Strengths and Limitations
o Data is based on a large, nationally-representative sample.
o Inability to infer temporal sequence based on cross-sectional data.
Implication for Adolescent health
o Early marijuana use initiation is a risk factor for poor academic
performance in high school students, particularly in males.
o It is therefore essential that pharmacists, student pharmacists, and
pharmacy technicians give attention, particularly at the community
level, to addressing early marijuana use initiation in adolescents,
especially in males.
a Adjusted for high school grade level, race/ethnicity, cigarette smoking and number of sex partners
o Total study population (N=9,745) comprised of 50.7% and 49.3% males and females, respectively.
o Of those who initiated marijuana use, approximately 17% initiated it at age 15 years and above
(males, 17.0%; females, 16.5%).
o Over a quarter of participants (26.6%) were 16 years of age (males, 27.7%; females, 25.5%) and
the majority (58.2%) were non-Hispanic whites (males, 59.2%; females, 57.1%)
Academic performance
Marijuana use
initiation (years)
Crude OR (95% CI) Adjusted OR (95% CI)a
Male Female Male Female
Never tried marijuana
≤12
13-14
≥15
Ref
8.00 (5.30-12.06)
4.52 (3.29-6.20)
2.46 (1.72-3.51)
Ref
8.20 (5.31-12.68)
3.91 (2.78-5.51)
2.09 (1.32-3.30)
Ref
3.34 (1.90-5.87)
2.26 (1.47-3.49)
1.94 (1.27-2.98)
Ref
2.76 (1.48-5.17)
1.68 (1.09-2.60)
1.58 (0.85-2.91)
59.5
9.1
14.5 17
65.7
4.8
13
16.5
0
10
20
30
40
50
60
70
Never tried marijuana ≤12 13-14 ≥15
Percent(%)
Marijuana use initiation (years)
Male Female