Temperament on Risk for Anxiety and Depression

Can Marijuana Make It Better? Prospective Effects of Marijuana and
Temperament on Risk for Anxiety and Depression
Victoria A. Grunberg, Kismet A. Cordova, L. Cinnamon Bidwell, and Tiffany A. Ito
University of Colorado Boulder
Increases in marijuana use in recent years highlight the importance of understanding how marijuana
affects mental health. Of particular relevance is the effect of marijuana use on anxiety and depression
given that marijuana use is highest among late adolescents/early adults, the same age range in which risk
for anxiety and depression is the highest. Here we examine how marijuana use moderates the effects of
temperament on level of anxiety and depression in a prospective design in which baseline marijuana use
and temperament predict anxiety and depression 1 year later. We found that harm avoidance (HA) is
associated with higher anxiety and depression a year later, but only among those low in marijuana use.
Those higher in marijuana use show no relation between HA and symptoms of anxiety and depression.
Marijuana use also moderated the effect of novelty seeking (NS), with symptoms of anxiety and
depression increasing with NS only among those with high marijuana use. NS was unrelated to symptoms
of anxiety and depression among those low in marijuana use. The temperament dimension of reward
dependence was unrelated to anxiety and depression symptoms. Our results suggest that marijuana use
does not have an invariant relationship with anxiety and depression, and that the effects of relatively
stable temperament dimensions can be moderated by other contextual factors.
Keywords: marijuana, harm avoidance, novelty seeking, anxiety, depression
Supplemental materials: http://dx.doi.org/10.1037/adb0000109.supp
Marijuana is the third most commonly used drug in the United
States (after alcohol and tobacco), and the leading illicit drug in
states where its recreational use is currently illegal (CNN Gallup,
2013; National Institute of Drug Abuse, 2014). It is estimated that
more than a third of the American population has used marijuana
and that roughly 7% of Americans currently are regular users
(CNN Gallup, 2013). The perception that marijuana is dangerous
has been decreasing since 2007, corresponding with increasing use
among young people (National Institute of Drug Abuse, 2014) and
increasing legalization for recreational and medical purposes (Colorado Amendment 64, 2012; Washington Initiative 502, 2012).
In the face of such high levels of use and rapid changes to laws
and perceptions, it is critically important to better understand the
consequences of marijuana use. One issue in particular need of
further exploration is the relation of marijuana use to mental
health. Anxiety and depression are the most common mental health
conditions in the United States (National Institute of Mental
Health, 2014b, 2014c), making understanding the factors that
affect them of particular clinical significance. Adding to the clinical relevance, the risk of developing anxiety and depression is
highest within the same age range in which marijuana use is the
highest. That is, 75% of all lifetime cases of anxiety and depression start by age 24 (Kessler et al., 2005) and among adolescents,
roughly 32% have had lifetime prevalence of anxiety disorders and
roughly 14% have had lifetime prevalence of mood disorders
(Merikangas et al., 2010). At the same time, marijuana use is
typically the highest in the teens through early twenties as compared with all other age ranges (Degenhardt et al., 2008; Kessler et
al., 2005), and about 52% of 18- to 25-year-olds have used
marijuana in their lifetime (National Institute of Drug Abuse,
2014).
Here, we take the approach that understanding anxiety and
depression within this population at heightened risk can be improved by examining whether behaviors that are frequent within
this same age range relate to symptoms of anxiety and depression.
That is, given the relatively high rate of marijuana use within late
adolescence/early adulthood and the possibility that it may increase in the face of increasing legalization, there is public health
relevance in knowing the relation of marijuana use to the risk of
anxiety and depression within this age range. This can improve our
understanding of whether increases in marijuana legalization
might affect rates of anxiety and depression, and whether anxiety
and depression prevention and treatment strategies could benefit
by targeting marijuana use.
There is relatively little relevant comorbidity data speaking to
the relation between marijuana and anxiety/depression, as most
large epidemiological studies collapse marijuana use into a broader
Victoria A. Grunberg and Kismet A. Cordova, Department of Psychology and Neuroscience, University of Colorado Boulder; L. Cinnamon
Bidwell, Institute of Cognitive Science, University of Colorado Boulder;
Tiffany A. Ito, Department of Psychology and Neuroscience, University of
Colorado Boulder.
This work was supported by National Institutes of Health (NIH)
DA024002 to Tiffany A. Ito and NIH K23DA033302 to L. Cinnamon
Bidwell.
Correspondence concerning this article should be addressed to Tiffany
A. Ito, Department of Psychology and Neuroscience, University of Colorado, 345 UCB, Boulder, CO 80309-0345. E-mail: [email protected]
.edu
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590
substance use disorder category (for review, see Degenhardt, Hall,
& Lynskey, 2003). Those studies that do separately examine
marijuana use focus only on marijuana dependence and/or examine a wide age range (Chen, Wagner, & Anthony, 2002; Degenhardt, Hall, & Lynskey, 2001). Results from studies that have
focused on recreational users and/or young adults are quite variable; some show a negative association between marijuana use and
anxiety/depression (e.g., Denson & Earleywine, 2006; Sethi et al.,
1986; Stewart, Karp, Pihl, & Peterson, 1997), others a positive
association (e.g., Bonn-Miller, Zvolensky, Leen-Feldner, Feldner,
& Yartz, 2005; Hayatbakhsh et al., 2007; Scholes-Balog, Hemphill, Patton, & Toumbourou, 2013), and still others no association
(e.g., Green & Ritter, 2000; Musty & Kaback, 1995). Such a
diverse pattern of results suggests that other factors may also
interact with marijuana use to affect anxiety and depression. Unfortunately, there has been a great deal of diversity in the extant
research along multiple dimensions (e.g., community vs. college
samples, samples unselected vs. selected for marijuana use, different types of marijuana, anxiety, and depression measures),
making it difficult to identify variables that explain the different
patterns of associations obtained. Here we begin the process of
identifying factors that affect the relation between marijuana use
and anxiety and depression by examining a variable that is itself
known to relate to anxiety and depression. We specifically examine relatively stable aspects of temperament whose relation to
anxiety and depression have been frequently studied and ask
whether marijuana use interacts with temperament in its relationship with anxiety and depression.
Temperament, Anxiety, and Depression
According to the biosocial model (Cloninger, Svrakic, & Przybeck, 1993), temperament affects mental health via genetically
determined biases that influence automatic responses to novelty,
punishment, and reward. The temperament dimension of harm
avoidance (HA) is particularly relevant for understanding anxiety
and depression as it is characterized by heightened apprehension,
shyness, pessimism, and inhibition of behaviors. Given these biases, it is not surprising that HA is positively associated with both
anxiety and depression (Hansenne et al., 1998; Jiang et al., 2003;
Manfredi et al., 2011; Matsudaira & Kitamura, 2006).
While HA likely increases anxiety and depression, marijuana
can have anxiolytic and euphoriant effects. Such positive mood
effects are reported among the top motives for marijuana use (Lee
et al., 2009; Newcomb, Chou, Bentler, & Huba, 1988; Simons,
Correia, Carey, & Borsari, 1998). Animal research suggests a
direct anxiolytic effect of cannabis administration (e.g.,
Guimarães, Chiaretti, Graeff, & Zuardi, 1990; de Paula Soares et
al., 2010; for a review, see Mechoulam, Parker, & Gallily, 2002).
The exact mechanism of these effects has not been determined,
although they seem to be restricted to the effects of cannabidiol
and not 9-tetrahydrocannabinol (e.g., Zuardi, Crippa, Hallak,
Moreira, & Guimarães, 2006) and likely involve serotonergic
receptors in the dorsal periaqueductal gray matter as the basis for
anxiolytic effects (de Paula Soares et al., 2010). Marijuana use
may also facilitate social contact (Green & Ritter, 2000), which
could, in turn, improve mood and ultimately mental health. The
potential for marijuana use to affect mood suggests a possible
moderating role of marijuana on the relation of HA to anxiety and
depression. Specifically, to the degree that marijuana produces
anxiolytic and/or euphoriant effects— either directly through its
biochemical effects on neurotransmitters and receptors or indirectly through expectations and/or the facilitation of mood and
beneficial social interactions—marijuana use may buffer individuals high in HA from increased risk for anxiety and depression.
The other major temperament dimensions in the biosocial model
have shown no consistent associations with anxiety or depression.
Novelty seeking (NS) is thought to bias individuals toward impulsivity and exploration in response to novelty; reward dependence
(RD) reflects a tendency to maintain previously rewarded behaviors. Although these dimensions have been associated with anxiety
and depression in some samples (with occasional negative associations of NS and RD with depression, Farmer et al., 2003; Hansenne et al., 1998), they most often show no association with
anxiety and depression (Copeland, Landry, Stanger, & Hudziak,
2004; Starcevic, Uhlenhuth, Fallon, & Pathak, 1996; Strakowski,
Dunayevich, Keck, & McElroy, 1995; Young et al., 1995). Given
the behavioral biases linked with the temperament dimensions, the
lack of associations with anxiety and depression are theoretically
sensible (i.e., the biases associated with these temperament dimensions would not seem to increase risk for anxiety and depression).
At the same time, these relations have most often been examined
in studies with relatively small samples (fewer than 100 participants), making small effects difficult to detect. More importantly
for the present analyses, the moderating effect of marijuana use has
never to our knowledge been tested.
Current Study
The present study seeks to better understand how marijuana use
relates to anxiety and depression within late adolescents/early
adults by examining how it might moderate the effects of temperament on symptoms of anxiety and depression. We also examine,
in a larger sample than past studies, the relation of temperament to
anxiety and depression. We did this in a prospective design in
which marijuana use and temperament assessed at baseline were
used to predict anxiety and depression symptoms assessed 1 year
later in a relatively large (n 338) sample of 18- to 21-year-old
male and female college students. Roughly equal numbers of men
and women allow us to test whether relations among temperament,
marijuana use, and anxiety/depression differ for men and women.
Hypotheses
Given past research and the nature of the behavioral biases
associated with HA, we predict that baseline HA will positively
predict both anxiety and depression symptoms assessed 1 year
later. However, given potential anxiolytic and euphoriant effects,
we expect marijuana to moderate this relationship, such that the
positive association of HA with anxiety and depression symptoms
will be most evident when marijuana use is low. Marijuana may
itself show a simple relation to anxiety and depression, with fewer
symptoms of anxiety and depression among those who use marijuana more frequently. We assess these relations while also controlling for baseline anxiety and depression. If HA and its interaction with marijuana use have effects independent of current
anxiety and depression, we expect these relations to be evident
even after controlling for baseline levels of psychopathology.
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MARIJUANA, TEMPERAMENT, ANXIETY, AND DEPRESSION 591
Given the lack of consistent relations of NS and RD with
anxiety and depression, we had no specific predictions for these
analyses, but we nevertheless tested them to provide a comprehensive assessment of the relations among temperament dimensions, marijuana use, and risk for anxiety and depression.
We have no a priori expectations that these relations will differ
for men and women, but given gender differences in rates of
anxiety and depression (Kessler, McGonagle, Swartz, Blazer, &
Nelson, 1993; McLean, Asnaani, Litz, & Hofmann, 2011), it is
important to assess whether factors that relate to anxiety and
depression differ for men and women.
Method
Participants
Potential participants were recruited via e-mail invitations to
their university account and advertisements on campus to take part
in a 3-year longitudinal study of marijuana use. Those who were
interested in the study were initially interviewed on the phone by
study personnel to determine whether their marijuana use fit into
one of three categories: never users (i.e., never tried marijuana),
relatively infrequent marijuana users (i.e., used marijuana 4 times
or less per month for less than 3 years), and regular frequent
marijuana users (i.e., used marijuana an average of 5 days a week
or more for at least the past year). Both quantity and frequency
criteria were implemented to ensure that variability in marijuana
use reflected relatively stable tendencies. Because the full protocol
also included electroencephalography measures, individuals who
reported a history of head trauma, neurological disorder, or the use
of prescription medication (with the exception of oral contraceptives or medical marijuana) were excluded from the study. One of
the interests in the larger study was on change in marijuana use
over time, so we oversampled participants with lower levels of use,
whom we expected to be more likely to change their use over time.
We continued sampling within each use category until we had
roughly equal numbers of men and women. Participants who met
criteria for inclusion were invited to participate in two sessions a
year for three total years. Data in the present analyses come from
the first sessions in years 1 and 2.
Our final sample consisted of 375 University of Colorado primarily freshman (see Table 1 for sample characteristics). Of the
337 participants who provided racial information, 1 identified as
Black, 12 as Asian, 11 as Hispanic, 1 as Pacific Islander, 2 as East
Indian, 1 as Middle Eastern, 63 as multiracial, and 246 as White.
Four additional participants were initially enrolled but later found
to have provided inaccurate information at the time of recruitment
and so were dropped from the study. Thirty-seven individuals did
not return to complete Year 2, so analyses are based on the 338
with complete data. Those who failed to return in Year 2 did not
differ from those who did in gender, age, race, marijuana use
group, temperament, or psychopathology, all p values .13. Only
the measures of interest to our current hypotheses will be described
Table 1
Sample Characteristics by Marijuana Use Group
Never Infrequent Frequent F or 2 value
Demographics
N (Year 1/Year 2) 126/114 146/133 103/91
Gender (% female) 57 (50%) 72 (54.1%) 47 (51.6%) 0.43
Age 18.30 (0.46) 18.38 (0.52) 18.34 (0.50) 0.76
Ethnicity (% White) 81 (71.1%) 93 (69.9%) 72 (80%) 3.10
Substance use Year 1
Total days of marijuana use (0–30) 0.00a 1.65 (1.88)b 26.07 (3.52)c 4,475.48
Total grams of marijuana use 0.00a 0.87 (1.43)a 24.45 (16.57)b 256.76
Average grams per use day 0.00a 0.32 (0.44)b 0.92 (0.56)c 134.33
Temperament Year 1
Harm avoidance 2.49 (0.66) 2.58 (0.64) 2.52 (0.51) 0.67
Novelty seeking 2.91 (0.42)a 3.08 (0.37)b 3.38 (0.40)c 36.59
Reward dependence 3.55 (0.58) 3.57 (0.53) 3.58 (0.46) 0.10
Psychopathology Year 1
Anxiety symptoms 4.40 (2.60) 4.67 (3.39) 4.91 (3.08) 0.71
Anxiety % at risk 4.39a 15.04b 13.19b 7.79
Depression symptoms 3.64 (2.67)a 4.73 (3.90)b 5.29 (4.00)b 5.81
Depression % at risk 0.88a 8.27b 14.29b 13.53
Psychopathology Year 2
Anxiety symptoms 3.90 (2.79) 4.66 (3.45) 4.40 (2.86) 1.88
Anxiety % subclinical or greater 7.02 11.28 6.59 2.05
Depression symptoms 3.80 (3.28)a 4.99 (4.28)b 4.84 (4.00)ab 3.23
Depression % subclinical or greater 5.26 12.03 10.99 3.62
Note. Gender shows number of females. Ethnicity shows number of Whites. Numbers in parentheses are
standard deviations. Possible ranges are 1–5 for harm avoidance, novelty seeking, and reward dependence; 0 –14
for ASR anxiety symptoms; and 0 –24 for ASR depression symptoms. Higher values indicate greater marijuana
use, HA, NS, RD, anxiety, and depression. Anxiety and depression symptoms reflect total number of symptoms
endorsed. % at risk shows percentage of participants who scored at or above the ASR “at-risk” threshold for clinical
levels of anxiety or depression (T score 65). F and 2 values reflect the test of the omnibus marijuana use group
main effect, df 2, 335, and 2, respectively. Marijuana use group means within the same row with different subscripts
differ at p .05. For omnibus marijuana use group effects, p .05. p .01. p .001.
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592 GRUNBERG, CORDOVA, BIDWELL, AND ITO
in detail, but where appropriate (e.g., when they preceded the
measures of interest), other measures collected will be noted.
Self-Report Measures
Temperament and Character Inventory (Year 1 and Year 2).
HA, NS, and RD were measured with the Temperament and
Character Inventory (TCI; Cloninger et al., 1993). HA was assessed with 33 items that assess anticipatory worry, fear of uncertainty, shyness with strangers, and fatigability (e.g., “Usually I am
more worried than most people that something might go wrong in
the future,” “I usually feel tense and worried when I have to do
something new and unfamiliar,” “When I meet a group of strangers, I am more shy than most people,” “I have less energy and get
tired more quickly than most people,” .93). NS was assessed
with 35 items that assess exploratory excitability, impulsivity,
extravagance, and disorderliness (e.g., “When nothing new is
happening, I usually start looking for something that is thrilling or
exciting,” “I often do things based on how I feel at the moment
without thinking about how they were done in the past,” “I often
spend money until I run out of cash or get into debt from using too
much credit,” “I like when people can do whatever they want
without strict rules and regulations,” .85). RD was assessed
with 30 items that assess sentimentality, openness to warm communication versus aloofness, attachment, and dependence (e.g., “I
am strongly moved by sentimental appeals, like when asked to
help crippled children,” “I like other people to know that I really
care about them,” “I like to discuss my experiences and feelings
openly with friends instead of keeping them to myself,” “I don’t
care very much whether other people like me or the way I do
things,” reverse-coded, .88).
All items were answered with respect to how the participants
usually or generally act and feel using a 5-point scale (1
definitely false to 5 definitely true). Separate mean scores were
created for overall HA, NS, and RD, with higher scores reflecting
greater HA, NS, and RD. The biosocial model currently includes
a fourth temperament dimension of persistence (P) that was previously included as part of RD (Cloninger et al., 1993). P is
associated with determination and industriousness. It has been
much less frequently measured in association with anxiety and
depression, and when it has been, shows inconsistent relations
(Cloninger, Svrakic, & Przybeck, 2006; Hansenne et al., 1999).
Measures of P were omitted from the present study out of space
considerations.
Marijuana use (Year 1). Self-reported marijuana use during
the past 30 days was assessed using the Time-Line Follow Back
(TLFB; Sobell & Sobell, 1992), a calendar-assisted structured
interview in which participants were asked to indicate over the past
30 days the quantity of marijuana used on each day. Frequency and
quantity reports were highly correlated, r .82, p .0001.
Relative to other substances such as alcohol and nicotine, where
individuals might consume an entire beer or cigarette, marijuana
users might just take a few hits. There are also many different ways
to consume marijuana (joints, vaporizers, edibles). Because of this
potential for variability, our main analyses used marijuana use
frequency as our measure of marijuana use. However, secondary
analyses were also conducted with marijuana quantity measures
and yielded identical results (see Supplement Tables S1, S2, and
S3 in the online supplemental material).
Adult Self-Report (ASR; Year 1 and Year 2). Symptoms of
anxiety and depression were measured with the Achenbach System
of Empirically Based Assessment Adult Self-Report (ASR;
Achenbach & Rescorla, 2003), a self-report measure of current
internalizing and externalizing psychopathology that is the adult
parallel to the Child Behavior Checklist. These internalizing and
externalizing scales on the ASR have been well validated and have
adequate psychometric characteristics (Achenbach & Rescorla,
2003). Of interest were anxiety problems and depressive problems.
Participants were asked how well each item described them over
the past 6 months, with responses ranging from 0 not true, 1
somewhat or sometimes true, and 2 very true or often true.
Anxiety problems were assessed with 7 items (e.g., “I am nervous
or tense,” Year 1: .76; Year 2: .77). Depressive problems
were assessed with 14 items (e.g., “I am unhappy, sad, or depressed,” Year 1: .77; Year 2: .80). A total score was
created for each construct with higher scores reflecting a continuous measure of greater endorsement of anxiety and depressive
problems. Because of the conceptual similarity between HA and
anxiety and depression, we conducted factor analyses to confirm
that HA was distinct from anxiety and depression (see online
supplemental material).
Procedure
Participants who met criteria for inclusion were invited to participate in a total of six laboratory sessions over 3 years. Data in
the present analyses come from the first sessions in Years 1 and 2
at which marijuana use, temperament, and psychopathology were
assessed. The assessments occurred approximately 12 months
apart (M 356.98 days, SD 19.78 days).
Participants were instructed to abstain from alcohol for 24 hr,
recreational drugs (including marijuana) for 6 hr, and caffeine and
cigarettes for 1 hr prior to each laboratory session. In both sessions, participants were breathalyzed to ensure a breath alcohol
concentration of zero. Adherence to other abstinence requirements
was verified verbally. Although it would have been preferable to
assess abstinence biochemically, it was prohibitively expensive.
While failure to meet the requirements could add variability to the
responses, none of the participants were visibly impaired, and we
have no reason to think failure to conform to the abstinence
requirements introduced any systematic artifact (i.e., failure to
meet the abstinence requirement seems unlikely to have created
the pattern of relationships among the variables that we observed).
Participants next completed the TLFB followed by a questionnaire
including demographics, the ASR, and the TCI. Prior to the ASR,
participants completed measures of handedness, ADHD symptoms
(Barkley & Murphy, 1998), the Beck Depression Index (Beck,
Steer, & Carbin, 1988), and the Beck Anxiety Index (Beck, Epstein, Brown, & Steer, 1988). Prior to completing the TCI, participants completed the Shortened Self-Regulation Questionnaire
(Carey, Neal, & Collins, 2004). Participants received $25 at each
session.
Analysis Strategy
We first performed preliminary descriptive analyses to assess
the relation between marijuana use, temperament, and anxiety and
depression symptoms, with separate analyses representing mariThis document is copyrighted by the American Psychological Association or one of its allied publishers. This article is intended solely for the personal use of the individual user and is not to be disseminated broadly.
MARIJUANA, TEMPERAMENT, ANXIETY, AND DEPRESSION 593
juana use either categorically or continuously. Categorical analyses were done with one-way analyses of variance (ANOVAs)
using a 3-level marijuana use group variable based on the participant’s use at time of study enrollment (i.e., never, infrequent,
frequent). Continuous analyses consisted of bivariate correlations
between number of days marijuana was used in past 30 days from
the baseline Year 1 TLFB and temperament and psychopathology
variables.
Our primary analyses assessed whether Year 1 HA, NS, and RD
predict Year 2 anxiety and depression symptoms, and whether this
relationship is moderated by marijuana use. This was tested using
a cross-lag structural regression approach (Rogosa, 1980). Under
this approach, two multiple regression equations are used to test
the relations shown in Figure 1, illustrated using HA and anxiety
symptoms as an example. Model 1 tests our hypothesized relations
that Year 2 anxiety is predicted by Year 1 HA, and that the relation
between HA and anxiety is moderated by marijuana use. More
specifically, 1 assesses the autoregressive or lagged effect of Year
1 anxiety predicting Year 2 anxiety. Because we assume that initial
anxiety and depression symptoms will be a strong predictor of
subsequent anxiety and depression, including this lagged effect
provides a strong test of the degree to which temperament and
marijuana use predict anxiety and depression over and above
baseline anxiety and depression. Of primary theoretical interest are
2 and 3. 2 tests the effects of Year 1 HA on Year 2 anxiety,
reflecting a simple crossed effect, whereas 3 assesses whether the
simple crossed effect of HA on Year 2 anxiety is moderated by
Year 1 marijuana use. As described by Baron and Kenny (1986),
this predicted moderation is tested by assessing the interaction
between Year 1 HA and Year 1 marijuana use. Although our data
are correlational, given the temporal precedence of the variables
(i.e., that HA and marijuana use in Year 1 are predicting anxiety in
Year 2), significant coefficients for 2 and 3 are consistent with
the possibility that initial HA affects subsequent anxiety, and that
the relation of initial HA on subsequent HA is moderated by initial
marijuana use, respectively (Rogosa, 1980).
To further test our hypothesized relations, additional autoregressive, cross-lagged, and cross-lagged moderation effects are tested
in Model 2 in which Year 2 HA is the outcome. Specifically, 1
assesses the autoregressive or lagged effect of Year 1 HA predicting Year 2 HA. These relations are not of particular theoretical
interest here, but because this tests the temporal stability of temperament, we expect the autoregressive effects in these second
models to be significant. Of primary theoretical interest are 2 and
3. 2 tests the effect of Year 1 anxiety symptoms on Year 2 HA.
Because we expect the relations between temperament and psychopathology to reflect the effect of the more stable temperament
variables affecting subsequent psychopathology rather than initial
symptoms of psychopathology affecting subsequent temperament,
we do not expect initial anxiety symptoms to predict subsequent
HA. Thus, we expect 2 to be nonsignificant. Similarly, we have
no theoretical expectation that the impact of initial anxiety symptoms on subsequent temperament will be moderated by marijuana
use, so we do not expect 3 to be significant. In this way, nonsignificant coefficients for 2 and 3, coupled with significant coefficients for 2 and/or 3, provide additional evidence for our
hypothesized relations. In sum, to the degree that relations between
temperament and anxiety reflect the effect of initial temperament
on subsequent anxiety and not the effect of initial anxiety on
subsequent temperament, we expect significant effects in 2 and/or
3, but not 2 and 3.
This framework just described was repeated 6 times to test the
relation of each aspect of temperament (HA, NS, and RD) on each
outcome variable (symptoms of anxiety and depression). Figure 1
shows a simplified model highlighting the autoregressive, crosslagged, and moderated cross-lagged relations. In addition to these
three variables, each model also contained five additional predictors. First, given the presence of marijuana use in the interaction
term to test for moderation (e.g., Year 1 HA
Year 1 marijuana
use), all models also included the simple effect of Year 1 marijuana use as a predictor. This variable is also of theoretical interest
because it assesses the simple effect of marijuana on anxiety and
depression symptoms. We also included gender and its interactions
with temperament and marijuana use (e.g., HA
Gender, Marijuana Use
Gender, HA
Marijuana Use
Gender) to test
whether interrelations among temperament, marijuana use, and
symptoms of anxiety and depression differ for males and females.
All continuous variables were mean-centered before analyses,
and gender was coded as 1 male and 1 female. All model
assumptions (e.g., homoscedasticity, normality of distributions)
were met. When the predicted interaction between temperament
and marijuana use reflecting our primary test of moderation was
significant, we explored the form of the interaction by plotting and
testing the simple effects of temperament on anxiety or depression
symptoms at lower and higher levels of marijuana use following
Aiken and West (1991). The values of lower and higher marijuana
use selected to test the simple effects were based on examination
of the distribution of marijuana use reported in the TLFB in Year
1 with the goal of assessing effects at values that reflect actual
levels of low and high use in our sample. Based on use within our
sample, we plot and statistically test the effects of temperament on
anxiety and depression at 0 days (low use) and 25.80 days (high
use) of marijuana use, with the latter reflecting the mean level of
use reported by frequent users on the TLFB in Year 1. The low
marijuana use group included all participants recruited as never
users (i.e., they all reported 0 days of use in the past 30 days on the
TLFB) as well as 48 infrequent users who also happened to have
no days of use in the 30 days prior to completion of the Year 1
Figure 1. Sample cross-lag structural regression model. Hypothesized
relations were tested with two multiple regression models. Heavier lines
indicate the two paths of primary theoretical interest assessing the crosslagged effect of initial temperament on subsequent psychopathology (2)
and the degree to which initial marijuana use moderates the cross-lagged
effect of initial temperament on subsequent psychopathology (3).
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594 GRUNBERG, CORDOVA, BIDWELL, AND ITO
TLFB. We also conducted ancillary simple effects tests using .5
standard deviations to represent low (M 2.07 days) and high (M
13.47 days) levels of marijuana use. Results were identical to those
reported here.
Results
Preliminary Analyses
Table 1 presents descriptive statistics from our sample by categorical marijuana use group classification at time of study enrollment (never, infrequent, frequent). Age, ethnicity, and gender measured in Year 1 did not differ across groups. One-way
ANOVAs on the temperament variables revealed a significant
effect of marijuana use group only on NS, with more frequent
marijuana use associated with higher novelty seeking. One-way
ANOVAs also revealed significant differences in depression
among the marijuana use groups in both Year 1 and Year 2, with
those who use marijuana reporting more depression symptoms.
Marijuana users were also more likely to meet or exceed the
“at-risk” threshold for clinical levels of depression in Year 1 (ASR
T score greater than or equal to 65). While there was no marijuana
use group effect on anxiety symptoms, those who use marijuana
were more likely to meet or exceed the “at-risk” threshold for
clinical levels of anxiety in Year 1.
In addition to examining marijuana use categorically based on
use at study enrollment, we can also examine marijuana use
continuously based on TLFB via bivariate correlations (see Table
2). When examined continuously, marijuana use was only weakly
associated with Year 1 depression symptoms, but not with Year 2
depression symptoms. It was unrelated to anxiety. More frequent
marijuana use was associated with higher NS. Of theoretical interest, HA was positively correlated with Year 1 and Year 2
anxiety and depression symptoms. Neither marijuana use frequency, NS, nor RD were correlated with anxiety or depression
symptoms.
Main Analyses
The preliminary correlational analyses (see Table 2) show consistent simple relations between HA and anxiety and depression
symptoms in both Years 1 and 2. To more specifically test our
hypotheses about the relation of temperament to subsequent anxiety and depression symptoms, as well as the moderating effect of
marijuana on this relation, we conducted a series of cross-lag
regression models, as described in the Analysis Strategy. To facilitate interpretation, Figure 2 presents the coefficients of greatest
interest in testing our hypotheses (cf. Figure 1) while Table 3
presents full model output including all predictors.
Harm avoidance and anxiety. The first model we ran tests
our primary hypotheses that initial temperament predicts subsequent psychopathology, and that this relation may be moderated by marijuana use (i.e., Model 1 in Figure 1). This was done
by regressing Year 2 anxiety on Year 1 HA, Year 1 marijuana
use, Year 1 anxiety, the HA
Marijuana Use interaction term,
gender, and all interaction terms involving gender. This model
revealed three significant effects (see Table 3). Not surprisingly, Year 1 anxiety symptoms significantly predicted Year 2
anxiety symptoms. There was also a significant gender effect,
with women reporting more Year 2 anxiety symptoms than
men. Of interest, when these other variables were included in
the model, HA was not an independent predictor of Year 2
anxiety symptoms. However, consistent with hypotheses, HA
did interact with marijuana use in predicting anxiety symptoms
(Figure 2, Panel A). To understand this interaction, we conducted simple slope analyses separately assessing the relation
between HA and Year 2 anxiety for those low and high in
marijuana use (Aiken & West, 1991). As can be seen in Figure
3, Panel A, when frequency of marijuana use was low, increases
in Year 1 HA were associated with greater anxiety in Year 2,
.15, t(329) 2.69, p .01. By contrast, as predicted,
marijuana use had a buffering effect as reflected in a nonsignificant relation between HA and anxiety when marijuana use
frequency was high, .14, t(329) 1.40, p .16.
To further evaluate our hypotheses, we also tested a second
model assessing the other possible cross-lagged effect—that initial
psychopathology predicts subsequent temperament (Model 2 in
Figure 1). This was tested by regressing Year 2 HA on Year 1 HA,
Year 1 anxiety, Year 1 marijuana use, the Anxiety
Marijuana
Use interaction term, gender, and all interaction terms involving
gender. Not surprisingly, Year 1 HA predicted Year 2 HA (see
Table 3). Of primary theoretical relevance, neither the simple
cross-lagged effect of Year 1 anxiety nor the moderated crosslagged effect of Year 1 Anxiety
Marijuana Use were significant
(Figure 2, Panel A). The only other significant effect in this model
was the Anxiety
Gender interaction. Tests of simple slopes
showed that Year 1 anxiety was associated with greater Year 2 HA
for women, .11, t(329) 2.15, p .03, but not men,
.04, t(329) .79, p .43.
Table 2
Bivariate Correlations Among Variables
Variable 1 2 3 4 5 6 7
1. Year 1 marijuana use —
2. Harm avoidance .01 —
3. Novelty seeking .40 .32 —
4. Reward dependence .01 .14 .12 —
5. Year 1 anxiety .05 .57 .06 .03 —
6. Year 1 depression .13 .55 .04 .02 .68 —
7. Year 2 anxiety .01 .46 .04 .00 .68 .50 —
8. Year 2 depression .05 .42 .05 .06 .51 .63 .69
p .10. p .05. p .01.
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MARIJUANA, TEMPERAMENT, ANXIETY, AND DEPRESSION 595
Harm avoidance and depression. Figure 2, Panel B shows
the relations of primary theoretical interest in the cross-lag
model assessing the relation between HA and depression symptoms. Considering the first regression model that tests whether
initial temperament predicts subsequent psychopathology, Year
1 depression symptoms were a significant predictor of Year 2
depression symptoms (see Table 3). The only other significant
effect was the predicted HA
Marijuana Use interaction.
Simple effects tests revealed a pattern of effects very similar to
that obtained for anxiety (Figure 3, Panel B): HA was significantly positively associated with depression symptoms when
marijuana use frequency was low, .15, t(329) 2.69, p
.01, but marijuana use appeared to have a buffering effect as reflected
in a nonsignificant negative relation between HA and depression
symptoms at high levels of marijuana use frequency, .09,
t(329) .92, p .36.
In the second model predicting Year 2 HA, the only significant
predictor was Year 1 HA (see Table 3). Of importance, Year 1
depression symptoms did not predict Year 2 HA, nor did the Year
1 Depression
Marijuana Use interaction.
Novelty seeking and anxiety. The cross-lag model in Figure
2, Panel C shows the coefficients of primary theoretical interest in
assessing the relation between NS and anxiety. Considering the
first regression model that tests whether initial temperament predicts subsequent psychopathology, three effects were significant.
Year 1 anxiety symptoms significantly predicted Year 2 anxiety
symptoms, and greater marijuana use frequency in Year 1 was
associated with less anxiety in Year 2 (see Table 3). While NS did
not have a direct effect on anxiety levels, its effect was moderated
by marijuana use, as reflected in the NS
Marijuana Use interaction. Simple effects displayed in Figure 3, Panel C show that the
relation between NS and anxiety occurs among those with high
marijuana use frequency. That is, when marijuana use frequency
was high, Year 1 NS was positively associated with anxiety
symptoms, .28, t(329) 3.46, p .001. There was no
relation between NS and anxiety symptoms when marijuana use
frequency was low, .08, t(329) 1.61, p .11.
In the second model predicting Year 2 NS, the only significant
predictor was Year 1 NS (see Table 3). Year 1 anxiety did not
predict Year 2 NS, nor did the Year 1 Anxiety
Marijuana Use
interaction.
Novelty seeking and depression. The regression models predicting Year 2 depression from NS revealed effects very similar to
those in the models predicting anxiety from NS (See Figure 2,
Panel D). In the first regression model that tests whether initial
temperament predicts subsequent psychopathology, there were
Figure 2. Cross-lag structural regression models assessing the relation of harm avoidance and marijuana use
to levels of anxiety (Panel A) and depression (Panel B), novelty seeking and marijuana use to levels of anxiety
(Panel C) and depression (Panel D), and reward dependence and marijuana use to levels of anxiety (Panel E) and
depression (Panel F). Heavier lines indicate the cross-lagged and moderated cross-lagged relations of primary
theoretical significance (see Table 3 for exact significance levels). p .05.
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596 GRUNBERG, CORDOVA, BIDWELL, AND ITO
Table 3
Full Regression Models
Harm avoidance
HA and anxiety HA and depression
Model 1: DV Anxiety t p Model 1: DV Depression t p
Year 1 anxiety 0.62 12.76 .001 Year 1 depression 0.59 11.30 .001
Year 1 HA 0.06 1.24 .22 Year 1 HA 0.08 1.52 .13
Marijuana use frequency 0.02 0.54 .59 Marijuana use frequency 0.03 0.65 .52
Gender 0.09 2.31 .02 Gender 0.01 0.17 .87
HA
Marijuana Use 0.11 2.69 .01 HA
Marijuana Use 0.10 2.22 .03
Marijuana Use
Gender 0.01 0.20 .84 Marijuana Use
Gender 0.02 0.50 .62
HA
Gender 0.00 0.09 .93 HA
Gender 0.00 0.07 .94
HA
Marijuana Use
Gender 0.02 0.35 .73 HA
Marijuana Use
Gender 0.02 0.49 .63
Model 2: DV HA t p Model 2: DV HA t p
Year 1 HA 0.76 18.88 .001 Year 1 HA 0.77 19.24 .001
Year 1 anxiety 0.03 0.79 .43 Year 1 depression 0.01 0.28 .78
Marijuana use frequency 0.05 1.59 .11 Marijuana use frequency 0.05 1.38 .17
Gender 0.05 1.39 .17 Gender 0.05 1.53 .13
Anxiety
Marijuana Use 0.04 1.19 .23 Depression
Marijuana Use 0.02 0.43 .67
Marijuana Use
Gender 0.01 0.17 .86 Marijuana Use
Gender 0.01 0.24 .81
Anxiety
Gender 0.07 2.24 .03 Depression
Gender 0.06 1.82 .07
Anxiety
Marijuana Use
Gender 0.01 0.26 .80 Depression
Marijuana Use
Gender 0.03 0.89 .37
Novelty seeking
NS and anxiety NS and depression
Model 1: DV Anxiety t p Model 1: DV Depression t p
Year 1 anxiety 0.67 16.67 .001 Year 1 depression 0.65 14.84 .001
Year 1 NS 0.03 0.58 .56 Year 1 NS 0.05 1.18 .24
Marijuana use frequency 0.10 2.22 .03 Marijuana use frequency 0.12 2.46 .02
Gender 0.08 1.78 .08 Gender 0.04 0.76 .45
NS
Marijuana Use 0.16 3.80 .001 NS
Marijuana Use 0.13 2.93 .00
Marijuana Use
Gender 0.09 1.87 .06 Marijuana Use
Gender 0.07 1.41 .16
NS
Gender 0.05 1.26 .21 NS
Gender 0.05 1.06 .29
NS
Marijuana Use
Gender 0.04 0.91 .36 NS
Marijuana Use
Gender 0.07 1.51 .13
Model 2: DV NS t p Model 2: DV NS t p
Year 1 NS 0.77 20.61 .001 Year 1 NS 0.77 20.59 .001
Year 1 anxiety 0.06 1.80 .07 Year 1 depression 0.06 1.68 .09
Marijuana use frequency 0.03 0.91 .36 Marijuana use frequency 0.01 0.35 .73
Gender 0.05 1.31 .19 Gender 0.03 0.96 .34
Anxiety
Marijuana Use 0.01 0.37 .72 Depression
Marijuana Use 0.02 0.61 .54
Marijuana Use
Gender 0.04 1.04 .30 Marijuana Use
Gender 0.02 0.64 .52
Anxiety
Gender 0.05 1.60 .11 Depression
Gender 0.02 0.49 .63
Anxiety
Marijuana Use
Gender 0.02 0.57 .57 Depression
Marijuana Use
Gender 0.04 1.11 .27
Reward dependence
RD and anxiety RD and depression
Model 1: DV Anxiety t p Model 1: DV Depression t p
Year 1 anxiety 0.66 16.19 .001 Year 1 depression 0.64 14.49 .001
Year 1 RD 0.04 1.08 .28 Year 1 RD 0.08 1.91 .06
Marijuana use frequency 0.01 0.14 .89 Marijuana use frequency 0.02 0.46 .65
Gender 0.12 2.97 .001 Gender 0.03 0.60 .55
RD
Marijuana Use 0.02 0.49 .62 RD
Marijuana Use 0.03 0.65 .52
Marijuana Use
Gender 0.02 0.59 .56 Marijuana Use
Gender 0.00 0.09 .93
RD
Gender 0.02 0.60 .55 RD
Gender 0.06 1.35 .18
RD
Marijuana Use
Gender 0.06 1.47 .14 RD
Marijuana Use
Gender 0.06 1.38 .17
(table continues)
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MARIJUANA, TEMPERAMENT, ANXIETY, AND DEPRESSION 597
three significant predictors of Year 2 depression symptoms (see
Table 3). Year 1 depression was positively associated with Year 2
depression symptoms, and Year 1 marijuana use was negatively
associated with Year 2 depression. The NS
Marijuana Use
interaction was also significant. The simple effects in Figure 3,
Panel D show that greater Year 1 NS was associated with greater
depression in Year 2 for those with high marijuana use frequency,
.26, t(329) 3.06, p .01. By contrast, there was no relation
between NS and depression when marijuana use was low,
.03, t(329) .62, p .54.
In the second model predicting Year 2 NS, the only significant
predictor was Year 1 NS (see Table 3). Year 1 depression levels
did not predict Year 2 NS, nor did the Year 1 Depression

Marijuana Use interaction.
Reward dependence and anxiety. Figure 2, Panel E shows
the cross-lag relations of primary theoretical interest in assessing
the relation between RD and anxiety levels. The first regression
model testing whether initial temperament predicts subsequent
psychopathology revealed only two significant effects: greater
Year 1 anxiety was associated with more Year 2 anxiety and
females reported more anxiety in Year 2 than males (see Table 3).
There were no effects of RD on anxiety symptoms, either independently or moderated by marijuana use.
The second regression model predicting Year 2 RD revealed 4
significant effects (see Table 3). Greater Year 1 RD and being
female were both associated with higher Year 2 RD. There was
also an Anxiety
Marijuana Use interaction. Tests of simple
slopes showed a significant negative relation between Year 1
Table 3 (continued)
Reward dependence
RD and anxiety RD and depression
Model 2: DV RD t p Model 2: DV RD t p
Year 1 RD 0.76 22.44 .001 Year 1 RD 0.76 22.26 .001
Year 1 Anxiety 0.01 0.36 .72 Year 1 depression 0.00 0.06 .96
Marijuana use frequency 0.05 1.51 .13 Marijuana use frequency 0.05 1.56 .12
Gender 0.14 3.92 .001 Gender 0.14 3.89 .001
Anxiety
Marijuana Use 0.08 2.44 .02 Depression
Marijuana Use 0.04 0.98 .33
Marijuana Use
Gender 0.10 3.03 .01 Marijuana Use
Gender 0.10 2.86 .01
Anxiety
Gender 0.02 0.58 .56 Depression
Gender 0.02 0.51 .61
Anxiety
Marijuana Use
Gender 0.01 0.21 .83 Depression
Marijuana Use
Gender 0.02 0.62 .53
Note. All regression coefficients are standardized.
Figure 3. Simple effects of harm avoidance and novelty seeking on levels anxiety and depression as a function
of marijuana use.
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598 GRUNBERG, CORDOVA, BIDWELL, AND ITO
anxiety levels and Year 2 RD among those who more frequently
use marijuana, .14, t(329) .2.26, p .02. The relation
between Year 1 anxiety and Year 2 RD was not significant for low
frequency marijuana users, .04, t(329) 1.06, p .29.
Finally, the Marijuana Use
Gender interaction was significant.
Among women, marijuana use was positively associated with
greater RD, .15, t(329) 3.19, p .002, but the relation was
nonsignificant for men, .05, t(329) 1.08, p .28.
Reward dependence and depression. The first regression
model predicting later psychopathology from initial temperament
revealed only that Year 1 depression symptoms predicted Year 2
depression symptoms (Figure 2, Panel F). In the second model
predicting later temperament from initial psychopathology, three
effects were significant. Year 1 RD predicted Year 2 RD, and
females reported higher Year 2 RD. There was also a Marijuana
Use
Gender interaction that showed the same pattern as this
same interaction in the model predicting anxiety from RD. That is,
among women, marijuana use frequency was positively associated
with greater RD, .15, t(329) 3.05, p .002, but the relation
was nonsignificant for men, .05, t(329) .94, p .35.
Discussion
Given the elevated rates of anxiety and depression within late
adolescence and early adulthood, the present study examined how
another behavior that occurs with relatively high frequency in this
age range—marijuana use—is associated with anxiety and depression. There has to date been no clear picture of how marijuana
relates to anxiety and depression; thus, we examined how temperament may impact these relations. Of particular interest was HA,
which is associated with greater anxiety and depression. One
question that has not yet been examined is whether marijuana use
moderates the impact of the behavioral biases associated with HA
on anxiety and depression.
The temperament dimension of HA is associated with apprehension, pessimism, and inhibition and has been associated with
both anxiety and depression (Hansenne et al., 1998; Jiang et al.,
2003; Manfredi et al., 2011; Matsudaira & Kitamura, 2006). Our
prospective analyses show a similar relation, but importantly demonstrate that it is moderated by level of marijuana use. Specifically, we find that HA measured at baseline is associated with
more symptoms of both anxiety and depression measured a year
later only for those low in marijuana use. By contrast, when
marijuana use is high, HA is unrelated to anxiety and depression
levels. Of importance, these analyses control for baseline anxiety
or depression levels, so our results show the predictive effect of
HA and marijuana use over and above levels of anxiety and
depression exhibited a year earlier. While the present study cannot
speak definitively to the mechanism of our effects, marijuana has
been suggested to produce anxiolytic and mood elevating benefits
(Denson & Earleywine, 2006; Sethi et al., 1986; Stewart et al.,
1997). Such mood benefits could attenuate the greater risk toward
anxiety and depression typically associated with HA. Using our
cross-lag analysis approach, we see no evidence that initial symptoms of anxiety and depression predict subsequent HA (Model 2 in
Figure 1), suggesting that the relations observed between HA,
marijuana use, anxiety, and depression are likely due to effects of
initial temperament and marijuana use on subsequent psychopathology rather than the converse.
Marijuana use also moderated the relation between NS and
anxiety and depression symptoms, but the pattern of modulation
differed from that with HA. For NS, it was people higher in
marijuana use who showed a positive association between NS and
both anxiety and depression symptoms. Those low in marijuana
use showed no relation between NS and levels of anxiety and
depression. Further, the pattern of the interaction was such that
levels of anxiety and depression were similarly high for those high
in NS and high in marijuana use, as well as those low in NS at all
levels of marijuana use. It was individuals low in NS and high in
marijuana use that had the lowest anxiety and depression (see
Figure 3, Panels C and D). This effect warrants further investigation as it is not clear what mechanism may account for the
seemingly protective effect of low NS coupled with high marijuana use or why this benefit of marijuana use is not seen when NS
is higher. As with HA, models assessing the relation of initial
symptoms of anxiety and depression to subsequent NS fail to show
effects of anxiety, depression, or marijuana use frequency, suggesting that the relations observed between NS, marijuana use,
anxiety, and depression are likely due to effects of initial temperament and marijuana use on subsequent psychopathology rather
than the converse.
Our results reveal no effect of RD on anxiety and depression
symptoms. There were no zero-order correlations between RD and
anxiety or depression, no independent effects of RD on Year 2
anxiety or depression, and no moderated effect on anxiety and
depression. Unexpectedly, RD was the one aspect of temperament
that was predicted by an aspect of psychopathology. Specifically,
Year 1 anxiety and marijuana use frequency interacted to predict
Year 2 RD. Tests of the simple effects show that among those who
use marijuana more frequently, reporting more symptoms of anxiety in Year 1 predicted lower RD in Year 2. Temperament is
considered to be relatively stable. Consistent with this, Year 1
temperament was always a significant and large predictor of Year
2 temperament in our models, a relation that was of similar
magnitude for RD as compared with HA and NS (see Table 3). We
are, therefore, uncertain what accounts for this sole effect of initial
psychopathology predicting subsequent temperament. We interpret this relation cautiously and note that the analogous RD and
marijuana use interaction was not significant for depression symptoms.
These results have a number of implications for understanding
how marijuana affects anxiety and depression, and for how temperament affects anxiety and depression. We have noted that the
relation between marijuana and anxiety/depression has been quite
variable in past research. We think the present results demonstrate
the importance of considering the impact of other factors known to
influence anxiety and depression. The interactions we observed
between HA and marijuana use and NS and marijuana use indicate
that different relations between marijuana use and anxiety/depression levels will be observed depending on the levels of HA and NS
within a sample. Consider, for example, the interaction between
HA and marijuana use in predicting anxiety (Figure 3, Panel A). If
a sample happened to be relatively low in HA, a positive relation
between marijuana use and anxiety would be expected but if the
sample happened to be high in HA, greater marijuana use might be
associated with less anxiety. To our knowledge, no studies examining the effect of marijuana use on anxiety and depression have
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MARIJUANA, TEMPERAMENT, ANXIETY, AND DEPRESSION 599
considered how these relations interact with preexisting temperament.
It is also important to consider that the simple relations we
observed between marijuana use and depression symptoms differed from those obtained in the more complex models. That is,
when only marijuana use was considered, results suggest a
positive association between marijuana use and depression.
This was seen in the marijuana use group main effects in the
preliminary categorical analyses, and in a significant (but
small) positive bivariate correlation between Year 1 marijuana
use and Year 1 depression symptoms. However, in the regression models that prospectively predict anxiety/depression and
also include HA or RD, the HA
Marijuana Use or RD

Marijuana Use interactions, and baseline anxiety or depression,
marijuana use was not an independent predictor of depression
symptoms. Moreover, in the models involving NS, marijuana
use negatively predicted depression symptoms (and anxiety).
These differing patterns of results first demonstrate the importance of measuring the effects of marijuana within the context
of other factors known to affect anxiety and depression, as well
as prior symptoms of anxiety and depression. The results might
also indicate a complex causal relation between marijuana use
and depression in which initial symptoms of depression facilitate marijuana use, which subsequently decreases depression.
This conclusion, however, is speculative and warrants more
explicit examination. At a minimum, our results suggest marijuana does not have an invariant effect of anxiety and depression, and that more research is needed to understand the possible mechanisms through which aspects of temperament and
marijuana use affects anxiety and depression.
Another intriguing question raised by our results is whether
temperament could affect marijuana use. HA is associated with
negative affective states such as apprehension and pessimism, as
well as social inhibition (Cloninger et al., 1993). Coping with
negative affect, enhancing positive affect, and facilitating social
interactions are among the top motivations reported for marijuana
use (Lee et al., 2009; Newcomb et al., 1988; Simons et al., 1998),
raising the possibility that people high in HA might use marijuana
as a way to manage their temperamental predispositions. As marijuana use increases, studying not only the outcomes of its use but
also the factors that motivate its use is of increasing relevance. Our
results suggest additional specific relations that might be fruitful to
examine.
Effects of Gender
Roughly equal numbers of men and women with similar rates of
marijuana use were recruited in this sample, providing the opportunity to assess whether predictors of level of anxiety and depression in this age range differ for men and women. There were some
gender main effects in the regression analyses predicting anxiety,
with women reporting more symptoms of anxiety in Year 2 than
men, even when controlling for Year 1 anxiety. This result indicates that anxiety increased more for women that for men in this
sample, broadly consistent with higher prevalence rates of anxiety
among women (e.g., McLean et al., 2011; National Institute of
Mental Health, 2014a). However, gender did not moderate any of
the effects of temperament, or the Temperament
Marijuana Use
interactions, suggesting that the way temperament relates to anxiety and depression—and how that relation is moderated by marijuana use— occurs similarly for men and women.
Limitations
While our prospective design, relatively large sample, and
roughly equal numbers of men and women were strengths of our
design, there are limitations to consider. We purposely focused our
analyses on a college sample because of the high clinical significance of anxiety, depression, and marijuana use in this age range.
However, it is important to interpret results with these contextual
factors in mind; it is possible that the relation among these variables differs in other types of samples.
Another factor to consider is our use of self-reported symptoms
of anxiety and depression. Although the measure we used to assess
anxiety and depression has demonstrated validity with clinical
assessments (Achenbach & Rescorla, 2003), no independent clinical assessments were available for our participants. Moreover, we
examined our hypotheses within the context of a broad range of
anxiety and depression symptomology. While the number of participants meeting clinical thresholds for anxiety and depression
was modest (see Table 1), subclinical levels of anxiety and depression are associated with meaningful functional impairments
(Dotson et al., 2014; Karsten, Nolen, Penninx, & Hartman, 2011;
Kessler, Zhao, Blazer, & Swartz, 1997). Subclinical symptoms are
also precursors to clinical conditions (Hill, Pettit, Lewinsohn,
Seeley, & Klein, 2014; Shankman et al., 2009).
A final important consideration is that our analyses are based on
correlational data. Given the variables involved—temperament,
substance use, and symptoms associated with psychopathology—
true experiments are not feasible. We attempted to maximize our
inferential power through methodological decisions such as the
longitudinal design so that marijuana use and temperament were
measured 1 year before anxiety and depression symptoms. Use of
cross-lag analyses also allowed us to statically assess the plausibility of our proposed model that initial temperament and marijuana use affect subsequent and depression over the alternative
model that initial anxiety/depression and marijuana use affect
subsequent temperament. Nevertheless, our conclusions are ultimately correlational and the implications of the results must be
interpreted with that limitation in mind. Moreover, that conclusions are based on only two points in time is another limitation to
consider.
Conclusions
Our results highlight the importance of simultaneously assessing
the effect of marijuana use on anxiety and depression within the
context of other factors known to predict psychopathology by
showing that marijuana use and temperament interact complexly in
predicting risk for anxiety and depression. These results may help
explain why marijuana’s effects on anxiety and depression have
been variable in past research. They also show that even for a
temperament dimension consistently linked with anxiety and depression (HA), other factors have important moderating influences
on its effects. Another important implication of our results is that
it is not only important to assess these complex relations among
multiple factors, but also the causal mechanisms they imply. Our
results suggest that marijuana’s anxiolytic and mood-enhancing
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600 GRUNBERG, CORDOVA, BIDWELL, AND ITO
effects (or perceived effects) may attenuate the effects of HA on
risk for anxiety and depression, raising the question of whether
such effects might motivate individuals high in HA to use marijuana. As marijuana use becomes more readily available and
accepted, it will be important to consider these kinds of potential
motivations for its use. Finally, from the perspective of treatment
and intervention, the lack of simple effects of marijuana use on
anxiety and depression argues against marijuana reduction interventions as strategies that will necessarily decrease risk for anxiety
and depression within this age range. Instead, the benefits of
decreasing marijuana use will depend on other characteristics, such
as temperament.
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Received January 13, 2015
Revision received May 26, 2015
Accepted June 8, 2015
This document is copyrighted by the American Psychological Association or one of its allied publishers.
This article is intended solely for the personal use of the individual user and is not to be disseminated broadly.
602 GRUNBERG, CORDOVA, BIDWELL, AND ITO

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