Adolescence and young adulthood is a critical period of neurological and psychological development [1–3]. Due to the plasticity of the developing brain, young people are particularly susceptible to the environmental, social, and physiological factors that may contribute to the development and progression of mental illness and behavioral disorders [4]. According to the National Comorbidity Survey, the mean age of onset for any mental health disorder is 14 [5]. Mental and behavioral problems in adolescence may impair neurological and emotional development, and, if unaddressed, these issues will likely extend into adulthood [5, 6]. This study examined the current literature on two of the most prevalent mental and behavioral issues among adolescents and young adults (AYA): anxiety and cannabis use.

Anxiety disorders (e.g. generalized anxiety disorder, social anxiety disorder) are highly prevalent among AYA and are associated with adverse outcomes later in life. The estimated prevalence of anxiety disorders in the United States is 31.9% for adolescents (ages 13–18) [7] and 14.7% for young adults (ages 18–25) [8]. The median age of onset for any anxiety disorder worldwide is 17, making early recognition and prevention crucial [9]. Some anxiety disorders begin at even younger ages due to changes in social relationships in childhood and adolescence [10, 11]; the median age of onset for separation and social anxiety disorders are 8 and 13, respectively [9]. Furthermore, anxiety disorders put AYA at greater risk for major depression, illicit substance dependence, reduced self-esteem, and educational underachievement in adulthood [11–13]. In addition to individual sequelae, anxiety disorders pose significant societal burdens, including lost work productivity and high medical resource use [14]. Indeed, the mean total annual cost per patient for pediatric anxiety is $6405, with costs increasing with elevated symptoms of anxiety [15].

Cannabis use is also pervasive among AYA, particularly so with increased legalization in the United States, and has likewise been under scrutiny from researchers due to potential long-term consequences. According to the 2019 Monitoring the Future national survey, 35.7% of 12th grade students, 28.8% of 10th grade students, and 11.8% of 8th grade students reported marijuana use within the past year [16]. Furthermore, according to the 2014 National Survey on Drug Use and Health (NSDUH), 1.09% of 12–17 year-olds reported daily cannabis use, as did 6.51% of 18–25 year-olds, the highest rate of any age category [17]. In 2014, only four states and the District of Columbia (D.C.) had legalized recreational cannabis use [18], but now, as of April 2021, recreational use has been legalized in 17 states, D.C., and Guam [19]. As cannabis legalization has expanded since the most recent national cannabis use rates were reported, it is possible that rates are even higher today [20, 21]. Furthermore, while there is conflicting evidence on the sequelae of early cannabis use [22], some studies have suggested a link between early use and adverse outcomes in adulthood such as illicit drug use, suicide attempts, and lower educational attainment [23, 24].

Both anxiety disorders and cannabis use have complex etiologies involving psychosocial, physiological, and environmental factors contributing to their development and progression [25–27]. It has been posited that anxiety may contribute to the etiology of cannabis use, or visa versa. However, this hypothesis is controversial, and the significance and directionality of the relationship has not been fully established [28–30]. Some research has found that cannabis may temporarily reduce anxiety symptoms, but the long-term effects of frequent cannabis use on mental health are unclear [29, 31, 32]. Cannabis use is common among those with anxiety disorders, but it is yet to be determined whether cannabis use itself contributes to the development and progression of anxiety disorders or if anxiety symptoms lead to cannabis use and potential dependence [31, 33]. Yet, despite this ambiguity, pediatricians today often receive questions from AYA, parents and caregivers about the potential use of cannabis as a treatment option for AYA patients with anxiety and other mental health problems [34].

The purpose of this scoping review was to describe the current state of scientific literature examining the relationship between anxiety and cannabis use among adolescents and young adults. The population of interest for this review includes AYA up to 25 years of age due to the high demand for information on cannabis as a treatment option for anxiety in pediatric clinics, which often provide care for patients well into young adulthood [35]. This topic is of particular importance to pediatricians due to the reported consequences of both early cannabis use and early onset of anxiety [11–13, 23, 24]. A literature search of recently published articles was conducted to elucidate current knowledge, identify gaps in the literature, and provide directions for future research. It is our intention that the information gathered in this review will inform clinicians and researchers interested in understanding and furthering current knowledge on cannabis use and anxiety in AYA.

Results

Included Studies

See Fig. 1 for the PRISMA flow diagram. Following the removal of duplicate articles, 2886 titles and abstracts were independently reviewed in duplicate. Two hundred fifty-seven full-text articles were reviewed in duplicate for inclusion, with 47 articles selected for data extraction. Of the 47 studies: 23 reported a positive association (e.g., higher anxiety associated with earlier onset of use, higher frequency of use, and/or greater cannabis-associated problems); seven reported a negative association (e.g., higher anxiety associated with less use); and 17 reported an unclear or no association between anxiety and cannabis use. See Tables 1, 2 and 3 for the study characteristics.

First Author, Year	Country	Study setting	Age, M (range)	Sample size, N (%female)	Race	Ethnicity	Cannabis measurement	Anxiety measurement	Association
Cerdá et al., 2013	United States	High School	6.7 at baseline (1st grade-age 19)	503 (0%)	56% Black;41% White;3% Asian, Mexican, Mixed Race	Partially combined with Race Reporting/NR	Self-Report: SRA; 16-item Substance Use Scale based on the National Youth Survey	Self-Report: CBCL	Recent, cumulative anxiety associated with earlier cannabis initiation (compared to control)
Cloak et al., 2015	United States	Community Environment	18.3–19.4 Across Groups (13–23)	122 (38.6–49%)	NR	NR	Clinical Interview: Structured InterviewBiometric Data: Urine Toxicology Screen	Self-Report: SCL-90R; BPRSBiometric data: Cortisol Levels	Longer duration of abstinence associated with less Anxiety; Higher lifetime cannabis use associated with more Anxiety symptoms
Degenhardt et al., 2013	Australia	High School	14.9 at baseline (14.9–29.0)	1756 (53%)	NR	NR	Self-Reported Use	Clinical Interview: CIS-R	Daily, weekly, and occasional cannabis users at higher likelihood of meeting criteria for anxiety
Duperrouzel et al., 2018	United States	Urban/City Environment, High School	15.41 (14–17)	250 (43.6%)	89.6% Hispanic;4.8% Black;4.4% White;1.2% Other	Combined with Race Reporting	Self-Report: Drug-Use History Questionnaire	Self-Report: DASS-21	Initial cannabis use frequency positively associated with subsequent changes in anxiety
Ecker et al., 2014	United States	University/College	19.68 (18–23)	230 (63.0%)	85.7% White;5.7% African American;4.3% Mixed;3.0% Asian American;1.3% Other	92.6% Non-Hispanic/Latino;7.6% Hispanic/Latino	Self-Report: MUF	Self-Report: SIAS	General, Social anxiety positively correlated with cannabis-related problems; General anxiety associated with cannabis use frequency
Ecker et al., 2018	United States	University/College	20.32 (18-NR)	244 (76.2%)	74.2% non-Hispanic Caucasian;13.5% African American/Black;5.7% Asian;5.0% Multiracial1.2% Hispanic Caucasian;.8% American Indian	Combined with Race Reporting	Self-Report: TFB; MPS	Self-Report: SIAS	Social anxiety associated with problem severity
Foster et al., 2016	United States	Community Environment	21.01 (18–36)	148 (36.5%)	59.7% Caucasian;24.8% African American;8.1% Mixed;3.4% Asian;3.4% Other;.67% Native American	NR	Self-Report: Marijuana Use Questionnaire; MPS	Self-Report: SIAS; BSI	General, Social anxiety associated with cannabis problems
Hellemans et al., 2019	Canada	University/College	20 (NR)	1043 (62.5%)	57.4% White;9.7% Black;9.4% Arab/West Asian;8.6% Asian;4.9% South Asian;4.2% Other;2.3% Indigenous;2.0% South East Asian;1.4% Latin American/Hispanic	Combined with Race Reporting	Self-Report: CUDIT-R	Self-Report: BAI	Problematic cannabis use associated with higher anxiety scores, but moderated by gender (stronger for females)
Hill et al., 2017	United States	Urban/City Environment, Rural Environment	Longitudinal (9–30)	1229 (49.9%)	89% White;7.25% African American;3.75% American Indian	NR	Self-Report: YAPA	Self-Report: CAPA (< 16); YAPA (19 +)	Anxiety disorders during childhood/early-adolescence (ages 9–16) and late-adolescence (19–21) were more prevalent amongst persistent, problematic users
Hines et al., 2020	United Kingdom	Community Environment	24 (NR)	1087 (53.4%)	5.3% “Black or minority ethnic group”	Combined with Race Reporting	Self-Reported Use	Clinical Interview: CIS-R	Use of high-potency cannabis associated with a moderate elevation in likelihood of generalized anxiety disorder (p = .02)
Kaasbøll et al., 2018	Norway	High School	NR (13–17)	36714 (49.3%)	NR	NR	Self-Reported Use	Self-Report: HSCL	Cannabis users endorsed higher anxiety symptoms
Keith et al., 2015	United States	University/College	19.9 (NR)	1776 (56.5%)	47.3% White;29.6% Asian/Pacific Islander;11.0% Hispanic;8.5% Multiracial;6.2% Black	Combined with Race Reporting	Self-Reported Use	Self-Reported Diagnostic and Treatment history	Anxiety associated with marijuana use
Keough et al., 2018	Canada	University/College	20.18 (NR)	91 (55%)	NR	44% Other;42% Canadian/European;14% South Asian	Self-Report: MPS	Self-Report: AS	Anxiety sensitivity positively correlated with cannabis-related problems
Laguerre et al., 2015	France	High School	17.54 (NR)	336 (63.1%)	NR	NR	Self-Reported Use	Self-Report: ASA-27	Separation anxiety higher in cannabis users than nonusers
Leadbetter et al., 2019	Canada	Community Environment	Baseline: 15.52 (12–18; Longitudinal)	662 (52%)	85% White	NR	Self-Reported Use;Clinical Interview: MINI	Clinical Interview: BCFPI	Cannabis use disorder associated with higher anxiety symptoms at ages 26–27 only
Otten et al., 2016	The Netherlands	Community Environment	13.02, 15.73, 18.54 (longitudinal)	1424 (53.1%)	NR	NR	Self-Reported Use	Self-Report: Anxiety Problems Scale of ASEBA	For short allele carriers (not non-carriers), use positively associated with higher and increasing levels of anxiety
Pang et al., 2017	United States	High School	14.67, 15.12, 15.51,16.14 (9th-10th Grade)	2057 (58%)	Across Substance Types:48.3–56.7% Hispanic/Latino;14.8–17.7% White;6.85–8.7% Asian;2.8–4.9% Black/African American;3.8–5.2% Native Hawaiian or Pacific Islander;4.4–7.3% Multiracial;7.0–10.0% Other	Combined with Race Reporting	Self-Report: YRBSS; Monitoring the Future	Self-Report: CASI; RCADS	Anxiety sensitivity symptoms associated with more negative cannabis effects of cannabis; Higher GAD symptoms initially report more positive cannabis effects, but have a slower increase in these effects across time
Rusby et al., 2019	United States	High School	14.4 (8th -10th grade)	466 (52.8%)	44% White, Non-Hispanic;38% Hispanic;18% Other or multiple races	Combined with Race Reporting	Self-Report: OHT	Self-Reported Mood (EMA)	Recent cannabis use associated with significantly greater anxious mood lability
Schuster et al., 2019	United States	Urban/City Environment	21.79 (18–25)	76 (44.7%)	63.2% White;15.8% Black;11.8% More than one race;9.2% Other	NR	Self-Report: CUDIT-R; TFB; MEEQBiometric Data: Urine Toxicology Screen	Self-Report: MASQ	Current anxious symptoms, arousal associated with greater cannabis use dependency in young adults who use cannabis at least weekly
Stapinski et al., 2016	Chile	Urban/City Environment, High School	14.5 (12–18)	2508 (44.5%)	NR	NR	Self-Reported Use	Self-Report: RCADS	Baseline generalized anxiety associated with cannabis use frequency at 18-month follow-up
Thompson et al., 2018	Canada	Urban/City Environment	15.5 at T1 (12–22; 18–29 ranges across timepoints)	662 (50.3%)	NR	NR	T1: Self-Reported UseT6: Clinical Interview: MINI	Self-Report: BCFPI	Chronic users reported higher anxiety symptoms; for young adults, chronic users reported more anxiety symptoms than all other classes except occasional users
Villarosa-Hurlocker et al., 2019	United States	University/College	20.24 (NR)	2034 (69.1%)	NR	67.95% White, Non-Hispanic;15.88% Hispanic/Latino Ethnicity	Self-Report: B-MACQ	Self-Report: SIAS; BFNE	When controlling for all other predictors, social anxiety associated with more cannabis-related problems
Wolitzky-Taylor et al., 2016	Unites States	High School	14.1 (NR)	3002 (54.1%)	47.4% Hispanic;6.7% Multiracial;16.6% Asian;16.1% Caucasian;4.9% African American;4.1% Native Hawaiian or Pacific Islander;1% American Indian or Alaska Native	Combined with Race Reporting	Self-Report: CAST	Self-Report: RCADS	Negative urgency mediated associations between cannabis use and generalized anxiety disorder, panic disorder, social phobia

First Author, Year	Country	Study setting	Age, M (range)	Sample size, N (% female)	Race	Ethnicity	Cannabis measurement	Anxiety measurement	Association
Ali et al., 2016	France	High School, Vocational school	NR(14–20)	5069 (54%)	NR	NR	Self-Report: ESPAD	Self-Report: SURPS	Higher anxiety sensitivity associated with decreased current frequency of use
Bierhoff et al., 2019	United States	University/College	20.49 (18–25)	2397 (64.7%)	65.5% White;21.8% Black;6.9% Asian;5.8% Other	92.2% non-Hispanic;7.8% Hispanic	Self-Reported Use	Self-Report: SAS	Use associated with lower levels of anxiety symptoms
Di Blasi et al., 2015	Italy	High School	16.39 (14–19)	1305 (51.4%)	NR	NR	Self-Report: CUPIT	Self-Report: SIAS	Higher social anxiety associated with lower use
Schmitts et al., 2015	Belgium	High School	15.61 (14–18)	877 (50%)	NR	~ 85% Belgian;NR% Italian, Moroccan, Turkish, Other minorities	Self-Report: MUF	Self-Report: STAI-CH; LSAS-CA-SR	Higher levels of social anxiety at first time point were related to a reduced probability of cannabis initiation at next time point
Schmitts et al., 2015	Belgium	High School	16.64 (14–21)	130 (42.3%)	NR	NR	Self-Report: MUF; CPQ-A; MEEQ	Self-Report: STAI-CH; LSAS-CA-SR	Cannabis users endorsed less social anxiety
Schmitts et al., 2016	Belgium	High School	15.7 (14–18)	1343 (325 cannabis users; 45.6%)	NR	~ 85% Belgian;NR% Italian, Moroccan, Turkish, Other minorities	Self-Report: MUF; CPQ-A; MEEQ	Self-Report: LSAS-CA-SR	Higher social anxiety associated with expected negative behavioral effects of cannabis use, less cannabis use
Schmitts et al., 2018	Belgium	High School	15.54 (14–18)	611 (49.3%)	NR	~ 88% Belgian;NR% Italian, Moroccan, Turkish, Other minorities	Self-Report: MUF; CPQ-A; MEEQ	Self-Report: STAI-CH; LSAS-CA-SR	Higher social anxiety at first time point less likely to have used cannabis by third time point, and have a higher level of negative behavioral effect expectancies

First Author, Year	Country	Study setting	Age, M (range)	Sample size, N (% female)	Race	Ethnicity	Cannabis measurement	Anxiety measurement	Association
Buckner et al., 2016	United States	University/College	20.2 (18–29)	276 (79.7%)	76.1% Non-Hispanic White;12.0% Non-Hispanic African American;4.7% Multiracial; 2.5% Asian or Asian American; 2.2% Hispanic White;1.1% Other;1.0% American Indian or Alaska Native;.4% Hispanic African American	Combined with Race Reporting	Self-Report: MUF; Investigator-developed questionnaire adapted from Gonzalez & Skewes	Self-Report: SIAS	Cannabis problems more likely related to solitary use than social anxiety experiences
Butler et al., 2019	Canada	High School	NR	6550 (51.7%)	NR	71.5% “Non-minority ethnicity”	Self-Reported Use	Self-Report: GAD-7	Anxiety associated with cannabis use frequency in one model, but not after including flourishing in later models
Cerdá et al., 2016	United States	High School	NR (13–19)	503 (0%)	56% Black;41% White;3% Asian, Mexican, Mixed Race	Partially combined with Race Reporting/NR	Self-Report: SRA; 16-item Substance Use Scale based on the National Youth Survey	Self-Report: CBCL	Higher anxiety and affective problems not associated with use
Cloutier et al., 2016	United States	Community Environment	16.2 (12–17)	56 (41.1%)	83.9% Caucasian;5.4% African American;7.1% multiracial;3.6% “Other”	9.1% Hispanic/Latino	Self-Report: AADIS; TMMQ	Self-Report: RCADS (social anxiety subscale); Youth Self-Report – Anxiety problems subscale	No association with anxiety across measures of use frequency
Colder et al., 2019	United States	Community Environment	12 (11–12)	387 (55%)	83.1% non-Hispanic Caucasian;9.1% African American	Partially combined with Race Reporting/NR	Self-Reported UseSelf-Report: MMQ; MACQ	Self-Report: SIAS	Elevations in social anxiety were not associated with coping motives, or with cannabis use or problems
Ecker et al., 2014	United States	University/College	20.28 (18-NR)	158 (75.3%)	77.2% Caucasian;8.9% African American;8.2% Mixed;5.1% Asian;.6% Other	8.2% Hispanic/Latino	Self-Report: Daily Drug-Taking Questionnaire; MPS	Self-Report: Social Phobia Scale	Non-significant correlation between cannabis use frequency and social anxiety
Elkington et al., 2016	United States	Urban/City Environment, Community Environment	12.58 (9–16)	340 (51.2%)	PHIV + : 57.8% Black;30.1% Hispanic;12.1% OtherPHIV-: 49.3% Black;32.1% Hispanic;18.6% Other	Combined with Race Reporting	Clinical Interview: DISC-IV	Clinical Interview: DISC-IV	Frequency of use not associated with having an anxiety disorder at baseline, follow-up points
Gage et al., 2015	United Kingdom	Rural Environment	16, 18 (Prospective assessments)	4561 (NR)	NR	NR	Self-Reported Use	Clinical Interview: CIS-R	No significant relationship
Gillen et al., 2016	United States	Residential military-style program for youth who have dropped out of high school	16.74 (16–19)	185 (0%)	54.1% White;24.3% Black;18.4% Did not report;1.6% Another ethnic group;1.1% Hispanic;.5% Asian	Combined with Race Reporting	Self-Report: CRAFFT; MMQ	Self-Report: Personality Inventory for Youth (Fear and Worry Subscale)	No significant relationship
Grunberg et al., 2015	United States	University/College	18.30–18.38 (18–21)	375 (46.9%)	73% White;18.7% Multi-Racial;3.6% Asian;3.3% Hispanic;.6% East Indian;.3% Black;.3% Middle Eastern.3% Pacific Islander	Combined with Race Reporting	Self-Report: TLFB	Self-Report: ASEBA	Initial cannabis use not correlated with anxiety at current or later time point
Khoddam et al., 2016	United States	High School	14.1 (NR)	3383 (53%)	45.9% Hispanic or Latino;15.8% Asian;15.3% White;5.9% Multiracial;5.6% Other;4.9% Black/African American;3.3% Native Hawaiian/Pacific Islander;0.9% American Indian/Alaska Native	Combined with Race Reporting	Self-Reported Use	Self-Report: RCADS	Anxiety symptoms not associated with use over and above conduct problems
Ninnemann et al., 2017	United States	High School	16.09 (NR)	964 (56%)	31% African American;29% White;28% Hispanic;12% Other	Combined with Race Reporting	Self-Report: MTF	Self-Report: Screen for Child Anxiety-Related Emotional Disorders	No significant relationship
Osuch et al., 2013	Canada	Urban/City Environment, Community Environment	19 (16–26)	429 (63.2%)	NR	NR	Self-Report: NIDA Modified ASSIST	Self-Report: STAI	No significant relationship
Phillips et al., 2018	United States	University/College	20.32 (18–25)	300 (60%)	69% Caucasian (Non-Latino/Hispanic);15% Latino/Hispanic;6% African American;6% Multi-racial;2% Asian;2% Pacific Islander/Hawaiian	Combined with Race Reporting	Self-Report: Marijuana Use Measure; MPIBiometric Data: Urine Toxicology Screen	Self-Report: BAI; SIAS	No significant relationship
Rahm-Knigge et al., 2019	United States	University/College	18.92 (NR)	1005 (67.6%)	83.75 White;5.1% Multi-racial;4.0% Asian;3.0% Do not wish to respond;2.2% Black or African American;.9% American Indian or Alaskan Native;0.9% Native Hawaiian or Other Pacific Islander	81% Not Hispanic or Latino;15.6% Hispanic or Latino;2.5% Do not wish to respond;.9% Missing	Self-Report: RBI	Self-Report: SAIS	No direct association, but certain profiles (Low Social Interaction Anxiety High Urgency) may be more likely to endorse use
Walters et al., 2018	United States	University/College	20.37 (18–25)	891 (69.6%)	69% White;15% Black/African American;8% Hispanic/Latino;6% Other;2% Asian/Pacific Islander	Combined with Race Reporting	Self-Report: CORE Alcohol and Drug Survey—Short form	Self-Report: PAI	No significant relationship
Wright et al., 2016	United States	University/College	21.2 (18–25)	84 (46.4%)	Control: 60% Caucasian;Cannabis Users: 67% Caucasian	NR	Self-Report: TLFB;Clinical Interview: Semi-structured interview	Self-Report: STAI	Overall, no association; Female cannabis users more likely to experience anxiety symptoms (p = .04)

Positive Association

Study Characteristics

Twenty-three epidemiologic and population-based studies identified a positive association between higher anxiety levels with cannabis use frequency, onset, and/or problems. These studies were conducted in eight countries: United States of America (13; 56.5%), Canada (4; 17.4%), Australia (1; 4.3%), Chile (1; 4.3%), France (1; 4.3%), The Netherlands (1; 4.3%), Norway (1; 4.3%), and the United Kingdom (1; 4.3%). Notably, two studies from Canada derived from the Victoria Healthy Youth Survey, which prospectively assessed a community sample of 662 youth for ten years [38, 39]. Study settings included high schools, university or college campuses, community environments, urban/city environments, and rural environments. Cannabis use and/or problems were assessed via: validated self-report questionnaires (12; 52.2%), self-reported frequency of use (7; 30.4%), or a multi-method approach (clinical interview with biometric data [1; 4.3%] or with self-reported use [1; 4.3%]; validated self-report questionnaire with biometric data [1; 4.3%]; self-reported use at one time point and a clinical interview at a later time point [1; 4.3%]). For the assessment of anxiety, validated self-report questionnaires (17; 73.9%), clinical interviews (3; 13%) ecological momentary assessment (1; 4.3%), self-reported diagnostic and treatment history (1; 4.3%), and a combination of validated self-report questionnaire and biometric data (1; 4.3%) were utilized.

Sample Characteristics

Sample sizes ranged from 76 to 36,714, with females comprising 0–76.2% of the samples. No studies reported gender options beyond “male” and “female,” with one exception which noted that three participants identified their gender as “Other”; however, these participants were excluded from gender-based analyses [40]. While all studies had at least half of their samples composed of participants 25 years of age or under, the range of included ages spanned six to 36 years of age. Seven studies (30.4%) did not present any racial or ethnic identity information about their samples, with two more studies only providing the percentage of the sample that identified with one identity (e.g., “85% White”). Four samples (17.4%) had a minoritized racial or ethnic minority as the most represented group in their study.

Primary Outcomes

All 23 studies reported positive associations between anxiety or symptoms of anxiety with cannabis use, frequency of use, onset, and/or problems. Anxiety was associated with earlier cannabis initiation [41], higher cumulative lifetime use [42], use dependency [43], and general endorsement of use (as opposed to frequency of use) [44]. Further, frequent cannabis users were more likely than infrequent or non-users to meet criteria for anxiety disorders [45], endorse higher anxiety symptoms [39, 46], and/or display increases in anxiety over time [39, 47] or at a specific time period in adulthood (i.e., 26–27 years of age) [38]. Recent cannabis use was associated with greater anxious mood lability [48]. Similarly, longer abstinence from cannabis use was associated with less anxiety [42]. Also in line with these findings, those with anxiety disorders in childhood or adolescence were more likely to report persistent and problematic cannabis use as young adults (compared to those without problematic cannabis use who did not experience anxiety disorders early in life) [49].

Studies also reported associations with specific types of anxiety, as well as potential mediators and moderators. Generalized and social anxiety were both associated with cannabis-related problems (but not use) [50–52], with social anxiety also being associated with more problem severity [53] and generalized anxiety associated with use frequency (as opposed to endorsement of any use) [50, 54]. Cannabis users were also more likely to endorse higher separation anxiety in adolescence compared to non-users [55]. Anxiety sensitivity was associated with cannabis-related problems [56] and more negative effects of cannabis [57]. Use of higher potency cannabis was associated with moderate elevations in the likelihood of meeting criteria for generalized anxiety disorder [58]. Gender moderated the relationship between problematic use with anxiety (stronger for females) [40]. Certain genotypes (i.e., short allele carriers vs. non-carriers) were also identified as moderators of the relationship between higher cannabis use and anxiety symptoms [59]. Finally, negative urgency (the tendency to act impulsively in the face of stress) mediated associations between cannabis use with generalized anxiety disorder, panic disorder, and social phobia [60].

Negative Association

Study Characteristics

Seven epidemiologic and population-based studies identified a negative association between anxiety levels and cannabis use. These studies were conducted in four countries: Belgium (4; 57.1%), France (1; 14.3%), Italy (1; 14.3%), and the United States of America (1; 14.3%). Notably, the studies occurring in Belgium were from the same research group and high school setting. Study settings included high schools, vocational schools, and university or college campuses. Cannabis use and/or problems were assessed via validated self-report questionnaires (6; 85.7%) or self-reported frequency of use (1; 14.3%). All seven studies used validated self-report questionnaires to assess anxiety.

Sample Characteristics

Sample sizes ranged from 130 to 5069, with females comprising 42.3–64.7% of the samples. No studies reported gender options beyond “male” and “female.” The samples were mostly adolescent, ranging from 14 to 19 years of age. Three studies (42.9%) did not present any racial or ethnic identity information about their samples, with three more studies only providing the percentages of the sample based on ethnicity (i.e., Hispanic/non-Hispanic; Belgian/Italian, Moroccan, Turkish, Other minorities).

Primary Outcomes

All seven studies reported a negative association between anxiety and cannabis use. Indeed, cannabis use in the last 30 days was associated with lower levels of overall anxiety symptoms compared to non-users [61] and lifetime cannabis use was associated with less social anxiety compared to non-users [62]. Specific types of anxiety were also noted with these negative associations. Namely, higher anxiety sensitivity was associated with decreased frequency of cannabis use [63]. Higher social anxiety was associated with non-use compared to moderate and risky cannabis use [64, 65] and was also associated with a reduced probability of cannabis initiation over time [66, 67]. Social anxiety was hypothesized as protective due to its association with more expectations of negative behavioral effects from the use of cannabis [65, 67].

Unclear or No Association

Study Characteristics

Seventeen epidemiologic and population-based studies did not identify significant evidence to associate anxiety and cannabis use. These studies were conducted in three countries: the United States of America (14; 82.4%), Canada (2; 11.8%), and the United Kingdom (1; 5.9%). Study settings included high schools, university or college campuses, community environment, urban/city environment, rural environment, and a residential military-style program for youth who have dropped out of high school. Cannabis use and/or problems were assessed via: validated self-report questionnaires (10; 58.8%), self-reported frequency of use (3; 41.2%), clinical interview (1; 5.9%), or a multi-method approach (validated self-report questionnaire with self reported use [1; 5.9%], with biometric data [1; 5.9%], or with a clinical interview [1; 5.9%]). Fifteen studies (88.2%) used validated self-report questionnaires to assess anxiety, and two studies used a clinical interview (11.8%).

Sample Characteristics

Sample sizes ranged from 56 to 6,550, with females comprising 0–79.7% of the samples. One study did not report sex and no studies reported gender options beyond “male” and “female.” While all studies had at least half of their samples composed of participants 25 years of age or under, the range of included ages spanned 11 to 29 years of age. Two studies (11.8%) did not present any racial or ethnic identity information about their samples, with two studies (11.8%) only providing the percentage of the sample that identified with one identity (e.g., “60% Caucasian;” “71.5% Non-minority ethnicity”). Four samples (23.5%) had a minoritized racial or ethnic population as the most represented group in their study.

Primary Outcomes

None of the 17 studies identified significant associations between anxiety and cannabis use. Specifically, anxiety and social anxiety were not significantly associated with use [68–78], use frequency [79–81], problems [69, 74, 82], or coping motives [69, 83]. Unclear findings also occurred, such as an association appearing in one model of a study, but losing significance as additional variables were added to later models [84]. Other factors were also identified that potentially are associated both with having anxiety and/or cannabis use, such as conduct problems [78], solitary cannabis use [82], having certain personality profiles (e.g., low social interaction anxiety with high urgency) [75], or being a female cannabis user [77].