Abstract
Objective:
To estimate the prevalence of past 12-month and lifetime cannabis use and cannabis use disorder among US veterans, describe demographic, substance use disorder, and psychiatric disorder correlates of non-medical cannabis use and cannabis use disorder, and explore differences in cannabis use and cannabis use disorder prevalence among veterans in states with and without medical marijuana laws.
Methods:
Participants were 3,119 respondents in the 2012–2013 National Epidemiologic Survey on Alcohol and Related Conditions-III (NESARC-III) who identified as US veterans. Weighted prevalences were calculated. Logistic regressions tested associations of non-medical cannabis use and cannabis use disorder with demographic and clinical correlates and examined whether prevalence differed by state legalization status.
Results:
The prevalence of any past 12-month cannabis use and cannabis use disorder was 7.3% and 1.8%, respectively. Lifetime prevalences were 32.5% and 5.7%, respectively. Past 12-month and lifetime cannabis use disorder prevalence estimates among non-medical cannabis users were 24.4% and 17.4%. Sociodemographic correlates of non-medical cannabis use and use disorder included younger age, male gender, being unmarried, lower income, and residing in a state with medical marijuana laws. Non-medical cannabis use and use disorder were associated with most psychiatric and substance use disorders examined.
Conclusions:
Among veterans, the odds of non-medical cannabis use and use disorder were increased among vulnerable subgroups, including those with lower income or psychiatric disorders and among participants in states with medical marijuana laws. Findings highlight the need for clinical attention (e.g., screening, assessment) and ongoing monitoring among veterans in the context of increasing legalization.
INTRODUCTION
The legal status of cannabis has changed dramatically in the United States (US). Although cannabis remains illegal at the federal level, 37 states and the District of Columbia have legalized cannabis for medical use, 17 states and the District of Columbia legalized adult recreational use (1), and adults are increasingly likely to perceive cannabis use as harmless (2). Concomitantly, the prevalence of adult non-medical cannabis use and cannabis use disorder has increased in general population and clinical samples (3–6).
Many conditions approved for medical cannabis use are common among veterans (e.g., posttraumatic stress disorder [PTSD]), and veteran groups have advocated for legalization (1, 7–9). However, little is known about the prevalence and correlates of cannabis use among US veterans. Studies of Veterans Health Administration (VHA) patients showed that 11%−14% used cannabis (10, 11). However, many US veterans do not utilize VHA care (12). Only one study examined cannabis use in a nationally representative sample that included veterans without regard to VHA enrollment (13), showing that 9% of veterans reported past-year cannabis use. Other studies examining trends, recreational versus medical cannabis use, or cannabis use disorder among veterans are older (4) or limited to particular subsamples (4, 13–15).
Given growing legalization and acceptability of cannabis use, nationally representative data are needed to understand cannabis use among veterans, including frequent use patterns (e.g., daily use) and cannabis use disorder, and to identify high-risk subgroups (3, 13, 16). In civilian samples, frequent cannabis use and cannabis use disorder are associated with other substance and psychiatric disorders, e.g., PTSD, anxiety and mood disorders (17–19) and may worsen their outcomes (20–22). Such disorders are overrepresented among veterans (23, 24). Additionally, since civilian studies show higher rates of adult cannabis use in states with legalized cannabis than in other states (16, 25–28), understanding the risk for cannabis use among veterans in states with and without medical marijuana laws is critical to understanding public health effects of legalization among veterans. Only one such study exists, a VHA medical record study suggesting that in 2009, ICD-9-CM cannabis use disorder was more common among veterans in VHA care in states with medical marijuana laws (4). More recent, representative information is needed.
Data from the 2012–2013 National Epidemiologic Survey on Alcohol and Related Conditions-III (NESARC-III) can be used to examine the prevalence and correlates of cannabis use and use disorder among US veterans prior to recreational cannabis sales (1), providing important baseline data for understanding veterans’ cannabis use and use disorder prior to the additional influence of recreational marijuana laws. NESARC-III data further afford the opportunity to examine an array of sociodemographic and psychiatric correlates of use, including DSM-5 psychiatric and substance use disorders. We analyzed NESARC-III data to address the following issues among veteran respondents: 1) the prevalence of past 12-month and lifetime cannabis use, frequent use and cannabis use disorder; 2) the demographic, substance use disorder, and psychiatric disorder correlates of these outcomes; and 3) differences in prevalence of cannabis use and cannabis use disorder between veterans in states with and without medical marijuana laws.
METHODS
Samples and procedures
The NESARC-III target population included US noninstitutionalized civilians, ≥18 years, in households and group quarters, including group homes and workers’ dormitories (29, 30). Respondents were selected using multistage probability sampling, including primary (counties/groups of contiguous counties), secondary (Census-defined blocks), and tertiary sampling units (households within secondary sampling units), with oversampling of Black, Asian, and Hispanic respondents. Interviews were conducted April 2012-June 2013. Data were adjusted for nonresponse and weighted to represent the US population (31). Weighting adjustments adequately compensated for nonresponse (30). All respondents gave informed consent and received $90.00 for participation. NIAAA and Westat Institutional Review Boards approved survey procedures. The overall response rate was 60.1%, comparable to other contemporaneous US national surveys (32, 33). The NESARC-III sample included 36,309 participants. The present study used data from the 3,119 respondents (8.6% of sample) who reported that they had ever served on active duty in the US Armed Forces, Military Reserves, or National Guard (excluding training only, including activation) and were no longer on active duty at time of data collection.
Assessments
Substance Use & Use Disorders
The Alcohol Use Disorder and Associated Disabilities Interview Schedule-5 (AUDADIS-5) was the assessment measure of conditions in the past 12-months and lifetime (ever) timeframes (34), which were not mutually exclusive. Non-medical cannabis use was defined as use without a prescription or other than prescribed (e.g., to get high) (16). Medical use was assessed by asking whether or not respondents had been prescribed or used “medical cannabis” ever and in the last 12-months (35). Any non-medical cannabis use was defined as ≥1 use within the last 12-months. Daily/near-daily non-medical use was defined as using 5–7 times per week on average over the past 12-months. Consistent with AUDADIS procedures, only those endorsing non-medical cannabis use were assessed for 12-month and lifetime cannabis use disorder, which required ≥ 2 of 11 criteria within the last 12 months. DSM-5 12-month and lifetime opioid (related to non-medical use of prescription opioids), alcohol, tobacco, and other drug use disorders were assessed and defined similarly. Test-retest reliability of 12-month and lifetime cannabis use was substantial (kappa=0.78, 0.77) in a general population sample (36). Test-retest reliabilities of cannabis use disorder (kappa=0.41, 0.41) and respective criteria scales (intraclass correlation coefficients [ICC]=0.70, 0.71) were fair to substantial in a sub-sample of NESARC-III participants (N=1006) (34). Procedural validity was assessed through blind clinician re-appraisal using the semi-structured, clinician-administered Psychiatric Research Interview for Substance and Mental Disorders, DSM-5 version (PRISM-5) (37) in a separate NESARC-III sub-sample (N=712). AUDADIS-5/PRISM-5 concordance was moderate for cannabis use disorder (kappa=0.60, 0.51) and substantial for its dimensional criteria scale (ICC=0.79, 0.78) (39). AUDADIS-5 and PRISM-5 concordance for alcohol and tobacco use disorders and corresponding criteria scales was fair to substantial (kappa=0.36–0.66; ICCs=0.68–0.91) (39).
DSM-5 psychiatric disorders assessed using the AUDADIS-5 included mood disorders (primary major depression, dysthymia, bipolar I and bipolar II disorders) and anxiety disorders (panic, agoraphobia, social and specific phobias, generalized anxiety disorder). Primary mood and anxiety diagnoses excluded substance- and medically-induced disorders. PTSD and schizotypal, borderline and antisocial personality disorders were also assessed. Test-retest reliability and validity of the diagnoses was fair to substantial (kappa=0.40–0.87) in the NESARC-III reliability sub-sample (38, 39).
Sociodemographic characteristics
Sociodemographic characteristics included sex, age, race/ethnicity, education, marital status, employment, family income, urbanicity, region, military service era, and residing in a state with medical marijuana laws by 2012. Medical marijuana law status was based on evaluations by legal and economic experts, as described elsewhere (40).
Statistical Analysis
Weighted prevalence estimates of non-medical and medical cannabis use and cannabis use disorder were calculated for the full veteran sample. Adjusted prevalence estimates and odds ratios (adjusted odds ratios) from multivariable logistic regressions were used to test the associations between sociodemographic characteristics and any non-medical cannabis use (i.e., with or without medical use) and cannabis use disorder, adjusting for all others. Similar logistic regressions were used to test associations between non-medical cannabis use and cannabis use disorder and each of the substance use and psychiatric disorders examined, adjusting for sociodemographic characteristics. Only 12 veterans reported medical cannabis use without non-medical use. Cannabis use disorder was not assessed in these participants, so the correlates of their cannabis use were not examined. Finally, logistic regression models run on the full veteran sample included state medical marijuana laws to examine whether any past 12-month non-medical, medical and non-medical, or non-medical only use or use disorder differed by state legalization status after adjusting for demographic covariates and were re-run after adjusting for additional state characteristics, including percent male, White, <30 years, and ≥25 years without a high school diploma. Analyses were performed using SUDAAN (41), which adjusts standard errors for complex survey design using Taylor series linearization. Odds ratios were considered statistically significant when 95% confidence intervals excluded 1.00.
RESULTS
Demographic characteristics; prevalence of cannabis use and cannabis use disorder
Veteran respondents were primarily White (79.5%), male (90.2%), ≥45 years (81.2%), and married or cohabitating (67.6%; Table 1). Many were retired, in school, or disabled (53.1%). Most resided in urban areas (75.0%); 29.6% resided in states with medical marijuana laws by 2012.
Table 1.
Sociodemographic characteristics of veteran respondents in the NESARC-III survey (n = 3,119)
| % | (SE)a | |
|---|---|---|
| Demographics | ||
| Sex | ||
| Male | 90.19 | (0.55) |
| Female | 9.81 | (0.55) |
| Age | ||
| 18–29 | 3.91 | (0.33) |
| 30–44 | 14.93 | (0.80) |
| 45–64 | 38.24 | (1.10) |
| ≥ 65 | 42.92 | (1.24) |
| Race/ethnicity | ||
| Black | 10.42 | (0.78) |
| Hispanic | 6.49 | (0.63) |
| White | 79.53 | (1.04) |
| Other | 3.55 | (0.45) |
| Education | ||
| < High school | 6.15 | (0.56) |
| High school | 25.78 | (0.93) |
| Some college or more | 68.07 | (0.99) |
| Marital status | ||
| Married or cohabiting | 67.62 | (0.92) |
| Widowed/separated/divorced | 24.98 | (0.80) |
| Never married | 7.40 | (0.46) |
| Employment | ||
| Employed full-time | 33.88 | (1.31) |
| Employed part-time | 8.24 | (0.56) |
| Unemployed | 4.81 | (0.39) |
| Other (e.g., retired, in school, disabled) | 53.07 | (1.43) |
| Family Income | ||
| $0-$19,999 | 16.02 | (0.72) |
| $20,000-$34,999 | 18.37 | (1.04) |
| $35,000-$69,999 | 32.10 | (1.10) |
| ≥ $70,000 | 33.50 | (1.24) |
| Urbanicity | ||
| Urban | 74.99 | (1.82) |
| Rural | 25.01 | (1.82) |
| Region | ||
| Northeast | 15.89 | (0.89) |
| Midwest | 22.69 | (0.98) |
| South | 40.21 | (1.81) |
| West | 21.20 | (1.50) |
| Service Era | ||
| WW2 or earlier 12/1946 or earlier |
5.02 | (0.53) |
| Korea and post-Korea 1/1947–2/1961 |
16.58 | (0.94) |
| Vietnam Era 3/1961–4/1975 |
33.05 | (1.12) |
| Post-Vietnam 5/1975—7/1990 |
18.15 | (0.80) |
| Gulf and post-Gulf 8/1990–8/2001 |
14.62 | (0.82) |
| Post 9/11 9/2001 –present |
12.60 | (0.77) |
| Lives in state with Medical marijuana laws by 2012 | 29.57 | (2.19) |
Based on weighted data. Percentages are rounded and may not total 100. At the time of NESARC-III data collection, Arizona, California, Colorado, Connecticut, Hawaii, Maine, Maryland, Massachusetts, Michigan, Montana, New Jersey, Nevada, New Mexico, Oregon, Vermont, and Washington had medical marijuana laws.
The prevalence of 12-month cannabis use and cannabis use disorder was 7.3% and 1.8%, respectively (Table 2). Lifetime use and cannabis use disorder prevalence was 32.5% and 5.7%, respectively. Among past 12-month users, 15.2% endorsed any medical use; 96.0% reported non-medical use. Among past 12-month users, 84.9% endorsed non-medical use only, 3.9% endorsed medical use only, and 11.2% endorsed both medical and non-medical use. The prevalence of 12-month cannabis use disorder among past 12-month users was 24.4%. Among those endorsing lifetime use, nearly all veterans endorsed non-medical use only (95.5%).
Table 2.
Prevalence of past 12-month and lifetime cannabis use and DSM-5 cannabis use disorder in U.S. veterans in NESARC-III sample (N=3,119)
| Cannabis Use | % | (SE)a |
|---|---|---|
| Past 12-month | ||
| Any use (n=272) | 7.26 | (0.54) |
| Cannabis use disorder (n=60) | 1.77 | (0.29) |
| Among past 12-month users | ||
| Any medical use | 15.15 | (2.55) |
| Any non-medical use | 96.04 | (1.22) |
| Both medical and non-medical use | 11.20 | (2.10) |
| Medical use only | 3.96 | (1.22) |
| Non-medical use only | 84.85 | (2.55) |
| Daily/near daily non-medical use | 24.68 | (3.12) |
| Cannabis use disorder | 24.38 | (3.48) |
| Lifetime | ||
| Any use (n=1,102) | 32.46 | (1.12) |
| Cannabis use disorder (n=191) | 5.69 | (0.51) |
| Among lifetime users | ||
| Any medical use | 4.54 | (0.87) |
| Any non-medical use | 99.44 | (0.17) |
| Both medical and non-medical use | 3.98 | (0.85) |
| Medical use only | 0.56 | (0.17) |
| Non-medical use only | 95.46 | (0.87) |
| Daily/near daily non-medical use | 30.36 | (1.62) |
| Cannabis use disorder | 17.42 | (1.43) |
SE = standard error; DSM = Diagnostic and Statistical Manual of Mental Disorders
Based on weighted data. Percentages are rounded and may not total 10.
Correlates of non-medical cannabis use and cannabis use disorder, past 12-months
Table 3 shows the prevalence of 12-month non-medical cannabis use and cannabis use disorder by sociodemographic characteristics and adjusted odds ratios indicating associations between each characteristic and cannabis use and use disorder. Men had higher odds of cannabis use than women (adjusted odds ratio=2.2, 95%CI=1.2–3.9) as did those aged 18–29 (adjusted odds ratio=9.0, 95%CI=4.1–19.9), 30–34 (adjusted odds ratio=8.8, 95%CI=4.7–16.3), and 45–64 (adjusted odds ratio=4.9. 95%CI=3.0–8.2) compared to those ≥65 years. Compared with married veterans, those widowed or separated (adjusted odds ratio=2.3, 95%CI=1.5–3.4) or not married (adjusted odds ratio=2.7, 95%CI=1.7–4.3) had higher odds of cannabis use. Compared to those earning ≥$70,000, those earning ≤$19,999 and $20,000-$34,999 had higher odds of cannabis use (adjusted odds ratios=2.4, 95%CI=1.3–4.4; 1.8, 95%CI=1.0–3.3 respectively). Similarly, men had higher odds of cannabis use disorder than women (adjusted odds ratio=10.6, 95%CI=2.7–42.1). Those aged 30–34 (adjusted odds ratio=2.8, 95%CI=1.3–6.0) had greater odds of cannabis use disorder than those 45–64; prevalence among those ≥65 was too sparse for comparison. Compared to married veterans, widowed or separated veterans had greater odds of cannabis use disorder (adjusted odds ratio=2.8, 95%CI=1.5–5.0), as did those earning ≤$19,999 compared to those earning ≥$70,000 (adjusted odds ratio=5.0, 95% CI=1.4–18.2).
Table 3.
Prevalence and adjusted odds ratios of past 12-month non-medical cannabis use and past 12-month cannabis use disorder: Relationship to demographic characteristics
| Past 12-month Non-Medical Cannabis Use | Past 12-month DSM-5 Cannabis Use Disorder | |||||||
|---|---|---|---|---|---|---|---|---|
| Characteristic | %a | (SE) | Adjusted odds ratiob | 95% CI | %a | (SE) | Adjusted odds ratiob | 95% CI |
| Sex | ||||||||
| Male | 7.15 | (0.55) | 2.18 | 1.21, 3.93 | 1.93 | (0.32) | 10.63 | 2.69, 42.06 |
| Female | 5.33 | (1.24) | Reference | 0.33 | (0.20) | Reference | ||
| Age | ||||||||
| 18–29 | 17.96 | (3.50) | 9.02 | 4.08, 19.92 | 5.32 | (2.42) | 2.94 | 0.83, 10.37 |
| 30–44 | 12.05 | (1.55) | 8.77 | 4.73, 16.27 | 3.82 | (0.94) | 2.79 | 1.29, 6.00 |
| 45–64 | 9.18 | (0.87) | 4.94 | 2.96, 8.23 | 2.36 | (0.57) | Reference | |
| ≥ 65 | 2.23 | (0.49) | Reference | 0.21 | (0.15) | --- | ||
| Race/ethnicity | ||||||||
| Black | 12.58 | (2.24) | 1.43 | 0.93, 2.19 | 3.69 | (1.43) | 1.39 | 0.62, 3.13 |
| Hispanic | 8.89 | (1.77) | 0.99 | 0.58, 1.67 | 2.60 | (1.12) | 1.00 | 0.36, 2.77 |
| Other | 11.32 | (2.61) | 1.25 | 0.64, 2.44 | 3.94 | (1.60) | 1.72 | 0.64, 4.62 |
| White | 5.88 | (0.54) | Reference | 1.35 | (0.28) | Reference | ||
| Education | ||||||||
| < High school | 4.00 | (1.44) | 0.68 | 0.29, 1.60 | 1.19 | (1.06) | 1.02 | 0.13, 7.82 |
| High school | 9.05 | (1.20) | 1.27 | 0.88, 1.85 | 2.78 | (0.75) | 1.57 | 0.80, 3.10 |
| Some college | 6.45 | (0.55) | Reference | 1.44 | (0.27) | Reference | ||
| Marital status | ||||||||
| Married | 4.25 | (0.57) | Reference | 0.94 | (0.25) | Reference | ||
| Widowed/separated | 10.72 | (1.17) | 2.26 | 1.50, 3.41 | 3.29 | (0.78) | 2.75 | 1.51, 5.02 |
| Not married | 19.14 | (2.19) | 2.70 | 1.69, 4.31 | 4.23 | (1.33) | 1.79 | 0.67, 4.79 |
| Employment | ||||||||
| Employed full-time | 6.99 | (0.79) | Reference | 1.91 | (0.44) | Reference | ||
| Employed part-time | 10.22 | (1.88) | 1.62 | 0.86, 3.05 | 1.05 | (0.46) | 0.51 | 0.17, 1.58 |
| Unemployed | 13.49 | (3.18) | 1.17 | 0.67, 2.03 | 2.67 | (1.10) | 0.65 | 0.27, 1.59 |
| Other (e.g., retired, in school, disabled) | 5.86 | (0.73) | 1.54 | 0.97, 2.45 | 1.71 | (0.44) | 1.86 | 0.81, 4.28 |
| Income | ||||||||
| $0-$19,999 | 13.79 | (1.85) | 2.35 | 1.26, 4.38 | 4.09 | (1.08) | 5.00 | 1.37, 18.21 |
| $20,000-$34,999 | 8.68 | (1.52) | 1.82 | 1.02, 3.26 | 2.16 | (0.79) | 3.27 | 0.85, 12.56 |
| $35,000-$69,999 | 5.99 | (0.72) | 1.34 | 0.78, 2.28 | 1.70 | (0.44) | 2.70 | 0.73, 9.92 |
| ≥ $70,000 | 3.72 | (0.68) | Reference | 0.51 | (0.28) | Reference | ||
| Urbanicity | ||||||||
| Urban | 6.67 | (0.54) | 0.70 | 0.47, 1.04 | 1.87 | (0.33) | 1.16 | 0.54, 2.51 |
| Rural | 7.86 | (1.25) | Reference | 1.46 | (0.51) | Reference | ||
| Region | ||||||||
| Northeast | 7.83 | (1.34) | 0.59 | 0.34, 1.04 | 2.65 | (1.13) | 1.33 | 0.53, 3.32 |
| Midwest | 5.34 | (0.78) | 0.36 | 0.22, 0.59 | 1.65 | (0.44) | 0.71 | 0.34, 1.50 |
| South | 4.93 | (0.66) | 0.30 | 0.18, 0.51 | 1.15 | (0.36) | 0.40 | 0.18, 0.89 |
| West | 11.94 | (1.79) | Reference | 2.41 | (0.58) | Reference | ||
SE = standard error; DSM = Diagnostic and Statistical Manual of Mental Disorders; CI = confidence interval.
Based on weighted data.
Odds ratios adjusted for sex, age, race/ethnicity, education, marital status, employment status, family income, and urbanicity.
indicates that OR not estimable due to low prevalence of outcome in reference group.
Table 4 shows the prevalence of 12-month non-medical cannabis use and cannabis use disorder by psychiatric and other substance other disorders and adjusted odds ratios indicating associations between these disorders and cannabis use and use disorder. All substance and psychiatric disorders were associated with cannabis use (adjusted odds ratios=2.0–12.6) except for 12-month PTSD. All substance use and psychiatric disorders were associated with cannabis use disorder (adjusted odds ratios=2.1–5.9) except for past 12-month PTSD, opioid use disorder, and other drug use disorders.
Table 4.
Prevalence and adjusted odds ratios of past 12-month non-medical cannabis use and past 12-month cannabis use disorder: Relationship to past 12-month psychiatric and other substance use disorders
| Past 12-month Non-Medical Cannabis Use | Past 12-month Cannabis Use Disorder | |||||||
|---|---|---|---|---|---|---|---|---|
| Disorder, past 12-months | % a | (SE) | Adjusted odds ratio b | 95% CI | % a | (SE) | Adjusted odds ratio b | 95% CI |
| Alcohol use disorder | ||||||||
| Yes | 22.80 | (2.38) | 3.37 | 2.37, 4.78 | 8.95 | (1.82) | 5.87 | 3.33, 10.34 |
| No | 5.03 | (0.47) | Reference | 0.89 | (0.19) | Reference | ||
| Opioid use disorderc | ||||||||
| Yes | 30.63 | (10.29) | 4.73 | 2.02, 11.06 | 8.05 | (6.40) | 2.85 | 0.58,14.03 |
| No | 6.79 | (0.52) | Reference | 1.72 | (0.28) | Reference | ||
| Drug Use Disorderd, | ||||||||
| Yes | 57.18 | (10.51) | 12.64 | 4.44, 35.94 | 8.21 | (5.04) | 2.57 | 0.63,10.51 |
| No | 6.66 | (0.51) | Reference | 1.73 | (0.29) | Reference | ||
| Tobacco use disorder, | ||||||||
| Yes | 15.15 | (1.43) | 2.01 | 1.39, 2.90 | 4.69 | (0.89) | 2.09 | 1.12, 3.93 |
| No | 4.84 | (0.56) | Reference | 1.01 | (0.24) | Reference | ||
| Any mood disorder, | ||||||||
| Yes | 21.10 | (3.03) | 2.90 | 1.88, 4.48 | 8.04 | (2.01) | 4.37 | 2.16, 8.82 |
| No | 5.40 | (0.47) | Reference | 1.07 | (0.22) | Reference | ||
| Any anxiety disorder, | ||||||||
| Yes | 15.57 | (2.43) | 2.27 | 1.54, 3.34 | 5.32 | (1.54) | 2.99 | 1.52, 5.90 |
| No | 6.00 | (0.46) | Reference | 1.37 | (0.25) | Reference | ||
| PTSD | ||||||||
| Yes | 16.70 | (3.93) | 1.66 | 0.94, 2.94 | 5.89 | (2.62) | 2.05 | 0.80, 5.27 |
| No | 6.37 | (0.51) | Reference | 1.52 | (0.25) | Reference | ||
SE = standard error; DSM = Diagnostic and Statistical Manual of Mental Disorders; CI = confidence interval.
Based on weighted data.
Odds ratios adjusted for sex, age, race/ethnicity, education, marital status, employment status, family income, and urbanicity.
Related to non-medical use of prescription opioids.
Excluding cannabis use disorder and opioid use disorder.
Correlates of non-medical cannabis use and cannabis use disorder, lifetime
Associations between lifetime cannabis use and cannabis use disorder and sociodemographic correlates were similar to 12-month associations (Supplemental Table 1). The only difference was related to income: all lower income levels had higher odds of lifetime use disorder than those earning ≥$70,000 (adjusted odds ratios, 2.10–2.51).
Associations with lifetime non-medical cannabis use and cannabis use disorder and substance use and other psychiatric disorders were also similar to 12-month findings, though associations with PTSD and opioid use disorder varied slightly (Supplemental Table 2). Lifetime cannabis use was associated with all substance use disorders and psychiatric disorders examined, including PTSD (adjusted odds ratios=1.45–8.96). Lifetime cannabis use disorder was associated with all disorders examined, including lifetime PTSD and opioid use disorder (adjusted odds ratios=2.82–7.58).
Past 12-month cannabis use and cannabis use disorder by state medical marijuana law status
In states with legalized medical marijuana, the prevalence and odds of any cannabis use, daily/near daily use, non-medical use, medical use, medical and non-medical use, and use disorder were significantly higher than in other states (adjusted odds ratios=1.63–4.39, Table 5).
Table 5.
Cannabis use and cannabis use disorder, last 12-months, among veterans, by state medical marijuana law status as of 2012
| No medical marijuana law by 2012 (n=2,164 ) |
Medical marijuana law by 2012 (n=955) |
Adjusted odds ratiob | 95% CI | Adjusted odds ratioc | 95% CI | |||
|---|---|---|---|---|---|---|---|---|
| Cannabis Variable, past 12-months | %a | (SE)a | % a | (SE)a | ||||
| Any non-medical use (n=260) | 5.51 | (0.52) | 10.44 | (1.35) | 2.41 | 1.64, 3.55 | 1.91 | 1.33, 2.75 |
| Medical and nonmedical use (n=272) | 5.51 | (0.52) | 11.41 | (1.42) | 2.67 | 1.83, 3.92 | 2.09 | 1.45, 2.99 |
| Non-medical use only (n=227) | 5.31 | (0.51) | 8.17 | (1.05) | 1.80 | 1.27, 2.56 | 1.63 | 1.10, 2.42 |
| Daily/near-daily, non-medical use (n=73) | 0.99 | (0.22) | 3.47 | (0.62) | 4.39 | 2.24, 8.59 | 3.08 | 1.47, 6.44 |
| DSM-5 Cannabis use disorder (n=60) | 1.39 | (0.32) | 2.66 | (0.58) | 2.37 | 1.29, 4.38 | 2.68 | 1.09, 6.60 |
SE = standard error; DSM = Diagnostic and Statistical Manual of Mental Disorders; CI = confidence interval.
Based on weighted data. Percentages are rounded and may not total 100
Odds ratios adjusted for sex, age, race/ethnicity, education, marital status, employment status, family income, and urbanicity.
Additionally adjusted for state level variables including % male, % white, % younger than 30 years, and % 25 years and older without a high school diploma.
Note. Medical use was assessed by asking whether or not respondents had been prescribed or used “medical cannabis” ever and in the last 12-months and could have been endorsed by veterans residing in states with or without medical marijuana laws.
DISCUSSION
Among veteran respondents in the NESARC-III survey, over 7% had used cannabis in the prior 12 months, and 1.8% met criteria for cannabis use disorder. Corresponding lifetime prevalence estimates were 32.5% and 5.7%, respectively. Approximately 1 in 4 (24.4%) who used non-medical cannabis in the past 12 months met criteria for 12-month cannabis use disorder, and more than 1 in 6 (17.4%) who reported lifetime non-medical use met criteria for lifetime cannabis use disorder. Sociodemographic correlates of non-medical use and cannabis use disorder included being younger, male, unmarried, and low income. Cannabis use and cannabis use disorder were associated with most psychiatric and substance use disorders examined. Finally, veterans in states with legalized medical cannabis were more likely than others to use cannabis non-medically and to have cannabis use disorder.
Two prior studies addressing cannabis use or cannabis use disorder among veterans in VHA care with mental health needs (10, 11) reported higher prevalence of cannabis use than the present study, perhaps due to the association of cannabis use with psychiatric disorders (10, 11). A study utilizing 2009 VHA-wide electronic medical record data (4) found a prevalence of past-year cannabis use disorder among VHA enrolled veterans ~70% lower than our findings using 2012–2013 NESARC-III data. This may reflect national increases in cannabis use disorder (3), or that VHA providers do not routinely assess cannabis use disorder, underestimating prevalence in the medical record. Veterans in VHA care tend to be of lower socioeconomic status, a risk factor for cannabis use disorder, and many are diagnosed with substance use and psychiatric disorders, characteristics associated with non-medical cannabis use and use disorder in the present study and previous research (17, 42–46). Given VHA patient characteristics and national increases in cannabis use disorder (3, 6), cannabis use and use disorders may be more common in VHA patients now than in 2009. Because the VHA serves approximately 6 million veterans a year (47), understanding VHA clinical and treatment needs related to cannabis use is of considerable national importance. Therefore, updated, comprehensive studies of cannabis use and use disorder prevalence in VHA patients are warranted.
In the only other study of cannabis use among veterans in a nationally representative survey (13), the prevalence of 12-month cannabis use in 2014 was slightly higher (9%) than in our study (7.3%). Interviewer administration of the NESARC-III surveys may have contributed to lower rates compared to the other self-administered survey. However, the previous study did not examine lifetime prevalence or DSM-5 substance use and psychiatric disorders, all of which are important in understanding the distribution of cannabis use among US veterans. Results from the present study are more easily compared to findings from the full NESARC-III sample, in which the prevalence of cannabis use and use disorder was also higher (16) than in our veteran subsample. Study findings provide an important benchmark of veteran status relative to their non-veteran counterparts prior to implementation of recreational marijuana laws. Whether such trends continue with increasing legalization will be an important focus for future study.
Identified demographic correlates of cannabis use and cannabis use disorder were similar to previous veteran and civilian studies (13, 17), as were associations between substance use and other psychiatric disorders and cannabis use and use disorder (13, 17, 19, 42). Importantly, our study extends earlier findings by examining DSM-5 diagnoses. Taken together, these findings add to evidence suggesting that certain individuals are consistently at increased risk for cannabis use and use disorder, while highlighting that veterans share risk factors with the general population. The demographic composition of the veteran population (i.e., predominantly male, bimodal age distribution including older veterans from earlier wars and younger veterans of recent conflicts) (48), and findings indicating that veterans experience disproportionately high levels of substance use and psychiatric disorders (46, 49) underscore the need for careful screening, assessment, and treatment of cannabis use disorder in clinical settings serving veterans, as well as on-going monitoring of cannabis use and related functional and symptom outcomes. Screening may be particularly important among veterans with substance use and psychiatric disorders, such as PTSD, as cannabis use during treatment of these disorders is associated with worse outcomes (21, 22).
PTSD is a condition of high relevance to veterans, with 9–13% of veterans meeting current criteria (23, 50). In this study, lifetime cannabis use and lifetime use disorder were significantly associated with lifetime PTSD. While past 12-month cannabis use and use disorder were not significantly associated with PTSD in a sociodemographically-adjusted model, associations were in the same direction, with near-significant confidence intervals. Among 2001–2002 NESARC survey respondents, lifetime PTSD was significantly associated with cannabis use disorder and marginally associated with lifetime cannabis use (51). In the full NESARC-III sample, PTSD was significantly associated with past 12-month and lifetime cannabis use disorder (17). Among veterans with cannabis use disorder enrolled in the VHA, PTSD is the most common psychiatric comorbidity (4). Together, these findings show a relationship between PTSD and cannabis use as well as cannabis use disorder, with more consistent associations with cannabis use disorder. Despite a lack of evidence that plant cannabis is an effective treatment for PTSD, 25 of 37 states with medical marijuana laws include PTSD as an approved condition for medical use (1, 8, 20), and a study of post-9/11 veterans showed that PTSD was one of the leading reasons for seeking medical cannabis (14). Given the relevance of PTSD to veterans, future efforts are needed to increase our understanding of the relationship between PTSD, cannabis use and use disorder, including the sequence of their occurrence and whether the association between PTSD and use differs by reasons for use (e.g., medical-only vs. medical and recreational), which was not examined in this cross-sectional study.
The current US opioid crisis has also focused attention on the role of cannabis in increasing or decreasing opioid use and adverse outcomes (40, 52). Our findings suggest veterans engaging in non-medical cannabis use have increased odds of opioid use disorder, findings that are consistent with a large study of non-veterans showing that cannabis use predicted higher risk of non-medical opioid use and use disorder among those with moderate to severe pain than among those without pain (52). Taken together, these studies add to evidence that advocating cannabis legalization to remediate the opioid crisis is premature.
Similar to past civilian and veteran studies (4, 16, 25, 28), we found higher odds of cannabis use and use disorder in states with medical marijuana laws, including odds of daily/near-daily cannabis use almost five times higher. Because frequent use increases risk for negative consequences (e.g., cannabis use disorder, respiratory symptoms, intoxication-related injury, psychotic symptoms) (16, 17, 53–55), this finding is of particular concern. Further, at the time of NESARC-III data collection, 17 states had medical marijuana laws, but none had enacted recreational marijuana laws. Presently, 17 states and the District of Columbia (all previously had medical marijuana laws) have recreational laws. Because recreational laws further increase adult non-medical cannabis use, frequent use and cannabis use disorders (27), continued study of how cannabis use and cannabis use disorder prevalence change among veterans as legalization expands will be important, as will efforts to examine other conditions potentially affected by marijuana laws, e.g., opioid and psychiatric medication use. Overall, results highlight the importance of careful clinical screening, assessment and monitoring of veterans as additional states pass permissive marijuana laws and continued consideration of policies guiding veterans and providers, particularly within the VHA, a federal system that currently defines cannabis as a Schedule I controlled substance.
Limitations are noted. NESARC-III relied on self-report, which is subject to bias. Data were cross-sectional; thus, causality cannot be determined. Assessment of medical cannabis use relied on a single question, did not differentiate between use recommended by a physician or for self-determined reasons, and thus may have been interpreted differently in states with and without medical marijuana laws. Cannabis use disorder was not assessed among those reporting medical use only, but should be in future surveys. AUDADIS-5 interviewers were not clinicians, though a validation sub-study utilizing clinicians revealed nearly identical past year prevalence (38). The relationship of study findings to veterans treated in the VHA is unknown, as NESARC-III did not assess whether respondents were receiving VHA care. Additionally, in this large, exploratory study, corrections for multiple testing were not made due to the paucity of data examining prevalence and correlates of cannabis use and use disorder among veterans. Finally, findings may underestimate cannabis use among veterans overall if many were excluded from the survey due to incarceration (56), institutionalization or homelessness.
In summary, our findings provide important information to inform future studies of veterans and may help guide clinical services. A clear risk for cannabis use disorder was evident among veterans reporting non-medical cannabis use, with up to 37% meeting criteria for a cannabis use disorder in their lifetime. The odds of use and cannabis use disorder were also higher among vulnerable veteran subgroups, including those of lower socioeconomic status and those with psychiatric and substance use disorders. Our results indicate that the odds of use, daily/near daily use, and disordered use are even higher among veterans in states with medical marijuana laws. Such findings highlight the importance of continued research examining the impact of changing marijuana laws on our nation’s veterans. These findings are also important to communicate to policy makers, healthcare professionals who may need to consider cannabis screening and intervention services when caring for veterans, and to veterans themselves so they can be well-informed about potential risks and benefits of cannabis use.
Supplementary Material
Acknowledgments:
R01DA048860, New York State Psychiatric Institute; Manuscript preparation is the result of work supported by resources from the VA Centers of Excellence in Substance Addiction Treatment and Education. Dr. Bohnert was supported by a VA Health Services Research and Development Investigator-Initiated Research Award (IIR 15–348).
Footnotes
Disclosures: Hasin receives support from Syneos Health for an unrelated project on measurement of opioid addiction in pain patients. Saxon received consulting fees from Indivior, Inc., travel support from Alkermes, Inc., research support from Medicasafe, Inc., and royalties from UpToDate, Inc.
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