Chronic Pain and Cannabis Use Frequency, Intensity, and Severity in Young Adults

Abstract

Introduction:

Cannabis use is common among young adults and is associated with many physical and mental health problems. Persons with chronic pain may be particularly susceptible to using cannabis at high rates, including for analgesic purposes, thus exposing themselves to greater risk of cannabis-related problems. However, little research has examined connections between chronic pain and cannabis use in the young adult population.

Materials and Methods:

Participants were young adults from the community who were recruited for a larger health behaviors study. The present sample included 403 persons from this larger sample who reported cannabis use in the past 90 days. Participants completed measures of demographic characteristics, cannabis and alcohol use, and chronic pain.

Results:

This young adult sample reported using cannabis on an average of 47.1 of the past 90 days, and 20.1% reported chronic pain. Chronic pain was associated with greater cannabis use frequency (IRR = 1.35, 95%CI 1.15; 1.57, p < .001), intensity (IRR = 1.61, 95%CI 1.18; 2.21, p = .003), and negative consequences (IRR = 1.23, 95%CI 1.02; 1.48, p < .030).

Discussion:

In this sample of young adults who use cannabis, chronic pain was significantly associated with frequent, intense cannabis use, as well as more cannabis-related negative consequences. These findings suggest that chronic pain may be a marker for a particularly high-risk pattern of cannabis use in this age group, thus identifying an especially vulnerable subset of young adults who may require heightened research and clinical attention.

Introduction

Cannabis is one of the most commonly used illicit substances among people aged 18–25 years, and the proportion of past-year users is significantly higher in this age group (35.4%) compared to adults aged 26 years or older (17.2%) or adolescents aged 12 to 17 years (10.5%; Substance Abuse and Mental Health Services Administration [SAMHSA], 2022). Cannabis use among young adults has also increased over time, with past-year rates increasing from 29.8% in 2002 to a historic high of 43% in 2021 (National Institute on Drug Abuse [NIDA], 2022). Cannabis use is associated with a variety of negative consequences among young adults, such as medical illness, psychiatric symptoms, injury, and emotional, academic, and social problems (Bechtold et al., 2015; Pearson, 2019; Suerken et al., 2016).

Young persons may be especially vulnerable to the negative consequences of cannabis use due to their unique, sensitive stage of neuroplasticity and developmental tendency toward impulsive decision-making (Schneider, 2008; Sun et al., 2020). Compared to older adults and adolescents, young adults demonstrate higher rates of cannabis use disorder and are less likely to perceive risk of harm from weekly cannabis smoking (SAMHSA, 2022) despite the documented negative physical and mental health effects of cannabis use. In addition, with the legalization of both medical (Cerdá et al., 2012; Chiu et al., 2021) and non-medical adult cannabis use (Chiu et al., 2021; Gunadi et al., 2022), the overall the perception that cannabis is harmful has decreased among adolescents and young adults over time (Yu et al., 2020). According to the health belief model (Janz & Becker, 1984; Sarvet et al., 2018), such risk perception is an important proximal antecedent of behavior because it directly influences the likelihood of engaging in that behavior. Indeed, research demonstrates an inverse association between perceived risk of cannabis use and rates of use among young adults (Rosenstock et al., 1988).

Young persons who use both cannabis and alcohol may face heightened risks. Alcohol remains the most commonly used substance among young adults, with over 50% of persons aged 18 to 25 years endorsing past month use in 2020 (SAMHSA, 2022). Almost a third (31.4%) of young adults report past month binge drinking, and these rates are higher than those for older adults (22.9%) or adolescents (4.1%; SAMHSA, 2022). Binge drinking is associated with numerous negative consequences for all persons, but particularly for adolescents and young adults due to the impact of alcohol consumption on neurodegeneration at a time of critical brain development (El Marroun et al., 2021). Co-use of alcohol and cannabis among young adults increased annually between 2002 and 2018 (McCabe et al., 2021). Such co-use is known to heighten the risk of negative consequences in young adulthood (Wade et al., 2020), particularly when the co-use is simultaneous (Lee et al., 2022).

Chronic pain may also pose heightened risk of problematic cannabis use in this age group. Chronic pain is a challenging, sometimes debilitating condition associated with poor daily functioning (Hanauer et al., 2021), low quality of life (Dueñas et al., 2020), interference with social and occupational functioning (Jonsdottir et al., 2014), and many mental health problems, including depressed mood (Ruelman et al., 2010; Voon et al., 2021), anxiety (Pitcher et al., 2019), posttraumatic stress (Outcalt et al., 2015), and poor psychological well-being (Topcu, 2018). Much of the research on chronic pain has focused on older adults and children (often with particular medical conditions), but evidence indicates that young adults also report chronic pain (Rosenbloom et al., 2017; Zelaya et al., 2020).

Due to its analgesic properties, cannabis is often used for pain management (Kosiba et al., 2019; Park & Wu, 2017) and is generally considered an effective augment or alternative to opioids (Kvamme et al., 2021; Yanes et al., 2019). However, to the degree that cannabis is a drug of abuse, extended use can create use-related problems (Martel et al., 2018). Indeed, chronic pain is known to be comorbid with problems associated with the use of several substances, including cannabis (Hasin et al., 2020; Richardson et al., 2012; Zvolensky et al., 2011). Among adults of all age groups with pain, nonmedical cannabis use has both grown and been associated with negative clinical outcomes (Kosiba et al., 2019). Some (Fales et al., 2019; Zvolensky et al., 2011), but not all (Fennell et al., 2022), reports suggest greater cannabis use specifically among young adults with chronic pain. Some past studies have also shown greater problematic cannabis use among young adults with pain compared to older adults (Haug et al., 2017), but others have failed to document associated heightened negative consequences in this age group (Fales et al., 2019; Fennell et al., 2022). In general, however, data on chronic pain and cannabis use among young adults are limited (Rosenbloom et al., 2017).

The purpose of this study was to examine the association between chronic pain and cannabis use and its consequences in a sample of young adults, while controlling for binge drinking, a known covariate in this age group. Given high overall rates of cannabis and decreasing cannabis risk perception over time among young adults, as well as the known association between chronic pain and problematic cannabis use in other age groups, we expected that young adults with chronic pain would be especially likely to (1) engage in high levels of cannabis use and (2) report negative consequences from its use.

Materials and Methods

Participant Recruitment

Participants were young adults recruited between January 2012 and March 2015 from Southern New England CraigsList.org and Facebook, as well as advertisements in public transportation, college newspapers, and commercial radio for a larger health behaviors study regarding substance use and sexual risk-taking (Stein et al., 2018). Possibly interested persons underwent a 10-minute anonymous screening over the telephone. Screening included basic demographics, substance use, sexual activity, and mental and physical health. Eligible individuals underwent an in-person interview at the research site, were remunerated $40, and were offered free sexually transmitted infection testing.

Eligibility criteria for the parent study included age between 18 and 25 years, current cannabis and/or alcohol use at least once in the last 30 days, the presence of at least one heterosexual sexual partner in the last six months, living within 30 minutes of the research site, and having no suicidal ideation in the past two weeks. Of the 2,645 persons screened, 1,217 were deemed ineligible. Ineligibility was most commonly due to the absence of active heterosexual activity (235), recent suicidal ideation (234), age outside the required range (148), or geographical distance from the study site (53). The remaining 1,428 eligible persons were invited for an interview, of whom 834 did not complete interviews (130 actively refused, 202 passively refused by not calling back to schedule their appointment, and 502 did not keep their scheduled appointment).

Written informed consent was obtained from the remaining 594 persons, with 23 persons later found to be ineligible and 13 withdrawing their participation. Additionally, 44 individuals were subsequently found not to have used cannabis or alcohol in the past 30 days and were therefore excluded from the parent study. The present analysis was further limited to the 403 persons in this remaining sample of 514 who reported any cannabis use in the past 90 days. No prior papers regarding pain have been written from these data.

All study procedures were approved by the Institutional Review Board at Rhode Island Hospital in Providence, RI.

Measures

Demographics.

Participants self-reported age, gender identity, race, and ethnicity (whether or not they identified as Latinx).

Cannabis use.

The Timeline Follow-back (TLFB; Sobell & Sobell, 1992) was used to assess cannabis use in the 90 days prior to the interview. The TLFB is a widely used, calendar-based measure of substance use that has demonstrated reliability and validity in past research (e.g., Fals-Stewart et al., 2000; Sobell et al., 1988), including in studies of cannabis use (e.g., Hjorthøj et al., 2012). In the present study, cannabis use frequency was defined as the number of days the participant reported using cannabis in the time period assessed; cannabis use intensity was defined as the total number of use occasions (days of use multiplied by the number of times using per day). Cannabis use severity was assessed using the Marijuana Problems Scale (MPS; Stephens et al., 2000). The MPS assesses 19 negative consequences of cannabis use (including social, occupational, physical and psychological problems such as “problems in your family,” “to miss days at work or miss classes,” and “lowered self-esteem”) on a scale from 0 (no problem) to 2 (serious problem). The total severity score is the sum of all item scores and ranges from 0 to 38. The MPS has demonstrated good internal reliability and clinical utility in past research (Stephens et al., 2000, 2004).

Alcohol use.

The TLFB (Sobell & Sobell, 1992) was used to assess alcohol use in the 90 days prior to the interview. Alcohol use days and days of binge drinking were calculated, the latter using the standard threshold of 4 drinks per drinking occasion for women and 5 drinks per drinking occasion for men (National Institute on Alcohol Abuse and Alcoholism, n.d.).

Chronic pain.

Pain was measured using an adaptation of the 12-item Short-Form Health Survey (SF-12; Ware et al., 1996). The SF-12 is a commonly used measure of health status that assesses eight main domains, of which bodily pain is one. Bodily pain is assessed with a single item; in this study, only this item was used in analyses. On this item, participants reported the degree to which pain “[interfered] with [their] normal work (including work outside the home and housework)” on a scale ranging from 1 (not at all) to 5 (extremely). Those who endorsed at least a 2 (a little bit of pain) were then administered a follow-up item developed for the purpose of this study on which they estimated the duration of the pain in weeks. Based on the SF-12 bodily pain question and the additional item assessing pain duration, chronic pain was defined dichotomously as the presence of at least “a little bit” of pain for at least 12 weeks. The minimum duration of pain is consistent with the 3-month threshold established by the World Health Organization (WHO, n.d.) and has been used in prior research (e.g., Outcalt et al., 2015; Pitcher et al., 2019). This standard duration, combined with having at least some pain, was used in this study in order to capture the experience of all persons who experienced any persistent or recurrent pain.

Analytical Methods

All analyses were conducted using Stata Statistical Software (StatCorp, 2021). We present descriptive statistics to summarize the demographic characteristics and substance use behaviors of the sample. The primary outcomes are either count variables (days of cannabis use and total times using cannabis) or are 0-limited and positively skewed (cannabis problem severity). Therefore, we used a generalized linear regression model with log link, Poisson family error distribution, and robust standard errors to estimate the adjusted association of chronic pain with each outcome. Control variables were age, gender, race (White, Black, Other), Latinx (yes), and frequency of binge drinking. We present the exponentiated (incidence rate ratios) coefficients, 95% confidence interval estimates, and tests of significance. To enhance interpretability, we also report the estimated average marginal effect (between group differences in expected means). For days of cannabis use, we express this as the difference in 30-day rates of use, and for total times using cannabis, we express this difference per day).

Results

Participants averaged 21.1 (± 2.09) years of age, 49.6% identified as men, 65.3% were White, 12.7% were Black, 22.0% identified other or multiple racial identifications, and 13.2% were Latinx (Table 1). Mean days using alcohol use days was 23.5 (± 16.4), and heavy alcohol use (4+ drinks for women and 5+ drinks for men) was reported on an average of 12.3 (± 12.6) days. Fifty-three participants (13.2%) reported opioid use in the past 90 days. On average, participants reported using cannabis on 47.1 (± 35.1) days in the 90 days prior to the interview. The mean cannabis problem severity score was 7.28 (± 6.22) (possible range was 0 – 38). Eighty-one (20.1%) participants reported chronic pain; those in the chronic pain group reported an average of 223.53 (SD = 223.79, median = 156) days of chronic pain. Similar proportions of women (n = 62, 20.5%) and men (n = 38, 24.5%) reported chronic pain (χ² = 3.50, p - .061).

Table 1.

Background Characteristics (n=403, except as noted)

	n (%)	Mean (± SD)	Median	Range
Age		21.1 (± 2.09)	21	18 – 25
Gender Identity (Male)	200 (49.6%)
Race
White	267 (65.3%)
Black	52 (12.7%)
Other	906 (22.0%)
Latinx (Yes)	53 (13.2%)
Alcohol Use Days (0–90)		23.46 (± 16.38)	23	0 – 90
Binge Drinking Days (0–90)		12.27 (± 12.60)	8	0 – 81
Opioid Use Days (0–90)		0.96 (± 6.28)	0	0 – 90
Cannabis Use Days (0–90)		47.05 (± 35.06)	43	1 – 90
Cannabis Use Occasions		120.70 (± 158.74)	65.00
Cannabis Problem Severitya		7.28 (± 6.22)	6	0 – 38
Chronic Pain (Yes)	81 (20.1%)

^aValid n = 386.

^bValid n = 390.

Adjusting for age, gender identity, race, ethnicity, and frequency of binge drinking, chronic pain was associated significantly and positively with cannabis use days (IRR = 1.35, 95%CI 1.15; 1.57, p < .001; Table 2). The estimated average marginal effect for chronic pain was approximately 15.3 (95%CI 6.6; 23.9) days. The total number of times participants reported using cannabis was also associated positively and significantly with chronic pain; the mean rate of cannabis use was about 1.61 (95%CI 1.18; 2.21, p = .003) times higher for participants who reported chronic pain than for those who did not. The estimated marginal effect was 66.5 (95%CI 15.1; 117.9) times in the past 90 days (about .74 times per day over the period assessed by the TLFB). Cannabis problem severity (IRR = 1.23, 95%CI 1.02; 1.48, p < .030) was also significantly higher among those reporting chronic pain. The estimated average marginal mean MPS score was about 1.59 (95%CI 0.075; 3.10) points higher for participants reporting chronic pain.

Table 2.

Generalized Linear Model with Log Link and Poisson Family Error Distribution Estimating the Adjusted Association of Chronic Pain with Cannabis Use Days, Total Times Used Cannabis, and Cannabis Problem Severity

	CANNABIS USE DAYS		TOTAL TIMES USED CANNABIS		CANNABIS PROBLEM SEVERITY
	IRR (95%CI)	(p = )	IRR (95%CI)	(p = )	IRR (95%CI)	(p = )
Age	1.00 (0.96; 1.03)	(.067)	1.00 (0.93; 1.06)	(.891)	0.98 (0.94; 1.02)	(.335)
Gender Identity (Male)	1.50 (1.29; 1.74)	(<.001)	1.65 (1.26; 2.16)	(<.001)	1.06 (0.89; 1.26)	(.504)
Race
Black	0.98 (0.78; 1.22)	(.834)	1.00 (0.64; 1.57)	(.989)	0.98 (0.78; 1.22)	(.804)
Other	1.09 (0.89; 1.33)	(.406)	1.17 (0.88; 1.56)	(.283)	1.12 (0.87; 1.44)	(.369)
White [REF]	[1.00]		[1.00]		[1.00]
Latinx (Yes)	0.96 (0.76; 1.21)	(.735)	1.06 (0.73; 1.52)	(.767)	0.92 (0.70; 1.22)	(.580)
Binge Days	1.01 (1.00; 1.01)	(.003)	1.01 (1.00 1.02)	(.014)	1.01 (1.00; 1.01)	(.065)
Chronic Pain (Yes)	1.35 (1.15; 1.57)	(<.001)	1.61 (1.18; 2.21)	(.003)	1.23 (1.02; 1.48)	(.030)
N =	403		403		386

Discussion

This sample of community young adults reported substantial rates of cannabis use, and a sizable subset also reported experiencing chronic pain. After controlling for demographic variables and binge drinking, a known covariate of cannabis use in this age group (McCabe et al., 2021), chronic pain was significantly associated with all three cannabis use variables examined, namely, cannabis use frequency, intensity, and severity. These findings provide converging evidence of an especially vulnerable subset of already vulnerable young adults who use cannabis.

The associations between chronic pain with cannabis use that were observed in these data corroborate prior reports in other age cohorts (Hasin et al., 2020). The present findings also extend prior, limited work on this association among young adults, an age group already known to carry risk of frequent and/or problematic cannabis use (SAMHSA, 2022), and a need to minimize its harms (SAMHSA, 2022; Sarvet et al., 2018). Consistent with public health reports of cannabis use patterns in young adults (SAMHSA, 2022), this sample of individuals who use cannabis reported, on average, cannabis use on almost half the days assessed. In addition, whereas frequency of cannabis use has been associated with chronic pain in prior studies of young adults (Fales et al., 2019; Zvolensky et al., 2011), evidence regarding the association between chronic pain and other characteristics of cannabis use in this age group has been less consistent. The link between chronic pain and cannabis problem severity seen here suggests that these distressed young adults may be the very individuals who are especially susceptible to cannabis’s negative consequences. This association is concerning due to the known negative physical and psychological consequences of cannabis use, in general (Pearson, 2019; Suerken et al., 2016; Sun et al., 2020), but particularly during the vulnerable, young adult stage of neurodevelopment (Schneider, 2008; Selamoglu et al., 2021).

Unlike in other studies of cannabis use among persons with chronic pain (Haug et al., 2017), this sample was not recruited specifically for the presence of chronic pain. That a fifth of this young adult sample nonetheless reported chronic pain suggests that many young adults are experiencing a potentially debilitating medical condition that may interfere with functioning and quality of life. This finding alone contributes to a growing literature on chronic pain among young adults. Further, the chronic pain in this sample of young adults was also associated with greater likelihood of cannabis use and its negative consequences, thus helping to identify an especially vulnerable subset of young adult cannabis users who may warrant particular clinical attention. These findings thus contribute to a small but important literature documenting chronic pain and its correlates among young adults (Rosenbloom et al., 2017; Zvolensky et al., 2011).

Whether the chronic pain predated the cannabis use is not possible to determine from our present data. We also cannot know whether persons who reported chronic pain used cannabis specifically to manage their pain, though analgesia does indeed appear to be a common motive for cannabis use in many people with chronic pain, including young adults (Ataiants et al., 2021; Fales et al., 2019). The association between chronic pain and cannabis use may be strengthened with such use. According to expectancy theory, expectations about substance use can influence subsequent substance use behavior, which, in turn, can strengthen those beliefs (Jones et al., 2001). Persons who use cannabis in order to reduce chronic pain may then continue using it for this purpose due to the negative reinforcement they experience. Prospective analyses are necessary to determine whether this pathway is indeed the case, as well as the extent to which any negative use-related consequences also experienced interact with this motivation for continued cannabis use.

This study has some limitations. First, all data were cross-sectional and self-report in nature, thereby precluding causal associations and often requiring participants to recall back several months. Future research should use prospective designs to determine causality. Self-report measurement is common and generally considered reliable in the substance use field, including for cannabis use specifically (Robinson et al., 2014). In addition, data collection occurred during a time period when medical cannabis use was legal in Rhode Island (the primary recruitment site) but not in Massachusetts (where some participants likely resided). Adult recreational cannabis use was not legal in either state, although possession of small amounts was decriminalized in 2008 in Massachusetts, prior to the study, and in 2013 in Rhode Island, during study data collection. The legal status of cannabis use at the time of data collection may have influenced participants’ reports of their cannabis use behavior, which may, in turn, have affected study results.

Another limitation is that chronic pain was assessed using the bodily pain item from a measure of general health (i.e., the SF-12). In addition, in order to capture the persistent or recurrent pain experience of persons experiencing any level of pain, a conservative minimum threshold of pain was applied to the analyses. It is possible that the use of this instrument and/or the application of this conservative threshold may have influenced our results. Future analyses should utilize other measures and definitions of pain. Finally, we did not explicitly assess whether persons with chronic pain specifically used cannabis to manage pain. However, regardless of their cannabis use motives, the fact that, compared to those without chronic pain, they used more frequently and intensely, and that they experienced more negative consequences from their use, is itself an important finding.

Our findings suggest that chronic pain is common among young adults and is also associated with more frequent, intense cannabis use and its negative consequences. These links between chronic pain and problem cannabis use corroborate documented associations in other age groups but carry particular significance in the young adult context, as this population is known overall to engage in high rates of cannabis use, minimize its risks, and co-use alcohol at hazardous levels. Given the dearth of evidence that explicitly connects chronic pain and cannabis use in young adults, increased attention to possible explanatory mechanisms, as well as prospective research designs, is required in order to inform interventions that target this vulnerable population.