Skip to main content

Increased cannabis intake during the COVID-19 pandemic is associated with worsening of depression symptoms in people with PTSD

Abstract

Background

Some evidence suggests substance use affects clinical outcomes in people with posttraumatic stress disorder (PTSD). However, more work is required to examine links between mental health and cannabis use in PTSD during exposure to external stressors such as the COVID-19 pandemic. This study assessed mental health factors in individuals with self-reported PTSD to: (a) determine whether stress, anxiety, and depression symptoms were associated with changes in cannabis consumption across the pandemic, and (b) to contrast the degree to which clinically significant perceived symptom worsening was associated with changes in cannabis intake.

Method

Data were obtained as part of a larger web-based population survey from April 3rd to June 24th 2020 (i.e., first wave of the pandemic in Canada). Participants (N = 462) with self-reported PTSD completed questionnaires to assess mental health symptoms and answered questions pertaining to their cannabis intake. Participants were categorized according to whether they were using cannabis or not, and if using, whether their use frequency increased, decreased, or remained unchanged during the pandemic.

Results

Findings indicated an overall perceived worsening of stress, anxiety, and depression symptoms across all groups. A higher-than-expected proportion of individuals who increased their cannabis consumption reached threshold for minimal clinically important worsening of depression, X2(3) = 10.795, p = 0.013 (Cramer’s V = 0.166).

Conclusion

Overall, those who increased cannabis use during the pandemic were more prone to undergo meaningful perceived worsening of depression symptoms. Prospective investigations will be critical next steps to determine the directionality of the relationship between cannabis and depressive symptoms.

Peer Review reports

Background

Posttraumatic stress disorder (PTSD) is a psychiatric disorder that can arise following exposure to actual or threatened death, serious injury, or sexual violence. PTSD is notably characterized by intrusion symptoms (e.g., flashbacks, recurring nightmares, etc.), avoidant behaviors, negative alterations in cognition and mood, and alterations in arousal and reactivity [1]. PTSD is also highly comorbid with anxious and depressive disorders [2]. The COVID-19 pandemic has widely exacerbated stress, anxious, and depressive symptoms, and there are indications that people with PTSD were particularly affected by this global external stressor [3,4,5,6]. Of note, PTSD is a known risk factor for increased substance use [7,8,9]. Cannabinoids in particular have relevancy to PTSD both as therapeutic products [10,11,12,13] as well as drugs of abuse [7, 9]. Since the beginning of the COVID-19 pandemic, evidence has mounted suggesting that many factors such as stress about world events, long periods of confinement, and changes in sleep patterns have contributed to increased stress-related mental health problems [14,15,16,17,18,19,20,21,22], a phenomenon that may influence patterns of substance use. While some work has examined changes in substance use behaviours during the pandemic [23], little is yet known about the mental health factors associated with changes in cannabis use patterns among individuals with PTSD during this period.

Mental health factors have long been known to affect substance use. For instance, past research has identified that exposure to a traumatic event is related to the initiation of cannabis consumption [24]. PTSD-related mental health issues have also been highlighted as possible risk factors for substance use disorders [25,26,27]. Recent work has shown that among Canadian and Australian samples, combined usage of substances including alcohol and cannabis increased during the COVID-19 pandemic [28, 29] – and the perceived worsening of PTSD symptoms during the pandemic was associated with these increases [29]. Among Canadians, approximately one third of substance-using individuals also reported an increase in alcohol and cannabis intake during the pandemic [30]. Cannabis became widely available to Canadians in 2018 following the introduction of the Cannabis Act, which legalized the possession, purchase, sharing, and sale of cannabis for individuals over 18 years of age [31]. Thus, since that time point, cannabis has been sharing a similar availability and legal status to alcohol in Canada. There is a need to better understand the mental health correlates of changes in substance use in people with PTSD during this unique period where cannabis legislation was quickly followed by a major global stressor.

There is some evidence to suggest that psychiatric comorbidities can affect cannabis consumption in people with PTSD. Recent evidence has indicated that both depressive and anxious symptoms are associated with greater odds of cannabis use in people with PTSD [32]. Perceived stress is similarly associated with increased cannabis intake [33, 34], and the relationship between perceived stress and cannabis use is mediated by depression and anxiety in people with PTSD [35]. Additionally, stress, anxiety, and depression are cited as some of the most common reasons for cannabis use among PTSD-prevalent groups such as veterans [36]. There is also a physiological basis to suspect that cannabinoids may directly modulate brain processes contributing to PTSD symptomology as well as comorbid stress, anxiety and depression symptoms. Individuals with PTSD exhibit reduced availability of the endocannabinoid anandamide and a consequent upregulation of its receptor (CB1) [37], which plays a key role in the mediation of stress and fear responses at relevant brain sites [10, 38,39,40,41,42,43]. The endocannabinoid system is also believed to be implicated in stress [44, 45], anxiety [46, 47], and depressive symptoms [48, 49].

Due to its prevalent use either under medical authorization or as self-medication for PTSD, we speculated that cannabis use might change with increases in stress, anxiety, and depression symptoms co-occurring with PTSD during a global stressor like the COVID-19 pandemic. The present study aimed to assess mental health factors in a sample of individuals with self-reported current diagnoses of PTSD in order to determine whether changes in the severity of stress, anxiety, and depression symptoms during the pandemic relative to pre-pandemic estimates were associated with changes in cannabis consumption. We addressed this objective first by comparing symptoms of stress, anxiety, and depression among groups of individuals with PTSD who reported different cannabis intake behaviours across the pandemic (those who increased their intake, those who did not change their intake, those who decreased their intake, and those who did not use cannabis in the month prior to the pandemic or during the pandemic). Next, we compared the proportions of those whose stress, anxiety, and depression symptoms underwent minimal clinically important differences (MCID, a framework for characterizing the minimum level of symptom change that would be considered meaningful and that would mandate a change in illness management [50] between the cannabis groups).

Methods

Data collection

The data for this study were obtained as part of a larger web-based population survey on the psychological, social, and economic impacts of the COVID-19 pandemic that was circulated via websites, social media, and multiple organizations and hospitals across Canada (please see ClinicalTrials.gov: NCT04369690 and [21]). The data included in this report contains survey entries from April 3rd until June 24th 2020. The survey was available in both official Canadian languages (English and French) and included custom-built questions regarding the COVID-19 pandemic (please see a copy of these items in previously published data supplement [21]), as well as validated questionnaires regarding mental health. It was developed in accordance with the Checklist for Reporting Results of Internet E-Surveys (CHERRIES; [51]). Data collected for the study was collected in an anonymous manner. Retrospective questions were used to estimate stress, anxiety and depression symptoms, as well as cannabis use frequency across two time-referents: in the last month before the beginning of the COVID-19 pandemic (the pandemic declaration by the World Health Organization occurred on 11 March 2020), and in the 7 days prior to filling out the survey.

Sample

The main inclusion criterion for the current sample was a self-reported current diagnosis of PTSD (i.e. selecting PTSD amongst a list of multiple mental disorders when answering the question: ‘Have you ever had a formal diagnosis of (Please select all that apply)’). 466 participants with self-reported current PTSD were identified from the overall sample of 6,981 participants (6.7%) who filled out the survey during that period. Four participants with self-reported current PTSD were excluded from the analysis as they met the following exclusion criteria: younger than 18 years of age or diagnosis of a psychotic disorder. The final sample consisted of 462 participants.

The sample of respondents was divided in four cannabis groups based on changes in cannabis use patterns from pre-pandemic to during the pandemic. Change scores were calculated by subtracting estimated pre-pandemic cannabis consumption frequencies from the frequencies reported during the pandemic. Individuals with a negative change score (i.e., a decrease in weekly cannabis consumption frequency from pre-pandemic to during the pandemic) were included in the decreased use group. Those with a positive change score (i.e., an increase in weekly cannabis consumption frequency) were included in the increased cannabis use group. Those with a change score of 0 were included in the no-change group. A cannabis non-user group was also formed to include the respondents who reported not having used cannabis at any of the sampled time referents.

Questionnaires

Three validated questionnaires were used to assess symptoms of stress, anxiety, and depression, all of which have previously been utilized with people with PTSD [52,53,54,55]. The 10-item version of the Perceived Stress Scale (PSS10; [56]) was used to assess stress symptoms [57]. Participants answered questions on a five-point Likert scale, with total scores ranging from 0 to 40, where higher scores indicate worse perceived stress. The Cronbach α and test-retest of the PSS10 were both reported as greater than 0.70 [58]. The Generalized Anxiety Disorder 7 (GAD-7; [59]), a 7-item questionnaire, was used to assess the severity of symptoms of anxiety. Scores range from 0 to 21, with a higher score indicating a more severe anxiety. Internal consistency was found to be excellent (Cronbach α = 0.92) and test-retest reliability was good (intraclass correlation = 0.83). The GAD-7 was also found to have good sensitivity (89%) and specificity (82%) [59]. The QIDS-SR16 [60] was used to assess depression symptoms. The QIDS-SR16 is a questionnaire assessing the nine symptom domains of depression used in the DSM-IV. It contains 16 items for which respondents are asked to rate the severity of symptoms. Scores range from 1 to 27, with higher scores indicating more severe depression symptoms [61]. Based on a meta-analysis, the QIDS-SR16 was found to be unidimensional and to have an internal consistency (Cronbach’s α) ranging from 0.69 to 0.89 [62].

Regarding cannabis consumption, participants were asked the following questions: “How frequently were you taking cannabis products: Total number of times in the past 7 days? Number of times per week in the last month before the pandemic?”.

Statistical analyses

Mixed ANCOVAs with cannabis groups (increased use, no change, decreased use, and non-users) as a between-subjects factor and time referent (before the pandemic and during the pandemic) as a repeated-measures factor were applied on PSS10, GAD-7 and QIDS-SR16 total scores. All ANCOVAs were adjusted for relevant covariates: age, occupation, and current diagnosis of addiction-related/substance use disorders. Levene’s test and Box’s test were used to ensure that equality of error variances and equality of covariance matrices were not violated.

The proportion of individuals whose perceived symptom worsening was above the threshold for MCID was compared across the cannabis groups using chi-squared tests which were subsequently broken down using Bonferroni-corrected z-tests according to the procedure described by Sharpe [63]. Cramer’s V was used as an effect size for these analyses [64]. For determining MCID, the thresholds for all three questionnaire assessments were based on previously established norms. For the PSS10, a 28.0% increase was identified as MCID [65]. For the GAD-7, an increase of four points was identified as MCID [66]. For the QIDS-SR16, an increase of 28.5% was identified as MCID [67].

Results

Sample characteristics

The descriptive data across the cannabis groups are reported in Table 1. The sample ranged between 18 and 78 years of age (mean ± SD = 48.02 ± 13.89), and was mostly composed of white (83.15%), female (71.3%) individuals. Sex and ethnicity distributions did not differ significantly between the cannabis groups. There was a significant difference between the cannabis groups in terms of age, F(3,458) = 5.602, p = 0.001 and occupation, X2(9)= 19.589, p = 0.021; those who did not change their cannabis use across the time referents (p < 0.05) and non-users (p < 0.05) were significantly older than those who decreased their use and counted a higher proportion of retired individuals compared to all other cannabis groups. In addition, there was a significant difference between the groups for current diagnosis of addiction-related/substance use disorders, X2(3)=10.197, p = 0.017. A significantly higher proportion of individuals who increased their cannabis use during the first wave of the pandemic had a self-reported diagnosis of a substance use disorder compared to non-users (p < 0.05).

Table 1 Demographic data for each of the four cannabis use groups

Perceived stress

PSS10 scores prior to and during the pandemic in each cannabis group are depicted in Fig. 1. There was no significant interaction between time referent and cannabis group for the PSS10, F(3,411) = 0.978, p = 0.403, nor significant main effect cannabis group on perceived stress scores, F(3,411) = 0.778, p = 0.507. A significant main effect of time referent was observed on PSS10 scores, F(1,411) = 12.948, p < 0.001 with a small effect size (η2p = 0.031). Overall, there was a significant increase in PSS10 scores from before the pandemic (M = 20.93, SE = 0.63) to during the pandemic (M = 24.31, SE = 0.70).

Fig. 1
figure 1

Comparison of  perceived mean stress symptoms scores on the PSS10 across the cannabis use groups at both time referents (before and during the pandemic). A significant main effect of time referent was observed on PSS10 scores, F(1,411) = 12.948, p < 0.001 with a small effect size (η2p = 0.031). Note.***p < 0.001

Anxiety symptoms

Anxiety symptoms severity as reflected by GAD-7 scores across the time referents for each cannabis groups are depicted in Fig. 2. There was no significant time referent by cannabis group interaction for the GAD-7, F(3,409) = 0.805, p = 0.491, nor significant main effect cannabis group on GAD-7 scores, F(3,409) = 2.036, p = 0.108. A significant main effect of time referent on anxiety scores on the GAD-7, F(1,409) = 9.989, p = 0.002 with a small effect size (η2p = 0.024) revealed a significant increase in anxiety scores from before the pandemic (M = 10.149, SE = 0.51) to during the pandemic (M = 12.24, SE = 0.55).

Fig. 2
figure 2

Comparison of mean anxiety symptoms scores on the GAD-7 across the cannabis use groups at both time referents (before and during the pandemic). A significant main effect of time referent showed that anxiety levels increased during the pandemic relative to pre-pandemic estimates in all groups. Note. **p = 0.002

Depression symptoms

Figure 3 shows depression symptoms severity as reflected by QIDS-SR16 scores prior to and during the pandemic for each cannabis group. There was no significant time referent by cannabis group interaction effect for QIDS-SR16 scores, F(3,411) = 0.805, p = 0.491. There was a significant cannabis group difference for QIDS-SR16 scores, F(3,383) = 2.903 p = 0.035 with a small effect size (η2p = 0.022). Post-hoc analyses revealed that those who decreased their cannabis use (M = 13.106, SE = 0.741) had significantly more severe depression symptoms compared to those who did not change their use during the pandemic (M = 10.974, SE = 0.602), p = 0.017, and those who did not use cannabis (M = 11.314, SE = 0.272), p = 0.016. Additionally, there was a non-significant trend for those who increased their cannabis use (M = 12.681, SE = 0.650) toward having more severe depression symptoms compared to those who did not change their use during the pandemic (p = 0.055) and non-users (p = 0.056). No other between-groups differences or trends emerged from the analysis.

Fig. 3
figure 3

Comparison of mean depressive symptoms scores on the QIDS-SR16 across the cannabis use groups at both time referents (before and during the pandemic). A significant main effect of time referent showed that anxiety levels increased during the pandemic relative to pre-pandemic estimates in all groups. A significant main effect of cannabis group showed that those who decreased their cannabis use had more severe depression symptoms than those who did not change their use and those who did not use. There was also a non-significant trend (†) for those who increased their cannabis use toward having more severe depression symptoms compared to those who did not change their use during the pandemic and non-users. Note.*p < 0.05, ***p < 0.001, †non-significant trends (p < 0.06)

Our findings also revealed a significant main effect of time referent on depression scores on the QIDS-SR16, F(1,383) = 21.590, p < 0.001 with a small effect size (η2p = 0.053). Overall, there was a significant increase in depression scores from before the pandemic (M = 10.85, SE = 0.54) to during the pandemic (M = 15.17, SE = 0.56).

Clinically important worsening

There was no significant difference across the cannabis groups in the proportions of individuals with MCID reflecting perceived stress or anxiety symptoms worsening based on retrospective estimates, PSS10: Chi-squared (3) = 6.886, p = 0.076 (Fig. 4a), GAD-7; Chi-squared (3) = 4.716, p = 0.194 (Fig. 4b). However, there were significant cannabis groups differences in the proportions of those with clinically significant worsening of depression symptoms based on retrospective estimates, QIDS-SR16: Chi-squared (3) = 10.795, p = 0.013 with a small effect size (Cramer’s V = 0.166; Fig. 4c). Specifically, a higher-than-expected proportion of individuals who increased their cannabis consumption during the pandemic reached the MCID threshold for depression worsening (72%), p < 0.05 (see Fig. 4c). No such difference was observed for those who did not change their cannabis use (46%), those who decreased their use, (40%), and non-users (50%).

Fig. 4
figure 4

Proportions of individuals with MCID across the cannabis use pattern groups on (A) PSS10, (B) GAD-7, and (C) QIDS-SR16. Only the QIDS-SR16 differed significantly across groups: a higher-than-expected proportion of individuals who increased their cannabis consumption during the pandemic reached the MCID threshold for depression worsening. Note.* = p < 0.05

Discussion

Intra-individual changes from before the pandemic to during the pandemic are of significant interest in terms of understanding the dynamic relationship between mental health factors and cannabis consumption in the context of a global crisis. Here, we have utilized a retrospective approach with data sampled in the early stages of the first wave of the pandemic. Overall, our findings revealed a significant increase in stress, anxiety, and depression symptom severity among all cannabis groups during the first wave of the pandemic relative to self-reported retrospective pre-pandemic estimates. Only overall depression scores differed significantly among the cannabis groups. Specifically, we found that compared to non-users and those who maintained a stable frequency of cannabis use during the pandemic, those who decreased or increased (trend) their cannabis use experienced higher depression symptoms both before and during the pandemic (i.e. no significant interaction with pandemic-related changes in depression). Those who used cannabis but did not change their frequency of use during the pandemic maintained the lowest QIDS-SR16 scores across this period. Our analysis also revealed that clinically important worsening of depression (based on retrospective estimates) was related to increased cannabis use in individuals with a self-reported current diagnosis of PTSD; no such association was observed for stress or anxiety.

Our findings indicated that 72% of those who increased their cannabis use during the pandemic experienced clinically important worsening of depression symptoms (based on retrospective estimates), compared with 40–50% for all other groups. Since we did not observe any significant interaction between cannabis use and retrospectively estimated pandemic-related changes in continuous variables reflecting symptom severity in our first analyses, the relationship between depressive symptoms worsening and increased cannabis use during the pandemic may have been more pronounced in cases of prominent and clinically significant symptom worsening rather than in cases of sub-clinical symptom changes. Lastly, we did not observe any significant differences in the proportions of those who experienced clinically important worsening of stress or anxiety among the cannabis use groups. Thus, it appears that depression symptoms alone were chiefly associated with changes in cannabis use patterns in the face of this external stressor.

Our findings with regards to depression may be consistent with other research on cannabis-use patterns during the pandemic. Recent evidence has identified self-isolation and coping with depression as primary drivers behind cannabis buying practices during the pandemic in a non-PTSD sample [68]. Our work would therefore appear to support those results for individuals with PTSD who experienced clinically meaningful worsening in depression symptoms (based on retrospective estimates), suggesting that depression symptoms are an important factor associated with cannabis intake in PTSD during a global crisis (an observation that is particularly relevant given the high comorbidity of PTSD and depression [69, 70]).

Our findings regarding stress may also be somewhat consistent with past research. Previous work has demonstrated for example that cannabis use may be associated with a blunted stress response [71]. Regarding anxiety, however, the evidence is less clear-cut. In the short-term, high doses of tetrahydrocannabinol (THC, the major psychoactive constituent of cannabis) are anxiogenic [72] while low doses are anxiolytic [42, 73, 74]. Meta-analyses indicate that, in the long-term, there is a weak but positive relationship between cannabis use and anxiety [75] (although it is unclear whether anxiety is a main motivating factor for cannabis use in PTSD specifically [76]). Some work has also suggested that the largest increases in medical cannabis intake during the pandemic were observed in participants with pre-existing anxiety [77]. We did not observe this in our sample, however, as there were no significant differences between our cannabis groups in terms of either GAD-7 scores or comorbid anxiety disorders. Interestingly, multiple studies have indicated that the relationship between cannabis and anxiety may also be specific to social anxiety disorder [78, 79]. While our questionnaire measures did not specifically isolate social anxiety symptoms, we did not observe high levels of self-reported current diagnoses of social anxiety disorder in this sample among any of the cannabis-using groups.

It remains unclear whether cannabis use may increase as a result of therapeutic use/self-medication or whether it instead may be a driving factor behind symptoms changes. Given the evidence of the association between the pandemic and worsening of mental health [80,81,82], it is possible that cannabis consumption was increased as a coping strategy in response to mental health challenges imposed by this global external stressor. Previous evidence has highlighted coping as a motive of cannabis use [76, 83,84,85], and recent work has more specifically indicated that cannabis users with greater difficulty tolerating sad mood states use cannabis more frequently [85]. Thus, one possibility in the current study is that, among those with lower resiliency to sad mood states, worsening of depressive symptoms may have motivated increased cannabis use as a coping strategy during the onset of the pandemic. However, research also points to cannabis as a risk factor for depressive symptoms [86]. The relationship between cannabis use and depression may thus be bidirectional. It is also worth noting that comorbid substance use could also have played a role in these effects (since other studies have reported increased use of both alcohol and cannabis among substance-using individuals during the pandemic [30]).

Interestingly, those who reported not changing their levels of cannabis use during the onset of the pandemic also reported the lowest overall depression symptoms. Indeed, some positive effects of cannabinoids have been shown for PTSD (e.g., the reduction of PTSD-related nightmares by Nabilone [12]). Since PTSD may be characterized by reduced levels of the endocannabinoids anandamide and a compensatory upregulation of central CB1 receptors [87], it is possible that supplementation with stable consumption of THC (which, like anandamide, acts as a CB1 partial agonist [42]) could re-normalize the central endocannabinoids system. Conversely, acute changes in cannabis consumption may alter this balance. However, more work is needed in this area since there is a dearth of information on the effects of THC on CB1 receptor expression in humans.

The present study has several limitations. Firstly, the information about cannabis use was limited to weekly frequency of use, and no information was available about other important factors such as dosage, the ratio of CBD/THC concentrations, or medical versus recreational use which are speculated to play an important role in responses to cannabis use [88]. This limitation is particularly important given the known differences in the effects of dosage and CBD versus THC concentrations on behaviour and emotion as well as recent concerns raised about the lack of adequate standardization of cannabinoid-based products [10, 89, 90]. Secondly, this study relied on self-reported diagnosis without clinician-based confirmation, and it was also based on retrospective assessment of pre-pandemic mental health and substance use. Because of the spontaneous nature of the pandemic, obtaining a prospective sample from before the pandemic was not possible. Our results may therefore be affected by recall bias. In addition, the nature of self-report measures is such that participants could omit or misreport information pertaining to their diagnoses or cannabis intake (which is a concern in all studies relying on self-report measures). Thirdly, the generalizability of this research is also somewhat restricted by the high proportion of females. Mian et al. [91] recently reported that females are significantly more likely to participate in survey-based cannabis research than males. Although the current data is issued from a larger survey which was not focused on cannabis, it is possible that volunteer bias influenced participant’s responses to this portion of the survey. For future research, it may be important to achieve more representative samples by oversampling groups which are more difficult to reach. This sample was also biased towards middle age white individuals, many with high total family income levels. Fourthly, while our study had adequate sample sizes overall, a larger sample would have allowed for more in-depth characterization of the data across the groups (particularly with regards to comparing those with clinically meaningful worsening in mental health (based on retrospective estimates) versus those who did not in a between-groups manner). Fifthly, several statistical tests were conducted, increasing the risks of type I error, and the observational nature of the study precludes any inference of causality. Finally, while the data reported in this sample were restricted to individuals with self-reported PTSD, we cannot rule out the possibility that our findings could also be more generalized to other populations. Overall, our findings support and expand upon prior work regarding substance use in individuals with PTSD and during the COVID-19 pandemic.

Conclusion

This work highlights the association between clinically significant worsening depressive symptoms and increased cannabis intake among individuals with PTSD during the early phases of the pandemic. This research adds to the knowledge of potential factors linked to increased substance use in people with PTSD following a major crisis. Future work should aim to prospectively determine whether depression or other comorbidities not addressed in this study are predictive of longitudinal changes in cannabis intake in people PTSD over the remaining course of the pandemic and, most importantly, whether this is accompanied by further worsening in mental health outcomes or whether cannabis may help stabilize certain types of psychiatric symptoms in the context of an external stressor.

Availability of data and materials

Data could be made available upon request and formal data sharing agreement. Requests should be submitted to Rebecca Robillard at Rebecca.robillard@uottawa.ca.

Abbreviations

PTSD:

Posttraumatic stress disorder

CB1:

Cannabinoid receptor type 1

MCID:

Minimal clinically important difference

CBD:

Cannabidiol

THC:

Delta-9-Tetrahydrocannabinol

References

  1. Association AP, others. Diagnostic and statistical manual of mental disorders (DSM-5®). American Psychiatric Pub; 2013. Available from: https://books.google.ca/books?hl=en&lr=&id=-JivBAAAQBAJ&oi=fnd&pg=PT18&dq=Diagnostic+and+statistical+manual+of+mental+disorders,+5th+Edition.+&ots=cdWQ-6ILy9&sig=-IQxeMRALVwSRWHhMBJVoERi3rA.

  2. Brady KT, Killeen TK, Brewerton T, Lucerini S. Comorbidity of psychiatric disorders and posttraumatic stress disorder. J Clin Psychiatry. 2000;61:22–32.

    PubMed  Google Scholar 

  3. Lakhan R, Agrawal A, Sharma M. Prevalence of depression, anxiety, and stress during COVID-19 pandemic. J Neurosci Rural Pract. 2020;11(04):519–25.

    Article  PubMed  PubMed Central  Google Scholar 

  4. Lebel C, MacKinnon A, Bagshawe M, Tomfohr-Madsen L, Giesbrecht G. Elevated depression and anxiety symptoms among pregnant individuals during the COVID-19 pandemic. J Affect Disord. 2020;277:5–13.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  5. Deng J, Zhou F, Hou W, Silver Z, Wong CY, Chang O, et al. The prevalence of depressive symptoms, anxiety symptoms and sleep disturbance in higher education students during the COVID-19 pandemic: A systematic review and meta-analysis. Psychiatry Res. 2021;301:113863.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  6. Hawes MT, Szenczy AK, Klein DN, Hajcak G, Nelson BD. Increases in depression and anxiety symptoms in adolescents and young adults during the COVID-19 pandemic. Psychol Med. 2021;1–9. https://doi.org/10.1017/S0033291720005358.

  7. Cornelius JR, Kirisci L, Reynolds M, Clark DB, Hayes J, Tarter R. PTSD contributes to teen and young adult cannabis use disorders. Addict Behav. 2010;35(2):91–4.

    Article  PubMed  Google Scholar 

  8. Cougle JR, Bonn-Miller MO, Vujanovic AA, Zvolensky MJ, Hawkins KA. Posttraumatic stress disorder and cannabis use in a nationally representative sample. Psychol Addict Behav. 2011;25(3):554.

    Article  PubMed  Google Scholar 

  9. Kevorkian S, Bonn-Miller MO, Belendiuk K, Carney DM, Roberson-Nay R, Berenz EC. Associations among trauma, posttraumatic stress disorder, cannabis use, and cannabis use disorder in a nationally representative epidemiologic sample. Psychol Addict Behav. 2015;29(3):633.

    Article  PubMed  PubMed Central  Google Scholar 

  10. Murkar A, Kent P, Cayer C, James J, Durst T, Merali Z. Cannabidiol and the remainder of the plant extract modulate the effects of ∆9-tetrahydrocannabinol on fear memory reconsolidation. Front Behav Neurosci. 2019;13:174.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  11. Fraser GA. The use of a synthetic cannabinoid in the management of Treatment-Resistant nightmares in posttraumatic stress disorder (PTSD). CNS Neurosci Ther. 2009;15(1):84–8.

    Article  PubMed  PubMed Central  Google Scholar 

  12. Jetly R, Heber A, Fraser G, Boisvert D. The efficacy of nabilone, a synthetic cannabinoid, in the treatment of PTSD-associated nightmares: a preliminary randomized, double-blind, placebo-controlled cross-over design study. Psychoneuroendocrinol. 2015;51:585–8.

    Article  CAS  Google Scholar 

  13. Orsolini L, Chiappini S, Volpe U, De Berardis D, Latini R, Papanti GD, et al. Use of medicinal cannabis and synthetic cannabinoids in post-traumatic stress disorder (PTSD): A Systematic Review. Med (Mex). 2019;55(9):525.

    Google Scholar 

  14. Choi EPH, Hui BPH, Wan EYF. Depression and anxiety in Hong Kong during COVID-19. Int J Environ Res Public Health. 2020;17(10):3740.

    Article  CAS  PubMed Central  Google Scholar 

  15. Czeisler M, Lane RI, Petrosky E, Wiley JF, Christensen A, Njai R, et al. Mental health, substance use, and suicidal ideation during the COVID-19 pandemic—United States, June 24–30, 2020. Morb Mortal Wkly Rep. 2020;69(32):1049.

    Article  CAS  Google Scholar 

  16. Czeisler M, Lane RI, Wiley JF, Czeisler CA, Howard ME, Rajaratnam SM. Follow-up survey of US adult reports of mental health, substance use, and suicidal ideation during the COVID-19 pandemic, September 2020. JAMA Netw Open. 2021;4(2):e2037665–5.

    Article  PubMed  PubMed Central  Google Scholar 

  17. Elbay RY, Kurtulmuş A, Arpacıoğlu S, Karadere E. Depression, anxiety, stress levels of physicians and associated factors in Covid-19 pandemics. Psychiatry Res. 2020;290:113130.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  18. Özdin S, Bayrak Özdin Ş. Levels and predictors of anxiety, depression and health anxiety during COVID-19 pandemic in Turkish society: The importance of gender. Int J Soc Psychiatry. 2020;66(5):504–11.

    Article  PubMed  PubMed Central  Google Scholar 

  19. Pappa S, Ntella V, Giannakas T, Giannakoulis VG, Papoutsi E, Katsaounou P. Prevalence of depression, anxiety, and insomnia among healthcare workers during the COVID-19 pandemic: A systematic review and meta-analysis. Brain Behav Immun. 2020:901–7.

  20. Rehman U, Shahnawaz MG, Khan NH, Kharshiing KD, Khursheed M, Gupta K, et al. Depression, anxiety and stress among Indians in times of Covid-19 lockdown. Community Ment Health J. 2021;57(1):42–8.

    Article  PubMed  Google Scholar 

  21. Robillard R, Saad M, Edwards J, Solomonova E, Pennestri MH, Daros A, et al. Social, financial and psychological stress during an emerging pandemic: observations from a population survey in the acute phase of COVID-19. BMJ open. 2020;10(12):e043805.

  22. Tang W, Hu T, Hu B, Jin C, Wang G, Xie C, et al. Prevalence and correlates of PTSD and depressive symptoms one month after the outbreak of the COVID-19 epidemic in a sample of home-quarantined Chinese university students. J Affect Disord. 2020;274:1–7.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  23. Vanderbruggen N, Matthys F, Van Laere S, Zeeuws D, Santermans L, Van den Ameele S, et al. Self-reported alcohol, tobacco, and Cannabis use during COVID-19 lockdown measures: results from a web-based survey. Eur Addict Res. 2020;26(6):309–15.

    Article  PubMed  Google Scholar 

  24. Werner KB, McCutcheon VV, Agrawal A, Sartor CE, Nelson EC, Heath AC, et al. The association of specific traumatic experiences with cannabis initiation and transition to problem use: differences between African-American and European-American women. Drug Alcohol Depend. 2016;162:162–9.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  25. Currie C, Wild TC, Schopflocher D, Laing L. Racial discrimination, post-traumatic stress and prescription drug problems among Aboriginal Canadians. Can J Public Health. 2015;106(6):e382–7.

  26. Swendsen J, Conway KP, Degenhardt L, Glantz M, Jin R, Merikangas KR, et al. Mental disorders as risk factors for substance use, abuse and dependence: results from the 10-year follow-up of the National Comorbidity Survey. Addiction. 2010;105(6):1117–28.

    Article  PubMed  PubMed Central  Google Scholar 

  27. Mills KL, Teesson M, Ross J, Peters L. Trauma. PTSD, and substance use disorders: findings from the Australian National Survey of Mental Health and Well-Being. Am J Psychiatry. 2006;163(4):652–8.

    Article  PubMed  Google Scholar 

  28. Biddle N, Edwards B, Gray M, Sollis K. Alcohol consumption during the COVID-19 period: May 2020. Httpscsrmcassanueduauresearchpublicationsalcohol-Consum–Covid-19-Period-May-2020. 2020 [cited 2021 Mar 16]; Available from: https://openresearch-repository.anu.edu.au/handle/1885/213196.

  29. Currie CL. Adult PTSD symptoms and substance use during Wave 1 of the COVID-19 pandemic. Addict Behav Rep. 2021;100341.

  30. Dozois DJ. Anxiety and depression in Canada during the COVID-19 pandemic: A national survey. Can Psychol Can. 2020;62(1):136–42.

  31. Government of Canada D of J. Cannabis Legalization and Regulation [Internet]. 2018 [cited 2022 Jun 1]. Available from: https://www.justice.gc.ca/eng/cj-jp/cannabis/.

  32. Young-Wolff KC, Sarovar V, Tucker LY, Goler NC, Alexeeff SE, Ridout KK, et al. Association of depression, anxiety, and trauma with cannabis use during pregnancy. JAMA Netw Open. 2020;3(2):e1921333–3.

    Article  PubMed  PubMed Central  Google Scholar 

  33. Tavolacci MP, Ladner J, Grigioni S, Richard L, Villet H, Dechelotte P. Prevalence and association of perceived stress, substance use and behavioral addictions: a cross-sectional study among university students in France, 2009–2011. BMC Public Health. 2013;13(1):1–8.

    Article  Google Scholar 

  34. Moitra E, Christopher PP, Anderson BJ, Stein MD. Coping-motivated marijuana use correlates with DSM-5 cannabis use disorder and psychological distress among emerging adults. Psychol Addict Behav. 2015;29(3):627.

    Article  PubMed  PubMed Central  Google Scholar 

  35. Ketcherside A, Filbey FM. Mediating processes between stress and problematic marijuana use. Addict Behav. 2015;45:113–8.

    Article  PubMed  Google Scholar 

  36. Metrik J, Bassett SS, Aston ER, Jackson KM, Borsari B. Medicinal versus recreational cannabis use among returning veterans. Transl Issues Psychol Sci. 2018;4(1):6.

    Article  PubMed  PubMed Central  Google Scholar 

  37. Neumeister A, Normandin MD, Pietrzak RH, Piomelli D, Zheng MQ, Gujarro-Anton A, et al. Elevated brain cannabinoid CB1 receptor availability in post-traumatic stress disorder: a positron emission tomography study. Mol Psychiatry. 2013;18(9):1034–40.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  38. Do Monte FH, Souza RR, Bitencourt RM, Kroon JA, Takahashi RN. Infusion of cannabidiol into infralimbic cortex facilitates fear extinction via CB1 receptors. Behav Brain Res. 2013;250:23–7.

    Article  CAS  PubMed  Google Scholar 

  39. Fogaça MV, Fedoce A, das G, Ferreira-Junior NC, Guimarães FS, Resstel LB. Involvement of M1 and CB 1 receptors in the anxiogenic-like effects induced by neostigmine injected into the rat prelimbic medial prefrontal cortex. Psychopharmacol. 2016;233(8):1377–85.

    Article  CAS  Google Scholar 

  40. Lange MD, Daldrup T, Remmers F, Szkudlarek HJ, Lesting J, Guggenhuber S, et al. Cannabinoid CB1 receptors in distinct circuits of the extended amygdala determine fear responsiveness to unpredictable threat. Mol Psychiatry. 2017;22(10):1422–30.

    Article  CAS  PubMed  Google Scholar 

  41. Lisboa SF, Reis DG, da Silva AL, Corrêa FM, Guimaraes FS, Resstel LB. Cannabinoid CB1 receptors in the medial prefrontal cortex modulate the expression of contextual fear conditioning. Int J Neuropsychopharmacol. 2010;13(9):1163–73.

    Article  CAS  PubMed  Google Scholar 

  42. Murkar A, De Koninck J, Merali Z. Cannabinoids: revealing their complexity and role in central networks of fear and anxiety. Neurosci Biobehav Rev. 2021;131:30–46.

  43. Pietrzak RH, Huang Y, Corsi-Travali S, Zheng MQ, Lin S, fei, Henry S, et al. Cannabinoid type 1 receptor availability in the amygdala mediates threat processing in trauma survivors. Neuropsychopharmacol. 2014;39(11):2519.

    Article  CAS  Google Scholar 

  44. Hillard CJ. Stress regulates endocannabinoid-CB1 receptor signaling. In: Seminars in immunology. Elsevier; 2014. pp. 380–8.

  45. Racz I, Bilkei-Gorzo A, Toth ZE, Michel K, Palkovits M, Zimmer A. A critical role for the cannabinoid CB1 receptors in alcohol dependence and stress-stimulated ethanol drinking. J Neurosci. 2003;23(6):2453–8.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  46. Rubino T, Guidali C, Vigano D, Realini N, Valenti M, Massi P, et al. CB1 receptor stimulation in specific brain areas differently modulate anxiety-related behaviour. Neuropharmacology. 2008;54(1):151–60.

    Article  CAS  PubMed  Google Scholar 

  47. Thiemann G, Watt CA, Ledent C, Molleman A, Hasenöhrl RU. Modulation of anxiety by acute blockade and genetic deletion of the CB1 cannabinoid receptor in mice together with biogenic amine changes in the forebrain. Behav Brain Res. 2009;200(1):60–7.

    Article  CAS  PubMed  Google Scholar 

  48. Beyer CE, Dwyer JM, Piesla MJ, Platt BJ, Shen R, Rahman Z, et al. Depression-like phenotype following chronic CB1 receptor antagonism. Neurobiol Dis. 2010;39(2):148–55.

    Article  CAS  PubMed  Google Scholar 

  49. Moreira FA, Grieb M, Lutz B. Central side-effects of therapies based on CB1 cannabinoid receptor agonists and antagonists: focus on anxiety and depression. Best Pract Res Clin Endocrinol Metab. 2009;23(1):133–44.

    Article  CAS  PubMed  Google Scholar 

  50. Cook CE. Clinimetrics corner: the minimal clinically important change score (MCID): a necessary pretense. J Man Manip Ther. 2008;16(4):82E–83E.

    Article  Google Scholar 

  51. Eysenbach G. Improving the quality of Web surveys: the Checklist for Reporting Results of Internet E-Surveys (CHERRIES). J Med Internet Res. 2004;6(3):e34.

    Article  PubMed  PubMed Central  Google Scholar 

  52. Mitchell AM, Crane PA, Kim Y. Perceived stress in survivors of suicide: psychometric properties of the Perceived Stress Scale. Res Nurs Health. 2008;31(6):576–85.

    Article  PubMed  Google Scholar 

  53. Hu E, Koucky EM, Brown WJ, Bruce SE, Sheline YI. The role of rumination in elevating perceived stress in posttraumatic stress disorder. J Interpers Violence. 2014;29(10):1953–62.

    Article  PubMed  Google Scholar 

  54. Williams N. The GAD-7 questionnaire. Occup Med. 2014;64(3):224–4.

    Article  Google Scholar 

  55. Surís A, Holder N, Holliday R, Clem M. Psychometric validation of the 16 item quick inventory of depressive symptomatology self-report version (QIDS-SR16) in military veterans with PTSD. J Affect Disord. 2016;202:16–22.

    Article  PubMed  Google Scholar 

  56. Cohen S. Perceived stress in a probability sample of the United States. 1988.

  57. Cohen S, Kamarck T, Mermelstein R. A global measure of perceived stress. J Health Soc Behav. 1983;24(4):385–96.

  58. Lee EH. Review of the psychometric evidence of the perceived stress scale. Asian Nurs Res. 2012;6(4):121–7.

    Article  Google Scholar 

  59. Spitzer RL, Kroenke K, Williams JB, Löwe B. A brief measure for assessing generalized anxiety disorder: the GAD-7. Arch Intern Med. 2006;166(10):1092–7.

    Article  PubMed  Google Scholar 

  60. Rush AJ, Trivedi MH, Ibrahim HM, Carmody TJ, Arnow B, Klein DN, et al. The 16-Item Quick Inventory of Depressive Symptomatology (QIDS), clinician rating (QIDS-C), and self-report (QIDS-SR): a psychometric evaluation in patients with chronic major depression. Biol Psychiatry. 2003;54(5):573–83.

    Article  PubMed  Google Scholar 

  61. Brown ES, Murray M, Carmody TJ, Kennard BD, Hughes CW, Khan DA, et al. The Quick Inventory of Depressive Symptomatology-Self-report: a psychometric evaluation in patients with asthma and major depressive disorder. Ann Allergy Asthma Immunol. 2008;100(5):433–8.

    Article  PubMed  PubMed Central  Google Scholar 

  62. Reilly TJ, MacGillivray SA, Reid IC, Cameron IM. Psychometric properties of the 16-item Quick Inventory of Depressive Symptomatology: a systematic review and meta-analysis. J Psychiatr Res. 2015;60:132–40.

    Article  PubMed  Google Scholar 

  63. Sharpe D. Chi-square test is statistically significant: Now what? Pract Assess Res Eval. 2015;20(1):8.

    Google Scholar 

  64. Kim HY. Statistical notes for clinical researchers: Chi-squared test and Fisher’s exact test. Restor Dent Endod. 2017;42(2):152.

    Article  PubMed  PubMed Central  Google Scholar 

  65. Eskildsen A, Dalgaard VL, Nielsen KJ, Andersen JH, Zachariae R, Olsen LR, et al. Cross-cultural adaptation and validation of the Danish consensus version of the 10-item Perceived Stress Scale. Scand J Work Environ Health. 2015;41(5):486–90.

  66. Toussaint A, Huesing P, Gumz A, Wingenfeld K, Haerter M, Schramm E, et al. Sensitivity to change and minimal clinically important difference of the 7-item Generalized Anxiety Disorder Questionnaire (GAD-7). J Affect Disord. 2020;265:395–401.

    Article  PubMed  Google Scholar 

  67. Masson SC. Minimum clinically important differences identified for commonly used depression rating scales. J Clin Epidemiol. 2013;66(7):805.

    Article  PubMed  Google Scholar 

  68. Bartel SJ, Sherry SB, Stewart SH. Self-isolation: a significant contributor to cannabis use during the COVID-19 pandemic. Subst Abuse. 2020;41(4):409–12.

    Article  CAS  Google Scholar 

  69. Campbell DG, Felker BL, Liu CF, Yano EM, Kirchner JE, Chan D, et al. Prevalence of depression–PTSD comorbidity: Implications for clinical practice guidelines and primary care-based interventions. J Gen Intern Med. 2007;22(6):711–8.

    Article  PubMed  PubMed Central  Google Scholar 

  70. Bleich A, Koslowsky M, Dolev A, Lerer B. Post-traumatic stress disorder and depression: An analysis of comorbidity. Br J Psychiatry. 1997;170:479.

    Article  CAS  PubMed  Google Scholar 

  71. Cuttler C, Spradlin A, Nusbaum AT, Whitney P, Hinson JM, McLaughlin RJ. Blunted stress reactivity in chronic cannabis users. Psychopharmacol. 2017;234(15):2299–309.

    Article  CAS  Google Scholar 

  72. Crippa JA, Zuardi AW, Martín-Santos R, Bhattacharyya S, Atakan Z, McGuire P, et al. Cannabis and anxiety: a critical review of the evidence. Hum Psychopharmacol Clin Exp. 2009;24(7):515–23.

    Article  CAS  Google Scholar 

  73. Berrendero F, Maldonado R. Involvement of the opioid system in the anxiolytic-like effects induced by ∆ 9-tetrahydrocannabinol. Psychopharmacol. 2002;163(1):111–7.

    Article  CAS  Google Scholar 

  74. Rubino T, Sala M, Vigano D, Braida D, Castiglioni C, Limonta V, et al. Cellular mechanisms underlying the anxiolytic effect of low doses of peripheral ∆ 9-tetrahydrocannabinol in rats. Neuropsychopharmacol. 2007;32(9):2036–45.

    Article  CAS  Google Scholar 

  75. Kedzior KK, Laeber LT. A positive association between anxiety disorders and cannabis use or cannabis use disorders in the general population-a meta-analysis of 31 studies. BMC Psychiatry. 2014;14(1):1–22.

    Article  Google Scholar 

  76. Metrik J, Jackson K, Bassett SS, Zvolensky MJ, Seal K, Borsari B. The mediating roles of coping, sleep, and anxiety motives in cannabis use and problems among returning veterans with PTSD and MDD. Psychol Addict Behav. 2016;30(7):743.

    Article  PubMed  PubMed Central  Google Scholar 

  77. Vidot DC, Islam JY, Camacho-Rivera M, Harrell MB, Rao DR, Chavez JV, et al. The COVID-19 cannabis health study: results from an epidemiologic assessment of adults who use cannabis for medicinal reasons in the United States. J Addict Dis. 2020;39(1):1–11.

  78. Buckner JD, Schmidt NB, Lang AR, Small JW, Schlauch RC, Lewinsohn PM. Specificity of social anxiety disorder as a risk factor for alcohol and cannabis dependence. J Psychiatr Res. 2008;42(3):230–9.

    Article  PubMed  Google Scholar 

  79. Buckner JD, Schmidt NB, Bobadilla L, Taylor J. Social anxiety and problematic cannabis use: Evaluating the moderating role of stress reactivity and perceived coping. Behav Res Ther. 2006;44(7):1007–15.

    Article  PubMed  Google Scholar 

  80. Yao H, Chen JH, Xu YF. Patients with mental health disorders in the COVID-19 epidemic. 2020.

  81. Pfefferbaum B, North CS. Mental health and the Covid-19 pandemic. N Engl J Med. 2020;383(6):510–2.

    Article  CAS  PubMed  Google Scholar 

  82. Cullen W, Gulati G, Kelly BD. Mental health in the Covid-19 pandemic. QJM Int J Med. 2020;113(5):311–2.

    Article  CAS  Google Scholar 

  83. Colder CR, Lee YH, Frndak S, Read JP, Wieczorek WF. Internalizing symptoms and cannabis and alcohol use: Between-and within-person risk pathways with coping motives. J Consult Clin Psychol. 2019;87(7):629.

    Article  PubMed  PubMed Central  Google Scholar 

  84. Farris SG, Metrik J, Bonn-Miller MO, Kahler CW, Zvolensky MJ. Anxiety sensitivity and distress intolerance as predictors of cannabis dependence symptoms, problems, and craving: The mediating role of coping motives. J Stud Alcohol Drugs. 2016;77(6):889–97.

    Article  PubMed  PubMed Central  Google Scholar 

  85. Hartmann SA, McLeish AC. Tolerance for specific negative affective states and coping-oriented cannabis use motives among college student cannabis users. J Am Coll Health. 2022;70(3):1–7.

  86. Bovasso GB. Cannabis abuse as a risk factor for depressive symptoms. Am J Psychiatry. 2001;158(12):2033–7.

    Article  CAS  PubMed  Google Scholar 

  87. Neumeister A, Seidel J, Ragen BJ, Pietrzak RH. Translational evidence for a role of endocannabinoids in the etiology and treatment of posttraumatic stress disorder. Psychoneuroendocrinol. 2015;1:577–84.

    Article  CAS  Google Scholar 

  88. Murillo-Rodriguez E, Pandi-Perumal SR, Monti JM. Cannabinoids and Neuropsychiatric Disorders. Springer; 2021.

  89. Bhattacharyya S, Morrison PD, Fusar-Poli P, Martin-Santos R, Borgwardt S, Winton-Brown T, et al. Opposite effects of ∆-9-tetrahydrocannabinol and cannabidiol on human brain function and psychopathology. Neuropsychopharmacol. 2010;35(3):764–74.

    Article  CAS  Google Scholar 

  90. Abizaid A, Merali Z, Anisman H, Cannabis. A potential efficacious intervention for PTSD or simply snake oil? J Psychiatry Neurosci. 2019;44(2):75.

    Article  PubMed  PubMed Central  Google Scholar 

  91. Mian MN, Altman BR, Earleywine M. Who volunteers for cannabis research? Examining potential research participation in cannabis research among emerging adults. Cannabis. 2019;2(2):135–43.

    Article  Google Scholar 

Download references

Acknowledgements

The authors wish to thank all the participants who gave their time to fill out this extensive survey during this difficult period. The authors also extend their gratitude to the individuals who kindly provided their comments on the survey content and format during the development stage, to Rachel Théoret, Samantha Kenny, Rebecca Burdayron and Christopher Kalogeropoulos for their help with preparing some documents for ethics application, to the organizations who helped circulate the survey in their networks, including the Canadian sleep promotion campaign Sleep On It Canada! (sleeponitcanada.ca) and Ottawa Public Health, and to NIVA inc, for their advice on distribution strategies. The authors thank the Clinical Investigation Unit at the Ottawa Hospital Research Institute, the University of Ottawa Heart Institute, the Royal Ottawa Mental Health Centre, and the Centre for Addiction and Mental Health for assistance with recruiting participants.

Funding

This study was supported by the Royal Ottawa Foundation for Mental Health. The funding body played no role in the design of the study and collection, analysis, and interpretation of data and in writing the manuscript.

Author information

Authors and Affiliations

Authors

Contributions

AM, JK, RR, and TK designed the study. LQ, MS, RR, and TK spearheaded data acquisition. AM analyzed the data and wrote the paper. RR was a major contributor to reviewing the data analysis and writing of the paper. AM, JK, LQ, MS, RR, and TK contributed to results interpretations. All authors reviewed and approved the final manuscript. All authors have agreed both to be personally accountable for the author’s own contributions and to ensure that questions related to the accuracy or integrity of any part of the work.

Corresponding author

Correspondence to R. Robillard.

Ethics declarations

Ethics approval and consent to participate

Electronic written informed consent was obtained from each participant. This study was approved by the Clinical Trials Ontario-Qualified Research Ethics Board (Protocol #2131).

Consent for publication

Not applicable.

Competing interests

RR received consultation fees from Eisai Co., Ltd. for a report unrelated to this article and In-kind research support from Dreem for a project unrelated to this article. All other authors declare that they have no competing interests.

Additional information

Publisher’s Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data.

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Murkar, A., Kendzerska, T., Shlik, J. et al. Increased cannabis intake during the COVID-19 pandemic is associated with worsening of depression symptoms in people with PTSD. BMC Psychiatry 22, 554 (2022). https://doi.org/10.1186/s12888-022-04185-7

Download citation

  • Received:

  • Accepted:

  • Published:

  • DOI: https://doi.org/10.1186/s12888-022-04185-7

Keywords