Cannabis use and patterns among middle and older aged Canadians prior to legalization: a sex-specific analysis of the Canadian Tobacco, Alcohol and Drugs Survey

As of October 2018, Canada became the second country in the world to legalize the recreational use of cannabis, also commonly known as marijuana, weed, and hashish [1]. According to the Government of Canada, the legalization of cannabis was implemented with three goals in mind; keeping it out of the hands of minors, reducing black market profits, and protecting the health of Canadians by providing access to safe cannabis via secure sources [2]. Prior to legalization, cannabis was the most commonly used illicit drug in Canada [3]. In 2014 alone, cannabis related costs burdened the Canadian economy with upwards of 2.8 billion dollars to combat economic, health and social consequences [3, 4]. While many people use cannabis without harm, it is important to note that adverse outcomes have been reported, especially among aging adults [5, 6]. In some adults, use of cannabis has been linked to an increased risk of psychiatric disorders such as schizophrenia and psychosis [7, 8], and chronic conditions such as heart disease, asthma, pneumonia, cognitive decline, and loss of executive functioning [9‐12]. A recent meta-analysis and systematic review noted that close to 1 in 8 people who have used cannabis experience cannabis dependence and cannabis abuse, while over 1 in 5 users may go on to develop a cannabis use disorder [13]. Although cannabis is commonly associated with age-related declines, legalization has been readily accepted by the Canadian public [14, 15].

In 2012, 42.5% of the entire Canadian population reported having ever used cannabis, with 12.2% reporting use in the past year [16]. The prevalence was highest among 18–24-year olds, with 33.3% reporting past-year use, followed by 20% among ages 15–17, 15.6% in ages 25–44, 6.7% in ages 45–64, and 0.8% in those aged 65+ [16]. While cannabis is clearly popular among younger Canadians, major substance use surveys have shown that cannabis use has steadily grown in adults [4, 17]. Studies from the United Kingdom and United States have also shown a similar trend with cannabis being one of the most widely used drugs in adults over the age of 50 [18, 19].

Additionally, cannabis use behaviours among males and females have been noted as distinct [20, 21]. Between 2002 and 2010, Canadian males report a 2.4% increase in their lifetime cannabis use, while use among females remained stagnant [16]. However, more recently, rates of female cannabis use has rapidly approached the rate of males [4]. Because substance use has historically been considered a male dominant problem, much of the literature has neglected to evaluate sex specific differences [22]. Pederson and colleagues (2015) noted that gender inequity among substance use research and health promotion efforts is a global challenge which must be addressed moving forward [23]. As such, it is essential that studies examine the sex specific differences of cannabis use and any related characteristics in Canada and across the globe.

In Canada, sociodemographic and economic factors associated with increased cannabis use include being a male, residing in the provinces of British Columbia and Nova Scotia, dwelling in urban areas, having a lower socioeconomic status, lower levels of post-secondary education attainment, and lower employment rates [6, 16, 24, 25]. Additionally, mental health complications such as depression, emotional distress, and psychosis have been associated with cannabis use [6, 26]. Finally, cannabis use may be linked to the uptake of other substances, such as tobacco, alcohol, and illicit substances such as opioids, amphetamines, and cocaine [6, 26]. Historically, given that younger Canadians have been the highest users of cannabis, most studies have focused on the youth and young adult population [26‐28]. These results may not be generalizable to older age groups or specific sexes, as they have been noted to be distinct in the ways they access, use and respond to cannabis [29].

Currently, middle and older aged adults represent more than 51% of the Canadian population, making up a significantly large portion of the demographic [30]. With the recent cannabis legalization and increased access to cannabis products across the nation, the relationship between cannabis use among older Canadians may undergo important changes. In order for the Canadian public health system to evaluate and update policies around legalization in the upcoming years, it is vital that information around cannabis utilization is available and can be reliably tracked. Therefore, the objective of this study is to identify the prevalence, characteristics, and patterns of past-year cannabis use among older Canadians, separately for males and females, prior to cannabis legalization in Canada.

Overall a total sample of 4789 individuals were included in this analysis, weighted to represent 8,890,444 females and 8,181,855 males aged 40 and above in Canada. After population weights were added, 60.4% of the respondents were aged 40 and above at the time of the survey. The total prevalence of cannabis use among females was 5.9% as compared to 9.0% in males, for a total of 7.4% in the entire sample.

The prevalence of past-year male and female cannabis use, for all 10 provinces, are displayed in Fig. 1. When examining all the provinces in Canada, British Columbia was noted as having the highest prevalence of past-year cannabis use in both sexes (16.5% females vs. 14.2% males) followed by Nova Scotia (8.9% female vs. 12.4% male). Contrarily, the lowest prevalence of female and male past-year cannabis use was reported in Québec (3.1% vs. 6.3%) and Ontario (3.6% female vs. 8.3% male).

The aim of this study was to assess the prevalence, characteristics, and patterns of pre-legalization cannabis use among middle and older aged Canadians, independently for males and females. In 2017, a year before Canadian cannabis legalization, the overall prevalence of past-year cannabis use in middle and older aged adults was 7.4%, which was higher than an earlier analysis conducted in 2012 [16]. In the present study, 9.0% males and 5.9% of females reported cannabis use in the past year. When examining the older male subgroup closer, determinants of use include having no partner, being a current cigarette smoker, and being an illicit drug user. Characteristics for older females, include residing in British Columbia or the Eastern-Atlantic provinces, residing in an urban community, suffering from poor mental health, cigarette smoking, using other tobacco products, and illicit drug use. This study clearly illustrates the sex-specific differences in cannabis use among older Canadians, providing baseline data for future studies investigating substance use and disorders among this age cohort and between sexes.

Middle and older aged males reported an increased overall prevalence of past-year cannabis use in 2017. While increased prevalence of cannabis among males was also recently reported in the United States by Hasin et al. [33] the reason for this finding might be multi-factorial. Although specific reasons remain debated, it is possible that cultural and behavioural acceptance of learned smoking habits in the male subgroups could be a contributing factor of increased cannabis use [34]. Additionally, it is interesting that our results note 62% of males who tried to quit or reduce their cannabis intake over the past 3 months, failed to do so (Table 1). These results are in agreeance with other investigations, which note that males have an increased prevalence of cannabis addiction and cannabis use disorders, making it difficult to quit overall cannabis intake [33, 35]. However, a study conducted by Herrmann (2015) highlighted that females were more likely to show more individual withdrawal symptoms, a higher severity, and more discomfort during the cannabis withdrawal process, when compared to males [36]. With increasing rates of cannabis use among females, it would be interesting to examine whether these trends hold true to the older Canadian sub-sample.

Supplementary characteristics note a high percentage (56%) of self-reported female medical cannabis users. This is in line with research in rat models that have found female rats to be more sensitive to Tetrahydrocannabinol’s (THC) pain blocking effects as compared to their male counterparts [37]. Although previous studies have identified that medical marijuana use is more commonly seen in men [38‐40], the trend of heightened mental health disorders among women may be the cause for the increased uptake of medical marijuana use in this population [41]. Additionally, it is important to note the rising popularity of vaporizers, such as e-cigarettes, as a delivery tool among this sample (Table 1). The increased prevalence of e-cigarette use has been noted across all age groups and should be monitored carefully given the rise in severe respiratory illnesses in relation to the concomitant use of e-cigarettes and cannabis products [28, 42‐44].

Among sociodemographic factors, having no partner was a determinant for past-year cannabis use among males. While many studies have reported marital and relationship status to be a general predictor of substance use in all sexes [33, 45‐47], it is important to note that no other studies have identified such an association to be specific to males. Many factors including the lack of social support, increased leisurely time allowing for more experimental behaviors, and lack of familial commitments, could be contributing to this association [46, 47]. Having said that, more exploration on the role that marital and romantic relationships in regulating drug usage is necessary.

In females, sociodemographic factors such as residing in urban communities was associated with past-year cannabis use. Hasin et al. (2018) has confirmed the notion of increased cannabis availability and subsequent usage in urban regions [33]. Additionally, a sex-based difference was noted among Slovakian females, that showed riskier substance use in females who reside in urban areas [48]. This study also highlighted that females residing in either British Columbia or the Eastern-Atlantic Provinces are more likely to be past-year cannabis users, compared to the other Canadian provinces. This finding is supported by a previous report by Statistics Canada, which found that British Columbians and Nova Scotians (one of four Eastern-Atlantic Provinces) had significantly higher prevalence of past-year marijuana use compared to other Canadian provinces [16]. Although Canada is one of the largest cannabis cultivators in the world, large quantities of cannabis have been known to be smuggled into Canada through Canadian seas and ports [49‐51]. Therefore, the close proximity of British Columbia and Nova Scotia to international shipping ports may make them prime location for illegally shipped contraband.

In regard to health factors, our findings indicate that females who experienced poorer self-reported mental health were more likely to be cannabis users as compared to those who reported very good or excellent mental health. An American study noted that mental well-being among cannabis users was significantly poorer than their non-using counterparts, especially among female users [52]. Although cannabis has been shown to have modest health benefits, long term use has been associated with cognitive impairment [53‐55]. The association between using cannabis and adverse mental health outcomes, such as increased depressive symptomology, worsening anxiety, and panic disorders, have been reported previously [41, 56]. Given that cannabis is often portrayed as a tool to improve mental health, adult cannabis users were likely to over-acknowledge its potential benefits [57, 58]. Therefore, these findings can also be indicative of individuals using cannabis products to manage declining mental health, as a form of self-therapy or prescribed rehabilitation [59]. Given the ambiguity surrounding the long-term effects of cannabis, it is important that public health professionals ensure that using cannabis does not exacerbate existing mental health problems or replace healthier mental health treatments.

Finally, among substance use variables, this study showed increased cannabis use among both male and female illicit drug users. In particular, a study by Han et al. (2017) highlighted the alarming rates of illicit drug use, in association with cannabis use in older populations [60]. While cannabis being a gateway drug into illicit drug use remains highly debated [61‐66], there is a general agreement among researchers to monitor the transition of marijuana to more lethal drugs [65‐67]. Given that the simultaneous use of multiple substances can make older adults susceptible to declining executive functions [68, 69], it is essential that measures to combat multiple substance use disorders are implemented to prevent additional burden of disease among this population.

Although novel and imperative to the body of substance use literature, this study is subjected to a few limitations. The CTADS relies on self-reported data and therefore is subjected to recall bias. This survey is also unable to capture some important variables including ethnicity and income, which may have influenced cannabis use behaviors in this sample. As is the case for all cross-sectional analyses, causational interpretation of these findings cannot be determined. The CTADS also neglects to include those living on the three Canadian territories and institutionalized populations, including those that are incarcerated, institutionalized, or active in the military. Some of these populations are identified in the literature to be active and substantial users of cannabis, and therefore their exclusion could have altered overall prevalence rates. Regardless of these limitations, this study allows for a large sample size and provides key insights on sex specific trends associated with cannabis use prior to legalization in Canada.

To our knowledge, this is the first nationally representative Canadian study to outline the prevalence, characteristics, and patterns of cannabis use in middle and older aged adults. In specific, predictors of past-year cannabis use for older and middle-aged males included having no partner, being a current cigarette smoker and illicit drug user. Predictors for females included residing in British Columbia, in the Eastern-Atlantic provinces and in an urban community, having poor mental health, smoking cigarettes, using tobacco products, and illicit drugs. This study highlights the importance of including middle and older aged adults in the discussion around cannabis, in order to create awareness around its use. Results from this study can help identify longitudinal trends of using cannabis in regard to the pre and post legalization era of cannabis in Canada. With the current landscape, it is important to further investigate the benefits of regular cannabis use among older Canadians, as well as identify potentials for harms in situations of misuse, overuse, and dependency. Additionally, our results suggest more research is needed around the female mental health and cannabis use, specifically the use of marijuana as a replacement for other beneficial mental health treatments and the potential trigger of worsening symptomology. Furthermore, as the population continues to age, it is important to examine substance use in this group distinctly and implement initiatives to offset any associated comorbidities.