Characteristics of Older Adult Users of Medical Cannabis
The current study included data from 9766 older adults (65 years and above, 60.0% female) who completed the intake questionnaire (Fig. 1). Among them, 4673 users (61.4% female) completed at least one follow-up visit. The interval between the intake and the follow-up visit was 90.6 (SD ± 58) days. The demographic characteristics of older adults at the intake visit are shown in Table 1. Data for patients who also attended a follow-up visit are shown in SI Table 1 (see the Electronic Supplementary Material). At intake, older adult users had a mean age of 73.2 (SD ± 6.8) years (median = 72.0 years) and women were older than men. More women than men attended the clinic (intake visit: z = 19.7, p < 0.0001; follow-up visit: z = 15.6, p < 0.0001). These patients represented 23.1% of all users attending the medical cannabis clinic who completed the intake questionnaire (n = 42,267, mean age = 51.5 ± 16.8 years). Older adult users resided in Ontario (57.9%), Alberta (16.3%), Newfoundland and Labrador (15.0%), or Nova Scotia (9.1%) (n = 7440). Among them, 64.4% were married or in common-law relationships, 28.2% were divorced, and 7.4% were single (n = 9334). Previous cannabis use was reported by 15.5% of older adults, which was more common in men than women. Older adults were most frequently referred to the clinic for pain disorders, and the most common concomitant medications were over-the-counter analgesics and opioids (Table 1). SI Table 2 shows that arthritis, chronic pain, and lower back pain were the most frequent pain conditions. Pain was more common in women than men, whereas oncological and neurological conditions were more common in men than women. All concomitant medications except opioids were used more often by women than men.
Type and Amount of Medical Cannabis Use Among Older Adults
At follow-up, 81.0% of older adults reported using cannabis oils and 11.1% reported using herbal cannabis (n = 4302). More men than women used herbal cannabis (z = 6.44; p < 0.0001) whereas more women than men preferred cannabis oils (z = 3.87; p = 0.0001).
Among those taking cannabis oils at follow-up (n = 2495), the majority consumed less than 2 mL/day (Table 2). Older adults preferred to use CBD over THC (almost exclusively or mostly CBD [83.6%] vs almost exclusively or mostly THC [4.4%]). Over half of older adults used almost exclusively CBD oils (males = 50%, females = 53.2%), whereas only 2.3% of men and 1.6% of women among older adults used oils containing THC almost exclusively. Men and women did not differ in amounts (χ2 = 1.19, p = 0.88) or composition (χ2 = 7.74, p = 0.10) of cannabis oils used. The amount of herbal cannabis used was less than 1.5 g/day for the majority of older adults (SI Table 3; see the electronic supplementary material), and was higher in men than women (χ2 = 9.64, p = 0.047).
Self-Reported Adverse Effects After Beginning Medical Cannabis Use
At follow-up, among older adults using cannabis oils (n = 3009), at least one adverse effect was reported by 23.7% of men (n = 1097) and 26.6% of women (n = 1912). These rates did not differ between men and women (z = 3.08; p = 0.08). The most common adverse effects were dry mouth (12.8%), drowsiness (8.6%), and dizziness (4.0%). Anxiety was reported by 1.3% and hallucinations by 0.5%.
Self-Reported Perception of Symptoms and Medication Use After Beginning Medical Cannabis Use
At follow-up, users were asked to rate if there were changes in their symptoms of pain, mood, and sleep since starting medical cannabis (n = 4303) (Fig. 2). A larger proportion of users reported improvement versus no change or worsening in these symptoms (pain symptoms [n = 3597], ratio 2.6, z = 1482.6, p < 0.0001; sleep [n = 3267], ratio 1.8, z = 549.4, p < 0.0001; mood [n = 2623], ratio 1.1, z = 16.4, p < 0.0001). No differences were found in the proportions of men and women rating pain (χ2 = 2.18, p = 0.70), sleep (χ2 = 8.65, p = 0.12), or mood (χ2 = 3.51, p = 0.62) symptoms.
Older adults were also asked if their doses of concomitant medications changed after starting medical cannabis use. Adequate data were available for four classes of drugs: opioids, nerve modulators, antidepressants, and benzodiazepines (Fig. 3). Across those drug classes, the majority of older adults reported that the dose remained unchanged, while 35.6% and 19.9% of older adults reported using a reduced dose of opioids and benzodiazepines, respectively. However, the proportion of those reporting use of a reduced dose was larger than those reporting use of an increased dose for all drug categories (opioids: ratio 4.5, z = 179.9, p < 0.0001; nerve modulators: ratio 2.1, z = 16.9, p < 0.0001; antidepressants: ratio 2.8, z = 25.9, p < 0.0001; benzodiazepines: ratio 5.2, z = 41.3, p < 0.0001). The percentages of men and women in each category of change in medication doses were similar (nerve modulators: χ2 = 4.48, p = 0.48; antidepressants: χ2 = 3.75, p = 0.59; benzodiazepines: χ2 = 5.32, p = 0.38) except for opioids (opioids: χ2 = 17.83, p = 0.003, more men reported using ‘significantly decreased’ doses of opioids [z = −2.35, p = 0.018, compared to the rest of the categories]).
Time Trends in Medical Cannabis Use Among Older Adults
Between 2014 and 2020, the proportion of older adults increased from 17.6% (total sample across all ages, n = 18555) pre-2018 to 31.2% (n = 8869) in 2019 (odds ratio [OR] = 1.20, p < 0.001), although this number decreased to 22.7% in 2020 (n = 5644), possibly due to the coronavirus disease 2019 (COVID-19) pandemic. Furthermore, the proportion of women among older adults increased from 56.5% pre-2018 to 61.7% in 2020 (OR = 1.08, p < 0.0001).
The types of cannabis used also changed over time. While herbal cannabis use declined from pre-2018 to 2020 (OR = 0.24; p < 0.0001), use of cannabis oils among older adults increased (OR = 1.66; p < 0.0001) (Fig. 4).