This is the first study to assess perspectives and usage patterns of cannabis in patients experiencing tinnitus. The results of this study demonstrate an active interest amongst patients with tinnitus to consider cannabis as a potential adjunctive treatment for symptom management. Moreover, cannabis use is both common and can be beneficial in this patient population. An understanding of patient attitudes towards cannabis use is a prerequisite to exploring its potential use in clinical practice.
One theory of tinnitus is that of neuronal hyperexcitability in the auditory brain region [25]. Believed to be initially triggered by trauma, damaged auditory nerve fibers undergo maladaptive neural plasticity, which leads to decreases in inhibition and increases in excitation of multiple regions of the peripheral and central auditory pathway. This leads to an imbalance that ultimately causes neural hyperexcitability and aberrant activity that creates a false sensation of sound that is perceived as tinnitus [25]. Antiepileptic drugs, such as lamotrigine and gabapentin, have been studied as pharmacological treatment for tinnitus, given their inhibitory effect in the central nervous system [26,27,28]. However, there is insufficient evidence to support the use of antiepileptic drugs for tinnitus and it has not shown to be beneficial compared to placebo [28].
Endocannabinoid receptors are expressed in the vestibular nucleus complex (VNC) and have been theorized to suppress abnormal neuronal activity, inhibit neurotransmitter release, and play an autoregulatory role [29]. Activity of cannabinoid 1 (CB1) receptors may guard against neuronal hyperexcitability, having been shown to suppress epileptiform and seizure activity in animals [25, 30, 31]. Through other pathways, cannabinoids have been shown to possess anti-inflammatory, antiemetic, anxiolytic, sedative, and antioxidant properties [32,33,34]. Furthermore, early models of tinnitus have similarities with neurological disorders, such as neuropathic pain and epilepsy, both of which can be modulated by cannabinoids [20, 22, 35,36,37]. Given that cannabinoids possess neuroprotective effects in the cochlea and can modulate neuroinflammatory responses in the auditory system, cannabis may be a novel pharmacological candidate for treatment of tinnitus [20, 38, 39].
However, the literature is divided on the impact of cannabis on tinnitus as studies have found opposing results. Only two studies to date have found associations with tinnitus as a cannabis-related side effect [40]. In animal studies, cannabinoids were found to increase tinnitus in rat models, and although it was found to be otoprotective, but it was not effective in reducing tinnitus in guinea pigs [41, 42]. In human studies, there are contrasting results in the association between cannabis and tinnitus. In one study, tinnitus was found to have no association with cannabis use, while another study found a correlation between tinnitus and cannabis use, but not frequency of use or tinnitus severity [43, 44]. Studies have also found that cannabis use can worsen or induce tinnitus [43,44,45,46]. However, causative conclusions cannot be drawn from these studies as they are mainly correlative in nature. If an association exists between cannabis and tinnitus, there are three possible directions: (1) the experience of tinnitus increases cannabis use, (2) cannabis use increases tinnitus symptoms, (3) an extrinsic factor increases both variables [44]. Mood disorders, a possible contributing extrinsic factor, have been shown to increase both cannabis use and tinnitus perception [12, 47]. The relationship between tinnitus and cannabis is complex and likely multifactorial, influenced by psychological factors, drug formulation, administration route, and concetration [20, 44]. It is possible that patients experiencing tinnitus rely on cannabis as a form of self-medication. Given the lack of high quality prospective research on the effect of cannabis on tinnitus, the available evidence can neither support nor refute its use. Further research is needed to explore the role of cannabis in tinnitus to guide therapeutic interventions.
Over 95% of patients in this study reported that they would consider cannabis as treatment for their tinnitus and its associated symptoms. Patients’ willingness to consider alternative therapies, such as cannabis, for tinnitus can be due to several reasons. Firstly, tinnitus can be exceedingly burdensome as it is associated with insomnia, irritability, concentration difficulties, interruptions in daily activities, and psychiatric symptoms such as anxiety and depression [16, 48]. Its consistent presence and the lack of control that patients experience results in varying emotional impacts, ranging from mild irritation, to anxiety, depression, insomnia, and even suicide [35]. Secondly, patients also often do not receive adequate symptom relief from conventional therapy [16,17,18]. Even conventional therapy, such as sound masking, may not be preferrable for patients given the cost associated with hearing aids and the introduction of additional noise stimulus that might not be much different than a patient’s tinnitus. Cognitive behavioral therapy is also not widely available or adequately funded by insurance or a public health system.
Antidepressants, anti-anxiolytics, and cognitive behavioral therapy are current treatments for tinnitus, with the latter being the best-established treatment to date [13]. This suggests that tinnitus may be maintained and influenced by psychological and cognitive factors. Psychiatric conditions may be the primary cause, or co-exist with neuro-otologic conditions [48]. Cannabis use is common in patients with mood and anxiety disorders and it has efficacy in reducing anxiety behaviors in patients with generalized anxiety disorder, panic disorder, and social anxiety, without producing anxiogenic effects [49]. Pharmacological treatment of mood disorders with anxiolytics and antidepressants resulted in a reduction in tinnitus symptoms [12, 49, 50]. Given the association of tinnitus with anxiety, depression, migraines, and insomnia, coupled with the therapeutic efficacy of cannabis in managing aforementioned symptoms, it is reasonable to consider that patients with tinnitus may also benefit from cannabis treatment.
In this study, sleep disturbances, emotional difficulties, such as anxiety, depression, and fear, and pain were the most frequently reported symptoms that patients would consider cannabis for. They were also the most reported tinnitus-related symptoms that improved with cannabis use. The overlap between these two entities highlights that psychological symptoms are a primary source of distress for patients with tinnitus and that patients are eager to alleviate these symptoms. Cannabis may an attractive therapeutic for these patients as when used for depression and anxiety, it also led to a decrease in pain, and improved quality of life and sleep [50].
Patients in this study were mostly likely to consider edibles, tablets, and cream if they were to use cannabis. However, smoking/vaporizing was one of the most commonly used routes of delivery. There appears to be a level of discordance between the preferred and actual method of cannabis use. Similar results were seen in a survey that assessed cannabis use amongst head and neck cancer patients [24]. The disconnect may be explained by concern of cost and physical health side effects of cannabis, which were reported in 29% and 53% of patients, respectively. The cost of oil, edible, tablet forms of cannabis are greater compared to the smoking and vaporizing forms, with the latter also being known to cause respiratory consequences.
This study found that 73% of patients were somewhat-to-much-more likely to consider cannabis use after its legalization in Canada in 2018. Previous research has shown that those who find a behavior socially acceptable are more likely to engage in it [51]. Similarly, the social acceptability of cannabis is higher in individuals that report anxiety or acute pain [52]. Adults with medical conditions have a high prevalence of cannabis use compared to adults without medical conditions, and are more likely to report cannabis use for medical reasons [53]. The primary concern for patients were the possible psychological side effects of cannabis, such as psychosis, paranoia, and social impairment. Given that patients with tinnitus may be increasingly debating or engaging in cannabis use, physicians can consider discussing cannabis’ safety profile and exploring patients’ concerns.
Half of the patients in this study received information regarding cannabis from a family member or friend, despite the majority of patients stating that they wish to receive information from a physician. Only 20% received information about cannabis from a healthcare professional. Individuals that receive most of their information regarding cannabis from social media, internet, or friends and relatives are more likely to believe unsupported claims about cannabis [54]. Given that 96% of respondents were interested in learning more about cannabis if it were shown to improve tinnitus, it is imperative that public health campaigns and otolaryngologists managing patients with tinnitus are the primary source of information for patients to ensure they are receiving accurate information.
This study has several limitations. The duration or severity of patients’ tinnitus was not captured as part of the survey and may have played a role in influencing motivation to use cannabis. A validated tinnitus scale, such as the Tinnitus Handicap Inventory, may have been helpful in quantifying tinnitus symptom severity. Many patients noted in the questionnaire that reasons for considering cannabis treatment were due to limited relief of symptoms from current treatments. Although symptom duration in patients experiencing tinnitus was not found to be associated with quality of life, it is possible that it may affect their perception of cannabis as a treatment option to manage their symptoms [15]. Furthermore, convenience sampling was utilized, which may have limited the representativeness of this tinnitus patient population. In addition, this study is subject to recall bias. Patients may not have been able to accurately recall whether or not they previously consumed cannabis, potentially leading to an underreporting of cannabis use pattern rates.