Hearing disorders affect an estimated 466 million people globally, making it one of the most prevalent sensory impairments worldwide. Although there are various causes of hearing loss, including genetic mutations, infections, and exposure to loud noise, several studies have suggested a potential role for the endocannabinoid system (ECS) in hearing function.
The ECS is a complex signaling system that plays a crucial role in regulating numerous physiological processes, including pain sensation, appetite, mood, and immune response. It consists of endogenous ligands known as endocannabinoids (e.g., anandamide and 2-arachidonoylglycerol), cannabinoid receptors (CB1 and CB2), and enzymes responsible for the synthesis and degradation of endocannabinoids.
Recent studies have demonstrated that the ECS is present in several areas of the auditory system, including the cochlear nucleus, vestibular nucleus, and hair cells of the inner ear. For example, Baek et al. (2008) investigated the expression of CB2 receptors in the brainstem cochlear and vestibular nuclei of rats. They found that CB2 receptors were highly expressed in these areas, suggesting a potential role for CB2 agonists in treating hearing disorders.
One common hearing disorder that has been associated with cannabis use is tinnitus. Tinnitus is a condition characterized by ringing or buzzing sounds in the ears that can be persistent or intermittent. Although the exact mechanisms underlying tinnitus remain unclear, several studies have suggested that it may involve alterations in the ECS.
For example, Bankhead (2019) reported on a study presented at an American Association of Occupational Health Nurses conference which found a possible link between marijuana use and tinnitus. The study analyzed data from over 15000 participants who completed a survey on occupational health risks. The results showed that marijuana users had a higher prevalence of tinnitus compared to non-users.
Similarly, Narwani et al. (2020) conducted a review of the current literature on cannabis and tinnitus. They found that although some studies have reported improvements in tinnitus symptoms with cannabis use, others have reported no significant effects or even worsening symptoms.
In addition to tinnitus, there is evidence to suggest that cannabis may also be beneficial for other hearing disorders such as Ménière’s disease. Ménière’s disease is a disorder characterized by episodic vertigo (a sensation of spinning), fluctuating hearing loss, tinnitus, and pressure or fullness in the ear.
Frejo et al. (2016) identified several clinical subgroups based on the presentation of Ménière’s disease symptoms. One subgroup was characterized by more severe anxiety and depression symptoms compared to other subgroups. This finding is particularly relevant given recent research into the anxiolytic effects of cannabidiol (CBD), one of the non-psychoactive cannabinoids found in cannabis.
Blessing et al. (2015) conducted a comprehensive review of preclinical and clinical studies investigating CBD as a potential treatment for anxiety disorders. They found that CBD has demonstrated anxiolytic effects in animal models as well as human trials involving patients with social anxiety disorder, post-traumatic stress disorder, generalized anxiety disorder, and obsessive-compulsive disorder.
Furthermore, Choukèr et al. (2010) investigated the role of the ECS in motion sickness-induced nausea and vomiting. They found that CB1 receptor agonists significantly reduced nausea scores compared to placebo.
Considering these findings together suggests that further research into the potential therapeutic effects of cannabinoids on hearing disorders may be warranted. However, there are several important considerations to keep in mind when interpreting these findings.
Firstly, cannabis use can have both positive and negative effects on hearing function depending on various factors such as dosage, duration of use, mode of administration (e.g., smoking vs oral ingestion), and individual differences in sensitivity to cannabinoids.
Secondly, although some cannabinoids such as CBD have demonstrated promising therapeutic effects without producing psychoactive effects like THC does; their efficacy has yet to be confirmed through large-scale randomized controlled trials.
Thirdly, even if cannabinoids prove efficacious for certain hearing disorders; their use may be contraindicated due to potential interactions with other medications or adverse side effects such as dizziness or sedation.
In conclusion; it seems plausible based on current research; that certain cannabinoids may hold promise as potential treatments for various hearing disorders such as tinnitus or Ménière’s disease; but further research is needed before definitive conclusions can be drawn about their safety or efficacy.