Behavioral Hearing Thresholds and Distortion Product Otoacoustic Emissions in Cannabis Smokers

The effects of cannabinoid agonism on auditory discrimination

Recent evidence suggests that cannabis can impair simple auditory processes, and these alterations might be due to cannabinoid agonism. The effect of cannabinoid agonism on relatively complex processes such as auditory discrimination is unknown. The goal of this study was to examine the impact of WIN 55,212-2, a CB 1 receptor and CB 2 receptor agonism, on auditory discrimination using a go/no-go task. Twenty-two male and female Sprague-Dawley rats were initially trained to lever-press for sucrose to either a pure tone or white noise cue in a go/no-go paradigm, where rats were reinforced for lever-pressing during one cue and punished for lever-pressing during the other auditory cue. After criterion performance was met, rats were then injected with WIN 55,212-2 at 1.2 mg/kg, 3 mg/kg, or a corresponding vehicle (saline) and were tested on auditory discrimination. On day 3, active lever-pressing was higher in both the low- and high-dose WIN groups compared with the saline group. Overall lever-pressing decreased over time in the high-dose WIN 55,212-2 group. There were no effects of the drug on discrimination or errors, suggesting that cannabinoid agonism did not negatively affect auditory discrimination. This is the first study to examine the impact of cannabinoids on the discrimination of tones, finding that, contrary to previous research, the low and high doses of WIN 55,212-2 did not adversely impact auditory-linked behaviors.

Endocannabinoid System and the Otolaryngologist

The endocannabinoid system is located throughout the central and peripheral nervous systems, endocrine system, gastrointestinal system, and within inflammatory cells. The use of medical cannabinoids has been gaining traction as a viable treatment option for varying illnesses in recent years. Research is ongoing looking at the effect of cannabinoids for treatment of common otolaryngologic pathologies. This article identifies common otolaryngologic pathologies where cannabinoids may have benefit, discusses potential drawbacks to cannabinoid use, and suggests future directions for research in the application of medical cannabinoids.

Tobacco, but Neither Cannabis Smoking Nor Co-Drug Use, Is Associated With Hearing Loss in the National Health and Nutrition Examination Survey, 2011 to 2012 and 2015 to 2016

INTRODUCTION

A relationship between tobacco smoking and hearing loss has been reported; associations with cannabis smoking are unknown. In this cross-sectional population-based study, we examined relationships between hearing loss and smoking (tobacco, cannabis, or co-drug use).

METHODS

We explored the relationship between hearing loss and smoking among 2705 participants [mean age = 39.41 (SE: 0.36) years] in the National Health and Nutrition Examination Survey (2011 to 12; 2015 to 16). Smoking status was obtained via questionnaire; four mutually exclusive groups were defined: nonsmokers, current regular cannabis smokers, current regular tobacco smokers, and co-drug users. Hearing sensitivity (0.5 to 8 kHz) was assessed, and two puretone averages (PTAs) computed: low- (PTA 0.5,1,2 ) and high-frequency (PTA 3,4,6,8 ). We defined hearing loss as threshold >15 dB HL. Multivariable logistic regression was used to examine sex-specific associations between smoking and hearing loss in the poorer ear (selected based on PTA 0.5,1,2 ) adjusting for age, sex, race/ethnicity, hypertension, diabetes, education, and noise exposure with sample weights applied.

RESULTS

In the age-sex adjusted model, tobacco smokers had increased odds of low- and high-frequency hearing loss compared with non-smokers [odds ratio (OR) = 1.58, 95% confidence ratio (CI): 1.05 to 2.37 and OR = 1.97, 95% CI: 1.58 to 2.45, respectively]. Co-drug users also had greater odds of low- and high-frequency hearing loss [OR = 2.07, 95% CI: 1.10 to 3.91 and OR = 2.24, 95% CI: 1.27 to 3.96, respectively]. In the fully adjusted multivariable model, compared with non-smokers, tobacco smokers had greater odds of high-frequency hearing loss [multivariable adjusted odds ratio = 1.64, 95% CI: 1.28-2.09]. However, in the fully adjusted model, there were no statistically significant relationships between hearing loss (PTA 0.5,1,2 or PTA 3,4,6,8 ) and cannabis smoking or co-drug use.

DISCUSSION

Cannabis smoking without concomitant tobacco consumption is not associated with hearing loss. However, sole use of cannabis was relatively rare and the prevalence of hearing loss in this population was low, limiting generalizability of the results. This study suggests that tobacco smoking may be a risk factor for hearing loss but does not support an association between hearing loss and cannabis smoking. More definitive evidence could be derived using physiological measures of auditory function in smokers and from longitudinal studies.

Cannabis related side effects in otolaryngology: a scoping review

BACKGROUND

Cannabis has been rapidly legalized in North America; however, limited evidence exists around its side effects. Health Canada defines side effect as a harmful and unintended response to a health product. Given drug safety concerns, this study's purpose was to review the unintended side effects of cannabis in otolaryngology.

METHODS

The Preferred Reporting Items For Systematic Reviews and Meta-analysis extension for Scoping Reviews (PRISMA-ScR) protocol was used to conduct a scoping review of the MEDLINE, EMBASE, CINAHL, and CENTRAL databases. (PROSPERO: CRD42020153022). English studies in adults were included from inception to the end of 2019. In-vitro, animal, and studies with n < 5 were excluded. Primary outcome was defined as unintended side effects (defined as any Otolaryngology symptom or diagnosis) following cannabis use. Oxford Centre for Evidence-Based Medicine: Levels of Evidence and risk of bias using the Risk of Bias in randomized trials (RoB 2) and Risk of Bias in Non-Randomized Studies of Interventions (ROBINS-I) tools were assessed.. Two authors independently reviewed all studies; the senior author settled any discrepancies.

RESULTS

Five hundred and twenty-one studies were screened; 48 studies were analysed. Subspecialties comprised: Head and Neck (32), Otology (8), Rhinology (5), Airway (5), Laryngology (1). Cannabis use was associated with unintended tinnitus, vertigo, hearing loss, infection, malignancy, sinusitis, allergic rhinitis, thyroid dysfunction, and dyspnea. About half (54.1%) of studies showed increased side effects, or no change in symptoms following cannabis use. Oxford Levels of Evidence was 2-4 with substantial heterogeneity. Risk of bias assessment with RoB2 was low to high and ROBINS-1 was moderate to critical.

CONCLUSION

This was the first comprehensive scoping review of unintended side effects of cannabis in Otolaryngology. The current literature is limited and lacks high-quality research Future randomized studies are needed to focus on therapeutic effects of cannabis in otolaryngology. Substantial work remains to guide clinicians to suggest safe, evidence-based choices for cannabis use.

Association Between Nonoptimal Blood Pressure and Cochlear Function

OBJECTIVES

The association between hearing loss and risk factors for cardiovascular disease, including high blood pressure (BP), has been evaluated in numerous studies. However, data from population- and laboratory-based studies remain inconclusive. Furthermore, most prior work has focused on the effects of BP level on behavioral hearing sensitivity. In this study, we investigated cochlear integrity using distortion product otoacoustic emissions (DPOAEs) in persons with subtle elevation in BP levels (nonoptimal BP) hypothesizing that nonoptimal BP would be associated with poorer cochlear function.

DESIGN

Sixty individuals [55% male, mean age = 31.82 (SD = 11.17) years] took part in the study. The authors measured pure-tone audiometric thresholds from 0.25 to 16 kHz and computed four pure-tone averages (PTAs) for the following frequency combinations (in kHz): PTA0.25, 0.5, 0.75, PTA1, 1.5, 2, 3, PTA4, 6, 8, and PTA10, 12.5, 16. DPOAEs at the frequency 2f1-f2 were recorded for L1/L2 = 65/55 dB SPL using an f2/f1 ratio of 1.22. BP was measured, and subjects were categorized as having either optimal BP (systolic/diastolic <120 and <80 mm Hg) or nonoptimal BP (systolic ≥120 or diastolic ≥80 mm Hg or use of antihypertensives). Between-group differences in behavioral thresholds and DPOAE levels were evaluated using 95% confidence intervals. Pearson product-moment correlations were run to assess the relationships between: (1) thresholds (all four PTAs) and BP level and (2) DPOAE [at low (f2 ≤ 2 kHz), mid (f2 > 2 kHz and ≤10 kHz), and high (f2 > 10 kHz) frequency bins] and BP level. Linear mixed-effects models were constructed to account for the effects of BP status, stimulus frequency, age and sex on thresholds, and DPOAE amplitudes.

RESULTS

Significant positive correlations between diastolic BP and all four PTAs and systolic BP and PTA0.25, 0.5, 0.75 and PTA4, 6, 8 were observed. There was not a significant effect of BP status on hearing thresholds from 0.5 to 16 kHz after adjustment for age, sex, and frequency. Correlations between diastolic and systolic BP and DPOAE levels were statistically significant at the high frequencies and for the relationship between diastolic BP and DPOAE level at the mid frequencies. Averaged across frequency, the nonoptimal BP group had DPOAE levels 1.50 dB lower (poorer) than the optimal BP group and differences were statistically significant (p = 0.03).

CONCLUSIONS

Initial findings suggest significant correlations between diastolic BP and behavioral thresholds and diastolic BP and mid-frequency DPOAE levels. However, adjusted models indicate other factors are more important drivers of impaired auditory function. Contrary to our hypothesis, we found that subtle BP elevation was not associated with poorer hearing sensitivity or cochlear dysfunction. We consider explanations for the null results. Greater elevation in BP (i.e., hypertension itself) may be associated with more pronounced effects on cochlear function, warranting further investigation. This study suggests that OAEs may be a viable tool to characterize the relationship between cardiometabolic risk factors (and in particular, stage 2 hypertension) and hearing health.

An Exploratory Study of Early Auditory Evoked Potentials in Cannabis Smokers

Purpose Cannabis is widely used for medicinal and recreational purposes. Studies have evaluated its health benefits and consequences, although there is limited work on its effects on the auditory system. In this exploratory study, we evaluate the effects of cannabis smoking on early auditory evoked potentials. Method We investigated auditory brainstem response (ABR) and electrocochleography waveforms in 18 cannabis smokers (44% women, 54% men; M _age = 23.06 years, range: 21-28 years) and 19 nonsmoker controls (63% women, 37% men; M _age = 23.74 years, range: 21-33 years). Threshold ABRs were recorded using rarefaction clicks at a rate of 17.7/s from 80 dB nHL to Wave V threshold. Resulting amplitudes and latencies for Waves I, III, and V were compared via independent-samples t tests. Electrocochleograms obtained with 90 dB nHL (7.1/s) alternating clicks were assessed for summating and compound action potentials, which were compared between groups using independent-samples t tests. Results ABR Wave I amplitudes were significantly lower in smokers (M = 0.14 μV, SD = 0.11) compared to nonsmokers (M = 0.21 μV, SD = 0.10, p = .039) at 80 dB nHL. Wave V latencies were significantly delayed in smokers at 80 dB nHL. Wave I and III latencies did not differ significantly between the two groups. Summating potential/compound action potential ratios were significantly elevated in smokers (M = 0.30, SD = 0.04) versus nonsmokers (M = 0.21, SD = 0.05, p = .042). Conclusion We identified significant differences in electrophysiological outcomes between cannabis smokers and nonsmokers. Cannabis smoking may have a subtle neurotoxic effect on the auditory system. Larger confirmatory studies are warranted.

Headphones and other risk factors for hearing in young adults

Background:

Personal listening device (PLD) use with headphones is increasing in young adults and in most listening environments occur in background noise. Headphone choice can be important because certain headphones are more effective in limiting background noise than stock earbuds. Binge drinking, marijuana, and hard drug use have also been associated with high-volume PLD use. The purpose of this study was to explore the relationship between preferred headphone type, listening level, and other health risk behaviors.

Methods:

Two-hundred and twenty undergraduates were recruited and completed a PLD use and risk behavior survey. Survey data included self-reported alcohol and marijuana use. Bilateral otoscopy, tympanometry, and pure-tone threshold testing (0.25–8 kHz) were completed. Participants listened to one hour of music using preferred headphone type with a probe microphone in the ear canal to measure equivalent continuous sound level (LAeq).

Results:

Mean LAeq was similar for the three types of headphones used. Participants who reported higher amounts of drinks per month and smoking marijuana within the last month had significantly higher LAeq levels than those who reported lower amounts of drinks per month and not smoking marijuana in the last month. There was no significant interaction between headphone type and reported drinks per month or marijuana use.

Conclusion:

Young adults with normal hearing who have higher preferred listening levels also reported more alcohol and marijuana use, although headphone type was not associated with any of these variables.

Self-Reported Drug Use and Hearing Measures in Young Adults

Purpose The purpose of this study was to examine marijuana or other substance use on pure-tone thresholds and distortion product otoacoustic emissions (DPOAEs) in young adults. Method Young adults (n = 243; 182 women, 61 men; M _age = 20.9 years, SD = 2.7 years) participated in this study. Survey data included personal music system use, marijuana use, and misuse of prescription medications. Otoscopy, tympanometry, pure-tone audiometry, and DPOAEs were obtained. Pure tones from octave frequencies of 0.25 through 8 kHz were obtained, and DPOAEs were recorded between f₂ frequencies of 1 and 6 kHz using two continuously presented stimulus tones swept in frequency. Results Those who reported marijuana or stimulant use had similar pure-tone averages (0.5, 1, 2, and 4 kHz) compared to those who reported never using marijuana or stimulants. Women who reported marijuana use in the past 30 days > two times had statistically significant higher mean DPOAEs compared to women who reported ≤ two times or no marijuana use in the past 30 days. Men, however, who reported marijuana use in the past 30 days > two times had lower, but not statistically significant, mean DPOAEs compared to men who reported ≤ two times or no marijuana use in the past 30 days. Women who reported ever using stimulants had statistically significant higher mean DPOAEs compared to women who reported never using stimulants; for men, mean DPOAEs were similar between those who reported ever using stimulants and those who never used stimulants. Conclusions The results of this study demonstrate different and contradictory associations between marijuana use, stimulant use, and hearing outcomes as a function of sex. Future research is needed to explore these associations utilizing larger sample sizes while accounting for additional harmful exposures to other noise exposures.