Lifestyle and dietary interventions for Ménière's disease

Restriction of salt, alcohol and coffee intake and Ménière's disease: insight from Mendelian randomization study

Background

Restricting salt, caffeine, and alcohol intake is commonly recommended as a first-line treatment for patients with Ménière's disease (MD). However, it remains unclear whether these interventions effectively improve symptoms of MD. Therefore, we conducted a bidirectional two-sample Mendelian randomization (MR) analysis to evaluate the relationship between these dietary modifications and MD.

Methods

Summary statistics for salt added to food, alcohol consumption, coffee consumption, and MD were sourced from the United Kingdom Biobank, GSCAN, and the FinnGen study, involving up to 941,280 participants. The main analyses were performed using the random-effects inverse-variance weighted (IVW) approach and were complemented by four additional methods. Multiple sensitivity analyses were performed to validate the findings, and both forward and reverse MR analyses were employed to address potential reverse causality bias.

Results

The primary MR results using the IVW method revealed that salt added to food (OR = 0.719, 95% CI: 0.429-1.206; p = 0.211), alcohol consumption (OR = 0.834, 95% CI: 0.427-1.628; p = 0.595), and coffee consumption (OR = 0.852, 95% CI: 0.555-1.306; p = 0.461) were not significantly correlated with MD. In reverse analysis, no evidence of significant effect was found from MD to salt added to food (OR = 1.000, 95% CI: 0.993-1.007; p = 0.957), alcohol consumption (OR = 0.998, 95% CI: 0.987-1.008; p = 0.682), and coffee consumption (OR = 0.998, 95% CI: 0.985-1.011; p = 0.72).

Conclusion

This MR analysis did not identify convincing evidence to support the idea that restricting salt, caffeine, and alcohol intake is beneficial for the treatment of MD.

Exploring causal correlations between inflammatory cytokines and Ménière's disease: a Mendelian randomization

Objectives

Previous studies have highlighted associations between certain inflammatory cytokines and Ménière's Disease (MD), such as interleukin (IL) -13 and IL-1β. This Mendelian randomization aims to comprehensively evaluate the causal relationships between 91 inflammatory cytokines and MD.

Methods

A comprehensive two-sample Mendelian randomization (MR) analysis was conducted to determine the causal association between inflammatory cytokines and MD. Utilizing publicly accessible genetic datasets, we explored causal links between 91 inflammatory cytokines and MD risk. Comprehensive sensitivity analyses were employed to assess the robustness, heterogeneity, and presence of horizontal pleiotropy in our findings.

Results

Our findings indicate that MD causally influences the levels of two cytokine types: IL-10 (P=0.048, OR=0.945, 95%CI =0.894~1.000) and Neurotrophin-3 (P=0.045, OR=0954, 95%CI =0.910~0.999). Furthermore, three cytokines exhibited significant causal effects on MD: CD40L receptor (P=0.008, OR=0.865, 95%CI =0.777-0.963), Delta and Notch-like epidermal growth factor-related receptor (DNER) (P=0.010, OR=1.216, 95%CI =1.048-1.412), and STAM binding protein (P=0.044, OR=0.776, 95%CI =0.606-0.993).

Conclusion

This study suggests that the CD40L receptor, DNER, and STAM binding protein could potentially serve as upstream determinants of MD. Furthermore, our results imply that when MD is regarded as the exposure variable in MR analysis, it may causally correlate with elevated levels of IL-10 and Neurotrophin-3. Using these cytokines for MD diagnosis or as potential therapeutic targets holds great clinical significance.

Low-sodium diet with adequate water intake improved the clinical efficacy in Ménière's disease

BACKGROUND

Ménière's disease (MD) is a common idiopathic inner ear disorder in otorhinolaryngology characterized by recurrent episodes of vertigo, fluctuating sensorineural hearing loss, tinnitus and ear fullness.

OBJECTIVE

To study the effects of low-sodium diet with adequate water intake on the clinical efficacy in MD.

METHODS

Fifty patients diagnosed with stage-3 unilateral MD were randomly divided into control group(n = 25) and experimental group(n = 25). The control group was given routine medication therapy, and the experimental group was restricted to an sodium intake of 1500 mg/d and a water intake of 35 ml/kg/d based in addition to the routine medication therapy. The two groups were assessed using pure tone audiometry, electrocochleography, Tinnitus Handicap Inventory (THI), and Dizziness Handicap Inventory (DHI).

RESULTS

The pure tone audiometry and electrocochleography showed better improvements after treatment in the experimental group than the control group (p < 0.05). The THI improved values in the experimental group were significantly higher than the control group (p < 0.001). The DHI improved values in the experimental group were significantly higher than the control group (p = 0.004).

CONCLUSIONS AND SIGNIFICANCE

Low-sodium diet with adequate water intake improved the hearing and alleviated vertigo and tinnitus in MD patients.

Examination of betahistine bioavailability in combination with the monoamine oxidase B inhibitor, selegiline, in humans-a non-randomized, single-sequence, two-period titration, open label single-center phase 1 study (PK-BeST)

Background

Betahistine was registered in Europe in the 1970s and approved in more than 80 countries as a first-line treatment for Menière's disease. It has been administered to more than 150 million patients. However, according to a Cochrane systematic review of betahistine and recent meta-analyses, there is insufficient evidence to say whether betahistine has any effect in the currently approved dosages of up to 48 mg/d. A combination with the monoamine oxidase B (MAO-B) inhibitor, selegiline, may increase the bioavailability of betahistine to levels similar to the well-established combination of L-DOPA with carbidopa or benserazide in the treatment of Parkinson's disease. We investigated the effect of selegiline on betahistine pharmacokinetics and the safety of the combination in humans.

Methods

In an investigator-initiated prospective, non-randomized, single-sequence, two-period titration, open label single-center phase 1 study, 15 healthy volunteers received three single oral dosages of betahistine (24, 48, and 96 mg in this sequence with at least 2 days' washout period) without and with selegiline (5 mg/d with a loading period of 7 days). Betahistine serum concentrations were measured over a period of 240 min at eight time points (area under the curve, AUC0-240 min). This trial is registered with EudraCT (2019-002610-39) and ClinicalTrials.gov.

Findings

In all three single betahistine dosages, selegiline increased the betahistine bioavailability about 80- to 100-fold. For instance, the mean (±SD) of the area under curve for betahistine 48 mg alone was 0.64 (+/-0.47) h*ng/mL and for betahistine plus selegiline 53.28 (+/-37.49) h*ng/mL. The half-life time of around 30 min was largely unaffected, except for the 24 mg betahistine dosage. In total, 14 mild adverse events were documented.

Interpretation

This phase 1 trial shows that the MAO-B inhibitor selegiline increases betahistine bioavailability by a factor of about 80 to 100. No safety concerns were detected. Whether the increased bioavailability has an impact on the preventive treatment of Menière's disease, acute vestibular syndrome, or post-BPPV residual dizziness has to be evaluated in placebo-controlled trials.

Clinical trial registration

https://clinicaltrials.gov/study/NCT05938517?intr=betahistine%20and%20selegiline&rank=1, identifier: NCT05938517.