The Vodka Trial: Clinical and Genetic Characteristics of Alcohol Responsiveness in Laryngeal Dystonia

Laryngeal dystonia (LD) is isolated task-specific focal dystonia, predominantly impairing speech production. Clinical observations and population survey studies have reported that up to 58% of patients with LD may have symptom improvement following alcohol intake.

To determine the objective characteristics of alcohol responsiveness in LD using a standardized alcohol challenge test and genetic testing.

A total of 109 patients with isolated focal LD participated in the study. Patients were administered two non-diluted drinks of 40-proof vodka 30 min apart, followed by assessments of voice symptoms, breath alcohol content, and side effects. Patients were considered alcohol-responsive (EtOH+) if their symptoms changed by ≥10% from baseline. Whole-exome sequencing was performed to identify genetic variants associated with the alcohol responsiveness of LD.

All patients tolerated the standardized alcohol challenge test without major adverse events. Fifty-two patients (47.7%) had an average of 44.4 ± 25.0% improvement of LD symptoms about 45 min after alcohol intake. Five genetic variants in GABAergic pathway-related genes were enriched in EtOH+ patients, and two of these, rs11644926 (ADCY7) and rs2230741 (ADCY9), were associated with the improvement of dystonic voice symptoms.

Alcohol responsiveness of LD symptoms is a robust feature related to the genes regulating the GABAergic synapses. This finding provides support for the evaluation of novel oral medications with mechanisms of action similar to alcohol for the treatment of patients with alcohol-responsive dystonia.