A proof-of-principle study of the short-term effects of 3,4-methylenedioxymethamphetamine (MDMA) on tinnitus and neural connectivity

Background

This study was conducted to investigate the short-term behavioural and neurophysiological effects of 3,4-methylenedioxymethamphetamine (MDMA) on tinnitus perception.

Methods

A double-blind randomized controlled cross-over design. Part 1. Behavioural measures of tinnitus following 30mg MDMA or placebo administration (N=5 participants) and Part 2. Behavioural measures of tinnitus and correlations between pairs of apriori regions of interest (ROI) using resting-state functional magnetic resonance imaging (rs-fMRI) before and after 70mg of MDMA or placebo (N=8 participants).

Results

The results to MDMA were similar to placebo. For the 70mg dose, there was a significant reduction after 4h in annoyance and ignore ratings. RsMRI showed decreased connectivity compared with placebo administration between the left hippocampal, right hippocampal, left amygdala and right amygdala regions, and between the right posterior parahippocampal cortex and the left amygdala after two hours of 70mg MDMA administration. Increased connectivity compared to placebo administration was found post MDMA between the right post-central gyrus and right posterior and superior temporal gyrus, and between the thalamus and frontoparietal network.

Conclusions

Following 70mg of MDMA two tinnitus rating scales significantly improved. There was, however, a placebo effect. Compared with placebo the rsMRI following the MDMA showed reductions in connectivity between the amygdala, hippocampus and parahippocampal gyrus. There is sufficient proof of concept to support future investigation of MDMA as a treatment for tinnitus.