A proof-of-principle study of the short-term effects of 3,4-methylenedioxymethamphetamine (MDMA) on tinnitus and neural connectivity
Durai, M., Kennedy, M. A., Maggo, S., Miller, A. L., Park, J., Poppe, T. N. E. R., Russell, B. R., Searchfield, G. D., Shekhawat, G. S., Spiegel, D., Sundram, F., Wise, K.
This double-blind, randomised, controlled cross-over study (n=13) explores MDMA's (30-70mg) impact on tinnitus through behavioural and rs-fMRI assessments. No notable effects were observed at the lower dose. However, the 70 mg dose significantly reduced tinnitus annoyance and ignore ratings post-administration. Neurophysiological analysis revealed decreased connectivity in emotion and memory-related brain regions (hippocampal and amygdala) and increased connectivity in sensory processing and attention areas (right post-central gyrus, posterior and superior temporal gyrus, thalamus, and frontoparietal network) with MDMA versus placebo.
Abstract
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.