SUMMARY OF THE STUDY: A total of 32 individuals with varying levels of tinnitus severity were recruited from the Urbana-Champaign area. Volunteers were divided into higher tinnitus distress and lower tinnitus distress groups and underwent brain imaging using functional MRI. The researchers observed that individuals with higher distress relied more on the emotional processing regions of the brain (amygdala and parahippocampus) compared to those with lower distress when listening to affective sounds. The lower distress group recruited more executive processing regions when listening to affective sounds compared to the higher distress group. This may indicate that individuals in the latter group were better able to control their emotional reaction to their internal tinnitus as well as the external sounds.
A second goal of the study was to understand the impact of physical activity levels on tinnitus-related distress. This was because the investigators had previously found, via a survey study also supported by the same student grant, that there was a significant negative correlation between tinnitus distress and activity level. In the present functional MRI study, indeed those who reported lower distress levels also reported higher activity levels and exhibited greater recruited of frontal cortex, suggesting greater habituation.
KEY OUTCOMES/ RELEVANCE TO TINNITUS AND HYPERACUSIS: Adults with more bothersome tinnitus engaged their amygdala to a greater extent when processing emotional sounds compared to those with mild tinnitus. In contrast, the mild tinnitus group exhibited greater involvement of the frontal cortex and limbic system nodes other than the amygdala, such as the insula. The study allows us to differentiate between the mild and bothersome tinnitus groups using neural response to affective sounds. The study also found support for initial survey results in that higher levels of physical activity correlated with lower levels of tinnitus severity. Further, groups with a higher level of physical activity recruited more executive processing regions compared to less active groups. Therefore, higher levels of physical activity may be of benefit in ameliorating tinnitus-related distress by improving the engagement of executive processing regions. Further research is necessary to corroborate these claims.
Thanks to ATA Scientific Advisory Committee Member Fatima Husain, Ph.D., and ATA funded researcher Jake Carpenter Thompson, Ph.D., for summarizing this study.
More information on the study can be found at: Ncbi.nlm.nih.gov/pubmed/26675290.