US Department of Defense
BLAST INJURY RESEARCH
COORDINATING OFFICE
Advancing Blast Injury Research to Protect and Heal Those Who Serve
Tinnitus, a "ringing in the ears," is the perception of noise in one or both ears in the absence of an external noise, and is often a consequence of acoustic trauma such as blast exposure. The Blast Injury Research Coordinating Office's 2011 State-of-the-Science meeting on tinnitus was motivated by its common occurrence among active-duty Service members, and in FY 2019, it remained the most common service-connected disability, occurring in 157,152 of 274,578– almost three-fifths – of newly disabled veterans, and in 1,971,201 of 4,743,108 – over two-fifths – of the entire population of disabled veterans.1 In two recent studies2, a group at the University of Illinois at Urbana-Champaign conducted a preliminary investigation of a novel method to alleviate suffering from tinnitus. "Mindfulness" meditation, a technique that teaches patients to better observe and accept their experiences, has been shown in a couple of previous studies to improve significantly patients' psychological distress from tinnitus. The Illinois study both furthers these results by application of a minimally-modified, well-characterized mindfulness curriculum used for treatment of depression, and leverages the group's expertise with neuroimaging methods to ask the intriguing question of whether the effects of the therapy are associated with an anatomical of physiological change: something that can provide external and objective information to a clinician.
From a patient standpoint of course the value of the therapy is in the subjective sense that the tinnitus has "gotten better," whether that means it that is experienced less frequently or intensely, or that it's less disturbing. The researchers made that experience measurable by the use of well-studied standard questionnaires to measure numerically the severity of tinnitus among their subjects, and in measurements of hearing sensitivity, comparing results from before treatment, after eight weeks of mindfulness therapy with trained instructors, at a follow-up period eight weeks later, and, for a few participants who chose to remain involved, a year later. While there was no measurable change in hearing sensitivity from the therapy, more than half the patients reported significant improvements on the questionnaires, and the benefit persisted for a year in three of four participants. The result suggests real benefit to the use of mindfulness therapies for tinnitus sufferers, justifying further studies with larger patient populations.
The investigation of changes in the brain was more challenging to interpret, but also more intriguing. Firstly, the group used magnetic resonance imaging (MRI) to get a static picture of the brain and to look for changes in grey matter – in the local density and number of the bodies of neurons in the brain. They saw some significant changes among their patients in the brain's superior frontal cortex; the information could be useful if those changes seemed to be an indicator of tinnitus severity. Consequently, the authors compare their results to other groups' findings on changes in brain structure associated with tinnitus, but they find no real commonalities, suggesting that either the samples just aren't large enough to discover a good physical "handle," or else that while mindfulness therapy does affect brain anatomy, tinnitus severity itself is not predicted by anything MRI can visualize in gross brain anatomy.
Their second investigation, of brain physiology, may prove more fruitful. For this work, the group used a variant MRI technique, resting-state functional magnetic resonance imaging (fMRI). This method requires substantially greater statistical investigation and computational and instrumental resources, but it can differentiate among regions of the brain that seem to be operating in a coordinated manner, in functional "networks." The group investigated whether meaningful changes in these networks seemed to be associated with either the mindfulness training or the tinnitus severity. In both cases, the data indicate a measurable and significant effect: there are changes in network function and connectivity that seem to predict the tinnitus severity as measures by a quantitative questionnaire, and others that seem to be modified by the mindfulness training. In both cases the results seem broadly to agree with those of other research teams. The authors theorize that some specific differences might arise because those other studies compared tinnitus sufferers to uninjured controls, whereas this study is trying to correlate the fMRI signal with changes in severity – that is, they may have found a means to probe the harm being done to the patient by the tinnitus.
These are preliminary studies, with small patient numbers and quite limited controls. The positive results, however, indicate a good direction for future research. Moreover, treatment of tinnitus is difficult because of the subjective nature of the disease: the clinician and researcher have no means to evaluate objectively the efficacy of a treatment during testing. By searching for a physical correlate of the patient's experience in the MRI and fMRI, the research team may enable new routes to improving therapies for Service members suffering from tinnitus.
1 Veterans Benefits Administration, Department of Veterans Affairs, Annual Benefit Report Fiscal Year 2018. (https://www.benefits.va.gov/REPORTS/abr/)
2 Zimmermann et al. (2019), Functional Brain Changes During Mindfulness-based Cognitive Therapy Associated with Tinnitus Severity," Frontiers in Neuroscience 13:747; Husain et al. (2019), "Assessing mindfulness-based cognitive therapy for tinnitus using behavioral measures and structural MRI: a pilot study," International Journal of Audiology 58:12, 889-901.
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