Comprehensive Characterization of Hearing Loss and Tinnitus in Military-Affiliated and Non-Military-Affiliated Individuals.

PURPOSE: Military-affiliated individuals (MIs) are at a higher risk of developing hearing loss and tinnitus. While these disorders are well-studied in MIs, their impact relative to non-military-affiliated individuals (non-MIs) remains understudied. Our study compared hearing, speech-in-noise (SIN) perception, and tinnitus characteristics between MIs and non-MIs. METHOD: MIs (n = 84) and non-MIs (n = 193) underwent hearing threshold assessment and Quick Speech-in-Noise Test. Participants with tinnitus completed psychoacoustic tinnitus matching, numeric rating scale (NRS) for loudness and annoyance, and Tinnitus Functional Index. Comorbid conditions such as anxiety, depression, and hyperacusis were assessed. We used a linear mixed-effects model to compare hearing thresholds and SIN scores between MIs and non-MIs. A multivariate analysis of variance compared tinnitus characteristics between MIs and non-MIs, and a stepwise regression was performed to identify predictors of tinnitus severity. RESULTS: MIs exhibited better hearing sensitivity than non-MIs; however, their SIN scores were similar. MIs matched their tinnitus loudness to a lower intensity than non-MIs, but their loudness ratings (NRS) were comparable. MIs reported greater tinnitus annoyance and severity on the relaxation subscale, indicating increased difficulty engaging in restful activities. Tinnitus severity was influenced by hyperacusis and depression in both MIs and non-MIs; however, hearing loss uniquely contributed to severity in MIs. CONCLUSIONS: Our findings suggest that while MIs may exhibit better or comparable listening abilities, they were significantly more affected by tinnitus than non-MIs. Furthermore, our study highlights the importance of assessing tinnitus-related distress across multiple dimensions, facilitating customization of management strategies for both MIs and non-MIs.

Contribution of Tinnitus and Hearing Loss to Depression: NHANES Population Study.

OBJECTIVES: Hearing loss affects the emotional well-being of adults and is sometimes associated with clinical depression. Chronic tinnitus is highly comorbid with hearing loss and separately linked with depression. In this article, the authors investigated the combined effects of hearing loss and tinnitus on depression in the presence of other moderating influences such as demographic, lifestyle, and health factors. DESIGN: The authors used the National Health and Nutrition Examination Survey data (2011-2012 and 2015-2016) to determine the effects of hearing loss and tinnitus on depression in a population of US adults (20 to 69 years). The dataset included the Patient Health Questionnaire-9 for depression screening, hearing testing using pure-tone audiometry, and information related to multiple demographic, lifestyle, and health factors (n = 5845). RESULTS: The statistical analysis showed moderate to high associations between depression and hearing loss, tinnitus, and demographic, lifestyle, and health factors, separately. Results of logistic regression analysis revealed that depression was significantly influenced by hearing loss (adjusted odds ratios [OR] = 3.0), the functional impact of tinnitus (adjusted OR = 2.4), and their interaction, both in the absence or presence of the moderating influences. The effect of bothersome tinnitus on depression was amplified in the presence of hearing loss (adjusted OR = 2.4 in the absence of hearing loss to adjusted OR = 14.9 in the presence of hearing loss). Conversely, the effect of hearing loss on depression decreased when bothersome tinnitus was present (adjusted OR = 3.0 when no tinnitus problem was present to adjusted OR = 0.7 in the presence of bothersome tinnitus). CONCLUSIONS: Together, hearing loss and bothersome tinnitus had a significant effect on self-reported depression symptoms, but their relative effect when comorbid differed. Tinnitus remained more salient than hearing loss and the latter's contribution to depression was reduced in the presence of tinnitus, but the presence of hearing loss significantly increased the effects of tinnitus on depression, even when the effects of the relevant demographic, lifestyle, or health factors were controlled. Treatment strategies that target depression should screen for hearing loss and bothersome tinnitus and provide management options for the conditions.

Misophonia and Hearing Comorbidities in a Collegiate Population.

OBJECTIVES: Misophonia is a little-understood disorder in which certain sounds cause a strong emotional response in those who experience it. People who are affected by misophonia may find that noises like loud chewing, pen clicking, and/or sniffing trigger intense frustration, anger, or discomfort. The relationship of misophonia with other auditory disorders including loudness hyperacusis, tinnitus, and hearing loss is largely underexplored. This project aimed to investigate the prevalence and hearing-health comorbidities of misophonia in a college-aged population by using an online survey. DESIGN: A total of 12,131 undergraduate and graduate students between the ages of 18 and 25 were given the opportunity to answer an in-depth online survey. These students were sampled in a roughly 50 of 50 sex distribution. The survey was created using Qualtrics and included the following components: electronic consent, demographics questionnaire, Misophonia Questionnaire (MQ), Khalfa's Hyperacusis Questionnaire (HQ), Tinnitus and Hearing Survey, and Tinnitus Functional Index (TFI). To be eligible for compensation, answers for each of the above components were required, with the exception of the TFI, which was only presented to students who indicated that they experienced tinnitus. Respondents were determined to have high or possible likelihood of having misophonia if they gave specific answers to the MQ's Emotion and Behavior Scale or the MQ Severity Scale. RESULTS: After excluding duplicate responses and age-related outliers, 1,084 responses were included in the analysis. Just over 20% (n = 217) of the sample was determined to have a high or probable likelihood of having misophonia. The sample was primarily White, female, and of mid-to-high socioeconomic status. There was a strong positive correlation between MQ total scores and HQ total scores. High likelihood misophonia status showed a significant relationship with self-reported hearing loss and tinnitus. No statistically significant relationship was found between misophonia and age, ethnicity, or socioeconomic status. MQ total scores differed significantly when separating respondents by sex, self-reported tinnitus, and loudness hyperacusis. White respondents had significantly higher MQ total scores than Asian/Asian American respondents. CONCLUSIONS: The estimated prevalence of misophonia was about 8% to 20% of the sample, which agrees with most of the currently published research examining misophonia symptoms in collegiate populations. Results of data analysis suggest that misophonia severity may be related to loudness hyperacusis, sex, and possibly tinnitus. Future studies are needed to further examine the characteristics of these relationships, possibly in populations more optimized to reflect the general population or those with hearing-health disorders.

Review and Perspective on Brain Bases of Tinnitus.

In advancing our understanding of tinnitus, some of the more impactful contributions in the past two decades have come from human brain imaging studies, specifically the idea of both auditory and extra-auditory neural networks that mediate tinnitus. These networks subserve both the perception of tinnitus and the psychological reaction to chronic, continuous tinnitus. In this article, we review particular studies that report on the nodes and links of such neural networks and their inter-network connections. Innovative neuroimaging tools have contributed significantly to the increased understanding of anatomical and functional connections of attention, emotion-processing, and default mode networks in adults with tinnitus. We differentiate between the neural correlates of tinnitus and those of comorbid hearing loss; surprisingly, tinnitus and hearing loss when they co-occur are not necessarily additive in their impact and, in rare cases, additional tinnitus may act to mitigate the consequences of hearing loss alone on the brain. The scale of tinnitus severity also appears to have an impact on brain networks, with some of the alterations typically attributed to tinnitus reaching significance only in the case of bothersome tinnitus. As we learn more about comorbid conditions of tinnitus, such as depression, anxiety, hyperacusis, or even aging, their contributions to the network-level changes observed in tinnitus will need to be parsed out in a manner similar to what is currently being done for hearing loss or severity. Together, such studies advance our understanding of the heterogeneity of tinnitus and will lead to individualized treatment plans.

An Inverse Relationship Between Gray Matter Volume and Speech-in-Noise Performance in Tinnitus Patients with Normal Hearing Sensitivity.

Speech-in-noise (SiN) recognition difficulties are often reported in patients with tinnitus. Although brain structural changes such as reduced gray matter (GM) volume in auditory and cognitive processing regions have been reported in the tinnitus population, it remains unclear how such changes influence speech understanding, such as SiN performance. In this study, pure-tone audiometry and Quick Speech-in-Noise test were conducted on individuals with tinnitus and normal hearing and hearing-matched controls. T1-weighted structural MRI images were obtained from all participants. After preprocessing, GM volumes were compared between tinnitus and control groups using whole-brain and region-of-interest analyses. Further, regression analyses were performed to examine the correlation between regional GM volume and SiN scores in each group. The results showed decreased GM volume in the right inferior frontal gyrus in the tinnitus group relative to the control group. In the tinnitus group, SiN performance showed a negative correlation with GM volume in the left cerebellum (Crus I/II) and the left superior temporal gyrus; no significant correlation between SiN performance and regional GM volume was found in the control group. Even with clinically defined normal hearing and comparable SiN performance relative to controls, tinnitus appears to change the association between SiN recognition and regional GM volume. This change may reflect compensatory mechanisms utilized by individuals with tinnitus who maintain behavioral performance.

Comparison of otoacoustic emissions in tinnitus and hyperacusis in adults with normal hearing sensitivity.

OBJECTIVE: To investigate the effect of tinnitus and/or hyperacusis on distortion product otoacoustic emission (DPOAE) measures in adults with normal hearing thresholds from 0.25 to 8 kHz, while accounting for extended high-frequency (EHF) thresholds. DESIGN: A behavioural study consisted of comprehensive audiological assessment, validated tinnitus and hyperacusis questionnaires, DPOAE amplitudes and input/output (I/O) functions. STUDY SAMPLE: Data of 56 participants with normal hearing were included for the analysis. Participants were categorised into four groups: (1) without tinnitus or hyperacusis, (2) with tinnitus only, (3) with hyperacusis only, and (4) with both tinnitus and hyperacusis. RESULTS: The groups with tinnitus showed elevated EHF thresholds compared with those without tinnitus. DPOAE amplitudes were not significantly affected by tinnitus and/or hyperacusis status; however, they were significantly affected by EHF thresholds. Further, no appreciable differences in DPOAE I/O functions were found across groups. CONCLUSIONS: The reported non-significant differences in DPOAEs in individuals with tinnitus and/or hyperacusis do not support a peripheral mechanism or an interaction between peripheral and central mechanisms underlying tinnitus or hyperacusis. Our findings, however, suggest the need to assess basal cochlear function (e.g. EHF thresholds) for a better understanding of differences in DPOAE measures in tinnitus and/or hyperacusis.

Invariant structural and functional brain regions associated with tinnitus: A meta-analysis.

Tinnitus is a common, functionally disabling condition of often unknown etiology. Neuroimaging research to better understand tinnitus is emerging but remains limited in scope. Voxel-based physiology (VBP) studies detect tinnitus-associated pathophysiology by group-wise contrast (tinnitus vs controls) of resting-state indices of hemodynamics, metabolism, and neurovascular coupling. Voxel-based morphometry (VBM) detects tinnitus-associated neurodegeneration by group-wise contrast of structural MRI. Both VBP and VBM studies routinely report results as atlas-referenced coordinates, suitable for coordinate-based meta-analysis (CBMA). Here, 17 resting-state VBP and 8 VBM reports of tinnitus-associated regional alterations were meta-analyzed using activation likelihood estimation (ALE). Acknowledging the need for data-driven insights, ALEs were performed at two levels of statistical rigor: corrected for multiple comparisons and uncorrected. The corrected ALE applied cluster-level inference thresholding by intensity (z-score > 1.96; p < 0.05) followed by family-wise error correction for multiple comparisons (p < .05, 1000 permutations) and fail-safe correction for missing data. The corrected analysis identified one significant cluster comprising five foci in the posterior cingulate gyrus and precuneus, that is, not within the primary or secondary auditory cortices. The uncorrected ALE identified additional regions within auditory and cognitive processing networks. Taken together, tinnitus is likely a dysfunction of regions spanning multiple canonical networks that may serve to increase individuals' interoceptive awareness of the tinnitus sound, decrease capacity to switch cognitive sets, and prevent behavioral and cognitive attention to other stimuli. It is noteworthy that the most robust tinnitus-related abnormalities are not in the auditory system, contradicting collective findings of task-activation literature in tinnitus.

Treatment of Posttraumatic Stress Disorder Alleviates Tinnitus-Related Distress Among Veterans: A Pilot Study.

PURPOSE: Military service personnel are at increased risk for developing tinnitus due to heightened exposure to acoustic trauma. The auditory disorder is the leading service-connected disability among veterans and is highly comorbidly diagnosed with posttraumatic stress disorder (PTSD). The biopsychosocial model illustrates that chronic health conditions are exacerbated or maintained by psychiatric distress. Therefore, alleviation of such psychiatric distress can have beneficial impacts on health conditions, such as tinnitus. The aim of this study was to determine whether individuals with both disorders who receive evidence-based therapy for PTSD will experience decreases in both PTSD and tinnitus-related distress. METHOD: Veterans with comorbid bothersome tinnitus and PTSD received cognitive processing therapy and were assessed for PTSD, tinnitus-related distress, and depression at baseline and 1 month posttreatment follow-up. RESULTS: At posttreatment follow-up, participants demonstrated significant decreases in PTSD symptoms compared to their baseline scores. Participants also demonstrated decreased tinnitus-related distress and depression, with high effect sizes. CONCLUSIONS: This pilot study demonstrated that clinical management addressing psychiatric distress, as associated with PTSD, may simultaneously provide benefit for patients with bothersome tinnitus. Although not statistically significant due to the small sample size, large effect sizes indicate that tinnitus-related distress decreased as a function of receiving evidence-based therapy for PTSD. Future clinical trials should increase sample sizes and compare effects to control conditions.

COVID-19 vaccination uptake in 441 socially and ethnically diverse pregnant women.

OBJECTIVE: To explore COVID-19 vaccination uptake, facilitators and barriers in ethnically-diverse pregnant women. DESIGN AND SETTING: An anonymous quality improvement questionnaire survey exploring COVID-19 vaccination uptake, causes of vaccine hesitancy and trusted sources of information among pregnant women in two acute district general hospitals in England (Berkshire and Surrey) between 1.9.21 and 28.2.22. POPULATION: 441 pregnant women attending routine antenatal clinic appointments. METHODS: Consented pregnant women completed the survey either electronically using a QR code or on paper. Descriptive data were summarised and free text responses were thematically analysed. RESULTS: 441 pregnant women, mean age 32 years (range 17-44), completed the survey. Twenty-six percent were from ethnic minority groups, and 31% had a co-morbid health condition. Most respondents (66.2%) had been vaccinated against COVID-19 with at least one dose (White British 71.9%, Asian 67.9%, White-other 63.6%, Black 33%). The most common reasons for not being vaccinated were concerns about effects on the unborn baby and future pregnancies, anxiety about possible adverse impact on the mother, not enough known about the vaccine, and lack of trust in vaccines. Comments included: "I'd rather not risk injecting the unknown into my body", and "I don't trust it." Although 23% used social media for information on COVID-19 vaccination, the most trusted sources were the patient's GP and midwife (43%) and official health-related websites such as NHS (39%). CONCLUSIONS: A third of these pregnant women had not been vaccinated against COVID-19. Trusted health professionals like midwives and GPs could have a crucial role in increasing vaccination uptake.

Evaluating the Efficacy of a Smartphone App for Tinnitus Relief Using Behavioral and Brain Imaging Measures.

PURPOSE: In this exploratory, open-label study, we used behavioral and brain imaging measures to assess the effectiveness of a smartphone application (ReSound Relief app), which aims to help reduce tinnitus-related distress. METHOD: Fourteen participants with a wide range of tinnitus-related symptoms and who were not currently undergoing any external treatment participated. They completed the 6-month study and reported different levels of engagement with the app. RESULTS: Across a range of tinnitus questionnaires, most participants showed either no change or decrease in tinnitus handicap. Resting-state and task-based functional magnetic resonance imaging (fMRI) data were collected at baseline and the end of the study. Resting-state fMRI of 12 participants revealed alterations in interregional connectivity of default mode, salience, emotion, auditory, and visual processing networks at the end of the intervention period compared to baseline. Ratings of affective sounds (as pleasant, neutral, or unpleasant) were assessed using fMRI, and comparison after 6 months of app usage revealed reduced activity in the left superior temporal gyrus (secondary auditory cortex), right superior occipital gyrus, and left posterior cingulate cortex. Our findings were not significant at a false discovery rate level of p < .05. CONCLUSIONS: The reported changes were not significant, possibly due to the small sample size, heterogeneity of the tinnitus handicap among subjects at the start of the project, and the length of the intervention period. Nevertheless, this study underscores the ease of usage of the app and the potential use of brain imaging to assess changes due to a passive, self-administered intervention for individuals with varying levels of tinnitus severity.

Marine and terrestrial nitrifying bacteria are sources of diverse bacteriohopanepolyols.

Hopanoid lipids, bacteriohopanols and bacteriohopanepolyols, are membrane components exclusive to bacteria. Together with their diagenetic derivatives, they are commonly used as biomarkers for specific bacterial groups or biogeochemical processes in the geologic record. However, the sources of hopanoids to marine and freshwater environments remain inadequately constrained. Recent marker gene studies suggest a widespread potential for hopanoid biosynthesis in marine bacterioplankton, including nitrifying (i.e., ammonia- and nitrite-oxidizing) bacteria. To explore their hopanoid biosynthetic capacities, we studied the distribution of hopanoid biosynthetic genes in the genomes of cultivated and uncultivated ammonia-oxidizing (AOB), nitrite-oxidizing (NOB), and complete ammonia-oxidizing (comammox) bacteria, finding that biosynthesis of diverse hopanoids is common among seven of the nine presently cultivated clades of nitrifying bacteria. Hopanoid biosynthesis genes are also conserved among the diverse lineages of bacterial nitrifiers detected in environmental metagenomes. We selected seven representative NOB isolated from marine, freshwater, and engineered environments for phenotypic characterization. All tested NOB produced diverse types of hopanoids, with some NOB producing primarily diploptene and others producing primarily bacteriohopanepolyols. Relative and absolute abundances of hopanoids were distinct among the cultures and dependent on growth conditions, such as oxygen and nitrite limitation. Several novel nitrogen-containing bacteriohopanepolyols were tentatively identified, of which the so called BHP-743.6 was present in all NOB. Distinct carbon isotopic signatures of biomass, hopanoids, and fatty acids in four tested NOB suggest operation of the reverse tricarboxylic acid cycle in Nitrospira spp. and Nitrospina gracilis and of the Calvin-Benson-Bassham cycle for carbon fixation in Nitrobacter vulgaris and Nitrococcus mobilis. We suggest that the contribution of hopanoids by NOB to environmental samples could be estimated by their carbon isotopic compositions. The ubiquity of nitrifying bacteria in the ocean today and the antiquity of this metabolic process suggest the potential for significant contributions to the geologic record of hopanoids.

An online survey study of the association between tinnitus and hyperacusis using validated questionnaires.

OBJECTIVE: To investigate the association between the highly comorbid tinnitus and hyperacusis conditions using standard questionnaires. DESIGN: A cross-sectional internet-based survey consisted of general demographic questions, questions about hearing and emotional status, Tinnitus Primary Function Questionnaire (TPFQ), and Hyperacusis Questionnaire (HQ). STUDY SAMPLE: Six hundred sixteen completed surveys were obtained primarily from students and staff in a large university. RESULTS: About 6% of the respondents could be classified as having hyperacusis based on the criterion of HQ scores ≥ 28 and had significantly increased odds of reporting having tinnitus (OR 10.11; 95% CI 3.76-35.3). Tinnitus severity (TPFQ) and HQ scores were correlated regardless of the hearing loss status. When predicting TPFQ scores, after controlling for demographic factors and affective states, hyperacusis status became an insignificant predictor. In contrast, both affirmative answers to having anxiety and depression, together with hearing loss status and tinnitus were significant predictors of HQ scores. CONCLUSIONS: Having hyperacusis did not appear to contribute significantly to tinnitus severity, but having tinnitus contributed to the likelihood of having hyperacusis. Our findings provide a nuanced view of how tinnitus and hyperacusis conditions co-occur and influence each other, which may be valuable to clinicians and researchers.

Evaluating the efficacy of hearing aids for tinnitus therapy - A Positron emission tomography study.

Brain imaging studies have revealed neural changes in chronic tinnitus patients that are not restricted to auditory brain areas; rather, the engagement of limbic system structures, attention and memory networks are has been noted. Hearing aids (HA) provide compensation for comorbid hearing loss and may decrease tinnitus-related perception and annoyance. Using resting state positron emission tomography our goal was to analyze metabolic and functional brain changes after six months of effective HA use by patients with chronic tinnitus and associated sensorineural hearing loss. 33 age and hearing loss matched participants with mild/moderate hearing loss were enrolled in this study: 19 with tinnitus, and 14 without tinnitus. Participants with tinnitus of more than 6 months with moderate/severe Tinnitus Handicap Inventory (THI) and Visual Analogue Scale (VAS) scores composed the tinnitus group. A full factorial 2X2 ANOVA was conducted for imaging analysis, with group (tinnitus and controls) and time point (pre-intervention and post-intervention) as factors. Six months after HA fitting, tinnitus scores reduced statistically and clinically. Analysis revealed increased glycolytic metabolism in the left orbitofrontal cortex, right temporal lobe and right hippocampus, and reduced glycolytic metabolism in the left cerebellum and inferior parietal lobe within the tinnitus group. The hearing loss control group showed no significant metabolic changes in the analysis. Parsing out the contribution of tinnitus independent of hearing loss, allowed us to identify areas implicated in declines in tinnitus handicap as a result of the intervention. Brain regions implicated in the present study may be part of chronic tinnitus-specific network.

A large-scale diffusion imaging study of tinnitus and hearing loss.

Subjective, chronic tinnitus, the perception of sound in the absence of an external source, commonly occurs with many comorbidities, making it a difficult condition to study. Hearing loss, often believed to be the driver for tinnitus, is perhaps one of the most significant comorbidities. In the present study, white matter correlates of tinnitus and hearing loss were examined. Diffusion imaging data were collected from 96 participants-43 with tinnitus and hearing loss (TINHL), 17 with tinnitus and normal hearing thresholds (TINNH), 17 controls with hearing loss (CONHL) and 19 controls with normal hearing (CONNH). Fractional anisotropy (FA), mean diffusivity and probabilistic tractography analyses were conducted on the diffusion imaging data. Analyses revealed differences in FA and structural connectivity specific to tinnitus, hearing loss, and both conditions when comorbid, suggesting the existence of tinnitus-specific neural networks. These findings also suggest that age plays an important role in neural plasticity, and thus may account for some of the variability of results in the literature. However, this effect is not seen in tractography results, where a sensitivity analysis revealed that age did not impact measures of network integration or segregation. Based on these results and previously reported findings, we propose an updated model of tinnitus, wherein the internal capsule and corpus callosum play important roles in the evaluation of, and neural plasticity in response to tinnitus.

Cognitive Flexibility and Inhibition in Individuals with Age-Related Hearing Loss.

Growing evidence suggests alterations in cognitive control processes in individuals with varying degrees of age-related hearing loss (ARHL); however, alterations in those with unaided mild ARHL are understudied. The current study examined two cognitive control processes, cognitive flexibility, and inhibition, in 21 older adults with unaided mild ARHL and 18 age- and education-matched normal hearing (NH) controls. All participants underwent comprehensive audiological and cognitive evaluations including Trail Making Test-B, Verbal Fluency, Stroop, and two Go/NoGo tasks. Group differences in cognitive flexibility and inhibition as well as associations between peripheral and central hearing ability and measures of cognitive flexibility and inhibition were investigated. Findings revealed that the ARHL group took significantly longer to complete the Stroop task and had higher error rates on NoGo trials on both Go/NoGo tasks relative to the NH controls. Additionally, poorer peripheral and central hearing were associated with poorer cognitive flexibility and inhibitory control. Our findings suggest slower and more inefficient inhibitory control in the mild ARHL group relative to the NH group and add to decades of research on the association between hearing and cognition.

Salience, emotion, and attention: The neural networks underlying tinnitus distress revealed using music and rest.

In the present study, we used an innovative music-rest interleaved fMRI paradigm to investigate the neural correlates of tinnitus distress. Tinnitus is a poorly-understood hearing disorder where individuals perceive sounds, in the absence of an external source. Although the great majority of individuals habituate to chronic tinnitus and report few symptoms, a minority report debilitating distress and annoyance. Prior research suggests that a diverse set of brain regions, including the attention, the salience, and the limbic networks, play key roles in mediating both the perception of tinnitus and its impact on the individual; however, evidence of the degree and extent of their involvement has been inconsistent. Here, we minimally modified the conventional resting state fMRI by interleaving it with segments of jazz music. We found that the functional connectivity between a set of brain regions-including cerebellum, precuneus, superior/middle frontal gyrus, and primary visual cortex-and seeds in the dorsal attention network, the salience network, and the amygdala, were effective in fractionating the tinnitus patients into two subgroups, characterized by the severity of tinnitus-related distress. Further, our findings revealed cross-modal modulation of the attention and salience networks by the visual modality during the music segments. On average, the more bothersome the reported tinnitus, the stronger was the exhibited inter-network functional connectivity. This study substantiates the essential role of the attention, salience, and limbic networks in tinnitus habituation, and suggests modulation of the attention and salience networks across the auditory and visual modalities as a possible compensatory mechanism for bothersome tinnitus.

Decreased resting perfusion in precuneus and posterior cingulate cortex predicts tinnitus severity.

Functional magnetic resonance imaging has been increasingly used to understand the mechanisms involved in subjective tinnitus; however, researchers have struggled to reach a consensus about a primary mechanistic model to explain tinnitus. While many studies have used functional connectivity of the BOLD signal to understand how patterns of activity change with tinnitus severity, there is much less research on whether there are differences in more fundamental physiology, including cerebral blood flow, which may help inform the BOLD measures. Here, arterial spin labeling was used to measure perfusion in four regions-of-interest, guided by current models of tinnitus, in a sample of 60 tinnitus patients and 31 control subjects. We found global reductions in cerebral perfusion in tinnitus compared with controls. Additionally, we observed a significant negative correlation between tinnitus severity and perfusion. These results demonstrate that examining perfusion from the whole brain may present a complementary tool for studying tinnitus. More research will help better understand the physiology underlying these differences in perfusion.

Tinnitus and cognition: Can load theory help us refine our understanding?

Objective: Tinnitus has been shown to be associated with specific cognitive deficits. Contemporary models of tinnitus, based primarily on human behavior, emphasize the influence of the cognitive response to tinnitus in tinnitus manifestation and level of associated annoyance. The models and hypotheses proposed thus far have (a) focused on the cognitive response to the onset of tinnitus, and not necessarily focused on the cognitive consequences of established chronic tinnitus, and (b) failed to dissociate the contributions of cognitive and perceptual load in their theories. Load theory states that we have a limited capacity of neural resources that can be used to process internal and external stimuli. This theory is differentially applied to perceptual load, which refers to the neural resources engaged in the processing of sensory stimuli in our environment, and cognitive load, which refers to the occupation of a more central resource that is involved in higher-level processing, such as stimulus discrimination, decision making, and working memory processing. Methods: A focused review was conducted on behavioral and brain-imaging studies examining cognitive deficits in tinnitus, in an attempt to reexamine the findings in a load theory framework. Results: Findings of these studies are discussed in the context of load theory, and a novel model for understanding these findings is proposed. Conclusion: We believe the incorporation of load theory into models of tinnitus may advance understanding of the cognitive impact of tinnitus and lead to better management of tinnitus.

Association Between Tinnitus Pitch and Consonant Recognition in Noise.

Purpose Difficulties in speech-in-noise understanding are often reported in individuals with tinnitus. Building on our previous findings that speech-in-noise performance is correlated with subjective loudness of tinnitus, this study aimed to investigate the effect of tinnitus pitch on consonant recognition in noise. Method Pure-tone audiometry and the Quick Speech-in-Noise Test were conducted on 66 participants categorized into four groups by their hearing sensitivity and self-report of tinnitus. Consonant recognition scores at various frequency ranges were obtained at the 5 dB SNR condition of the Quick Speech-in-Noise Test. Participants with tinnitus also completed a tinnitus pitch-matching procedure. Correlation analyses were conducted between tinnitus pitch and the frequency of the worst consonant recognition, and the error rates based on word and sentence position were compared. Results Regardless of hearing sensitivity, tinnitus pitch did not correlate with the frequency of the worst consonant recognition. Sentence-initial word recognition was affected by hearing loss, whereas sentence-final word recognition was not affected by hearing loss or tinnitus. In contrast to individuals with normal hearing, participants with hearing loss varied in full-sentence recognition, with those reporting tinnitus exhibiting significantly higher error rates. Conclusions The findings suggest that the effect of tinnitus on consonant recognition in noise may involve higher level functions more than perceptual characteristics of tinnitus. Furthermore, for individuals with speech-in-noise concerns, clinical evaluation should address both hearing sensitivity and the presence of tinnitus. Future speech-in-noise studies should incorporate cognitive tests and, possibly, brain imaging to parse out the contribution of cognitive factors, such as cognitive control, in speech-in-noise in tinnitus.