Tinnitus, Traumatic Brain Injury, and Posttraumatic Stress Disorder in the Military

Therapeutic Function of Liraglutide for Mitigation of Blast-Induced Hearing Damage: An Initial Investigation in Animal Model of Chinchilla

INTRODUCTION

Auditory injuries induced by repeated exposures to blasts reduce the operational performance capability and the life quality of military personnel. The treatment for blast-induced progressive hearing damage is lacking. We have recently investigated the therapeutic function of liraglutide, a glucagon-like peptide-1 receptor agonist, to mitigate blast-induced hearing damage in the animal model of chinchilla, under different blast intensities, wearing earplugs (EPs) or not during blasts, and drug-treatment plan. The goal of this study was to investigate the therapeutical function of liraglutide by comparing the results obtained under different conditions.

MATERIALS AND METHODS

Previous studies on chinchillas from two under-blast ear conditions (EP/open), two blast plans (G1: 6 blasts at 3-5 psi or G2:3 blasts at 15-25 psi), and three treatment plans (blast control, pre-blast drug treatment, and post-blast drug treatment) were summarized. The auditory brainstem response (ABR), distortion product otoacoustic emission (DPOAE), and middle latency response (MLR) recorded within 14 days after the blasts were used. Statistical analysis was performed to evaluate the effect of liraglutide under different conditions.

RESULTS

ABR threshold shifts indicated that the conditions of the EP and open ears were substantially different. Results from EP chinchillas indicated that the pre-blast treatment reduced the acute ABR threshold elevation on the day of blasts, and the significance of such an effect increased with the blast level. Liraglutide-treated open chinchillas showed lower ABR threshold shifts at the later stage of the experiment regardless of the blast levels. The DPOAE was less damaged after G2 blasts compared to G1 when pre-blast liraglutide was administrated. Lower post-blast MLR amplitudes were observed in the pre-blast treatment groups.

CONCLUSIONS

This study indicated that the liraglutide mitigated the blast-induced auditory injuries. In EP ears, the pre-blast administration of liraglutide reduced the severity of blast-induced acute damage in ears with EP protection, especially under G2. In animals with open ears, the effect of liraglutide on the restoration of hearing increased with time. The liraglutide potentially benefits post-blast hearing through multiple approaches with different mechanics.

The Impact of Tinnitus Severity on Work Functioning among U.S. Military Veterans with Tinnitus

Tinnitus is highly prevalent among military Veterans. Severe tinnitus can be associated with negative impacts on daily life. Veterans with severe tinnitus may also have greater difficulties in functional roles, including work. However, few studies have explicitly explored this relationship. Traumatic brain injury (TBI), also prevalent among Veterans, is associated with tinnitus and can additionally impair work functioning. This quantitative investigation used a population-based survey to assess the relationship between tinnitus severity, measured using the Tinnitus Functional Index (TFI), and the impact of tinnitus on work, measured using a composite score from the Tinnitus History Questionnaire, among a stratified random sample of VA healthcare-using Veterans diagnosed with tinnitus, with and without comorbid TBI. Analyses were weighted to account for sampling design and Veteran non-response; multiple imputation was used to account for missing data. Results indicated that for every 1-point increase in TFI score, there was an average 8% increase in the odds of reporting a high level of impact on work functioning (OR: 1.08; 95% CI: 1.06, 1.11). Veterans with a comorbid TBI diagnosis, compared with those without, were more likely to have high tinnitus-related impact on work functioning (OR: 2.69, 95% CI: 1.85, 3.91), but the relationship between tinnitus severity and the impact of tinnitus on work functioning did not differ by TBI status. These data can help researchers and clinicians understand complex symptoms experienced by Veterans with tinnitus, with and without TBI, supporting the improved provision of clinical services to these patients.

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.

Acceptability of Cognitive Behavioral Therapy for Tinnitus: A Study With Veterans and Nonveterans

PURPOSE

Cognitive behavioral therapy (CBT) is a gold standard yet underutilized treatment for tinnitus, and tinnitus is especially highly prevalent among veterans. The aims of this study were twofold: to determine (a) if CBT for tinnitus is underutilized because participants find it less acceptable than other behavioral treatments for tinnitus and (b) if veterans and nonveterans rate behavioral treatments for tinnitus differently.

METHOD

This cross-sectional study was conducted online with a sample of 277 adults in the United States who self-reported at least some level of bothersome tinnitus in the past week. The sample for this study consisted of 129 veterans and 148 nonveterans. Participants read descriptions of CBT, tinnitus retraining therapy (TRT), and mindfulness-based stress reduction (MBSR). For each treatment, presented to them in random order, they provided credibility, expectancy, and acceptability ratings.

RESULTS

Among 277 participants, 147 (53.07%) reporting gender were women, 216 (77.98%) reporting race/ethnicity were White, and 129 (46.57%) were veterans of any branch of the U.S. Armed Forces. Veteran ratings of credibility, expectancy, and acceptability were significantly lower than nonveteran ratings across treatments. There were differences in credibility, expectancy, and acceptability ratings across treatments, and post hoc testing revealed that TRT was consistently rated higher than CBT or MBSR.

CONCLUSIONS

Despite strong research support, CBT was rated as less acceptable than a different, less widely empirically supported treatment. Veterans' ratings of acceptability were lower than those of nonveterans across all treatments.

A mouse model of repeated traumatic brain injury-induced hearing impairment: Early cochlear neurodegeneration in the absence of hair cell loss

PURPOSE

Traumatic Brain Injury (TBI) is a major cause of death and disability worldwide. Mounting evidence suggests that even mild TBI injuries, which comprise >75% of all TBIs, can cause chronic post-concussive neurological symptoms, especially when experienced repetitively (rTBI). The most common post-concussive symptoms include auditory dysfunction in the form of hearing loss, tinnitus, or impaired auditory processing, which can occur even in the absence of direct damage to the auditory system at the time of injury. The mechanism by which indirect damage causes loss of auditory function is poorly understood, and treatment is currently limited to symptom management rather than preventative care. We reasoned that secondary injury mechanisms, such as inflammation, may lead to damage of the inner ear and parts of the brain used for hearing after rTBI. Herein, we established a model of indirect damage to the auditory system induced by rTBI and characterized the pathology of hearing loss.

METHODS

We established a mouse model of rTBI in order to determine a timeline of auditory pathology following multiple mild injuries. Mice were subject to controlled cortical impact at the skull midline once every 48 h, for a total of 5 hits. Auditory function was assessed via the auditory brainstem response (ABR) at various timepoints post injury. Brain and cochleae were collected to establish a timeline of cellular pathology.

RESULTS

We observed increased ABR thresholds and decreased (ABR) P1 amplitudes in rTBI vs sham animals at 14 days post-impact (dpi). This effect persisted for up to 60 days (dpi). Auditory temporal processing was impaired beginning at 30 dpi. Spiral ganglion degeneration was evident at 14 dpi. No loss of hair cells was detected at this time, suggesting that neuronal loss is one of the earliest notable events in hearing loss caused by this type of rTBI.

CONCLUSIONS

We conclude that rTBI results in chronic auditory dysfunction via damage to the spiral ganglion which occurs in the absence of any reduction in hair cell number. This suggests early neuronal damage that may be caused by systemic mechanisms similar to those leading to the spread of neuronal death in the brain following TBI. This TBI-hearing loss model provides an important first step towards identifying therapeutic targets to attenuate damage to the auditory system following head injury.

REM Sleep Impairment May Underlie Sleep-Driven Modulations of Tinnitus in Sleep Intermittent Tinnitus Subjects: A Controlled Study

(1) Background: Poor sleep and fragmented sleep are associated with several chronic conditions. Tinnitus is an auditory symptom that often negatively combines with poor sleep and has been associated with sleep impairment and sleep apnea. The relationship between tinnitus psychoacoustic characteristics and sleep is still poorly explored, notably for a particular subgroup of patients, for whom the perceived loudness of their tinnitus is highly modulated by sleep. (2) Methods: For this observational prospective study, 30 subjects with tinnitus were recruited, including 15 "sleep intermittent tinnitus" subjects, who had reported significant modulations of tinnitus loudness related to night sleep and naps, and a control group of 15 subjects displaying constant non-sleep-modulated tinnitus. The control group had matching age, gender, self-reported hearing loss grade and tinnitus impact on quality of life with the study group. All patients underwent a polysomnography (PSG) assessment for one complete night and then were asked to fill in a case report form, as well as a report of tinnitus loudness before and after the PSG. (3) Results: "Sleep Intermittent tinnitus" subjects had less Stage 3 sleep (p < 0.01), less Rapid-Eye Movement (REM) Sleep (p < 0.05) and more Stage 2 sleep (p < 0.05) in proportion and duration than subjects from the control group. In addition, in the "sleep Intermittent tinnitus" sample, a correlation was found between REM sleep duration and tinnitus overnight modulation (p < 0.05), as well as tinnitus impact on quality of life (p < 0.05). These correlations were not present in the control group. (4) Conclusions: This study suggests that among the tinnitus population, patients displaying sleep-modulated tinnitus have deteriorated sleep quality. Furthermore, REM sleep characteristics may play a role in overnight tinnitus modulation. Potential pathophysiological explanations accounting for this observation are hypothesized and discussed.

Evaluation and Management of Tinnitus: Are There Opportunities for Improvement?

OBJECTIVE

To review current information about diagnosis and management of tinnitus aiming to identify opportunities for achieving a cost-effective, efficient, evidence-based approach that meets the needs of tinnitus sufferers.

DATA SOURCES

PubMed/MEDLINE.

REVIEW METHODS

In total, 249 relevant published reports were reviewed. Pertinent keywords and MeSH terms identified reports via PubMed and EMBASE. Acknowledged experts were consulted on ways to improve tinnitus management.

CONCLUSIONS

There may be opportunities to improve evaluation and management of patients with tinnitus using modern modes of communication and a multidisciplinary therapeutic approach.

IMPLICATIONS FOR PRACTICE

Tinnitus can adversely affect quality of life while being time-consuming and costly to evaluate and manage. Based on both personal experience and the reports of others, patients with tinnitus who choose to see a physician primarily want to know two things: (1) that the tinnitus that is so distressing will not remain at the same level of severity forever and (2) that something can be done to help cope with the tinnitus that is so annoying. Recent advancements in internet communications, social media, information technology, artificial intelligence, machine learning, holistic medical care, mind-body integrative health care, and multidisciplinary approaches in medical therapeutics may be possibly making new ways of meeting the needs of patients with tinnitus.

The association between stress, emotional states, and tinnitus: a mini-review

Extensive literature supporting the view of tinnitus induced stress in patients is available. However, limited evidence has been produced studying the opposite, that is, does stress cause tinnitus? The hypothalamus pituitary adrenal axis, one of the main neuroendocrine systems involved in stress response, is commonly disturbed in tinnitus patients. Patients with chronic tinnitus have been shown to develop abnormal responses to psycho-social stress, where the hypothalamus pituitary adrenal axis response is weaker and delayed, suggesting chronic stress contributes to the development of chronic tinnitus. The sympathetic branch of the autonomic nervous system also plays a major role in stress response and its chronic hyperactivity seems to be involved in developing tinnitus. Psycho-social stress has been shown to share the same probability of developing tinnitus as occupational noise and contributes to worsening tinnitus. Additionally, exposure to high stress levels and occupational noise doubles the likelihood of developing tinnitus. Interestingly, short-term stress has been shown to protect the cochlea in animals, but chronic stress exposure has negative consequences. Emotional stress also worsens pre-existing tinnitus and is identified as an important indicator of tinnitus severity. Although there is limited body of literature, stress does seem to play a vital role in the development of tinnitus. This review aims to highlight the association between stress, emotional states, and the development of tinnitus while also addressing the neural and hormonal pathways involved.

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.

Meeting the complex healthcare needs of veterans

ABSTRACT

More than half of US veterans seek care outside of the Veterans Health Administration. Physical and mental healthcare needs can be complicated by experiences during military service. Community clinicians can deliver more holistic and comprehensive care to veterans through understanding the unique needs of the veteran population.

Self-reported auditory problems are associated with adverse mental health outcomes and alcohol misuse in the UK Armed Forces

PURPOSE

Auditory problems, such as hearing loss and tinnitus, have been associated with mental health problems and alcohol misuse in the UK general population and in the US Armed Forces; however, few studies have examined these associations within the UK Armed Forces. The present study examined the association between auditory problems and probable common mental disorders, post-traumatic stress disorder and alcohol misuse.

METHODS

5474 serving and ex-service personnel from the UK Armed Forces were examined, selected from those who responded to phase two (data collection 2007-09) and phase three (2014-16) of a military cohort study. Multivariable logistic regression was used to examine the association between auditory problems at phase two and mental health problems at phase three.

RESULTS

9.7% of participants reported ever experiencing hearing problems alone, 7.9% reported tinnitus within the last month alone, and 7.8% reported hearing problems with tinnitus. After adjustment, hearing problems with tinnitus at phase two was associated with increased odds of probable common mental disorders (AOR = 1.50, 95% CI 1.09-2.08), post-traumatic stress disorder (AOR = 2.30, 95% CI 1.41-3.76), and alcohol misuse (AOR = 1.94, 95% CI 1.28-2.96) at phase three. Tinnitus alone was associated with probable post-traumatic stress disorder (AOR = 1.80, 95% CI 1.03-3.15); however, hearing problems alone were not associated with any outcomes of interest.

CONCLUSIONS

The association between auditory problems and mental health problems emphasises the importance of the prevention of auditory problems in the Armed Forces: through enhanced audiometric screening, improved hearing protection equipment, and greater levels of utilisation of such equipment.

A Longitudinal Exploration of Self-Reported Hearing Loss, Tinnitus, and Posttraumatic Stress Disorder Treatment Outcomes in Australian Veterans

OBJECTIVE

Tinnitus, hearing loss, and posttraumatic stress disorder (PTSD) are common conditions among veterans. Shared underlying symptoms, such as hypervigilance and heightened sense of threat, may interfere with talk-based psychological treatments. The aim was to investigate the prevalence and risk factors for self-reported tinnitus and hearing loss among Australian treatment-seeking veterans, as well as links with PTSD symptoms and quality of life (QOL) after treatment.

METHODS

Australian veterans participating in hospital-based PTSD treatment (n = 523) completed self-report measures of subjective hearing impairment, service-related factors, PTSD symptoms, and QOL at treatment intake and discharge, as well as 3- and 9-month follow-ups. Univariate analyses of covariance modeled symptom change over time.

RESULTS

More than half of veterans on PTSD treatment self-reported doctor-diagnosed hearing loss or tinnitus, whereas 43% reported both. However, 75% reported subjective mild to moderate hearing impairment, and only 1% reported severe impairment. Service-related factors, such as longer length of service and exposure to explosions, were risk factors for having any hearing condition. After controlling for intake scores, there were no significant differences on PTSD or QOL outcomes over time between those with and without hearing conditions.

CONCLUSIONS

Although self-reported tinnitus and hearing loss are prevalent among veterans, those with severe hearing impairments are unlikely to be represented in this context. There is a need for psychological treatments that are accessible to patients with severe hearing impairments, which should be examined routinely among military members accessing psychological treatments.

Mental Health Symptoms Among Veteran VA Users by Tinnitus Severity:A Population-based Survey

INTRODUCTION

Tinnitus is prevalent among Service members and Veterans and is often comorbid with mental health disorders. Associations between the severity of individuals' tinnitus and mental health symptoms are not well described.

MATERIALS AND METHODS

We conducted a population-based survey of a stratified random sample of 1,800 Veterans diagnosed with tinnitus. We used the Tinnitus Functional Index to measure tinnitus severity and the Primary Care-Posttraumatic Stress Disorder (PTSD) screen and the Hospital Anxiety and Depression Scale to assess PTSD, depression, and anxiety. Descriptive statistics and bivariable and multivariable regression models were used to estimate associations between Veterans' tinnitus severity and mental health symptoms. Inverse probability weights were used to account for sample stratification and survey non-response. Multivariable odds ratios (ORs) and 95% confidence intervals (CIs) controlled for Veterans' demographics, military history, and health diagnoses.

RESULTS

A total of 891 Veterans completed surveys (adjusted response rate = 53%). Large proportions rated their tinnitus as severe (29.4%; 95% CI: 27.2-31.6) or very severe (18.7%; 95% CI: 16.8-20.5). In multivariable regression models, and compared with Veterans with none/mild tinnitus, the likelihood of screening positive for PTSD was increased for those who reported moderate (OR = 4.0; 95% CI: 1.6-10.3), severe (OR = 7.5; 95% CI: 3.1-18.5), or very severe (OR = 17.5; 95% CI: 4.4-70.0) tinnitus. Similarly, Veterans' likelihood of positive depression screens were elevated for those with moderate (OR = 2.6; 95% CI: 1.1-5.9), severe (OR = 3.0; 95% CI: 1.4-6.5), or very severe (OR = 15.5; 95% CI: 4.3-55.5) tinnitus, as was the likelihood of positive anxiety screens for those with severe (OR = 2.6; 95% CI: 1.1-6.3) or very severe (OR = 13.4; 95% CI: 4.0-44.3) tinnitus.

CONCLUSIONS

Mental health symptoms are strongly associated with Veterans' tinnitus severity. A better understanding of the interplay between these conditions may help improve the provision of interdisciplinary (Audiology and Mental Health) care for Service members and Veterans.

Perception of, and Reaction to, Tinnitus: The Depression Factor

Tinnitus is the perception of a self-generated sound and an individual's psychological reaction to it. This article discusses one element of the reaction: depression. Epidemiologic studies have noted high comorbidity of tinnitus and depression. Findings from recent brain imaging studies have noted shared neural networks in depression and severe tinnitus. As further evidence of this overlaps, antidepressants, counseling, and psychology-based approaches have been used to treat tinnitus. Multifaceted treatment strategies, using both sound-based therapies (not discussed in this paper) and psychology-based approaches, are a necessary part of the treatment options, with the aim of enhancing self-efficacy in patients with tinnitus.

Incidence Rates of Tinnitus in Active Duty Military Service Members Between 2001 and 2015

Purpose Due to hazards in the contemporary operating environment, U.S. military service members are at increased risk for tinnitus. Previous research has characterized tinnitus prevalence in military veterans, but no population-based study of tinnitus has been conducted in active duty military service members. This study evaluated the incidence of tinnitus diagnoses in military electronic health records based on International Classification of Diseases, 9th Revision (ICD-9) codes for active duty service members between 2001 and 2015. Method Data on 85,438 active duty military service members who served between 2001 and 2015 were drawn from the Defense Medical Epidemiological Database and stratified by race, age, sex, marital status, service branch, and military pay grade. Results The incidence rate of tinnitus in U.S. military service members (per 1,000) rose consistently from 1.84 in 2001 to 6.33 in 2015. Service members most often diagnosed with tinnitus were White (72%), married (72%), males (88%), in the enlisted pay grade of E-5 to E-9 (55%), in the Army (37%), and were 35 years of age or older (50%). Statistically significant differences (p < .001) were found between observed and expected counts across all 6 demographic variables. Conclusions This is the first study to assess the incidence rates of tinnitus in active duty service members. Although there are many risk factors for auditory damage in the contemporary military operating environment, the extant literature on tinnitus in active duty military service members is limited. Future studies should consider the relationship between tinnitus-related psychological comorbidity and objective health-related quality of life, as it impacts operational readiness in active duty military service members.

Health Care Utilization and Mental Health Diagnoses Among Veterans With Tinnitus

Purpose Tinnitus is prevalent among military Veterans and may frequently co-occur with mental health disorders. This study examined health care utilization and mental health diagnoses among Veterans with and without tinnitus who receive Department of Veterans Affairs (VA) health care. Method We randomly sampled 10% of VA health care users for a 5-year period between 2011 and 2016. Tinnitus and other diagnoses were identified using International Classification of Diseases diagnosis codes; Veterans assigned 1 or more inpatient codes or 2 or more outpatient codes were considered to have the respective diagnosis. We examined demographics, military service, clinical characteristics, and health care utilization of Veterans with and without tinnitus diagnoses. Bivariable and multivariable logistic regression was used to estimate associations between tinnitus and mental health diagnoses of interest. Results Among 617,534 eligible Veterans, 3.8% met criteria for tinnitus diagnosis. Prevalence of tinnitus was associated with sex, age, race, marital status, and VA service connection status; additionally, hearing loss and traumatic brain injury were frequently codiagnosed with tinnitus. Veterans with tinnitus had higher annual health care utilization than those without. While controlling for potential confounders, tinnitus diagnoses were associated with mental health diagnoses, including anxiety, depression, and substance use disorders. Conclusion Findings suggest that Veterans who are diagnosed with tinnitus have more health care utilization and are more frequently diagnosed with mental health disorders than Veterans who are not diagnosed with tinnitus. This suggests a need for coordinated tinnitus and mental health care services for Veterans in the VA system of care.