The sound of stress: Blunted cortisol reactivity to psychosocial stress in tinnitus sufferers

A review of the auditory-gut-brain axis

Hearing loss places a substantial burden on medical resources across the world and impacts quality of life for those affected. Further, it can occur peripherally and/or centrally. With many possible causes of hearing loss, there is scope for investigating the underlying mechanisms involved. Various signaling pathways connecting gut microbes and the brain (the gut-brain axis) have been identified and well established in a variety of diseases and disorders. However, the role of these pathways in providing links to other parts of the body has not been explored in much depth. Therefore, the aim of this review is to explore potential underlying mechanisms that connect the auditory system to the gut-brain axis. Using select keywords in PubMed, and additional hand-searching in google scholar, relevant studies were identified. In this review we summarize the key players in the auditory-gut-brain axis under four subheadings: anatomical, extracellular, immune and dietary. Firstly, we identify important anatomical structures in the auditory-gut-brain axis, particularly highlighting a direct connection provided by the vagus nerve. Leading on from this we discuss several extracellular signaling pathways which might connect the ear, gut and brain. A link is established between inflammatory responses in the ear and gut microbiome-altering interventions, highlighting a contribution of the immune system. Finally, we discuss the contribution of diet to the auditory-gut-brain axis. Based on the reviewed literature, we propose numerous possible key players connecting the auditory system to the gut-brain axis. In the future, a more thorough investigation of these key players in animal models and human research may provide insight and assist in developing effective interventions for treating hearing loss.

Tinnitus and treatment-resistant depression

Tinnitus, a frequent disorder, is the conscious perception of a sound in the absence of a corresponding external acoustic sound source in the sense of a phantom sound. Although the majority of people who perceive a tinnitus sound can cope with it and are only minimaly impaired in their quality of lfe, 2-3% of the population perceive tinnitus as a major problem. Recently it has been proposed that the two groups should be differentiated by distict terms: "Tinnitus" describes the auditory or sensory component, whereas "Tinnitus Disorder" reflects the auditory component and the associated suffering. There is overwhelming evidence that a high tinnitus burden is associated with the increased occurrence of comorbidities, including depression. Since no causal therapeutic options are available for patients with tinnitus at the present time, the identification and adequate treatment of relevant comorbidities is of great importance for the reduction of tinnitus distress. This chapter deals with the relationship between tinnitus and depression. The neuronal mechanisms underlying tinnitus will first be discussed. There will also be an overview about depression and treatment resistant depression (TRD). A comprehensive review about the state-of-the-art evidences of the relationship between tinnitus and TRD will then be provided.

Chronic stress induced loudness hyperacusis, sound avoidance and auditory cortex hyperactivity

Hyperacusis, a debilitating loudness intolerance disorder, has been linked to chronic stress and adrenal insufficiency. To investigate the role of chronic stress, rats were chronically treated with corticosterone (CORT) stress hormone. Chronic CORT produced behavioral evidence of loudness hyperacusis, sound avoidance hyperacusis, and abnormal temporal integration of loudness. CORT treatment did not disrupt cochlear or brainstem function as reflected by normal distortion product otoacoustic emissions, compound action potentials, acoustic startle reflexex, and auditory brainstem responses. In contrast, the evoked response from the auditory cortex was enhanced up to three fold after CORT treatment. This hyperactivity was associated with a significant increase in glucocorticoid receptors in auditory cortex layers II/III and VI. Basal serum CORT levels remained normal after chronic CORT stress whereas reactive serum CORT levels evoked by acute restraint stress were blunted (reduced) after chronic CORT stress; similar changes were observed after chronic, intense noise stress. Taken together, our results show for the first time that chronic stress can induce hyperacusis and sound avoidance. A model is proposed in which chronic stress creates a subclinical state of adrenal insufficiency that establishes the necessary conditions for inducing hyperacusis.

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.

Is a blunted cortisol response to stress a premorbid risk for insomnia?

STUDY OBJECTIVES

Vulnerability to stress-related sleep disturbances (sleep reactivity) is an established heritable risk factor for insomnia disorder with unclear biological underpinnings. Preliminary research points to a blunted cortisol response to stress as a biological predisposition to familial risk for insomnia, but the role of cortisol response in sleep reactivity is unknown. Therefore, the current studies examined whether sleep reactivity is associated with a blunted cortisol response to two laboratory stressors among participants without insomnia.

METHODS

Two community samples of adults with no lifetime history of insomnia completed the Trier Social Stress Test (N = 35) or the Cold Pressor Task (N = 34). Participants were grouped by insomnia-risk using sleep reactivity scores from the Ford Insomnia Response to Stress Test (FIRST). Physiological responses were measured via markers of the hypothalamic-pituitary-adrenal (HPA) axis (salivary cortisol) and autonomic nervous system (ANS; heart rate, mean arterial pressure, and salivary alpha amylase).

RESULTS

Participants with high insomnia-risk (FIRST score > 18) exhibited blunted cortisol responses to both stressors. There were no group differences in ANS responses across stressors.

CONCLUSIONS

Insomnia-risk as indicated by sleep reactivity is associated with blunted cortisol responses to psychosocial and physical laboratory stressors among premorbid adults without insomnia disorder. This study replicates previous research and supports a blunted cortisol response to stress as a biomarker for insomnia vulnerability that may be detected using the FIRST. Prospective research is needed to elucidate whether a blunted cortisol response to stress is one mechanism by which sleep reactive individuals may be at risk of developing insomnia.

Tinnitus and the triple network model: a perspective

Tinnitus is defined as the conscious awareness of a sound without an identifiable external sound source, and tinnitus disorder as tinnitus with associated suffering. Chronic tinnitus has been anatomically and phenomenologically separated into three pathways: a lateral “sound” pathway, a medial “suffering” pathway, and a descending noise-canceling pathway. Here, the triple network model is proposed as a unifying framework common to neuropsychiatric disorders. It proposes that abnormal interactions among three cardinal networks—the self-representational default mode network, the behavioral relevance-encoding salience network and the goal-oriented central executive network—underlie brain disorders. Tinnitus commonly leads to negative cognitive, emotional, and autonomic responses, phenomenologically expressed as tinnitus-related suffering, processed by the medial pathway. This anatomically overlaps with the salience network, encoding the behavioral relevance of the sound stimulus. Chronic tinnitus can also become associated with the self-representing default mode network and becomes an intrinsic part of the self-percept. This is likely an energy-saving evolutionary adaptation, by detaching tinnitus from sympathetic energy-consuming activity. Eventually, this can lead to functional disability by interfering with the central executive network. In conclusion, these three pathways can be extended to a triple network model explaining all tinnitus-associated comorbidities. This model paves the way for the development of individualized treatment modalities.

Unexpected Consequences of Noise-Induced Hearing Loss: Impaired Hippocampal Neurogenesis, Memory, and Stress

Noise-induced hearing loss (NIHL), caused by direct damage to the cochlea, reduces the flow of auditory information to the central nervous system, depriving higher order structures, such as the hippocampus with vital sensory information needed to carry out complex, higher order functions. Although the hippocampus lies outside the classical auditory pathway, it nevertheless receives acoustic information that influence its activity. Here we review recent results that illustrate how NIHL and other types of cochlear hearing loss disrupt hippocampal function. The hippocampus, which continues to generate new neurons (neurogenesis) in adulthood, plays an important role in spatial navigation, memory, and emotion. The hippocampus, which contains place cells that respond when a subject enters a specific location in the environment, integrates information from multiple sensory systems, including the auditory system, to develop cognitive spatial maps to aid in navigation. Acute exposure to intense noise disrupts the place-specific firing patterns of hippocampal neurons, “spatially disorienting” the cells for days. More traumatic sound exposures that result in permanent NIHL chronically suppresses cell proliferation and neurogenesis in the hippocampus; these structural changes are associated with long-term spatial memory deficits. Hippocampal neurons, which contain numerous glucocorticoid hormone receptors, are part of a complex feedback network connected to the hypothalamic-pituitary (HPA) axis. Chronic exposure to intense intermittent noise results in prolonged stress which can cause a persistent increase in corticosterone, a rodent stress hormone known to suppress neurogenesis. In contrast, a single intense noise exposure sufficient to cause permanent hearing loss produces only a transient increase in corticosterone hormone. Although basal corticosterone levels return to normal after the noise exposure, glucocorticoid receptors (GRs) in the hippocampus remain chronically elevated. Thus, NIHL disrupts negative feedback from the hippocampus to the HPA axis which regulates the release of corticosterone. Preclinical studies suggest that the noise-induced changes in hippocampal place cells, neurogenesis, spatial memory, and glucocorticoid receptors may be ameliorated by therapeutic interventions that reduce oxidative stress and inflammation. These experimental results may provide new insights on why hearing loss is a risk factor for cognitive decline and suggest methods for preventing this decline.

Hair-cortisol and hair-BDNF as biomarkers of tinnitus loudness and distress in chronic tinnitus

The role of stress and its neuroendocrine mediators in tinnitus is unclear. In this study, we measure cortisol as an indicator of hypothalamus–pituitary–adrenal (HPA) axis alterations and brain-derived neurotrophic factor (BDNF) as a marker of adaptive neuroplasticity in hair of chronic tinnitus patients to investigate relationships with tinnitus-related and psychological factors. Cross-sectional data from chronic tinnitus inpatients were analyzed. Data collection included hair sampling, pure tone audiometry, tinnitus pitch and loudness matching, and psychometric questionnaires. Elastic net regressions with n-fold cross-validation were performed for cortisol (N = 91) and BDNF (N = 87). For hair-cortisol (R² = 0.10), the strongest effects were sampling in autumn and body-mass index (BMI) (positive), followed by tinnitus loudness (positive) and smoking (negative). For hair-BDNF (R² = 0.28), the strongest effects were hearing aid use, shift work (positive), and tinnitus loudness (negative), followed by smoking, tinnitus-related distress (Tinnitus Questionnaire), number of experienced traumatic events (negative), and physical health-related quality of life (Short Form-12 Health Survey) (positive). These findings suggest that in chronic tinnitus patients, higher perceived tinnitus loudness is associated with higher hair-cortisol and lower hair-BDNF, and higher tinnitus-related distress with lower hair-BDNF. Regarding hair-BDNF, traumatic experiences appear to have additional stress-related effects, whereas hearing aid use and high physical health-related quality of life appear beneficial. Implications include the potential use of hair-cortisol and hair-BDNF as biomarkers of tinnitus loudness or distress and the need for intensive future research into chronic stress-related HPA axis and neuroplasticity alterations in chronic tinnitus.

Audiometric Characteristics and Tinnitus Features in a Cohort of 170 Spanish Patients

BACKGROUND

Tinnitus is a rather prevalent, quite heterogeneous, and difficult to treat auditory disorder. The aim of this article is to provide the design and results of a cross-sectional study related to audiological and tinnitus features in a group of 170 Spanish patients.

METHODS

Audiometric characteristics were assessed on the basis of the pure-tone audiometry of both ears in 170 tinnitus patients and 85 control subjects. The audiometric status of each tinnitus participant was assessed on the basis of the average auditory threshold (AAT) in the whole frequency range (from 125 Hz to 8 kHz), and low (from 125 Hz to 2 kHz) and high (from 3 kHz to 8 kHz)-frequency intervals. Tinnitus features were evaluated through personal interview with patients and included tinnitus duration, laterality, pitch, sound, and distress (Tinnitus Handicap Inventory, THI). Correlational analysis was carried out between audiological (AAT) and tinnitus (THI) variables.

RESULTS

A very weak Spearman rank correlation factor is found between both variables.

CONCLUSIONS

The subjective outcome of tinnitus distress (THI) was not correlated with the objective measure of hearing loss (AAT) in our cohort.

A State-of-Art Review of Digital Technologies for the Next Generation of Tinnitus Therapeutics

Background: Digital processing has enabled the development of several generations of technology for tinnitus therapy. The first digital generation was comprised of digital Hearing Aids (HAs) and personal digital music players implementing already established sound-based therapies, as well as text based information on the internet. In the second generation Smart-phone applications (apps) alone or in conjunction with HAs resulted in more therapy options for users to select from. The 3rd generation of digital tinnitus technologies began with the emergence of many novel, largely neurophysiologically-inspired, treatment theories that drove development of processing; enabled through HAs, apps, the internet and stand-alone devices. We are now of the cusp of a 4th generation that will incorporate physiological sensors, multiple transducers and AI to personalize therapies. Aim: To review technologies that will enable the next generations of digital therapies for tinnitus. Methods: A "state-of-the-art" review was undertaken to answer the question: what digital technology could be applied to tinnitus therapy in the next 10 years? Google Scholar and PubMed were searched for the 10-year period 2011-2021. The search strategy used the following key words: "tinnitus" and ["HA," "personalized therapy," "AI" (and "methods" or "applications"), "Virtual reality," "Games," "Sensors" and "Transducers"], and "Hearables." Snowballing was used to expand the search from the identified papers. The results of the review were cataloged and organized into themes. Results: This paper identified digital technologies and research on the development of smart therapies for tinnitus. AI methods that could have tinnitus applications are identified and discussed. The potential of personalized treatments and the benefits of being able to gather data in ecologically valid settings are outlined. Conclusions: There is a huge scope for the application of digital technology to tinnitus therapy, but the uncertain mechanisms underpinning tinnitus present a challenge and many posited therapeutic approaches may not be successful. Personalized AI modeling based on biometric measures obtained through various sensor types, and assessments of individual psychology and lifestyles should result in the development of smart therapy platforms for tinnitus.

Clinical and genetic risk factors for radiation-associated ototoxicity: A report from the Childhood Cancer Survivor Study and the St. Jude Lifetime Cohort

BACKGROUND

Cranial radiation therapy (CRT) is associated with ototoxicity, which manifests as hearing loss and tinnitus. The authors sought to identify clinical determinants and genetic risk factors for ototoxicity among adult survivors of pediatric cancer treated with CRT.

METHODS

Logistic regression evaluated associations of tinnitus (n = 1991) and hearing loss (n = 2198) with nongenetic risk factors and comorbidities among CRT-treated survivors in the Childhood Cancer Survivor Study. Genome-wide association studies (GWASs) of CRT-related tinnitus and hearing loss were also performed.

RESULTS

Males were more likely to report CRT-related tinnitus (9.4% vs 5.4%; P = 5.1 × 10^-4 ) and hearing loss (14.0% vs 10.7%; P = .02) than females. Survivors with tinnitus or hearing loss were more likely to experience persistent dizziness or vertigo (tinnitus: P < 2 × 10^-16 ; hearing loss: P = 6.4 × 10^-9 ), take antidepressants (tinnitus: P = .02; hearing loss: P = .01), and report poorer overall health (tinnitus: P = 1.5 × 10^-6 ; hearing loss: P = 1.7 × 10^-6 ) in comparison with controls. GWAS of CRT-related tinnitus revealed a genome-wide significant signal in chromosome 1 led by rs203248 (P = 1.5 × 10^-9 ), whereas GWAS of CRT-related hearing loss identified rs332013 (P = 5.8 × 10^-7 ) in chromosome 8 and rs67522722 (P = 7.8 × 10^-7 ) in chromosome 6 as nearly genome-wide significant. A replication analysis identified rs67522722, intronic to ATXN1, as being significantly associated with CRT-related hearing loss (P = .03) and de novo hearing loss (P = 3.6 × 10^-4 ).

CONCLUSIONS

CRT-associated ototoxicity was associated with sex, several neuro-otological symptoms, increased antidepressant use, and poorer self-reported health. GWAS of CRT-related hearing loss identified rs67522722, which was supported in an independent cohort of survivors.

LAY SUMMARY

Hearing loss and subjective tinnitus (the perception of noise or ringing in the ear) are long-term side effects of cancer treatment and are common in children treated with radiation to the brain. These toxicities can affect childhood development and potentially contribute to serious learning and behavioral difficulties. This study's data indicate that males are at greater risk for hearing loss and tinnitus than females after radiation therapy to the brain. Those who develop these toxicities are more likely to use antidepressants and report poorer overall health. Health care providers can improve the management of survivors by informing patients and/or their parents of these risks.

Objective and Measurable Biomarkers in Chronic Subjective Tinnitus

Tinnitus is associated with increased social costs and reduced quality of life through sleep disorders or psychological distress. The pathophysiology of chronic subjective tinnitus, which accounts for most tinnitus, has not been clearly elucidated. This is because chronic subjective tinnitus is difficult to evaluate objectively, and there are no objective markers that represent the diagnosis or therapeutic effect of tinnitus. Based on the results of studies on patients with chronic subjective tinnitus, objective and measurable biomarkers that help to identify the pathophysiology of tinnitus have been summarized. A total of 271 studies in PubMed, 303 in EMBASE, and 45 in Cochrane Library were found on biomarkers related to chronic subjective tinnitus published until April 2021. Duplicate articles, articles not written in English, review articles, case reports, and articles that did not match our topic were excluded. A total of 49 studies were included. Three specimens, including blood, saliva, and urine, and a total of 58 biomarkers were used as indicators for diagnosis, evaluation, prognosis, and therapeutic effectiveness of tinnitus. Biomarkers were classified into eight categories comprising metabolic, hemostatic, inflammatory, endocrine, immunological, neurologic, and oxidative parameters. Biomarkers can help in the diagnosis, measure the severity, predict prognosis, and treatment outcome of tinnitus.

Changes in Heart Rate Variability Following Acoustic Therapy in Individuals With Tinnitus

Purpose The aim of the study was to investigate changes in autonomic function, as measured by heart rate variability, in individuals with tinnitus following acoustic therapy implemented using tinnitus maskers presented via hearing aids. Method Twenty-six individuals with tinnitus and hearing impairment completed an 8-week field trial wearing hearing aids providing acoustic therapy via three tinnitus masker options set just below minimum masking level. Tinnitus handicap was measured using the Tinnitus Handicap Inventory at baseline (before starting acoustic therapy) and posttreatment (at end of 8-week trial). Resting heart rate and heart rate variability were measured using electrocardiography at baseline and posttreatment. Results There was a significant decrease in tinnitus handicap posttreatment compared to baseline. There was no change in heart rate, but there was a significant increase in heart rate variability posttreatment compared to baseline. Conclusions Acoustic therapy using tinnitus maskers delivered via hearing aids provided tinnitus relief and produced a concurrent increase in heart rate variability, suggesting a decrease in stress. Heart rate variability is a potential biomarker for tracking efficacy of acoustic therapy; however, further research is required.

Evidence for biological markers of tinnitus: A systematic review

Subjective tinnitus is a phantom sound heard only by the affected person and may be a symptom of various diseases. Tinnitus diagnosis and monitoring is based on subjective audiometric and psychometric methods. This review aimed to synthesize evidence for tinnitus presence or its severity. We searched several electronic databases, citation searches of the included primary studies through Web of Science, and further hand searches. At least two authors performed all systematic review steps. Sixty-two records were included and were categorized according the biological variable. Evidence for possible tinnitus biomarkers come from oxidative stress, interleukins, steroids and neurotransmitters categories. We found conflicting evidence for full blood count, vitamins, lipid profile, neurotrophic factors, or inorganic ions. There was no evidence for an association between tinnitus and the remaining categories. The current review evidences that larger studies, with stricter exclusion criteria and powerful harmonized methodological design are needed. Protocol published on PROSPERO (CRD42017070998).

Psychological Comorbidities of Tinnitus

In this chapter, I address the topic of tinnitus in the context of the patient's trajectory of care, with special attention to psychological comorbidities. Although most patients will cope with tinnitus and need no more than information and reassurance from professionals, a proportion of patients will need more supportive management. Assessment of psychological comorbidities is important to determine how urgent they should be seen in the clinic and their specific needs. The most frequent complaints are stress, depression, and anxiety. Although the direction of this relationship is still unclear (are comorbidities at the origin of tinnitus or are they a consequence of it), it is evident that the more serious comorbidities are at the onset of tinnitus, the worse the prognosis. Therefore, an assessment at the initial visit in the clinic is of utmost importance. There are valid and reliable psychometric tools to quickly draw a portrait of the psychological state of patients that can be used by audiologists, psychologists, or doctors. Therapeutic avenues can then be discussed with the patients to ensure them the best support possible.

Neurobiology of Stress-Induced Tinnitus

Emotional stress has accompanied humans since the dawn of time and has played an essential role not only in positive selection and adaptation to an ever-changing environment, but also in the acceleration or even initiation of many illnesses. The three main somatic mechanisms induced by stress are the hypothalamus-pituitary-adrenal axis (HPA axis), the sympathetic-adreno-medullar (SAM) axis, and the immune axis. In this chapter, the stress-induced mechanisms that can affect cochlear physiology are presented and discussed in the context of tinnitus generation and auditory neurobiology. It is concluded that all of the presented mechanisms need to be further investigated. It is advised that clinical practitioners ask patients about stressful events or chronic stress preceding the tinnitus onset and measure the vital signs. Finally, taking into account that tinnitus itself acts as a stressor, the implementation of anti-stress therapies for tinnitus treatment is recommended.

Adapting Personal Therapies Using a Mobile Application for Tinnitus Rehabilitation: A Preliminary Study

OBJECTIVES

To develop a smartphone application providing sound therapy and cognitive behavioral therapy (CBT) for treating tinnitus and performing a proof-of-concept pilot study evaluating its potential efficacy.

METHODS

An interactive smartphone application available on iOS and Android platforms was developed, which provided an 8-week tinnitus-specific CBT and personalized and frequency-matched sound therapy. Included patients presented to our tertiary clinic between 2017 and 2018, while those waitlisted were regarded as controls. Three surveys were administrated: Tinnitus Handicap Inventory (THI), Generalized Anxiety Disorder 7-item (GAD-7), and Perceived Stress Scale (PSS).

RESULTS

A total of 30 patients enrolled in this study consisting of 20 treatment and 10 control patients and mean age was 55.4 ± 11.6 years. Treatment and control patients had similar age, sex, and pre-enrolment GAD and PSS (all P > .05). Baseline THI scores were also similar between treatment and control cohorts (50.1 ± 21.9 vs 62.0 ± 20.7; P = .15). After 8 weeks, though changes in GAD and PSS scores were similar (P > .05), the treatment group reported a significantly greater improvement in THI scores (17.7 ± 15.8 vs 5.3 ± 10.5, P = .04).

CONCLUSIONS

This pilot study demonstrated potentially promising efficacy of a smartphone-based CBT and sound therapy platform for treating tinnitus and encourages future randomized controlled trials on this treatment modality.

Tinnitus and stress in adults: a scoping review

OBJECTIVE

Tinnitus and stress are recurrently reported together. The strength and direction of this relationship is not clear. The aim of this review is to catalogue the evidence of this relationship, how it has been described in adults and which instruments were used.

DESIGN

Five-stage framework was followed. An online search of databases and published journals were conducted. The main inclusion criteria were original studies published in English and conducted in an adult human population, in which both tinnitus and stress were measured using different instruments.

STUDY SAMPLES

5699 records were identified in the searching stage and 50 studies were eligible for data extraction.

RESULTS

Measurements of perceived stress were most frequently used. Tinnitus patients tend to report louder and more bothersome tinnitus when they are stressed, but not all tinnitus patients associated stress with the onset or the severity of their tinnitus. Any positive correlation reported between stress and tinnitus levels varied in strength according to the used instrument. Post-intervention changes in stress and tinnitus levels showed inconsistency.

CONCLUSION

There is considerable room for further research to study the relationship between stress and tinnitus. We highlight principal issues that should be considered in future studies.

The Cortisol Awakening Response: A Feasibility Study Investigating the Use of the Area Under the Curve With Respect to Increase as an Effective Objective Measure of Tinnitus Distress

Purpose Tinnitus is a chronic medical condition that can result in distress, concentration difficulties, and clinical depression. An effective, objective measure of tinnitus distress does not currently exist. Endocrinal studies into the condition have been few, with those investigating the cortisol awakening response limited in scope. It was hypothesized that distressed individuals with tinnitus would awaken and be unable to effectively prepare for the day ahead due to a blunted cortisol response. Method Twenty individuals with varying tinnitus distress were compared with a control group (n = 10) in a pilot study, which measured salivary cortisol concentrations on awakening. Multiple exclusion variables were applied. Results In line with previous studies, total cortisol volume (as measured by area under the curve) was not found to be significantly different in the most distressed individuals with tinnitus, F(2, 26) = 0.254, p = .777ns. However, a separate measure of changing cortisol levels-the area under the curve with respect to increase (or AUC_i)-was found to be significantly less robust in those individuals reporting the most severe tinnitus distress, F(2, 26) = 7.671, p = .002. This indicates that fewer resources would be available to cope with the demands of the day ahead. Additionally, the AUC_i correlated negatively with tinnitus distress later the same day. Conclusions Relationships between proposed objective and self-reported components of self-reported tinnitus distress are considered, with some aspects of tinnitus distress more closely related to physiological mechanisms than others. It is suggested that, with further research, the cortisol awakening response (AUC_i) may be put forward as a credible objective biomarker of tinnitus distress.

Changes in tinnitus and physiological biomarkers of stress in response to short-term broadband noise and sounds of nature

BACKGROUND

Tinnitus is the perception of sound when no external sound source is present. In some cases, this perception coincides with, or results in, stress. Tinnitus-related distress has been associated with increased levels of cortisol and elevated levels of sympathetic tone. Our primary hypothesis was that short-term sound exposure would reduce tinnitus perception and various physiological measures of stress. A secondary hypothesis was that a self-selected nature sound would reduce physiological markers of stress more than broadband noise.

METHODS

Twenty-one participants with constant bothersome tinnitus underwent an audiological assessment. Measurements of blood pressure, heart rate, salivary cortisol and cortisone concentrations, and tinnitus ratings were carried out three times: prior to and, in a counterbalance order, after 30 min of broadband noise and after 30 min of a self-selected nature sound (from: ocean waves, stream, rain or shower sounds).

RESULTS

Findings revealed significant reductions in blood pressure measurements following broadband noise. None of the other stress measures demonstrated a statistically significant change. Both broadband noise and nature sounds elicited significant improvements in ratings of tinnitus.

CONCLUSIONS

While both sound types had a positive impact on many dimensions of tinnitus, only the broadband noise was associated with a reduction in blood pressure. These results are consistent with a complex interaction between sound and tinnitus and suggest a multifactorial basis to sound therapy that includes a reduction in arousal.

Tinnitus and suicide: An unresolved relation

Tinnitus is an auditory phantom sensation which can be a devastating condition for the affected person causing annoyance and discomfort. It may be associated with psychiatric conditions. Patients with highly annoying tinnitus and different comorbidities may have a higher risk of expressing suicidal behaviour and ideation. We aimed to review available reports on the prevalence of suicide and suicidal behaviour with tinnitus patients in order to collate current concepts and to identify possible alarming signs and risk factors. A comprehensive search for appropriate studies listed in PubMed, Ovid and Cochrane databases was conducted using appropriate keyword combinations. We identified 22 publications including original articles, case reports and reviews of which 10 fit our stringent search criteria. Most importantly, from the present studies it appears not feasible to univocally conclude on the co-incidence of tinnitus and suicide. This is due to methodological differences in these approaches, complex interrelations between tinnitus and other psychiatric comorbidities and confounding factors such as the inclusion of patients suffering from post-traumatic stress disorder. More concerted actions involving different medical disciplines are needed to reflect the ethiological heterogeneity of tinnitus and suicide or suicidal behaviour to test for a relationship.

Noise-induced hearing loss alters hippocampal glucocorticoid receptor expression in rats

Although the effects of intense noise exposure on the peripheral and central auditory pathway have been well characterized, its effects on non-classical auditory structures in the brain, such as the hippocampus, are less well understood. Previously, we demonstrated that noise-induced hearing loss causes a significant long-term reduction in hippocampal neurogenesis and cell proliferation. Given the known suppressive effects of stress hormones on neurogenesis, the goal of the present study was to determine if activation of the stress response is an underlying mechanism for the long-term reduction in hippocampal neurogenesis observed following noise trauma. To accomplish this, we monitored basal and reactive blood plasma levels of the stress hormone corticosterone in rats for ten weeks following acoustic trauma, and quantified changes in hippocampal glucocorticoid and mineralocorticoid receptors. Our results indicate that long-term auditory deprivation does not cause a persistent increase in basal or reactive stress hormone levels in the weeks following noise exposure. Instead, we observed a greater decline in reactive corticosterone release in noise-exposed rats between the first and tenth week of sampling compared to control rats. We also observed a significant increase in hippocampal glucocorticoid receptor expression which may cause greater hippocampal sensitivity to circulating glucocorticoid levels and result in glucocorticoid-induced suppression of neurogenesis, as well as increased feedback inhibition on the HPA axis. No change in mineralocorticoid receptor expression was observed between control and noise exposed rats. These results highlight the adverse effect of intense noise exposure and auditory deprivation on the hippocampus.

[Tinnitus: psychosomatic aspects]

Tinnitus is a common symptom of unclear origin that can be multifactorially caused and maintained. It is frequently, but not inevitably, associated with hearing loss. Emotional distress and maladaptive coping strategies - that are associated with or amplified by the tinnitus percept - pose key targets for psychological interventions. Once somatic contributors are identified and treated as applicable, psychological approaches comprise normalizing psychoeducational and psychotherapeutic interventions. Measures to improve hearing perception (e. g., hearing aids or cochlear implants) can also contribute to tinnitus habituation through direct (improvement of hearing perception) or indirect (improvement of emotional wellbeing or quality of life) effects.

Sensory neurologic disorders: Tinnitus

Tinnitus is the sensation of hearing a sound with no external auditory stimulus present. It is a public health issue correlated with multiple comorbidities and precipitating factors such as noise exposure, military service, and traumatic brain injury, migraine, insomnia, small vessel disease, smoking history, stress exposure, anxiety, depression, and socioeconomic status. Clinical experience and a recent literature review point at tinnitus as a neuropsychiatric condition involving both auditory and nonauditory cortical areas of the brain and affecting brain-auditory circuitry. In fact, brain-ear connections have been highlighted in different models. Forward management of this disorder should take this body of research into consideration as tinnitus remains a challenging condition to evaluate and treat with current management protocols still symptomatic at best. With a better understanding of the etiologic factors and comorbidities of tinnitus, additional research trials and new therapeutic approaches could see the light to tackle this public health disability bringing hope to patients and doctors.

Childhood Trauma Affects Stress-Related Interoceptive Accuracy

Early life adversity (ELA) may cause permanent disturbances in brain-body signaling. These disturbances are thought to contribute to physical symptoms and emotional dysregulation in adulthood. The current study investigated the effects of childhood trauma on young adults' interoceptive accuracy as an indicator of brain-body communication that may be dysregulated by ELA. Sixty-six participants completed an online questionnaire followed by a laboratory session including the socially evaluated cold pressor stress test during which ECG, salivary cortisol, and interoceptive accuracy were assessed. Childhood trauma was negatively related to interoceptive accuracy (IAc) after the stressor. This stress effect could not be observed for heart rate and cortisol, which were unrelated to IAc. Participants reporting higher baseline unpleasantness exhibited lower IAc after the stressor, while increases in unpleasantness due to the stressor were associated with higher IAc. Unpleasantness at baseline mediated the effect of childhood trauma on IAc after the stressor.

Associations Between Perceived Stress and Chemotherapy-Induced Peripheral Neuropathy and Otoxicity in Adult Cancer Survivors

CONTEXT

The most common adverse effects from neurotoxic chemotherapy are chemotherapy-induced neuropathy (CIPN), hearing loss, and tinnitus. Although associations between perceived stress and persistent pain, hearing loss, and tinnitus are documented, no studies have examined these associations in cancer survivors who received neurotoxic chemotherapy.

OBJECTIVES

In this cross-sectional study, we evaluated for associations between perceived stress and the occurrence of CIPN, hearing loss, and tinnitus, in 623 adult cancer survivors who received platinum and/or taxane compounds.

METHODS

Survivors completed self-report measures of hearing loss, tinnitus, and perceived stress (i.e., Impact of Events Scale-Revised [IES-R]). Separate logistic regression analyses were done for each neurotoxicity to evaluate whether each of the IES-R subscale (i.e., intrusion, avoidance, hyperarousal) and total scores made a significant independent contribution to neurotoxicity group membership.

RESULTS

Of the 623 survivors in this study, 68.4% had CIPN, 34.5% reported hearing loss, and 31.0% reported tinnitus. Older age, higher body mass index, poorer functional status, being born prematurely, cancer diagnosis, and higher intrusion (P = 0.013), hyperarousal (P = 0.014), and total (P = 0.047) IES-R scores were associated with CIPN. Older age, being male, poorer functional status, a worse comorbidity profile, and a higher IES-R hyperarousal (P = 0.007) score were associated with hearing loss. Being male, having less education, a worse comorbidity profile, and a higher IES-R hyperarousal (P = 0.029) score were associated with tinnitus.

CONCLUSION

These findings suggest that increased levels of perceived stress are associated with the most common chemotherapy-induced neurotoxicities.

Differential electrophysiological correlates of panic disorder in non-pulsatile tinnitus

AIMS

The prevalence of panic disorder (PD) reportedly is up to fivefold higher in people with tinnitus than it is in the general population. The brain networks in the two conditions overlap but the pathophysiological link remains unclear. In this study the electrophysiological brain activity is investigated in adults with non-pulsatile tinnitus with and without concurrent PD.

METHODS

Resting-state EEGs of 16 participants with non-pulsatile tinnitus and PD were compared with those of 16 peers with non-pulsatile tinnitus without PD and as many healthy controls. The sLORETA technique was used to identify group-specific electrophysiological frequencies in the brain and to approximate the brain regions where differences occurred. The influence of distress was investigated and functional connectivity charted using the Region-of-Interest (ROI) approach (amygdala, anterior cingulate cortex (ACC), insula, precuneus).

RESULTS

The comorbid group showed significantly diminished theta activity (p < 0.05) in the precuneus (BA7) compared to the tinnitus group without PD as well as in another region of the precuneus (BA31) as compared to the controls. Higher levels of distress influenced results in the tinnitus group without PD, while in those with PD a diminished connectivity was observed between the dorsal ACC and the other three ROIs as contrasted to the controls.

CONCLUSIONS

Adults with non-pulsatile tinnitus and concurrent PD show differential brain activity patterns to tinnitus only sufferers and healthy controls. Higher levels of distress may modulate brain activity in the absence of PD. Screening for distress is recommended in both clinical and research settings.

Familial Risk for Insomnia Is Associated With Abnormal Cortisol Response to Stress

Objectives

Abnormalities in the stress system have been implicated in insomnia. However, studies examining physiological stress regulation in insomnia have not consistently detected differences in the hypothalamic-pituitary-adrenal (HPA)-axis response to stress. One explanation may be that deficits in the stress system are associated specifically with a biological vulnerability to insomnia rather than the phenotypic expression of insomnia. To examine stress response as a function of vulnerability to insomnia, this study tested response to the Trier Social Stress Test in a sample of healthy sleepers with varying familial risks for insomnia.

Methods

Thirty-five healthy individuals with and without familial risk for insomnia were recruited to complete a laboratory stressor. Participants with one or both biological parents with insomnia were categorized as positive for familial risk, whereas those without biological parents with insomnia were categorized as negative for familial risk. Participants completed the Trier Social Stress Test in the laboratory, and psychological and physiological (autonomic and HPA-axis) responses were compared.

Results

Despite self-reported increases in anxiety, those positive for familial risk exhibited a blunted cortisol response relative to those without familial risk for insomnia. Individuals with blunted cortisol also reported heightened reactivity to personal life stressors, including increased sleep disturbances, elevated cognitive intrusions, and more behavioral avoidance.

Conclusions

Findings from this study provide initial evidence that abnormal stress regulation may be a biological predisposing factor conferred via familial risk for insomnia. This deficit may also predict negative consequences over time, including insomnia and the associated psychiatric comorbidities.

Tinnitus, depression, and suicidal ideation in adults: A nationally representative general population sample

Tinnitus is strongly associated with psychiatric symptoms, including depression and suicidality. We aimed to further investigate the association of tinnitus with depressive mood and/or suicidal ideation, and explore the shared risk factors for these within a representative sample of the adult general population. We also investigated potential mediation pathways among tinnitus, suicidal ideation, depression, shared risk factors, and perceived stress levels. We analysed data from 28,930 adults (aged ≥19 years) from the fourth and fifth Korea National Health and Nutrition Examination Surveys (KNHANES) conducted from 2008 to 2012 in South Korea. We investigated the presence and severity of tinnitus, depressive mood, suicidal ideation, perceived usual stress level, and socioeconomic and health-related variables. We conducted logistic regression and mediation analyses. Tinnitus and its severity were significantly associated with depressive mood and suicidal ideation. Tinnitus, depressive mood, and suicidal ideation shared common socioeconomic and health-related risk factors. Tinnitus significantly mediated the association of shared risk factors for depressive mood and suicidal ideation. Perceived usual stress level mediates the association of tinnitus with depressive mood and suicidal ideation. The correlation of perceived usual stress levels with depression and suicidal ideation was also mediated by tinnitus. Our findings implicate that tinnitus may contribute substantially to the development of depressive symptom and suicidal ideation in adults via apparent interactions with shared risk factors and stress levels.

The role of questioning environment, personality traits, depressive and anxiety symptoms in tinnitus severity perception

Psychological factors have been described as important for tinnitus severity, but attempts to incorporate them in one picture are sparse. This study investigated to what extent traits (personality), states (depressive and anxiety symptoms), sociodemographic factors and questioning environment influence tinnitus severity perception and how they interplay. Data were obtained from 212 subjects in a survey that was undertaken in 2016 at Vilnius University hospital and via internet. Measures included the Tinnitus Handicap Inventory (THI), Visual Analogue Scale (VAS), Hospital Anxiety and Depression Scale (HADS), Big Five Personality Dimensions Scale and sociodemographic questions. A series of stepwise forward and multiple regression analyses were undertaken to discover how factors interconnect. Female gender, age, living in rural area, but not level of education, were found to be associated with THI and HADS. Total HADS score and of both subscales were linked to scores on THI, VAS scales and all personality traits, except agreeableness (and consciousness for anxiety). Anxiety was the most important predictor for tinnitus severity, followed by depressive symptoms. Only neuroticism from personality dimensions was a predictor of THI score, whereas THI scores did not predict scores on neuroticism. All results in scales were higher in the internet group, except agreeableness and neuroticism, while extroversion correlated negatively with THI score only in the hospital group. Tinnitus severity was highly correlated with depressive, anxiety symptoms and neuroticism. Respondents recruited through internet had higher scores on most parameters. Results emphasize the importance of psychological factors in tinnitus management.

Characteristics of somatic tinnitus patients with and without hyperacusis

Objective

Determine if somatic tinnitus patients with hyperacusis have different characteristics from those without hyperacusis.

Patients and methods

172 somatic tinnitus patients with (n = 82) and without (n = 90) hyperacusis referred to the Tinnitus Unit of Sapienza University of Rome between June 2012 and June 2016 were compared for demographic characteristics, tinnitus features, self-administered questionnaire scores, nature of somatic modulation and history.

Results

Compared to those without hyperacusis, patients with somatic tinnitus and hyperacusis: (a) were older (43.38 vs 39.12 years, p = 0.05), (b) were more likely to have bilateral tinnitus (67.08% vs 55.56%, p = 0.04), (c) had a higher prevalence of somatic modulation of tinnitus (53.65% vs 36.66%, p = 0.02) and (d) scored significantly worse on tinnitus annoyance (39.34 vs 22.81, p<0.001) and subjective hearing level (8.04 vs 1.83, p<0.001).

Conclusion

Our study shows significantly higher tinnitus modulation and worse self-rating of tinnitus and hearing ability in somatic tinnitus patients with hyperacusis versus somatic tinnitus patients without hyperacusis. These differences could prove useful in developing a better understanding of the pathophysiology and establishing a course of treatment for these two groups of patients.

Does Tinnitus Depend on Time-of-Day? An Ecological Momentary Assessment Study with the "TrackYourTinnitus" Application

Only few previous studies used ecological momentary assessments to explore the time-of-day-dependence of tinnitus. The present study used data from the mobile application “TrackYourTinnitus” to explore whether tinnitus loudness and tinnitus distress fluctuate within a 24-h interval. Multilevel models were performed to account for the nested structure of assessments (level 1: 17,209 daily life assessments) nested within days (level 2: 3,570 days with at least three completed assessments), and days nested within participants (level 3: 350 participants). Results revealed a time-of-day-dependence of tinnitus. In particular, tinnitus was perceived as louder and more distressing during the night and early morning hours (from 12 a.m. to 8 a.m.) than during the upcoming day. Since previous studies suggested that stress (and stress-associated hormones) show a circadian rhythm and this might influence the time-of-day-dependence of tinnitus, we evaluated whether the described results change when statistically controlling for subjectively reported stress-levels. Correcting for subjective stress-levels, however, did not change the result that tinnitus (loudness and distress) was most severe at night and early morning. These results show that time-of-day contributes to the level of both tinnitus loudness and tinnitus distress. Possible implications of our results for the clinical management of tinnitus are that tailoring the timing of therapeutic interventions to the circadian rhythm of individual patients (chronotherapy) might be promising.

Evidence for Ancestral Programming of Resilience in a Two-Hit Stress Model

In a continuously stressful environment, the effects of recurrent prenatal stress (PS) may accumulate across generations and alter stress vulnerability and resilience. Here, we report in female rats that a family history of recurrent ancestral PS facilitates certain aspects of movement performance, and that these benefits are abolished by the experience of a second hit, induced by a silent ischemia during adulthood. Female F4-generation rats with and without a family history of cumulative multigenerational PS (MPS) were tested for skilled motor function before and after the induction of a minor ischemic insult by endothelin-1 infusion into the primary motor cortex. MPS resulted in improved skilled motor abilities and blunted hypothalamic-pituitary-adrenal (HPA) axis function compared to non-stressed rats. Deep sequencing revealed downregulation of miR-708 in MPS rats along with upregulation of its predicted target genes Mapk10 and Rasd2. Through miR-708 stress may regulate mitogen-activated protein kinase (MAPK) pathway activity. Hair trace elemental analysis revealed an increased Na/K ratio, which suggests a chronic shift in adrenal gland function. The ischemic lesion activated the HPA axis in MPS rats only; the lesion, however, abolished the advantage of MPS in skilled reaching. The findings indicate that MPS generates adaptive flexibility in movement, which is challenged by a second stressor, such as a neuropathological condition. Thus, a second “hit” by a stressor may limit behavioral flexibility and neural plasticity associated with ancestral stress.

Mindfulness practice reduces cortisol blunting during chemotherapy: A randomized controlled study of colorectal cancer patients

BACKGROUND

The objective of this randomized clinical experiment was to test the influence of a mindfulness meditation practice, when delivered during 1 session of active chemotherapy administration, on the acute salivary cortisol response as a marker of neuroendocrine system activity in cancer patients.

METHODS

A mindfulness, attention-control, or resting exposure was assigned to 57 English- or Spanish-speaking colorectal cancer patients at 1 county oncology clinic and 1 university oncology clinic at the start of chemotherapy. Saliva samples were collected at the start of chemotherapy and at subsequent 20-minute intervals during the first 60 minutes of chemotherapy (4 samples in all). Self-reporting on biobehavioral assessments after chemotherapy included distress, fatigue, and mindfulness.

RESULTS

An area-under-the-curve analysis (AUC) showed a relative increase in cortisol reactivity in the mindfulness group after adjustments for biological and clinical measures (β = 123.21; P = .03). More than twice as many patients in the mindfulness group versus the controls displayed a cortisol rise from the baseline to 20 minutes (69% vs 34%; P = .02). AUC values were uncorrelated with biobehavioral measure scores, although mindfulness scores were inversely correlated with fatigue (r = -0.46; P < .01) and distress scores (r = -0.54; P < .01).

CONCLUSIONS

Findings suggest that mindfulness practice during chemotherapy can reduce the blunting of neuroendocrine profiles typically observed in cancer patients. Implications include support for the use of mindfulness practice in integrative oncology. Cancer 2017;123:3088-96. © 2017 American Cancer Society.

Stress Reactivity in Chronic Tinnitus

Tinnitus is primarily an auditory symptom. Yet not only patients and clinicians, but also current pathophysiological models relate the onset and maintenance of tinnitus to stress. Here physiological and psychological stress reactivity was investigated in 19 patients with subjective chronic tinnitus and 19 comparable healthy controls. All participants underwent five consecutive measurements in one session including three resting conditions and two stress tasks in between (mental arithmetic and concentration on tinnitus/ear noise). Stress reactivity was assessed by heart rate (HR), heart rate variability (HRV) and subjective ratings for each of the five measurements. In patients with tinnitus, mean HR was overall decreased and blunted in response to acute stress induced by mental arithmetic compared to controls. HRV measures did not differ between both groups. Tinnitus sufferers indicated more subjective stress and increased awareness of tinnitus after the mental arithmetic task (during both resting and concentration on tinnitus measurements), but perceived similar levels of stress during mental arithmetic stress. In contrast to controls, HR and HRV were not correlated and also strain reports and physiological data were not associated in tinnitus. Our data show hints for a de-synchronization of physiological and psychological stress reactivity in chronic tinnitus.

Variable Effects of Acoustic Trauma on Behavioral and Neural Correlates of Tinnitus In Individual Animals

The etiology of tinnitus is known to be diverse in the human population. An appropriate animal model of tinnitus should incorporate this pathological diversity. Previous studies evaluating the effect of acoustic over exposure (AOE) have found that animals typically display increased spontaneous firing rates and bursting activity of auditory neurons, which often has been linked to behavioral evidence of tinnitus. However, only a subset of studies directly associated these neural correlates to individual animals. Furthermore, the vast majority of tinnitus studies were conducted on anesthetized animals. The goal of this study was to test for a possible relationship between tinnitus, hearing loss, hyperactivity and bursting activity in the auditory system of individual unanesthetized animals following AOE. Sixteen mice were unilaterally exposed to 116 dB SPL narrowband noise (centered at 12.5 kHz) for 1 h under ketamine/xylazine anesthesia. Gap-induced prepulse inhibition of the acoustic startle reflex (GPIAS) was used to assess behavioral evidence of tinnitus whereas hearing performance was evaluated by measurements of auditory brainstem response (ABR) thresholds and prepulse inhibition PPI audiometry. Following behavioral assessments, single neuron firing activity was recorded from the inferior colliculus (IC) of four awake animals and compared to recordings from four unexposed controls. We found that AOE increased spontaneous activity in all mice tested, independently of tinnitus behavior or severity of threshold shifts. Bursting activity did not increase in two animals identified as tinnitus positive (T+), but did so in a tinnitus negative (T−) animal with severe hearing loss (SHL). Hyperactivity does not appear to be a reliable biomarker of tinnitus. Our data suggest that multidisciplinary assessments on individual animals following AOE could offer a powerful experimental tool to investigate mechanisms of tinnitus.

Genetics of Tinnitus: An Emerging Area for Molecular Diagnosis and Drug Development

Subjective tinnitus is the perception of sound in the absence of external or bodily-generated sounds. Chronic tinnitus is a highly prevalent condition affecting over 70 million people in Europe. A wide variety of comorbidities, including hearing loss, psychiatric disorders, neurodegenerative disorders, and temporomandibular joint (TMJ) dysfunction, have been suggested to contribute to the onset or progression of tinnitus; however, the precise molecular mechanisms of tinnitus are not well understood and the contribution of genetic and epigenetic factors remains unknown. Human genetic studies could enable the identification of novel molecular therapeutic targets, possibly leading to the development of novel pharmaceutical therapeutics. In this article, we briefly discuss the available evidence for a role of genetics in tinnitus and consider potential hurdles in designing genetic studies for tinnitus. Since multiple diseases have tinnitus as a symptom and the supporting genetic evidence is sparse, we propose various strategies to investigate the genetic underpinnings of tinnitus, first by showing evidence of heritability using concordance studies in twins, and second by improving patient selection according to phenotype and/or etiology in order to control potential biases and optimize genetic data output. The increased knowledge resulting from this endeavor could ultimately improve the drug development process and lead to the preventive or curative treatment of tinnitus.

Salivary Stress-Related Responses in Tinnitus: A Preliminary Study in Young Male Subjects with Tinnitus

Objective: This preliminary study examined if baseline measures of stress-related biomarkers as measured by salivary secretions of specific autonomic [measured by salivary α-amylase (sAA)], endocrine (measured by salivary cortisol), and immune (measured by salivary neopterin) responses are greater in male subjects with tinnitus in response to an induced-stress task.

Method: Twenty male subjects with no significant hearing loss, 10 with tinnitus, and 10 without tinnitus were enrolled in this study.Salivary secretions were collected before and after the induced stress task at four different time intervals.

Results: sAA levels were lower in the tinnitus group in comparison to subjects without tinnitus, suggesting impaired sympathetic activity in the subjects with tinnitus although these levels remained stable throughout the stress experiment.While no significant effects could be obtained for salivary cortisol or neopterin, salivary neopterin levels were trending toward significance over all measurements. Behavioral measures of stress were found to correlate negatively with measures of sAA and salivary neopterin.

Conclusion: The results of this study suggest impaired stress-related sAA mechanisms in male subjects with tinnitus, as evidenced by the different stress reactions induced in the endocrine system (as measured by salivary cortisol) and the immune system (as measured by salivary neopterin).

Increased percentages of regulatory T cells are associated with inflammatory and neuroendocrine responses to acute psychological stress and poorer health status in older men and women

RATIONALE

The percentage of regulatory T cells (TRegs)-a subtype of T lymphocyte that suppresses the immune response-appears to be reduced in a number of stress-related diseases. The role of the TReg in stress-disease pathways has not yet been investigated.

OBJECTIVES

The aim of the study was to investigate the association between biological responsivity to acute psychosocial stress and the percentage of TRegs in healthy older adults. The secondary purpose was to measure the associations between TReg percentage and psychological and physical well-being in the participants.

METHODS

Salivary cortisol and plasma interleukin (IL)-6 samples were obtained from 121 healthy older men and women from the Whitehall II cohort following acute psychophysiological stress testing. Three years later at a follow-up visit, we measured TReg percentages and psychological and physical well-being were recorded using the Short Form 36 Health Survey and the Center for Epidemiologic Studies Depression Scale.

RESULTS

Blunted cortisol responses (p = 0.004) and elevated IL-6 responses (p = 0.027) to acute psychophysiological stress were associated with greater TReg percentage independently of age, sex, BMI, smoking status, employment grade, time of testing, and baseline measures of cortisol and IL-6, respectively. Percentage of TRegs was associated cross-sectionally with lower physical (p = 0.043) and mental health status (p = 0.008), and higher levels of depressive symptoms (p = 0.002), independently of covariates.

CONCLUSIONS

Increased levels of TRegs may act as a defence against increased inflammation and may be a pre-indication for chronically stressed individuals on the cusp of clinical illness.

The Relevance of Interoception in Chronic Tinnitus: Analyzing Interoceptive Sensibility and Accuracy

In order to better understand tinnitus and distress associated with tinnitus, psychological variables such as emotional and cognitive processing are a central element in theoretical models of this debilitating condition. Interoception, that is, the perception of internal processes, may be such a psychological factor relevant to tinnitus. Against this background, 20 participants suffering from chronic tinnitus and 20 matched healthy controls were tested with questionnaires, assessing interoceptive sensibility, and participated in two tasks, assessing interoceptive accuracy: the Schandry task, a heartbeat estimation assignment, and a skin conductance fluctuations perception task assessing the participants' ability to perceive phasic increases in sympathetic activation were used. To test stress reactivity, a construct tightly connected to tinnitus onset, we also included a stress induction. No differences between the groups were found for interoceptive accuracy and sensibility. However, the tinnitus group tended to overestimate the occurrence of phasic activation. Loudness of the tinnitus was associated with reduced interoceptive performance under stress. Our results indicate that interoceptive sensibility and accuracy do not play a significant role in tinnitus. However, tinnitus might be associated with a tendency to overestimate physical changes.

Hair cortisol: A new tool for evaluating stress in programs of stress management

AIMS

Longitudinal and experimental studies have shown that chronic stress contributes to the onset and progression of different diseases. Although it is not possible to eliminate stress completely, people can learn to manage it by participating in different kinds of stress management interventions. This study examined the effectiveness of stress management interventions on neuroendocrine responses in stressed students and health professionals, by measuring hair cortisol in comparison to salivary cortisol.

MAIN METHODS

Salivary and hair cortisol measurements were performed in 37 subjects (31women, 6 men; mean age 34.0±10.6) who attended to a Coping Stress and Quality of Care Program at the University of Buenos Aires. Cortisol was measured at the beginning and at the end of the program. The State-Trait Anxiety Inventory STAI was used to evaluate state and trait anxiety.

KEY FINDINGS

In subjects who completed the program, no differences were observed in salivary cortisol levels between the first and the last session. However, in these subjects, hair cortisol obtained in the last session was significantly lower than hair cortisol in the first session.

SIGNIFICANCE

Hair cortisol appears to be a better biomarker than salivary cortisol for evaluation of the effectiveness of a stress reduction program and it seems to be a better indicator of stress system dysregulation as well.

Tinnitus and anxiety disorders: A review

BACKGROUND

The most common form of tinnitus is a subjective, auditory, and distressing phantom phenomenon. Comorbidity with depression is high but other important psychiatric disorders such as anxiety disorders have received less attention. The current paper reviews the literature on the associations between tinnitus and anxiety disorders and the underlying pathophysiology, and discusses the clinical implications.

METHODOLOGY

PubMed and Web of Science were searched for all articles published up until October 2014 using combinations of the following search strings "Tinnitus", "Anxiety disorder", "Panic Disorder", "Generalized Anxiety Disorder", "Post traumatic stress disorder", "PTSD" "Social Phobia", "Phobia Disorder", "Obsessive Compulsive Disorder", "Agoraphobia".

RESULTS

A total of 117 relevant papers were included. A 45% lifetime prevalence of anxiety disorders is reported in tinnitus populations, while an important overlap in associated (sub)cortical brain areas and cortico-subcortical networks involved in attention, distress, and memory functions is suggested. A disturbed hypothalamic-pituitary-adrenal axis function can be found in tinnitus and in anxiety disorders but, in comorbidity, the direction of the dysfunction is unclear.

CONCLUSION

Comorbidity is high and screening for and treatment of anxiety disorders is recommended in moderate to severe tinnitus, as, given the overlap in the structural and functional brain circuitries involved, theoretically, their management could improve (subjective) levels of tinnitus although further empirical research on this topic is required.

Psychophysical and neural correlates of noised-induced tinnitus in animals: Intra- and inter-auditory and non-auditory brain structure studies

Tinnitus, a ringing in the ear or head without an external sound source, is a prevalent health problem. It is often associated with a number of limbic-associated disorders such as anxiety, sleep disturbance, and emotional distress. Thus, to investigate tinnitus, it is important to consider both auditory and non-auditory brain structures. This paper summarizes the psychophysical, immunocytochemical and electrophysiological evidence found in rats or hamsters with behavioral evidence of tinnitus. Behaviorally, we tested for tinnitus using a conditioned suppression/avoidance paradigm, gap detection acoustic reflex behavioral paradigm, and our newly developed conditioned licking suppression paradigm. Our new tinnitus behavioral paradigm requires relatively short baseline training, examines frequency specification of tinnitus perception, and achieves sensitive tinnitus testing at an individual level. To test for tinnitus-related anxiety and cognitive impairment, we used the elevated plus maze and Morris water maze. Our results showed that not all animals with tinnitus demonstrate anxiety and cognitive impairment. Immunocytochemically, we found that animals with tinnitus manifested increased Fos-like immunoreactivity (FLI) in both auditory and non-auditory structures. The manner in which FLI appeared suggests that lower brainstem structures may be involved in acute tinnitus whereas the midbrain and cortex are involved in more chronic tinnitus. Meanwhile, animals with tinnitus also manifested increased FLI in non-auditory brain structures that are involved in autonomic reactions, stress, arousal and attention. Electrophysiologically, we found that rats with tinnitus developed increased spontaneous firing in the auditory cortex (AC) and amygdala (AMG), as well as intra- and inter-AC and AMG neurosynchrony, which demonstrate that tinnitus may be actively produced and maintained by the interactions between the AC and AMG.