Occupation and 20-year hearing decline: findings from The HUNT Study

BACKGROUND

Studies show that certain occupations are associated with an increased risk of hearing loss. However, many studies are cross-sectional, and the few longitudinal studies are mostly small or focus on only one occupation.

AIMS

We aimed to quantify the long-term hearing decline among workers in different occupations and assess whether the change differs between the occupations.

METHODS

The study population was 4525 adults who participated in two population-based health studies in Norway, HUNT2 1996-1998 and HUNT4 2017-2019. Linear regression models assessed the association between occupations (clerks as reference) and 20-year hearing decline (hearing thresholds at 3-6 kHz, averaged over both ears) from HUNT2 to HUNT4. Models were adjusted for age, sex, recurrent ear infections, smoking and ear pathology.

RESULTS

Among the participants (40% men), the mean age at HUNT2 was 31.2 ± 5.4 years (range 20-39) and the average 20-year hearing decline was 11.3 ± 9.8 dB. Occupations that were associated with larger hearing decline included other craft and related trades workers (3.9 dB, 95% confidence interval [CI] 0.2-7.7) and building frame and related trades workers (3.4 dB, 95% CI 1.3-5.4). Among occupations with larger hearing decline, a higher proportion of the workers reported exposure to noise.

CONCLUSIONS

This large longitudinal study shows a larger long-term hearing decline among building frame workers and craft and related trades workers. Differences between occupations were modest, which may indicate successful preventive measures in Norway during the last two decades.

Suicide trends in Norway during the first year of the Covid-19 pandemic. A register-based cohort study

Background

There is a concern that the COVID-19 pandemic will lead to an increase in suicides. Several reports from the first months of the pandemic showed no increase in suicide rates while studies with longer observation times report contrasting results. In this study, we explore the suicide rates in Norway during the first year of the pandemic for the total population as well as for relevant subgroups such as sex, age, geographical areas, and pandemic phases.

Methods

This is a cohort study covering the entire Norwegian population between 2010 and 2020. The main outcome was age-standardized suicide rates (per 100,000 inhabitants) in 2020 according to the Norwegian Cause of Death Registry. This was compared with 95% prediction intervals (95% PI) based on the suicide rates between 2010 and 2019.

Results

In 2020, there were 639 suicides in Norway corresponding to a rate of 12.1 per 100,000 (95% PI 10.2–14.4). There were no significant deviations from the predicted values for suicides in 2020 when analyzing age, sex, pandemic phase, or geographical area separately. We observed a trend toward a lower than predicted suicide rate among females (6.5, 95% PI 6.0–9.2), and during the two COVID-19 outbreak phases in 2020 (2.8, 95% PI 2.3–4.3 and 2.8, 95% CI 2.3–4.3).

Conclusion

There is no indication that the COVID-19 pandemic led to an increase in suicide rates in Norway in 2020.

Hearing status among Norwegian train drivers and train conductors

Background

There is a general perception that train drivers and conductors may be at increased risk of developing noise-induced hearing loss.

Aims

To study job-related hearing loss among train drivers and train conductors.

Methods

Audiograms from train drivers and train conductors were obtained from the medical records of the occupational health service of the major Norwegian railway company. The results were compared with audiograms from an internal control group of railway workers and an external reference group of people not occupationally exposed to noise. The monaural hearing threshold level at 4kHz, the mean binaural value at 3, 4 and 6kHz and the prevalence of audiometric notches (≥25 dB at 4kHz) were used for comparison.

Results

Audiograms were available for 1567 drivers, 1565 conductors, 4029 railway worker controls and 15 012 people not occupationally exposed to noise. No difference in hearing level or prevalence of audiometric notches was found between study groups after adjusting for age and gender.

Conclusions

Norwegian train drivers and conductors have normal hearing threshold levels comparable with those in non-exposed groups.

The effect of emotional distress on persistent pelvic girdle pain after delivery: a longitudinal population study

OBJECTIVE

To study the prognosis for pelvic girdle pain, and to explore the association between presence of emotional distress during pregnancy and pelvic girdle syndrome 6 months after delivery.

DESIGN

Longitudinal population study.

SETTING

Norway, for the period 1999-2008.

POPULATION

A follow-up of 41 421 women in the Norwegian Mother and Child Cohort who reported pelvic girdle pain at 30 weeks of gestation.

METHODS

Data were obtained by self-administered questionnaires in weeks 17 and 30 of gestation, and 6 months after delivery.

MAIN OUTCOME MEASURE

Pelvic girdle syndrome 6 months after delivery, defined as pain in the anterior pelvis and on both sides in the posterior pelvis.

RESULTS

Six months after delivery, 78.0% of the women had recovered, 18.5% reported persistent pain in one or two pelvic locations, 3.0% reported pelvic girdle syndrome and 0.5% reported severe pelvic girdle syndrome. The recovery rates decreased with increasing levels of pain severity in pregnancy. Being emotionally distressed at two time points during pregnancy was associated with the presence of pelvic girdle syndrome (adjusted OR 1.5, 95% CI 1.2-1.9) and severe pelvic girdle syndrome (adjusted OR 1.9, 95% CI 1.1-3.1), after adjustment for pain severity in pregnancy, other medical conditions, body mass index, age at menarche, previous low back pain, and smoking during pregnancy.

CONCLUSIONS

In this follow-up of women with pelvic girdle pain in pregnancy, the recovery rates after delivery were high. Our findings suggest that the presence of emotional distress during pregnancy is independently associated with the persistence of pelvic girdle pain after delivery.

Post-traumatic stress disorder: a right temporal lobe syndrome?

In a recent paper (Georgopoulos et al 2010 J. Neural Eng. 7 016011) we reported on the power of the magnetoencephalography (MEG)-based synchronous neural interactions (SNI) test to differentiate post-traumatic stress disorder (PTSD) subjects from healthy control subjects and to classify them with a high degree of accuracy. Here we show that the main differences in cortical communication circuitry between these two groups lie in the miscommunication of temporal and parietal and/or parieto-occipital right hemispheric areas with other brain areas. This lateralized temporal-posterior pattern of miscommunication was very similar but was attenuated in patients with PTSD in remission. These findings are consistent with observations (Penfield 1958 Proc. Natl Acad. Sci. USA 44 51-66, Penfield and Perot 1963 Brain 86 595-696, Gloor 1990 Brain 113 1673-94, Banceaud et al 1994 Brain 117 71-90, Fried 1997 J. Neuropsychiatry Clin. Neurosci. 9 420-8) that electrical stimulation of the temporal cortex in awake human subjects, mostly in the right hemisphere, can elicit the re-enactment and re-living of past experiences. Based on these facts, we attribute our findings to the re-experiencing component of PTSD and hypothesize that it reflects an involuntarily persistent activation of interacting neural networks involved in experiential consolidation.

The synchronous neural interactions test as a functional neuromarker for post-traumatic stress disorder (PTSD): a robust classification method based on the bootstrap

Traumatic experiences can produce post-traumatic stress disorder (PTSD) which is a debilitating condition and for which no biomarker currently exists (Institute of Medicine (US) 2006 Posttraumatic Stress Disorder: Diagnosis and Assessment (Washington, DC: National Academies)). Here we show that the synchronous neural interactions (SNI) test which assesses the functional interactions among neural populations derived from magnetoencephalographic (MEG) recordings (Georgopoulos A P et al 2007 J. Neural Eng. 4 349-55) can successfully differentiate PTSD patients from healthy control subjects. Externally cross-validated, bootstrap-based analyses yielded >90% overall accuracy of classification. In addition, all but one of 18 patients who were not receiving medications for their disease were correctly classified. Altogether, these findings document robust differences in brain function between the PTSD and control groups that can be used for differential diagnosis and which possess the potential for assessing and monitoring disease progression and effects of therapy.

A longitudinal and retrospective study of PTSD among older prisoners of war

OBJECTIVE

The authors examined the longitudinal changes in posttraumatic stress disorder (PTSD) symptom levels and prevalence rates over a 4-year time period among American former prisoners of war (POWs) from World War II and the Korean War. Retrospective symptom reports by World War II POWs dating back to shortly after repatriation were examined for 1) additional evidence of changing PTSD symptom levels and 2) evidence of PTSD cases with a long-delayed onset.

METHOD

PTSD prevalence rates and symptom levels were measured by the Mississippi Scale for Combat-Related Posttraumatic Stress Disorder. For the longitudinal portion of the study, participants were 177 community-dwelling World War II and Korean POWs. For the retrospective portion, participants were 244 community-dwelling World War II POWs.

RESULTS

PTSD prevalence rates and symptom levels increased significantly over the 4-year measurement interval. Retrospective symptom reports indicated that symptoms were highest shortly after the war, declined for several decades, and increased within the past two decades. Long-delayed onset of PTSD symptoms was rare. Demographic and psychosocial variables were used to characterize participants whose symptoms increased over 4 years and differentiate participants who reported a long-delayed symptom onset.

CONCLUSIONS

Both longitudinal and retrospective data support a PTSD symptom pattern of immediate onset and gradual decline, followed by increasing PTSD symptom levels among older survivors of remote trauma.

Attachment style classification and posttraumatic stress disorder in former prisoners of war

Adult attachment style and post-traumatic stress disorder (PTSD) symptomatology were investigated in 107 former prisoner of war veterans. Those with secure attachment styles scored significantly lower on measures of PTSD than did those with insecure styles, and attachment style was a stronger predictor of PTSD symptom intensity than was trauma severity. The suggested association between attachment style and PTSD's development and persistence are discussed in relation to research and clinical practice.

Otoacoustic emissions and improved pass/fail separation using wavelet analysis and time windowing

A new method is presented for the purpose of improving pass/fail separation during transient evoked otoacoustic emission (TEOAE) hearing screening. The method combines signal decomposition in scales using the discrete wavelet transform, non-linear denoising and scale-dependent time windowing. The cross-correlation coefficient between two subaveraged, processed TEOAE signals is used as a pass/fail criterion and assessed in relation to the pure-tone, mean hearing level. The performance is presented in terms of receiver operating characteristics for a database of 5,214 individuals. The results show that the specificity improves from 68% to 83% at a sensitivity of 90% when compared with the conventional wave reproducibility parameter.

Comorbidity and course of psychiatric disorders in a community sample of former prisoners of war

OBJECTIVE

The authors assessed DSM-III-R disorders among American former prisoners of war. Comorbidity, time of onset, and the relationship of trauma severity to complicated versus uncomplicated posttraumatic stress disorder (PTSD) were examined.

METHOD

A community sample (N=262) of men exposed to combat and imprisonment was assessed by clinicians using the Structured Clinical Interview for DSM-III-R.

RESULTS

The rates of comorbidity among the men with PTSD were lower than rates from community samples assessed by lay interviewers. Over one-third of the cases of lifetime PTSD were uncomplicated by another axis I disorder; over one-half of the cases of current PTSD were uncomplicated. PTSD almost always emerged soon after exposure to trauma. Lifetime PTSD was associated with increased risk of lifetime panic disorder, major depression, alcohol abuse/dependence, and social phobia. Current PTSD was associated with increased risk of current panic disorder, dysthymia, social phobia, major depression, and generalized anxiety disorder. Relative to PTSD, the onset of the comorbid disorders was as follows: major depression, predominantly secondary; alcohol abuse/dependence and agoraphobia, predominantly concurrent (same year); social phobia, equal proportions primary and concurrent; and panic disorder, equal proportions concurrent and secondary. Trauma exposure was comparable in the subjects with complicated and uncomplicated PTSD.

CONCLUSIONS

The types of comorbid diagnoses and their patterns of onset were comparable to the diagnoses and patterns observed in other community samples. The findings support the validity of the PTSD construct; PTSD can be distinguished from comorbid disorders. Uncomplicated PTSD may be more common than previous studies suggest, particularly in clinician-assessed subjects exposed to severe trauma.

Posttraumatic stress disorder in a community group of former prisoners of war: a normative response to severe trauma

OBJECTIVE

The goal of this study was to assess and describe the long-term impact of traumatic prisoner of war (POW) experiences within the context of posttraumatic psychopathology. Specifically, the authors attempted to investigate the relative degree of normative response represented by posttraumatic stress disorder (PTSD) in comparison to other DSM axis I disorders often found to be present, either alone or concomitant with other disorders, in survivors of trauma.

METHOD

A community group of 262 U.S. World War II and Korean War former POWs was recruited. These men had been exposed to the multiple traumas of combat, capture, and imprisonment, yet few had ever sought mental health treatment. They were assessed for psychopathology with diagnostic interviews and psychodiagnostic testing. Regression analyses were used to assess the contributions of age at capture, war trauma, and postwar social support to PTSD and the other diagnosed disorders.

RESULTS

More than half of the men (53%) met criteria for lifetime PTSD, and 29% met criteria for current PTSD. The most severely traumatized group (POWs held by the Japanese) had PTSD lifetime rates of 84% and current rates of 59%. Fifty-five percent of those with current PTSD were free from the other current axis I disorders (uncomplicated PTSD). In addition, 34% of those with lifetime PTSD had PTSD as their only lifetime axis I diagnosis. Regression analyses indicated that age at capture, severity of exposure to trauma, and postmilitary social support were moderately predictive of PTSD and only weakly predictive of other disorders.

CONCLUSIONS

These findings indicate that PTSD is a persistent, normative, and primary consequence of exposure to severe trauma.

[Tinnitus--etiology, diagnosis and treatment]

Tinnitus is the sensation of sound, a sensation generated by the auditory system because of a pathology, without any external acoustic or electrical stimulation. 15% of the adult population have experienced shorter or longer periods of tinnitus. Three percent of these, in total about 7,000-10,000 persons in Norway, suffer from continuous tinnitus followed by symptoms that demonstrate handicap or occupational disability. The authors discuss the cause of tinnitus and its relation to different kinds of hearing loss. Treatment is dependent on a specific diagnosis. There is no universal medical or surgical treatment. Today, cognitive therapy is emphasised, to the tinnitus patients to understand what causes the tinnitus, to accept the condition and to inform them about relaxation techniques. Physical therapy and training are also emphasised. Active treatment with regular counselling can reduce the occupational and social disabilities.

Effects of noise and exercise on distortion product otoacoustic emissions

The effect of physical exercise on both distortion product otoacoustic emissions (DPOAE), and on the temporary effects of noise on human cochlear function was examined. Changes in DPOAEs were compared to changes in behavioural thresholds and the possible relation between contralateral suppression of DPOAEs and susceptibility to noise exposure was investigated. Békésy audiometry, tympanometry and DPOAEs were measured in 8 subjects on 3 separate occasions: before and after noise exposure; before and after exercise at 60% of maximal oxygen uptake (VO2max); and before and after a combination of noise exposure and exercise, all of 10 min duration. Noise exposure was third-octave band noise of 102 dB SPL centered at 2 kHz. The magnitude of the effect of noise exposure on DPOAE amplitude averaged in the 2-4 kHz range was comparable but weakly correlated to the magnitude of the temporary threshold shift (TTS) measured as the change in Békésy threshold at 3 kHz. There was no effect of physical exercise without noise exposure on either the Békésy threshold or the DPOAE amplitude. Physical exercise significantly increased the noise-induced TTS and the effect of noise exposure on DPOAE amplitude. A positive correlation was found between the temporary effect of noise exposure and the contralateral suppression effect on DPOAE amplitude.

The effect of noise exposure on the details of distortion product otoacoustic emissions in humans

The effect of noise exposure on amplitude and phase of distortion product otoacoustic emissions (DPOAEs) was examined by five different paradigms: across a wideband of frequency, microstructure, input/output function, primary frequency ratio tuning curve, and group delay. The aim was to investigate the vulnerability of these different features to moderate levels of noise exposure. Nine subjects were exposed to third-octave-band noise. The DPOAE amplitude was reduced frequency specifically with the greatest reduction approximately half an octave above the frequency of the noise. The degree of amplitude reduction was greatest at low stimulus levels. There were no observed effects on the shape of the primary ratio tuning curve. A weak tendency to a decrease was seen in group delays. Distinct microstructure was seen in the amplitude against frequency of five out of seven subjects. The maximum to minimum ratio of the microstructure decreased, and the whole pattern shifted toward lower frequencies after noise exposure. Evidence of multiple internal reflection or interference was seen in the periodicity of the microstructure. Using a simple model of the microstructure based on multiple reflections, the noise-induced changes were reevaluated. A reduction in maximum to minimum microstructure ratio could be interpreted as a decrease in the internal reflection coefficient. The implications of these observations for the interpretation of the DPOAE measurements are considered.

Transient evoked otoacoustic emissions as screening for hearing losses at the school for military training

The present study was designed to investigate the applicability of transient evoked otoacoustic emissions (TEOAEs) as a method of screening for hearing losses among recruits attending obligatory military service. TEOAEs, tympanometry and puretone audiometry were recorded in 95 male recruits. Sixty-one recruits were tested after a 2-month period of gunfire exposure in order to document any permanent change in cochlear function. Screening by pure-tone audiometry showed an unexpectedly high prevalence of hearing losses > 20 dBHL, probably due to technical reasons. Thresholds were corrected using lower thresholds obtained at the end of service or by ENT specialists. The accuracy with which normal and impaired ears could be identified with TEOAEs analysed in frequency bands was determined by decision theory. Impairment was defined as mean hearing thresholds > or = 30 dBHL averaged from three neighbouring frequencies. Adequate accuracy was obtained in the middle frequencies. Further improvement of the technique is needed before it can be deemed suitable for detecting hearing losses at low and high frequencies. TEOAEs are quicker to measure and offer greater objectivity than pure-tone audiometry. A small decrease in TEOAE level was found after the training period. The TEOAEs were highly repeatable and had a higher sensitivity than pure-tone audiometry to detection of small changes in cochlear function under conditions normally found when testing recruits.

Transient-evoked otoacoustic emissions. Helpful tool in the detection of pseudohypacusis

The object of the present study was to demonstrate the use of TEOAEs for diagnosing pseudohypacusis. Thirty-four patients were investigated for suspected pseudohypacusis based on the case history and clinical and audiological findings. TEOAEs confirmed the diagnosis in all cases except four patients with a pre-existing organic hearing loss exceeding 25-30 dB HL. All the remaining 30 patients showed normal TEOAE responses except four of the ears in which final assessment revealed hearing threshold lower than 30 dB in the middle frequency region. The method can be time-saving when performed at the first consultation. With its element of surprise, the patient can be confronted with the existence of a functional hearing loss. This frequently results in marked threshold improvement on repeat pure-tone audiometry.

Temporary threshold shift and otoacoustic emissions after industrial noise exposure

The objective of the present study was to investigate whether employees in a noise-exposed environment developed changes in cochlear function as manifested by elevation of pure-tone threshold and/or reduction in transient evoked otoacoustic emission (TEOAE) amplitude. Pure-tone air-conduction audiometry, otoacoustic emissions (OAEs) and tympanometry were recorded in 13 healthy employees on three consecutive days both before and after 7 h of noise exposure. Employees exposed to an industrial noise level of 85-90 dBA developed significant pure-tone air-conduction threshold elevation at 4 and 6 kHz. A significant reduction of the TEOAE amplitude was found. There was no correlation between temporary threshold shift (TTS) and TEOAE reduction.

Reproducibility and short-term variability of transient evoked otoacoustic emissions

The reproducibility and short-term, less than 3 days, variability of transient evoked otoacoustic emissions (TEOAEs) were studied in 23 young, otologically healthy subjects engaged either in strenuous physical exercise or relatively sedentary occupations. Tympanometry was also performed. TEOAEs were highly reproducible. No differences were found between the two subject groups, nor any significant diurnal variations in TEOAE amplitudes. The latter were, however, significantly (p = 0.005) correlated to middle ear pressures. Tympanometry should therefore be performed in studies of possible intrinsic or extrinsic influences on TEOAE amplitudes.

Otoacoustic emissions in the first year of life

Transient evoked otoacoustic emissions (TEOAEs) were successfully recorded in 192 ears of 100 consecutive full-term neonates tested on the third or fourth postnatal day. A follow-up study was performed in 35 of these infants at the ages of 3, 6 and 12 months. The number of infants presenting decreased linearly with postnatal age. TEOAE amplitudes were largest in the youngest age group. Both the time required for testing each infant and the number of ears in which TEOAEs could not be identified increased with age. Otomicroscopical changes indicating secretory otitis media were found in all the latter ears. Recording of TEOAEs is a suitable method for screening peripheral auditory function in infants, and can be most successfully performed at the age of 3 or 4 days.

[Otoacoustic emissions]

Otoacoustic emissions provide a new method for objective assessment of peripheral auditory function. Emissions have been recorded in 80 patients and comparisons made with subjective hearing tests and brain stem response audiometry. Our experiences confirm that this procedure is rapid and easy to perform, and that the presence of emissions is a reliable indication of normal function in the middle ear and cochlea. This is particularly useful in neonates, young children and adults whose inability to cooperate prevents the use of behavioural audiometry. Recording of otoacoustic emissions can replace brain stem response audiometry as the primary objective assessment of auditory function in these groups.

Posttraumatic stress disorder as a consequence of the POW experience

To estimate the relative contributions of trauma and premorbid disposition in the development and persistence of posttraumatic stress disorder (PTSD) symptoms, we conducted structured psychiatric interviews of 62 former World War II POWs. Half these men satisfied DSM-III criteria for PTSD in the year following repatriation. Eighteen (29%) continued to meet the criteria for PTSD 40 years later. Family history of mental illness and preexisting psychopathology were at best only weakly correlated with persistent PTSD symptoms. The strongest predictors of PTSD were proportion of body weight lost and the experience of torture during captivity. This study demonstrates that former POWs frequently develop posttraumatic stress disorder and that for one half of those who develop the symptoms, they persist for over 40 years. Familial risk factors and preexisting psychopathology are superseded by the overwhelming nature of the trauma. The persistence of the symptoms for many years is a reflection of the severity of the trauma.