Research on noise-induced hearing loss in Sweden Ann-Christin Johnson PhD Karolinska Institutet Dept. Clinical Science, Intervention and Technique, Unit of Audiology and Center for Hearing and Communication Research

What causes hearing loss? Frequency [Hz] -10 Loss of Threshold [dB] Normal hearing Noise Induced Hearing Loss

The noise problem  Hearing disabilities in Sweden  15 % of the population > 1 million people  Numbers are increasing  is < 65 years old  Hidden numbers - stigma  Communication demands has increased in society and at work

Noise cause hearing loss and annoyance  Noise at Swedish workplaces  ~ are exposed to noise at work >85 dBA  ~1200 acknowledged noise-related work injuries/year = 7 % of all work injuries  Increasing number of women since 1998  Problems at work  % of employees are disturbed by noise at least ¼ of the time  ~ employees are disturbed by noise that mask communication

Where is the noise and how loud is it? Estimated by Ulf Landström, University of Gävle Military Schools and education Restaurants/Entertainmen t Mechanical industry Health care Office Musicians Day-care centers Commerce Government offices Ground development Transport Building industry Mining Warehouses Metal industry Technical work Police

Research consortium at KI – Hearing disability in working life  With focus on  Work environment  Risk factors  Audiological epidemiology  Different noise exposed populations  Twin studies  The Life-Gene project – hearing  Hearing and stress  Experimental studies in animals Many different research groups 6

Audiological epidemiology  Military pilots Retrospective study from medical records  Presented on a poster Johnson AC, Hellstadius A and Rosenhall R – Karolinska Institutet  Hearing in young men – military conscripts  Presented in the afternoon session  Follow-up study planned Muhr P and Rosenhall U – Karolinska Institutet  Cross-sectional study on different musicians  Advanced hearing measurements  Noise dosimetry and noise diaries Hagerman B, Lindblad AC, Svensson E – Karolinska Institutet 7

Audiological epidemiology  Twin studies: Hearing, work environment, age and genetic factors  Questionnaires and audiometry from 1100 male twins from 1998  Repeated data collection including genetic analyzes,  Planned study of female twins Analyzes of previously collected data Data collection  Longitudinal data  Genetics, work environment and age Å. Skjönsberg, R Bogo, N Pedersen, AC Johnson, M Svartengren – Karolinska Institutet

Audiological epidemiology  Hearing Loss and Stress  Data from a longitudinal Occupational Survey  answers  Hearing problems (self-estimated) significantly associated with stress-related illness, sleeping problems, burn-out syndromes  A sample, > 300, of the population has been audiometrically tested Hasson D, Theorell T, Canlon B – Karolinska Institutet 9

Audiological epidemilogy  The Life-Gene study  Large population based, prospective study in lifestyle, health and genetics  National Swedish study involving several universities  500,000 participants: ”0-45 years” at baseline  Including children and “born into cohort”  Information collected at several occasions  Including biobanks  Includes also hearing screening and questionnaires Life Gene is lead by Nancy L Pedersen – Karolinska Institutet  Internet-based platform for self-test of hearing  Under development  Used for research with questionnaires

Experimental studies in animals Some examples …..  NIHL in animal models  molecular and structural effects of noise  susceptibility to noise  influence of hereditary factors and gender  New treatment strategies for NIHL  pharmacological therapy  cell and tissue transplantation (tissue engineering)  gene therapy and stem cell technology Groups lead by M Ulfendahl, A Fridberger and B Canlon – Karolinska Institutet

Human noise studies in other universities in Sweden The Noise Network  Risk for hearing loss after combined exposure to noise and vibrations  Longitudinal study in industrial workers Burström L et al – University of Umeå  Noise in pre-schools – Health and preventions  Intervention study with pre- and after measurements of hearing, questionnaires, noise levels and cortisol Kjellberg A, Landström U et al – University of Gävle  Noise in office landscapes  Experimental and intervention studies on normal hearing and hearing impaired persons Hygge S et al – University of Gävle 12

Human Noise studies in other universities in Sweden The Linné center for Hearing and Deafness - HEAD Universities of Linköping and Örebro  MP3 – players. Use and hearing loss risk in young people  Presented in the afternoon session Kähäri K – University of Örebro  Hearing impaired in working life. Influence of cognition, noise and work load Lyxell B et al - University of Linköping  Many other projects on Hearing, Deafness and Cognition Rönnberg J, Lyxell B et al - University of Linköping Möller C, Danermark B et al – University of Örebro  Genetic influence on workplace related hearing loss Carlsson P-I et al - University of Örebro 13

Genetic influence on workplace- related hearing impairment A series of studies lead by Per-Inge Carlsson from the University of Örebro  Carriers of mutations Connexin 26 – heterozygotes  Are these carriers more susceptible to noise exposure?  Genetic, environmental factors and noise susceptibility  Selection from large group N= Looking at the  Most damaged - Noise susceptible group (10%) 103  Least damaged - Noise resistant group (10%) 112  Blood samples for genetic analyses  Differences between noise susceptible and noise resistant groups were investigated  Connexin26 mutations do not contribute to noise susceptibility  More smokers in noise susceptible group  Genetic variation in the protective antioxidant system can influence noise susceptibility  Genetic variation (SNP) in genes involved in the potassium recycling system might contribute to noise susceptibility

Groups with interaction  Several larger groups that work together  FAS-center at KI  Noise network in several places  Linné-center HEAD in Örebro and Linköping  Interaction between the groups  Started and will hopefully develop the noise research further 15

Acknowledgements The following scientists from the Karolinska Institutet are also involved in the consortium on Hearing Disabilities in Working Life and Society  Gunnel Backenroth-Ohsako,  Barbara Canlon  Björn Hagerman  Nancy L. Pedersen  Ulf Rosenhall  Åsa Skjönsberg  Thöres Theorell  Mats Ulfendahl A special thanks to  Per-Inge Carlsson and his colleagues for the material from the genetic studies

Questions ?!

References  PER-INGE CARLSSON, ERIK BORG, LARS GRIP, NIKLAS DAHL, MARIE-LOUISE BONDESON. Variability in noise susceptibility in a Swedish population: The role of 35delG mutation in the Connexin 26 (GJB2) gene. Audiological Medicine; :  Per-Inge Carlsson, Lut Van Laer, Erik Borg, Marie-Louise Bondeson, Melissa Thys, Erik Fransen and Guy Van Camp. Variability in noise susceptibility among Swedish industrial workers. The influence of genetic variation in oxidative stress genes. Hearing Research; ,  Carlsson P-I, Fransen E, Stenberg E, Bondeson M-L. The influence of genetic factors, smoking and cardiovascular diseases on human noise susceptibility. Audiological Medicine; : 1-6  Van Lear L, Carlsson P-I, Ottschytsch N, E Borg et al. The contribution of genes involved in potassium recycling in the inner ear to noise-induced hearing loss. Human mutation. 27(8):  Konings A, Van Lear L, Pawelczyk M, Carlsson P-I, E Borg et al. Association between variations in CAT and noise induced hearing loss in two independent noise-exposed populations. Human molecular genetics. 16(15): , 200