Christopher R. Cederroth, Niklas K. Edvall, Inger Uhlén, Barbara Canlon, Jan Bulla, Jose A. Lopez-Escamez, Andra Lazar, David M. Baguley, Darek J. Hoare, Silvano Gallus, Alessandra Lugo, [Cederroth,CR, Edvall,NK, Canlon,B] Laboratory of Experimental Audiology, Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden. [Cederroth,CR, Hoare,DJ, Baguley,DM] National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre, Nottingham University Hospitals NHS Trust, Ropewalk House, Nottingham, UK. [Cederroth,CR, Baguley,DM] Hearing Sciences, Division of Clinical Neuroscience, School of Medicine, University of Nottingham, Nottingham, UK. [Lugo,A, Gallus,S] Department of Environmental Health Sciences, Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Milan, Italy. [Lazar,A, Uhlen,I] Hörsel och balansmottagningen, Karolinska Universitetssjukhuset, Stockholm, Sweden. [Lopez-Escamez,JA] Otology & Neurotology Group, Department of Genomic Medicine, Pfizer-Universidad de Granada-Junta de Andalucía Centro de Genómica e Investigación Oncológica (GENYO), PTS, Granada, Spain. [Lopez-Escamez,JA] Department of Otolaryngology, Hospital Universitario Virgen de las Nieves, Instituto de Investigacion Biosanitaria ibs.GRANADA, Granada, Spain. [Bulla,J] Department of Mathematics, University of Bergen, Bergen, Norway. [Bulla,J] Department of Psychiatry and Psychotherapy, University of Regensburg, Regensburg, Germany., and This study was funded by the GENDER-NET Co-Plus Fund (GNP-182, to C.R.C., S.G., J.A.L.E. and J.B.). In addition, C.R.C. has received research funding from Decibel Therapeutics, Inc., Svenska Läkaresällskapet (SLS-779681), Tysta Skolan, Hörselforskningsfonden (#503), the European Union’s Horizon 2020 Research and Innovation Programme under the Marie Skłodowska-Curie Grant Agreement ESIT No 72204655 [60], and was co-funded by the NIHR Nottingham Biomedical Research Centre. C.R.C. and A.Lu. were partially supported by the European Union’s Horizon 2020 Research and Innovation Programme, Grant Agreement UNITI No 848261. B.C. has received funding from the Swedish Medical Research Council K2014-99X-22478-01-3, Karolinska Institutet and Tysta Skolan. S.G. is an Honorary Associate Professor at the University of Nottingham, School of Medicine. DJH is an Adjunct Professor at University College Cork and funded by the UK National Institute for Health Research (NIHR) Biomedical Research Programme, however the views expressed are not necessarily those of the NIHR, the NHS or the Department of Health and Social Care.
The following are available online at http://www.mdpi.com/2077-0383/9/8/2412/ s1, We gratefully acknowledge the support and generosity of Nancy Pedersen, head of LifeGene., Many individuals with tinnitus report experiencing hyperacusis (enhanced sensitivity to sounds). However, estimates of the association between hyperacusis and tinnitus is lacking. Here, we investigate this relationship in a Swedish study. A total of 3645 participants (1984 with tinnitus and 1661 without tinnitus) were enrolled via LifeGene, a study from the general Swedish population, aged 18–90 years, and provided information on socio-demographic characteristics, as well as presence of hyperacusis and its severity. Tinnitus presence and severity were self-reported or assessed using the Tinnitus Handicap Inventory (THI). Phenotypes of tinnitus with (n = 1388) or without (n = 1044) hyperacusis were also compared. Of 1661 participants without tinnitus, 1098 (66.1%) were women and 563 were men (33.9%), and the mean (SD) age was 45.1 (12.9). Of 1984 participants with tinnitus, 1034 (52.1%) were women and 950 (47.9%) were men, and the mean (SD) age was 47.7 (14.0) years. Hyperacusis was associated with any tinnitus [Odds ratio (OR) 3.51, 95% confidence interval (CI) 2.99–4.13], self-reported severe tinnitus (OR 7.43, 95% CI 5.06–10.9), and THI ≥ 58 (OR 12.1, 95% CI 7.06–20.6). The association with THI ≥ 58 was greater with increasing severity of hyperacusis, the ORs being 8.15 (95% CI 4.68–14.2) for moderate and 77.4 (95% CI 35.0–171.3) for severe hyperacusis. No difference between sexes was observed in the association between hyperacusis and tinnitus. The occurrence of hyperacusis in severe tinnitus is as high as 80%, showing a very tight relationship. Discriminating the pathophysiological mechanisms between the two conditions in cases of severe tinnitus will be challenging, and optimized study designs are necessary to better understand the mechanisms behind the strong relationship between hyperacusis and tinnitus., GENDER-NET Co-Plus Fund GNP-182, Decibel Therapeutics, Inc., Svenska Lakaresallskapet SLS-779681, Tysta Skolan, Horselforskningsfonden 503, European Union (EU) 72204655 848261, NIHR Nottingham Biomedical Research Centre, Swedish Medical Research Council (SMRC) K2014-99X-22478-01-3, Karolinska Institutet, National Institute for Health Research (NIHR)