MedicalResearch.com Interview with: Christopher R. Cederroth | Ph.D. Docent Associate Professor Experimental Audiology | Department of Physiology and Pharmacology Karolinska Institutet Sweden MedicalResearch.com: What is the background for this study? Response: Tinnitus is experienced is experienced by a large proportion of the population and affects more than 15% of the population worldwide (estimated 70 million people in Europe). However, for near 3% of the population, tinnitus becomes a chronic bothersome and incapacitating symptom. Severe tinnitus interferes with sleep, mood, and concentration and thus impacts life quality, ultimately leading to sick leave and disability pension. A high cost to society has been reported, and since the prevalence of tinnitus has been predicted to double in Europe by 2050, there is an important need for an effective treatment. And today there are none, with the exception of cognitive behavioral therapy, which helps coping with it but does not remove the tinnitus. There has been a number of innovative treatment approaches, but they are overall not successful and it is now agreed that it is likely because tinnitus is a heterogeneous condition – meaning that we cannot consider tinnitus a single entity but an ensemble of different forms or subtypes, which need to be defined. Tinnitus has always been considered a condition influenced by environmental factors, but our initial studies suggested the opposite. Adoption studies are excellent in showing the influence of shared-environment effects and establish a genetic basis for a disease or a trait. It allows to test the transmission of a trait between the adoptee and their biological or their adoptive parent. Transmission via the biological parent is expected to be due to a heritable genetic effect, while transmission via the adoptive parent is associated with home-environment, the so-called shared-environmental effect. We used medical registry data to identify tinnitus patients and adoptees. (more…)