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OHSU neuroscientist Laurence Trussell, Ph.D., collaborated on a discovery linking serotonin to the neurological condition known as tinnitus. (OHSU\/Christine Torres Hicks)<\/p>\n
The same neurotransmitter commonly leveraged to relieve symptoms of depression and anxiety also may exacerbate a vexing condition known as tinnitus, according to new research published today<\/a> in the Proceedings of the National Academy of Sciences.<\/p>\n Tinnitus is a constant sensation of ringing or buzzing in the ears, creating a continual irritation for some and severe anxiety for others. Global prevalence is estimated as high as 14%, with many severely affected.<\/p>\n Researchers with Oregon Health & Science University and Anhui University in China found in a mouse model that elevated levels of the neurotransmitter serotonin in the brain also resulted in elevated behavioral symptoms of tinnitus.<\/p>\n The findings should be especially meaningful for millions of people around the world who suffer from tinnitus, said co-senior author Laurence Trussell, Ph.D., professor of otolaryngology in the OHSU School of Medicine and a scientist in the OHSU Vollum Institute<\/a> and Oregon Hearing Research Center<\/a>.<\/p>\n \u201cPeople with tinnitus should work with their prescribing physician to find a drug regimen that gives them a balance between relief of psychiatric symptoms, like depression and anxiety, while minimizing the experience of tinnitus,\u201d Trussell said. \u201cThis study highlights the importance of clinicians recognizing and validating patient reports of medication-associated increases in tinnitus.\u201d<\/p>\n Those medications include a common class of antidepressants known as selective serotonin reuptake inhibitors, or SSRIs. They alleviate symptoms of moderate to severe depression and anxiety by increasing the level of serotonin in the brain.<\/p>\n \u201cWe\u2019ve suspected that serotonin was involved in tinnitus, but we didn\u2019t really understand how,\u201d said co-author Zheng-Quan Tang, Ph.D., of Anhui University in China. \u201cNow, using mice, we\u2019ve found a specific brain circuit involving serotonin that goes straight to the auditory system, and found that it can induce tinnitus-like effects. When we turned that circuit off, we were able to ameliorate the tinnitus significantly.<\/p>\n \u201cThis gives us a much clearer picture of what\u2019s going on in the brain \u2014 and points toward new possibilities for treatment.\u201d<\/p>\n Tang started the research as a postdoctoral scholar in Trussell\u2019s lab.<\/p>\n \u2018A delicate balance\u2019<\/p>\n