🔊 Popular antidepressants could cause tinnitus

Scientists have just discovered a direct link between serotonin, the brain chemical targeted by antidepressants, and the onset of ringing in the ears, also known as tinnitus, which affects millions of people.

Tinnitus manifests as persistent whistling or buzzing sounds with no external sound source. For some, it is a temporary annoyance, but for others it can become a real ordeal, associated with anxiety and sleep disorders. About 14% of the world's population suffers from it, often without an effective solution. The link with certain psychiatric drugs had long been suspected, but without a clear explanation.


Researchers from Oregon Health & Science University (OHSU) and Anhui University in China used mice to study this link. By artificially increasing serotonin levels in their brains, they observed that the animals adopted behaviors typical of tinnitus. Laurence Trussell, co-author of the study, says this observation confirms the hypothesis of a direct role for serotonin in triggering these phantom auditory sensations.

The identified mechanism involves a specific neural circuit that directly connects serotonin-producing neurons to the auditory system. By activating this circuit using a technique called optogenetics, the researchers were able to reproduce tinnitus symptoms in mice. Zheng-Quan Tang, another co-author, states that the discovery of this direct connection finally clarifies a mechanism that had long remained unclear. Turning off this circuit significantly reduced the symptoms.

These findings align with reports from patients taking SSRI antidepressants (selective serotonin reuptake inhibitors), who sometimes report worsening of their tinnitus. The study, published in the Proceedings of the National Academy of Sciences, reveals a delicate balance between the beneficial effects of antidepressants and their unwanted auditory consequences.

Scientists are considering the development of drugs that act specifically on certain brain regions, to preserve the antidepressant effects while avoiding activation of auditory areas. This approach could offer a new therapeutic avenue for people suffering from both depression and tinnitus, two disabling conditions that profoundly affect quality of life.