New AI biomarkers reveal severity of tinnitus through involuntary facial and pupil responses

The experiences of around 50 to 60 million Americans are characterised by a distracting condition known as tinnitus, which manifests as a persistent ringing, buzzing, or clicking in the ears. The distress associated with this condition is significant; an estimated 15% of those affected endure severe cases that disrupt sleep, impair mental health, and interfere with daily life. Despite its prevalence, tinnitus remains under-discussed, with surveys indicating that only about half of the sufferers have consulted a healthcare professional regarding their symptoms.

Recent research from Mass General Brigham has brought new insights into this condition, identifying two involuntary biomarkers that offer a closer look at the severity of tinnitus. Daniel Polley, a leading figure in the study and director of the Eaton-Peabody Laboratories at Mass Eye and Ear, remarked, “These biomarkers get to the root of the distress,” highlighting their potential to transform the understanding and treatment of tinnitus.

Tinnitus can arise from various factors such as hearing loss, continuous exposure to loud noise, ear infections, and certain medical conditions like Ménière’s disease. Given the complexity and varied origins of the phantom sounds, diagnosing tinnitus typically relies on a combination of medical history, physical examinations, and subjective assessments through questionnaires and psychoacoustic tests. Polley noted a prevailing inadequacy in the diagnostic process, likening it to determining cancer severity merely through self-reported experiences: “Imagine if cancer severity were determined by giving patients a questionnaire — this is the state of affairs for some common neurological disorders like tinnitus.”

In their innovative study, Polley and his team examined the sympathetic nervous system’s response to auditory stimuli by analysing subtle facial movements in 97 participants, comprising both tinnitus sufferers and individuals with normal hearing. Through advanced AI technology, researchers detected involuntary facial twitches linked to levels of distress. Notably, when subjects with severe tinnitus were exposed to various sounds, their pupils dilated markedly—an indication of heightened neurological response—while participants with milder conditions showed similar reactions only in response to distressing sounds.

The findings, published in Science Translational Medicine, reveal a new understanding of tinnitus severity through physical signs that are often overlooked. Polley stated, “For the first time, we directly observed a signature of tinnitus severity,” marking a significant advancement in how this condition may be assessed objectively.

Though there is currently no definitive cure for tinnitus, existing management strategies include hearing aids, sound therapy, and cognitive behavioural therapy. The insights gained from this research may pave the way for novel therapies that combine neural stimulation with immersive software to reduce the perception of the phantom sounds. The low-tech nature of the approach suggests that its implementation could become widespread, potentially accessible at hearing health clinics and beneficial in clinical trials.

This study arrives at a time when the growing body of research underscores a need for a deeper understanding of tinnitus and its impact on individuals’ lives. A systematic review highlighted its global prevalence, noting that about 14.4% of adults experience tinnitus at some point, with the severity increasing with age. Among younger adults, 9.7% report symptoms, climbing to 23.6% in those aged 65 and older.

Furthermore, recent studies have identified specific plasma metabolites associated with persistent tinnitus, suggesting a biochemical component that could serve as future biomarkers. With findings indicating that metabolites such as homocitrulline and certain phosphatidylethanolamines play a role, researchers are now exploring metabolomic profiling as a viable avenue for advancing understanding of tinnitus pathophysiology.

As research efforts expand to include diverse patient populations, including older adults and those with co-occurring conditions, there is hope for a more comprehensive approach to diagnosis and treatment. Polley’s innovative work stands at the forefront of this evolution, offering a glimpse into a future where tinnitus can be assessed and potentially treated with greater precision and understanding.