Long COVID is not just about fatigue and brain fog. A new Ohio State University study finds it can quietly chip away at several senses at once, with measurable problems in smell, hearing and balance. Older adults and people who were sicker during the initial infection showed the broadest impairments. Instead of trusting symptoms alone, researchers put 60 adults through a full lab workup to see exactly where the damage shows up, creating a detailed map of possible post-COVID sensory fallout and hinting that both peripheral and central nervous system issues may be in play.
Study size, timeline and publication
The analysis focused on 60 people, ages 27 to 78, who had COVID between Jan. 17, 2020 and Dec. 21, 2023 and reported symptoms that lingered for roughly four to 50 months, according to the BMC Medicine paper. The researchers compared what participants said they were experiencing with what tests could actually confirm, highlighting where subjective complaints and objective lab results line up and where they do not.
How the team tested the senses
To get that level of detail, investigators used a broad battery of standardized tools: odor identification and threshold tests, a retronasal candy task to gauge flavor, pure-tone audiometry and words-in-noise tests for hearing, video head impulse testing and balance assessments for vestibular function, plus several cognitive screens. These measures let the team tease apart losses that start in the nose or inner ear from those that likely stem from the brain, as reported by MedicalXpress.
What objective testing found
When the lab data came back, a sizable share of participants showed clear deficits. About 65.5% had impaired smell, 53.4% had hearing problems, 31.6% had vestibular or balance deficits and 16% had taste deficits, while 19.1% scored in the impaired range on cognitive screening. In the smaller subgroup of eight people who had been hospitalized during their initial COVID illness, all eight had confirmed smell dysfunction, seven had balance problems, six had hearing loss and four had cognitive deficits, according to MedicalXpress.
Severity, age and brain fog point to central involvement
Patterns in the data linked older age and more severe acute COVID to wider-ranging sensory loss. Tasks that required identifying smells or flavors, instead of simply detecting them, were especially connected to cognitive problems, which suggests involvement of the central nervous system rather than just the nose or inner ear. "Our goal is to understand why some long COVID patients experience different profiles of sensory losses while others do not," lead author Kai Zhao said in an Ohio State release.
What this means for patients and clinicians
The study also found that what people report does not always match what tests show, which means clinicians may need objective sensory testing instead of relying on checklists alone, especially when complaints overlap. Federal recommendations call for multidisciplinary evaluation and symptom-specific care for post-COVID conditions, including referrals to ENT, audiology, vestibular therapy and cognitive rehabilitation when appropriate, according to the CDC.
The authors stress that this is an exploratory study with a modest sample size and say larger, longer-term research will be needed to see which sensory problems recover, which persist and how to treat them. For now, the work gives clinicians more concrete targets to investigate when patients show up months after infection still wrestling with brain fog, dizziness or changes in hearing and smell.
