Oregon Health & Science University-led researchers have found a correlative link between hearing loss and the development of Parkinson’s disease (PD). They find the risk of PD rises somewhat with the severity of hearing loss, and declines when hearing aids are promptly issued.

Previous studies have noted sensory impairments, like vision, hearing and smell, as preceding signs of neurodegenerative diseases. Hearing loss has been associated with Alzheimer’s disease, which shares clinical, genetic, and pathological overlap with PD. These declines in sensory function may reflect early signs of damage within neural pathways indicative of overall neurodegeneration.

In a cohort study, “Hearing Loss, Incident Parkinson Disease, and Treatment With Hearing Aids,” published in JAMA Neurology, more than 3 million US veterans with hearing loss were cross-referenced with incidents of PD. The analysis found hearing loss associated with increased rates of PD, with the severity of hearing loss correlating to greater risk.

Data from the U.S. Department of Veterans Affairs included 3,596,365 veterans (96% male with a mean age of 67), who had audiograms conducted between 1999 and 2022, and were grouped based on their hearing abilities. Of these, 20.8% had normal hearing, while the remainder experienced varying degrees of hearing loss, categorized as mild, moderate, moderate to severe, or severe.

At 10 years following their audiogram, the authors suggest that the incidence of PD increased with the severity of hearing loss. Veterans with mild hearing loss showed 6.1 additional cases per 10,000 individuals, moderate loss 15.8 per 10,000, and moderate to severe loss 16.2 cases per 10,000, while those with severe to profound hearing loss saw an increase of 12.1 per 10,000.

Intriguingly, veterans who were promptly fitted with hearing aids had a reduction of 21.6 cases per 10,000.

The findings require further research into potential mechanisms linking hearing loss to neurodegenerative diseases like PD.

In the meantime, the study authors suggest that “…hearing screening should be enforced at the primary care level even in the absence of a patient expressing hearing concerns. Hearing screening and hearing intervention are low-cost, low-risk interventions that may influence later development of synucleinopathy. It may be the most important modifiable risk factor for dementia in midlife and could prove to be the same for PD.”

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