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Hearing loss is associated with additional risk of developing Parkinson disease (PD), with worse hearing conferring a greater risk, according to study results published in JAMA Neurology.
Previous studies have established a link between hearing loss and incident Alzheimer disease; however, there are limited data exploring the association between hearing loss and PD and the effect of hearing aids on PD incidence among individuals with hearing loss.
Using the Department of Veterans Affairs (VA) database, researchers aimed to determine the association of hearing loss with later development of PD.
Primary exposure was hearing loss, measured using a clinical hearing test (ie, audiogram). Patients were categorized into groups based on pure tone average (PTA) values calculated from 500 to 4000 Hz: 20 dB (normal hearing); 20 to less than 35 dB (mild hearing loss); 35 to less than 50 dB (moderate hearing loss); 50 to less than 65 dB (moderate to severe hearing loss); and 65 dB and higher (severe to profound hearing loss).
Primary study outcome was incident PD, defined using International Classification of Diseases (ICD) codes.
Of 3,596,365 veterans included in the study, 750,010 (20.8%) had normal hearing, and among the remaining with hearing loss, 1,080,651 (30.0%), 1,039,785 (28.9%), 568,296 (15.8%), and 157,623 (4.3%) had mild (20 to <35 dB), moderate (35 to <50 dB), moderate to severe (50 to <65 dB), and severe to profound (65-120 dB) hearing loss, respectively. The majority of participants in all groups were men and White. Overall, hearing loss was associated with older age, frailty, smoking, and hearing aid nonuse.
Mean follow-up was 27,499,618 person-years (PYs; mean, 7.6 years). Among those with hearing loss, incidence rate for PD was 3.69 to 11.6 per 10,000 PYs and 103 to 1140 per 10,000 PYs for death.
Compared with study participants with normal hearing, those with mild hearing loss had a greater cumulative incidence of PD at 5, 10, 15, and 20 years, with the number of additional cases of PD per 10,000 PYs ranging from 2.0 (95% CI, 0.9-3.1) to 9.5 (95% CI, 7.7-11.4) at the 5- and 20-year follow-up, respectively. Similarly, those in other hearing loss groups (except the severe to profound group at 1 year) vs the normal hearing group had greater cumulative incidence of PD. Overall, hearing loss of any severity vs normal hearing was linked to increased risk for PD at 10 years (hazard ratio [HR], 1.26; 95% CI, 1.2-1.32; P <.001).
When stratifying by comorbidity, individuals with hearing loss without prodromal PD disorders, tinnitus, and traumatic brain injury (TBI) had risk for PD, with this risk increasing with hearing loss severity and time. Comorbid hearing loss and prodromal PD disorders vs either condition alone was associated with an additional 21.7 (95% CI, 6.7-36.6) cases of PD.
In addition, the researchers noted a significant reduction in incident PD at 1 year among individuals who used a hearing aid.
Study limitations included the inclusion of only US veterans, who were predominantly White and men, therefore, limiting generalizability of the results; and lack of determining the mechanisms involved in the association between hearing loss and PD.
“Given that hearing loss, even that of mild severity, synergizes with known prodromal disorders and leads to a greater-than-additive risk of incident PD, hearing screening should be enforced at the primary care level even in the absence of a patient expressing hearing concerns,” the researchers wrote.
