Auditory Biomarkers in Neurodegenerative Disorders: A Literature Review.

The prevalence of neurodegenerative diseases is escalating globally. However, the conventional diagnostic framework fails to identify the pathology until substantial neuronal damage occurs. The evidence from the recent literature indicates that auditory dysfunction commonly precedes motor and cognitive symptoms across multiple neurodegenerative diseases. The pathophysiology involves both the peripheral and cortical auditory structures, which produce distinctive patterns reflects systemic neurodegeneration. Hence, this suggests auditory assessment as a valuable tool for early identification of neural degeneration. This review synthesises the contemporary literature on auditory dysfunctions and underlying pathophysiology in Alzheimer's disease, Parkinson's disease, Frontotemporal dementia, Amyotrophic lateral sclerosis, etc. The analysis included the temporal trajectories of auditory impairment, subjective-objective measurements, and evaluated the importance of early identification and longitudinal tracking. Objective measures of central auditory processing, including Auditory Brainstem Responses, P300, Mismatch Negativity, and speech-in-noise testing, provide objective, non-invasive diagnostic tools and its sensitivity comparable to established biomarkers. Integration of standardised auditory assessment batteries into clinical protocols could enable the early identification of pathology, differential diagnosis and the development of novel therapeutic strategies for both auditory and cognitive deficits. Current review suggests that future longitudinal studies with neurodegenerative conditions should focus on the clinical utility of auditory, cognitive, and neuroimaging biomarkers and facilitate clinical translation of these findings.