Hearing Loss and Dementia: Risk Factor, Early Marker, or Both?

Background/Objectives: Hearing loss and dementia are highly prevalent conditions in older adults and represent a growing public health challenge. Over the past decade, a substantial body of epidemiological evidence has demonstrated a consistent association between age-related hearing loss and cognitive dysfunction, including incident dementia. However, the nature of this relationship remains incompletely understood. Methods: This narrative review provides a structured overview of current evidence, focusing on epidemiological findings, mechanistic pathways, and clinical implications. Hearing loss has been associated with both accelerated cognitive decline and increased dementia risk, with a clear severity-impact relationship. Results: Several interacting mechanisms have been proposed, including increased cognitive load, structural and functional brain changes, social isolation, and shared vascular and metabolic risk factors. Emerging concepts such as the "auditory brain" and central auditory dysfunction further suggest that hearing impairment may also represent an early manifestation of neurodegenerative processes. Intervention studies have yielded mixed results. While hearing rehabilitation improves communication and quality of life, randomized evidence has not consistently demonstrated a reduction in cognitive decline in the general population, but potential benefits may exist in higher-risk subgroups. Increasing attention has been directed toward the role of neuroplasticity, with evidence suggesting that delayed intervention may limit the effectiveness of rehabilitation due to long-standing auditory deprivation. Conclusions: Taken together, current evidence suggests that hearing loss may represent both a potentially modifiable risk factor and an early marker of cognitive decline. Early identification and timely management of hearing impairment may therefore play an important role in maintaining cognitive and brain health and improving quality of life in older adults.