Cortical Auditory Evoked Potentials in Cognitive Impairment and Their Relevance to Hearing Loss: A Systematic Review Highlighting the Evidence Gap

As the global population ages, the prevalence of Alzheimer's disease (AD) and mild cognitive impairment (MCI) continues to rise. Early detection is critical for effective intervention, yet current diagnostic tools often rely on neuropsychological assessments that can be influenced by language barriers, cultural differences, or hearing impairment. Cortical Auditory Evoked Potentials (CAEPs)—electroencephalography-derived measures of central auditory processing—are proposed as a non-invasive, objective, and culturally neutral alternative for identifying cognitive decline.

However, both hearing loss and cognitive impairment are known to alter CAEP morphology, typically by reducing amplitudes and prolonging latencies. Because hearing loss is a recognized, modifiable risk factor for dementia, it is essential to distinguish whether observed CAEP changes stem from auditory dysfunction, cognitive decline, or a combination of both. This systematic review aimed to synthesize existing evidence on how CAEPs are affected in populations with MCI or AD, specifically accounting for their hearing status.

The researchers conducted a rigorous systematic search across multiple databases (PubMed, Cochrane, Web of Science, and Scopus) following PRISMA guidelines. Despite a comprehensive search strategy, the authors identified no eligible studies that met all inclusion criteria—specifically, studies that included both a cognitive impairment group (MCI or AD) and a hearing loss assessment alongside CAEP measurements. Consequently, the review resulted in an empty set of findings, underscoring a critical lack of integrated research in this field.

The absence of literature on this intersection is a major hurdle for clinical diagnostics. Because hearing loss and cognitive decline share similar electrophysiological signatures in CAEPs, failing to control for one while measuring the other leads to confounding results. Furthermore, the authors note that vestibular dysfunction—which is frequently comorbid with both hearing loss and dementia—is an often-overlooked factor that may also distort CAEP responses. Future research must integrate cognitive, auditory, and vestibular evaluations to accurately interpret CAEP data and validate their utility as a prognostic marker for early-stage cognitive decline.