Animal models of early-onset hearing loss: A systematic review of the effects on cognition, social behavior, vocalization, and neurobiological mechanisms

Abstract

Hearing loss in children can impair memory, learning, and communication. Despite the need for effective interventions, the mechanisms by which early-onset hearing loss affect cognition, social behaviors and vocalizations as well as the underlying neurobiological mechanisms remain poorly understood. Despite the wide use of animal models to investigate these mechanisms, it is unclear how experimental factors, such as species, hearing loss induction method, severity, onset, and duration, influence outcomes. To address this gap, we conducted a systematic review (PROSPERO: CRD42024515848) to synthesize the fragmented animal literature and clarify how experimental variables shape behavioral and neurobiological outcomes. Studies were identified through a comprehensive search strategy and screened both manually and with AI assistance. Outcomes were analyzed using vote counting and grouped into cognitive, social, vocal, or neurobiological domains. 33 studies met our inclusion criteria, with most focusing on cognitive (n = 20) and neurobiological (n = 15) outcomes and fewer on social (n = 9) and vocal (n = 9) outcomes. Severe hearing loss was most frequently investigated, although induction methods varied widely. Reporting quality was generally poor, often resulting in unclear or high risk of bias. Across studies, hearing loss had negative or neutral effects on cognition and vocalization, and negative, neutral, or occasionally positive effects on social behavior. Experimental parameters did not consistently explain direction of effects within each domain. The most commonly investigated neurobiological mechanisms included oxidative stress, cellular damage, neurogenesis, and neuroplasticity. Our findings highlight the complexity of outcome variability and underscore the need for standardized methods and better reporting to enable robust cross-study comparisons.