Hearing and early life adversity: effects of developmental stress on sensory processing

In children, early hearing loss can cause prolonged difficulty with auditory perception and language processing. Yet children with hearing loss are at greater risk of long-term language, cognitive, and socioemotional deficits when raised with environmental challenges that are stressful, such as low socio-economic status. The neural circuits underlying language and auditory processing are shaped by auditory experience over the course of development, allowing listeners to make sense of environmental sounds including speech. Evidence is accumulating from work in animal models that these sensory circuits are also affected by adverse stressful experiences early in life. Recent experiments indicate that stress can exacerbate sensory deficits caused by developmental hearing loss. These effects are driven by shifts in mechanisms underlying developmental plasticity, as well as by consequences of altered activity of the hypothalamic-adrenal-pituitary (HPA) stress axis. Viewed through an interdisciplinary lens, the research reviewed here suggests that some of the challenges experienced by children with hearing loss may be intensified by early life adversity and ameliorated by interventions that target both sensory deprivation and stress.