Developmental Language Disorder

Abstract

This chapter describes the history of research in Language Disorders (LD) outlining changes in terminology and methodology and focuses on three newer research methodologies: population studies, the characterization of longitudinal change, and neuroimaging. Population studies have identified a clear social gradient in language ability, challenged assumptions about the role of non-verbal skills, and highlighted vulnerabilities in associated developmental domains. The fluidity of pre-school language development and increasing stability in the middle school years has become apparent in longitudinal population analyses and the importance of social disadvantage and the home-learning environment underlined. Neurobiological “differences” between those with and without LD are recognized, however little is known about the developmental pathways or the role of biological and environmental mechanisms in shaping them. Fully describing and understanding the ontogony of LD remains elusive. How environmental, genetic, epigenetic, and neurobiological effects interact and unfold over developmental time and across population samples remain priorities for research.