The importance of language use when studying the neuroanatomical basis of bilingualism

Studies on the neuroanatomical basis of bilingualism have yielded various but inconsistent differences between bilinguals and monolinguals. In this commentary, we will discuss how differences in background variables between language groups could explain part of this variation. We will furthermore argue that besides language proficiency and age of acquisition, more research needs to be done on the effects of language use and language context. Green and Abutalebi's Adaptive Control Hypothesis could guide the investigation of how language use and context could affect the structure of the brain. Lastly, given the inconsistency in (the direction of) neuroanatomical effects of bilingualism, we discuss how structural differences are difficult to interpret in the absence of behavioural data. A more theory-driven approach is needed to interpret the potential effects of bilingualism on a behavioural as well as neural level.