Language functions in right-hemisphere damage and schizophrenia: apparently similar pragmatic deficits may hide profound differences

Sir, In a recent article discussing the cognitive roots of schizophrenic communicative behaviour, Mitchell and Crow (2005) emphasized the importance of full access to right hemisphere language functions to ensure successful social communication. Based on the literature describing communicative deficits among right-hemisphere-damaged (RHD) patients, as well as on the literature reporting functional neuroimaging studies of healthy individuals, these authors suggested that ‘the core deficit in psychosis is a failure of segregation of right from left hemisphere functions’ (p. 963). In other words, Mitchell and Crow (2005) argue for a reduction of the language lateralization in schizophrenia (SZ). The role of so-called ‘RH functions’ in the pathophysiology of SZ proposed by Mitchell and Crow (2005) could prove crucial to an understanding of SZ from a neurobiological point of view; this proposal may also account for the presence of social communication deficits in SZ. However, the apparent similarities noted by Mitchell and Crow (2005) between the pragmatic deficits following RH damage and those present in patients with SZ seem to be only at the surface level. Indeed, the underlying cognitive dysfunctions appear to be quite different in these two populations.As Mitchell and Crow (2005) rightly remind us in their article, language requires more than the classical syntax, phonology and …