Semantic dementia (SD) is a disorder of conceptual knowledge resulting from degeneration of the anterior temporal lobes. It is one of the canonical clinical syndromes, along with the behavioural variant of frontotemporal dementia (bvFTD) disorder and expressive language disorder of progressive non-uent aphasia (PNFA), associated with a non-Alzheimer, frontotemporal lobar degeneration (FTLD) pathology (Neary et al., 1998; Josephs et al., 2011). People with SD lose the ability to name and understand words, to recognize faces and to understand the signicance of objects. Although relatively rare, recognition of this disorder is important because of its distinct implications for management. Moreover, in recent years it has attracted considerable academic interest because of its potential to shed light on the organization and neural basis of semantic memory. From a neurobiological perspective, a central interest is the relationship between SD and other clinical presentations of FTLD.