Disconnection of Language and Memory in Semantic Dementia: A Comparative and Theoretical Analysis

Michael   J.   Passmore; Janet   L.   Ingles; John   D.   Fisk; Sultan      Darvesh

Abstract

In this paper, we present an illustrative case of Semantic Dementia (SD) and we review the literature on this relatively rare progressive neurodegenerative disorder. After reviewing the clinical, neuroimaging, neuropathological, and genetic features of SD, we propose a theoretical framework that addresses features of SD and relates them to features of other well known neuropsychiatric syndromes. Our on-line / off-line disconnection model seeks to conceptualize SD as a syndrome of disconnection between two large distributed cortical networks, namely, between those networks that subserve language function and those that subserve memory function.

Keywords: semantic dementia, picks disease, frontotemporal lobar degeneration, primary progressive aphasia, reduplicative paramnesia, confabulation, delusion, disconnection