Anosognosia for amnesia as a clue to understand the nature of dementia

Abstract

Dementia is a clinical syndrome characterized by a loss of intelligence once possessed by an individual. Clinically intelligence can be defined as an ability of an individual to get involved in social life as a responsible and independent member by employing his/her own cognitive resources in the most effective way. This ability has been attributed either to a unique faculty called g-factor or to the sum of several slave mental faculties such as memory, language, spatio-manual capacity and so on. Dementia is thus thought to be caused either by a loss of g-factor, or by the simultaneous loss of two or three slave faculties. Based on a long term observation of a couple of cases of senile degenerative dementia and many cases of Korsakoff amnesic syndrome, the author refutes both interpretation and proposes a qualitatively different hypothesis that senile degenerative dementia is a manifestation of the disorganization of the structure of consciousness, one of whose function is to bring up the stored mental contents to the state of awareness and make them available to the conscious manipulation. In degenerative dementia, slowly progressive dissolution of the structure of consciousness causes the breakdown of the integrity of social activity as well as personality. It is hard to confirm whether the mental resources themselves are destroyed or not in this process. © 2008 Tohoku University Medical Press.