Abstract

INTRODUCTION

Dementia is not a disease. It is a generic term that refers to the cognitive and behavioural disorder resulting from chronic brain disease or encephalopathy. Chronic encephalopathies may be non-progressive, occurring, for example, as a consequence of brain trauma or cerebral hypoxia, or progressive, arising as a result of an intrinsic, extrinsic or metabolic cerebral disorder. The primary focus of this article is the dementia syndromes that result from progressive degenerative disease. However, vascular disease will also briefly be addressed, because vascular dementia is relatively common and is an important cause of dementia.

The traditional view of dementia as a global loss of intellect is inaccurate. Cerebral diseases do not affect the brain uniformly, but preferentially affect certain brain regions and spare others. Moreover, psychological processes themselves are regionally organized in specific brain regions. Different cerebral diseases therefore are associated with distinctive and characteristic neuropsychological syndromes, whose identification can