Cognitive impairment in Alzheimer disease

Abstract

The most important cognitive deficit of AD is the progressive loss of memory that is manifested according to the traditional classification in both STM and LTM tasks (see Tables 8.1, 8.2 and 8.3). The earliest and most prominent symptom in AD is a profound impairment in the ability to acquire and remember new information whether tested by recall or recognition (Grady et al., 1988; Welsh et al., 1991). Many patients have purely episodic memory impairment for a number of years (Perry & Hodges, 2000; Perry et al., 2000). Semantic memory, the database of conceptual knowledge that gives meaning to sensory experience, is eventually affected in AD, but early in the disease patients show mild and variable impairment of semantic memory. Written language deficits are frequently noted and occur at early beginning of the disease (Eustache & Lambert, 1996). They initially take the form of a lexical agraphia: the characteristic symptom is the production of errors so called “de regulation” (of regulation) occurring during the writing of words with irregular orthography (e.g. femme > fame). On the contrary, deficits of phonological type often appear with the progression of the dementia.