ABSTRACT
Alzheimer’s disease (AD) is the most common cause of dementia in the elderly, accounting for 50%–80% of patients with dementia (Chui, 1989; Evans et al., 1989). As recently as the 1970’s, AD was considered to be a widespread degenerative disease affecting all cognitive functions in a global manner. However, more recent neuropathological (Kemper, 1984; Morrison et al., 1990; Van Hoesen & Damasio, 1987) and neuroimaging studies (Grady et al., 1988; Grady et al., 1990; Haxby et al., 1990; Haxby et al., 1988; Kumar et al., 1991; McGeer et al., 1990) have shown that AD does not affect all parts of the brain equally. Moreover, a more accurate view of the cognitive functioning of patients with AD is that this disease, particularly in its early stages, leads to a selective breakdown of particular cognitive functions rather than to a global loss (Schwartz, 1990). In addition, some cognitive functions may be spared until relatively late in the course of the disease.
