As the baby boom generation approaches retirement age and average life expectancy continues to rise, dementia will become an increasingly prevalent syndrome (Manton 1990; Myers 1990; Chapter 14). For example, estimates in the USA project that Alzheimer's disease (AD) will increase from its current level of approximately 4 million to more than 14 million affected individuals over the next 50 years (Khachaturian et al. 1994). Thus, neuropsychological research on dementia has increasingly focused on identifying the pattern, progression and neuropathological correlates of the cognitive deficits associated with various dementing disorders (La Rue 1992; Poon et al. 1992). These efforts have led to an increased understanding of the particular neuropsychological deficits that occur in the early stages of dementia. Furthermore, investigators have recently begun to identify cognitive changes that appear to presage the development of dementia. These recent advances in research on the neuropsychological detection of preclinical dementia, and their potential clinical implications, will be discussed in the present chapter.
PRECLINICAL DETECTION OF ALZHEIMER'S DISEASE
To date, the available epidemiological and biological evidence suggest a view of AD as a chronic disease, and the emerging picture is that of a long preclinical period of neuropathological changes prior to the appearance of the full dementia syndrome (for a discussion, see Katzman and Kawas 1994). Many of the recent attempts to identify cognitive markers of incipient AD are also consistent with the view of AD as a chronic disease.