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Declining Cognitive Function

Alex Bahar-Fuchs

Declining cognitive function and forgetfulness are common phenomena in the aging population (Killiany et al., 2002; Spaan, Raaijmakers, & Jonker, 2003). In some individuals these changes might be part and parcel of normal aging, but in others they might constitute markers of an early dementing process. Alzheimers disease (AD) is regarded as a frequent, if not the most frequent cause of dementia above the age of sixty years in Europe, North America and Australia, it's incidence increasing exponentially with age (Jorm & Jolley, 1998; Salman, 2004; Waite, Broe, Grayson, & Creasey, 2001). Symptomatic treatments for use in the earlier stages of AD have been available for some time (Delagarza, 2003; Racchi, Mazzucchelli, Porrello, Lanni, & Govoni, 2004). These are most beneficial early in the course of the disease, and their efficiency in later stages is uncertain (Blackwell et al., 2004; Mundt, Freed, & Greist, 2000; Robert, Schuck, Dubois, & Olie, 2003). While no drug has been shown to completely protect neurons, agents that inhibit the degradation of acetylcholine are the mainstay of symptomatic treatment for Alzheimer's Disease (Cummings, 2004; Delagarza, 2003). Studies that have focused on the pathogenic mechanism of AD have led to the development of disease-modifying approaches, with anti-amyloid immunotherapy considered a very promising direction (Citron, 2004; Cummings, 2004). The expectation that these interventions are likely to be most beneficial in the pre-symptomatic stages highlights the importance of developing successful early detection of the neuropsychological features of dem entia more than ever before (Citron, 2004; Delagarza, 2003; Kawas, 2003).

There is now a growing body of literature on neuropsychological detection of early dementia (Blackwell et al., 2004; Borson et al., 1999; Fowler, Saling, Conway, Semple, & Louis, 2002; Robert et al., 2003; Saling, Maccuspie-Moore, Anderson, & Chiu, 2002b; Shulman, 2000; Solomon, Hirschoff, Kelly, & Relin, 1998), and a number of useful directions have emerged. Concomitantly, there is a growing demand for compact test procedures which can be deployed for screening purposes in general practice and in other busy clinical settings (Blackwell et al., 2004; Shulman, 2000; Solomon et al., 1998). While a number of previous screening protocols have been published (Chiu et al., 2004; Lin, Wang, Chen, & Chiu, 2003; Mundt et al., 2000; Robert et al., 2003; Solomon et al., 1998), these often lack a sound theoretical backing. The items used in some of these procedures do not have a coherent and demonstrated relationship to the specific neurocognitive systems involved in the earliest stages of AD, and this in turn compromises their usefulness.

The aim of the current study was to carry out a preliminary evaluation of a new screening procedure which attempts to circumvent some of these shortcomings. In subsequent sections I will provide a short review of some pertinent features of Alzheimer type dementia. Subsequently, recent findings related to the specific neurocognitive systems implicated in early AD will be reviewed, followed by a description of trends in the current screening methods for memory difficulties associated with early disease stages. Finally, the aims of the current study and the hypotheses will be discussed.

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