INTRODUCTION

Cognitive impairment in late life is a growing public health care problem. By the year 2050, conservative estimates indicate as many as 7 to 14 million individuals in the USA (US Census Figures) will be affected by some form of dementia requiring specialized care or institutionalization (Khachaturian 1994). Alzheimer's disease (AD) is by far the most prevalent of the disorders accounting for at least 60% of the progressive dementias. Vascular dementias are believed to account for 20% and a variety of other dementias account for the remaining 20%. Many of these ‘other’ dementias are treatable and some, if treated, are reversible (Breitner and Welsh 1995).

A challenge facing today's clinician is reliably detecting dementia in scenarios where the distinctions between early dementia and normal aging are quite difficult. Accurate diagnoses at this stage are important in allaying anxieties when dementia is not suspected. In the cases of dementia, diagnostic certainty as to the type of dementia can have consequences particularly if the disorder is treatable. In the future, should effective treatment strategies become available for AD and some of the other irreversible forms of dementia, early clinical intervention will be important in an effort to prevent the expression of fulminant symptoms.

At present there is no diagnostic test or biological marker for AD which will permit reliable prediction of who is likely to develop the disease (Roses 1995). Consequently, the diagnosis of this late onset dementia as well as some of the other common neurodegenerative conditions continues to rely on sound clinical methods. It is in this area that neuropsychology has made a significant contribution.