Cognitive screening and detailed neuropsychological assessment provide a reliable means of detecting dementia in its earliest stages, tracking the progression of cognitive decline over time, and aiding in the differential diagnosis of various dementing disorders. In addition, recent studies have shown that mild cognitive changes, and particularly declines in memory function, are evident in the "preclinical" phase of Alzheimer's disease and may help to identify elderly individuals who are likely to develop dementia in the near future. Until effective and easily obtainable biological markers for detecting the onset and progression of Alzheimer's disease are developed, neuropsychological assessment will continue to have an important role in the dementia evaluation.