This review describes and evaluates developments in the early diagnosis and the treatment of Alzheimer's disease. It is hoped that early diagnosis of the disorder will enable treatment that will reduce or arrest the associated cognitive loss so that affected individuals can retain significant function and institutionalization can be delayed or averted. Diagnostic techniques, including use of neuropsychological measures, functional imaging measures, and biological markers, are reviewed; such techniques are useful for confirming diagnosis but do not replace a comprehensive clinical evaluation. Potential treatment modalities, such as techniques to enhance neurotransmission, replace estrogen effects, reduce the effects of free radicals, and combat inflammation, are explored. Cholinesterase inhibitors are the only modality thus far shown in large-scale studies to be effective, but their effect is small.