[Neuropsychology and early diagnosis].

The presence of histopathological lesions characteristic of Alzheimer's disease, senile plaques and neurofibrillar degeneration in the brains of cognitively normal individuals has been well documented in several longitudinal clinicopathological studies over the last two decades. Clinical and pathological epidemiological data suggest that Alzheimer's disease can begin to develop almost a decade before the first clinical manifestations appear. The present article reviews the studies investigating cognitive alterations before the disease manifests. All these studies reveal the presence of alterations in preclinical phases in cognitive functions other than memory, such as those related to attention, processing speed and verbal fluency. Assessment of memory with tools sensitive to hippocampal memory impairment is recommended. The best predictor is having each individual's baseline performance, which can then be used for comparison with subsequent performance. Once reduced performance is detected (even when within the "normal" range), affected persons should be referred to specific units able to diagnose the disease in the early stages.