Neuronal Changes in Normal Human Aging and Alzheimerʹs Disease

This article discusses age-related changes in brain weight, total number of cortical neurons, cortical dendrites, spine, and synapse density. The conclusion is that the present outlook is less grim than it was 30 years ago. Age-related reduction appears to be specific to brain region and cortical layer rather than a general feature. In addition, we describe a different pattern of changes that occur in Alzheimerʹs disease patients. This review concludes that the association cortices in particular are affected in aging and Alzheimerʹs disease and that the primary visual and somatosensory cortices are relatively spared.