Morphometric analyses of neuronal populations and dendritic extent in normal aging and dementia of Alzheimer type: a frank appraisal of the difficulties.

This comprehensive review provides an insightful and frank discussion of the methodological limitations in the literature dealing with analyses of neuronal numbers and the extent of the dendritic tree, both in animal models of physiological aging and human CNS tissue from aged control subjects as well as from patients with Alzheimer's disease. Of special interest are data from Flood and Coleman's own laboratory in which the unique behaviour of hippocampal nerve cells in autopsy studies suggests that hippocampal pyramidal neurones are a key to the neurobiology of dementia of the Alzheimer type. Such investigations could elucidate what happens to the dendritic apparatus of neurones which develop neurofibrillary change, and eventually help determine whether the paired helical filaments of neurofibrillary tangles are even more critical for the pathogenesis of senile dementia than the amyloid of neuritic plaques and of congophilic vessels.