Cell loss in the nucleus raphes dorsalis in Alzheimer's disease.

Marked neuron loss in the predominantly serotonergic nucleus raphes dorsalis (NRd) in Alzheimer's disease (AD) has repeatedly been reported in the literature. However, most of these studies quantitated only part of the NRd and data were expressed as numerical density. Applying a 3-dimensional sampling scheme throughout the entire rostrocaudal extent of the NRd and sampling neurons regardless of their size and staining characteristics, an overall neuron loss of 39.4% was demonstrated and a tendency for cell shrinkage was likely to be present. No rostrocaudal gradient in neuron loss could be shown. These NRd data are in accordance with neuron loss in other subcortical structures in AD.