Neuronal Size and Density in the Nucleus Basalis of Meynert in Alzheimer's Disease

Neuronal size and density were measured in the nucleus basalis of Meynert in 7 elderly patients with Alzheimer's disease (AD) and 7 controls. The number of neurons in AD patients was reduced to 36% of the control value. The population of large neurons (perikaryonal diameter greater than 30 micron) had disappeared almost completely. In addition to cell death, shrinkage may play a role, since there were relatively more neurons in the small size classes in the AD patients than in the controls. The nuclear diameter was reduced to 79% of the control values, and the perikaryonal diameter to 75%, and thus the cytoplasm/nucleus ratio was close to equal in the two groups. Correlations of the morphometric measurements with choline acetyltransferase activities and muscarinic receptor binding are also presented.