Number of neurons in nucleus locus ceruleus in demented and non-demented patients: rapid estimation and correlated parameters.

The total number of neurons in nucleus locus ceruleus (nLC) was counted in 20 patients with dementia (19 with dementia of the Alzheimer type) and 10 non-demented patients with the assistance of an image analyzer. The average number of neurons in a single representative section of nLC through the site of maximal neuronal density was then determined in each case. Both the mean total neuronal count and the average number of neurons in single sections correlated significantly with age, severity of dementia and length of nLC. The mean total number of neurons for demented (5571.700 +/- 4151.073) and non-demented (12533.700 +/- 2336.320) subjects differed significantly. The mean number of neurons derived by averaging counts of single representative sections from demented subjects (67.9 +/- 31.19) correlated significantly with the total number of nLC neurons determined by Quantimet-assisted analysis and differed significantly from the mean number of neurons derived by averaging counts of single representative sections of non-demented subjects of comparable age (110.0 +/- 16.59). With both methods of estimating neuronal numbers, the number of surviving nLC neurons in demented patients fell into 2 distinct groups, with cut-off points at 5,000 neurons (mean total counts) and 67 neurons (average of single representative section counts). These findings provide clear evidence that samples of the nLC neuronal population derived from single section counts produce data of comparable utility to those obtained from more laborious total neuronal counts in the human locus ceruleus.