LOCUS-COERULEUS CELL LOSS IN LOBAR ATROPHY

The locus coeruleus (LC) provides the noradrenergic innervation for mu ch of the cerebrum and spinal cord, and it decreases in cell number wi th normal aging and in several degenerative dementing diseases (e.g. A lzheimer's disease [AD], Parkinson's disease, Down's syndrome). In AD and Down's syndrome there is over 50% cell loss in the LC, and the los s is greatest in the rostral portions of the nucleus; in Parkinson's d isease there is over 50% cell loss, but the cell loss is the same thro ughout the rostral-caudal extent of the nucleus. The purpose of the pr esent study was to examine the LC in various non-AD forms of dementia (i.e. the so-called lobar atrophies). Computer mapping was used to qua ntify the rostral-caudal distribution of LC neurons in the brains of 1 5 patients with lobar atrophy (five with frontal lobe dementia, three with frontal lobe dementia and motor neuron disease, three with progre ssive aphasia, and four with Pick's disease), and in six age-matched n ormal subjects. The normal LC spans a rostral-caudal distance of appro ximately 12 mm, and contains about 17000 neurons on either side of the brain. Compared to normals, there was no overall loss of cells in mos t of the Pick's disease brains, but in the other lobar atrophy brains there was an average of 17% fewer neurons. In the lobar atrophy brains , cell loss occurred only in a caudal portion of the nucleus. These da ta indicate that specific subpopulations of LC neurons are vulnerable to degeneration in different dementing diseases.