Topography of nerve cell loss from the locus caeruleus in middle aged persons with Down's syndrome.

A topographical analysis of nerve cell loss from the locus caeruleus in middle aged patients with Down's syndrome (whose brains show the pathological changes of Alzheimer's disease), has shown that cell loss is confined to dorsal areas, being least most rostrally and greatest caudally. By contrast, there is no significant cell loss from ventral parts of the locus, at any point along its rostrocaudal length. Dorsally located neurones of the locus project to cerebral cortex; ventrally located neurones to non-cortical areas such as basal ganglia, cerebellum and spinal cord. These data suggest that the damage to nerve cells of the locus caeruleus in Down's syndrome at middle age, like that seen in Alzheimer's disease itself, relates to primary pathological events within the cortical projection fields of affected cells with perikaryal loss following on as a later change.