The noradrenergic system in Alzheimer and multi-infarct dementias.

The number of melanin containing nerve cells of the locus coeruleus and vagus nucleus is reduced in Alzheimer's disease by 60% with decrease of 22% in the protein synthetic capability of remaining cells. These changes are matched by reductions in brain noradrenaline in eight regions, averaging 36%. In multi-infarct dementia, however, all three of these features are unchanged. These findings indicate that degeneration of central noradrenergic nerve cells is a specific aspect of the pathogenic process underlying Alzheimer's disease.