Nerve cell loss in the thalamus in Alzheimer's disease and Parkinson's disease.

Serial sections through the thalamus from the fixed right cerebral hemispheres of 15 cases (5 Parkinson's disease, 5 Alzheimer's disease (AD) and 5 controls) were used to obtain quantitative estimates of neuronal loss, neurofibrillary tangle formation and Lewy body inclusions within individual thalamic nuclei. Severe neuronal loss and tangle formation were evident in the anterodorsal nucleus from the AD cases. Nerve cell damage was also present in the centromedian nucleus but was not associated with tangle formation and occurred in all but 2 of the brains examined. It is likely that the anterodorsal neurons are damaged locally by the Alzheimer's disease process whereas the changes in the centromedian nucleus may be related to ageing.