Reductions in soluble brain proteins in older subjects with Down's syndrome.

Soluble proteins from temporal cortex and caudate nucleus from 6 cases of Down's syndrome (5 aged over 50 and 1 aged 27 years) and 7 controls were analysed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis. In older Down's syndrome cases, reductions in tubulin and 5 other proteins were observed in cortex which had the neuropathology of Alzheimer's disease but not in caudate nucleus. No protein changes or neuropathological features of Alzheimer's disease were found in the youngest Down's syndrome case. The protein changes appear to be associated with the neuropathological features of Alzheimer's disease and not with Down's syndrome itself.