DECREASED LEVELS OF SOLUBLE AMYLOID BETA-PROTEIN PRECURSOR ARE ASSOCIATED WITH ALZHEIMERS-DISEASE IN CONCORDANT AND DISCORDANT MONOZYGOTIC TWIN PAIRS

We conducted immunochemical measurements of soluble amyloid beta-prote in precursor (beta PP) in cerebrospinal fluid (CSF) from three monozyg ous twin pairs. Two of the twin pairs are discordant for Alzheimer's d isease and one pair showed concordance for Alzheimer's disease, which was confirmed neuropathologically. All affected individuals displayed substantially lower levels of soluble beta PP in CSF compared with the unaffected individuals. There were no differences in total protein le vels in CSF samples from the affected twins compared with those of the unaffected twins. These studies suggest that decreased soluble beta P P in CSF may reflect neuropathological processes in Alzheimer's diseas e involving beta PP.