AMYLOID PLAQUES IN CEREBELLAR CORTEX AND THE INTEGRITY OF PURKINJE-CELL DENDRITES

We probed serial and near serial sections of cerebellum from 13 Alzheimer's disease (AD), 10 older Down's syndrome (DS) patients, and 9 age-matched, non-AD controls, using single and double labeling immunohistochemistry to investigate the pathologic consequences of beta-amyloid or A4 (A beta) deposits in cerebellum and their relationship to Purkinje cells (PCs). Our data showed that A beta deposits in cerebellum of AD and older DS adults only form diffuse or preamyloid plaques and the density of A beta lesions per unit area of molecular layer correlated with the number of PCs per unit length of the subjacent PC layer in double immunostained sections (r = 0.85; p<0.001). About 65% of these cerebellar A beta deposits were in physical contact with PC dendrites. No A beta plaques were found in the cerebellum of controls. Despite the abundance of A beta deposits in the cerebellar cortex of AD and older DS patients, neither PC bodies nor PC dendrites in physical contact with A beta lesions showed evidence of structural abnormalities.