The spatial patterns of prion protein deposits in Creutzfeldt-Jakob disease: comparison with beta-amyloid deposits in Alzheimer's disease.

Similar pathological processes may be involved in the deposition of extracellular proteins in the brains of patients with Creutzfeldt-Jakob disease (CJD) and Alzheimer's disease (AD). Hence, this study compared the spatial patterns of prion protein (PrP) deposits in the cerebral cortex and hippocampus in cases of sporadic CJD with those of beta-amyloid (Abeta) deposits in sporadic AD. PrP and Abeta deposits were aggregated into clusters and, in 90% of brain areas in CJD and 57% in AD, the clusters were regularly distributed parallel to the tissue boundary. In a significant proportion of cortical analyses, the mean diameter of the clusters of PrP and Abeta deposits were similar to those of the cells of origin of the cortico-cortical pathways. Abeta deposits in AD were distributed more frequently in larger-sized clusters than PrP deposits in CJD. In addition, in the hippocampus and dentate gyrus, clustering of Abeta deposits was observed in AD but PrP deposits were rare in these regions in CJD. The size, location and distribution of the extracellular protein deposits within the cortex of both disorders was consistent with the degeneration of the cortico-cortical pathways. Furthermore, spread of the pathology along these pathways may be a pathogenic feature common to CJD and AD.