Cerebral amyloid angiopathy (CAA) is defined by beta-amyloid peptide (Abeta) depositions in cerebral vessels and is associated with Alzheimer's disease (AD). The relationship between sporadic CAA and AD, and the origin of Abeta in CAA are poorly understood. The aim of our study was to investigate the relationship between CAA and AD. Autopsy brains (n=113, 61.1% female, 55.8% clinically demented, age range 54-102 years, mean +/- SE 83.5+/-0.93 years) underwent standardized neuropathological assessment. CAA was evaluated in frontal, frontobasal, hippocampal, and occipital regions. Using immunohistochemistry, the severity of Abeta deposition in vessels was assessed semiquantitatively for each region separately. Evaluation of APOE genotype in 53 cases using real-time PCR showed significant correlations with severe AD pathology and CAA. CAA was present in 77 cases (68.1%), with the occipital region being affected significantly more often and more severely than other regions (P<0.01). Of brains without AD pathology 23.5% revealed CAA, whereas 24% with AD pathology showed no CAA. In concordance with other studies, the severity of both AD pathology and CAA showed a low, but significant correlation. This correlation, however, was only caused by the significant increase of occipital CAA with increasing AD pathology (P<0.01), and was independent of APOE genotype. Our results suggest that progressing AD pathology not only increases the severity of CAA, but also shifts its topographical distribution towards the occipital cortex.