["Pittsburgh Compound B ([¹¹C] PiB) is a specific positron emission tomography (PET) marker of cerebral amyloid deposits. Only few data have been published on in vivo longitudinal changes of amyloid load in Alzheimer's disease (AD) patients, with conflicting results. Therefore, little is known about the factors that influence these changes.", 'A group of 24 patients with probable AD diagnosed by combining established clinical criteria with an AD-typical pattern in [(18)F] fluoro-deoxy-glucose PET underwent [¹¹C] PiB-PET examinations at baseline and after 24 months. The difference of amyloid load between the two examinations and the association with clinical and neurobiological variables was examined with a regions-of-interest approach and voxel-based analyses.', 'Cerebral [¹¹C] PiB uptake ratio increased significantly by an annual rate of 3.92%. Although the increase occurred in all parts of the neocortex, no increase was detected in the archipallium. The increase was gene-dose-dependent (analysis of variance p = .012) to the number of apolipoprotein E ε4 alleles. Progression of dementia symptoms was correlated to the [¹¹C] PiB increase in numerous regions associated with cognition.'] Is progression of cerebral amyloid load associated with the apolipoprotein E ε4 genotype in Alzheimer 's disease?