How Beta-Amyloid Builds Up in the Brain
Alzheimer’s disease biomarker begins to accumulate in different brain regions at the same time.
One major hallmark of Alzheimer’s disease is the accumulation of beta-amyloid peptides in the brain. Even though these molecules play an important role in the development of the disease and show a consistent spatiotemporal distribution, it has not been clear exactly how they aggregate in different brain regions over time. A study published Nov. 16 in the Journal of Nuclear Medicine addresses this question, providing evidence that beta-amyloid peptides start to accumulate in different brain regions simultaneously rather than originating and spreading from a small number of seed regions.
The researchers applied mathematical modeling to positron emission tomography imaging data from 769 subjects, comprising healthy controls, individuals with mild cognitive impairment, and patients with Alzheimer’s disease. The model that best described the imaging data suggested that beta-amyloid peptides start to accumulate in different brain regions at the same time, with the same growth rate for all regions. Moreover, the results indicated that some brain regions have a higher carrying capacity than others, accumulating more beta-amyloid over time.
Taken together, the findings suggest the properties of the local tissue environment determine the distribution of beta-amyloid in the brain. The observations also provide evidence against a competing hypothesis that beta-amyloid spreads from a small number of seed regions over a long period of time.