As we age, our risk of developing Alzheimer's disease (AD) increases. Researchers have been working to find ways to accurately detect the disease in its earliest stages (ideally before there are symptoms), and study treatments which can prevent progression of the disease. Two important hallmarks of Alzheimer's disease are the accumulation in the brain of the proteins tau and amyloid-β.Both are considered important treatment targets. In order to develop effective treatment strategies, it is necessary to understand where these different proteins tend to concentrate in brain.
A recent study co-authored by ATRI's Michael Donohue reviewed over 1000 tau PET scan images of the brains of older adults who were cognitively unimpaired, meaning they didn't have any symptoms of Alzheimer's disease. The researchers wanted to see if they could identify regions of the brain where tau accumulates the most, and how it is related to patterns of amyloid-β accumulation.
The study found that the inferior temporal cortex, fusiform gyrus, and middle temporal cortex had the highest rates of tau accumulation. Interestingly, the accumulation of tau in these regions was not always related to the accumulation of amyloid-β. This suggests that early tau accumulation may be a separate process from amyloid-β accumulation.
The researchers also found that the accumulation of tau in the inferior temporal cortex was most strongly related to mild levels of amyloid-β. In contrast, when amyloid-β levels were high, the accumulation of tau in the amygdala and fusiform gyrus was also important. This means that the accumulation of tau in these regions was associated with higher levels of amyloid-β.
The study has important implications for future clinical trials aimed at preventing or treating Alzheimer's disease. By identifying the regions of the brain where tau accumulates the most in preclinical AD, researchers can better design clinical trials of treatments that target tau specifically by monitoring the effects of these therapies in these regions.