We can now trace how Alzheimer's spreads
SCIENTISTS have pinpointed a specific part of the brain where Alzheimer's begins and traced how the disease spreads.
High-resolution brain-scans of 96 healthy adults over the age of 65 revealed the first footprint of Alzheimer's in a dozen individuals who went on to experience symptoms.
Reduced metabolic activity was seen in the lateral entorhinal cortex (LEC), a small region linked to the hippocampus where long-term memories are stored.
The change, associated with declining memory, occurred at a time when all 12 volunteers were free of dementia and was not seen in the 84 participants who did not develop Alzheimer's. The study also showed how, over time, the effects of Alzheimer's spread from the LEC to other areas of the brain's cerebral cortex. One region especially targeted was the parietal cortex, an area involved in various functions, including spatial orientation and navigation.
Lead researcher Professor Scott Small, director of the Alzheimer's Disease Research Centre at Columbia University in New York, said: "It has been known for years that Alzheimer's starts in a brain region known as the entorhinal cortex. But this study is the first to show in living patients that it begins specifically in the lateral entorhinal cortex, or LEC.
The scientists suspect Alzheimer's spreads through a kind of neural domino effect. Neurons are first compromised in the LEC, which in turn reduces the integrity of their neighbours. A high-resolution form of functional magnetic resonance imaging (fMRI) was used to map metabolic activity in the brains of the study participants, all enrolled in the Washington Heights-Inwood Columbia Ageing Project (Whicap).
"Now that we've pinpointed where Alzheimer's starts, and shown that those changes are observable using fMRI, we may be able to detect Alzheimer's at its earliest preclinical stage, when the disease might be more treatable and before it spreads to other brain regions," said Prof Small.
The new imaging method could also be used to assess potential new drug treatments at early stages of the disease, said the researchers.