Alzheimer's Disease Progression

From the outside, Alzheimer’s disease is a tragic mystery, changing people once full of life into people who depend on others for their most basic needs. It’s especially frustrating because it still puzzles doctors and scientists.

There may not be a cure yet, but now scientists can watch the progression of Alzheimer’s as it happens, as described in a new study published in the journal Neuron.

While they still can’t stop or reverse the disease, the work done by researchers at the National Institute of Radiological Sciences in Chiba, Japan, is offering further insight into the development of Alzheimer’s. The scientists are improving the detection of tau protein clumps in the brain, which signal the presence of Alzheimer’s and related neurodegenerative diseases.

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How Does It Work?

It’s all thanks to the creation of imaging agents that can highlight tau proteins, pinpointing their location in the brain. With these imaging agents, scientists can identify tau pathology as it progresses. This improves on previous technologies that detect amyloid beta plaques, insoluble deposits of proteins that accumulate in the brains of patients with Alzheimer’s.

Tau proteins also clump together and tangle in the brain. The ability to see these tau, or neurofibrillary, tangles is what sets this research apart. Through positron emission tomography, or PET scanning, researchers saw the tau tangles in patients’ brains, giving them a clearer picture than ever before of the damage they cause.

"PET images of tau accumulation are highly complementary to images of senile amyloid beta plaques and provide robust information on brain regions developing or at risk for tau-induced neuronal death," said senior author Dr. Makoto Higuchi of the National Institute of Radiological Sciences in Japan in a press release. "This is of critical significance, as tau lesions are known to be more intimately associated with neuronal loss than senile plaques."

Researchers tested both human and animal subjects with the fluorescent compounds they developed to view tau tangles. These tau ligand compounds, called PBBs, bind to tau and become visible through PET imaging tests. The PBBs are useful for tau visualization in both Alzheimer’s and non-Alzheimer’s tauopathies, which are neurodegenerative diseases that involve the accumulation of tau proteins in the brain.

Other Avenues for Research

Alzheimer’s may be the most well-known of the tauopathies, but there are many other diseases that could benefit from PET imaging for tau proteins, alongside the more common amyloid beta plaque detection.

“These compounds may accordingly be useful for the differential diagnosis of neurological conditions in elderly subjects on the basis of the distribution of tau lesions, thereby opening up novel avenues for research in elucidating mechanisms of tau-mediated neurodegeneration, as well as tau-focused biomarkers and therapies,” the researchers stated in their report.

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