PET Imaging Agent Has Potential for Diagnosing Alzheimer’s Disease

Japanese investigators are reporting on a new development and early laboratory tests of an imaging agent that shows potential for identifying the hallmark signs of Alzheimer’s disease (AD) in the brain--features that up to now cannot confirm a diagnosis until after patients have died.

The study’s findings were published online December 1, 2011, in the journal ACS Medicinal Chemistry Letters. Dr. Masahiro Ono and colleagues from Kyoto University (Japan) explained in their article that no established laboratory test or medical imaging technology now exists for AD, which is claiming an increasingly heavy toll with the aging of the world’s population. Patients now obtain a diagnosis of AD based on their medical history and symptoms, and symptoms such as memory loss frequently are the same as those of normal aging. Currently, the only conclusive way to diagnose AD involves an autopsy with examination of brain samples for the presence of the tangles and clumps of abnormal protein that occur in the disease.

The scientists described the synthesis and lab testing of a new positron emission tomography (PET) imaging agent called FPPDB [18F-labeled phenyldiazenyl benzothiazole], which bound tightly to ß-amyloid plaques and neurofibrillary tangles--hallmarks of AD--in human brain samples. In healthy laboratory mice, FPPDB stayed in the body long enough for a PET scan. With additional development, the imaging agent may allow early AD diagnosis in humans, the scientists noted.

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