PET Scans Show the Plaque Buildup Associated With Alzheimer's Disease
Until now, the beta-amyloid plaques thought to cause the cognitive decline of Alzheimer's patients have been visible only after the fact: during autopsies of their brains. But using a sophisticated imaging technique known as positron emission tomography, Australian researchers at Austin Hospital in Melbourne have detected the beta-amyloid protein and traced its buildup in people not yet showing Alzheimer's symptoms.
Beta-amyloid is normally processed and absorbed by the brain, but sometimes, especially in elderly patients, it can build up and ossify, forming plaques that are deadly to brain cells. Using PET imaging, researchers tested for the presence of beta-amyloid in 150 people with an average age of 72. None of the patients had developed the dementia associated with Alzheimer's, but some showed mild cognitive impairment, which usually has a 60 percent chance of developing into Alzheimer's. The PET scans of 60 percent of those with mild cognitive impairment showed signs of beta-amyloid; the amount of buildup was directly related to the severity of memory loss.
"The biggest implication is that it opens the door for preventing Alzheimer's disease in those that are going to develop it,"says Christopher Rowe, the director of the Department of Nuclear Medicine and Centre for PET at Austin Hospital. Neither PET scanning nor anti-amyloid drugs are currently available to the public. But Rowe says he's "optimistic" that PET scanning, in conjunction with therapeutic anti-amyloid drugs currently in development, may provide early diagnosis and improved treatment in the near future.
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