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When can PET be used in the diagnosis of Alzheimer's?

Agneta Nordberg, professor at the Department of Neurobiology, Care Sciences and Society. We asked four questions for Agneta Nordberg on early diagnostics using a PET scanner.

Bild på Agneta NordbergWhy is it so important to identify high-risk people at an early stage?

"Early discovery will one day make it possible for us to give earlier treatment. All research being done now suggests that it takes perhaps 15 or 20 years after onset for the disease to be discovered. There's also much to suggest that accumulation of the toxic beta-amyloid must be reduced as soon as possible for the course of the disease to be slowed."

How can PET scans be used?
"PET scans help us to visualise the beta-amyloid plaque in the brain, something which could only previously be done on deceased people. Doing this, we've been able to see that beta-amyloid accumulates at an early stage of the disease, and our research suggests that the presence of beta-amyloid can be a way to of distinguishing the high-risk patients from those who will only develop mild cognitive impairment."

When will PET scans become routine?
"PET scans are quite expensive, but as PET equipment becomes more common in our hospitals, the procedure will be more accessible and costs will probably decrease. We've just concluded a comparative study of six European centres, and our results show that it's a reliable method, which, however, needs further evaluation. Examinations of amyloid using PET scans will probably be introduced relatively soon, in combination, that is, with measurements of biomarkers in the cerebrospinal fluid during memory tests."

So who should be examined?
"People with a high risk of developing Alzheimer's are an obvious group to be offered this, but also people with memory impairment being tested for Alzheimer's disease."

Early signs of Alzheimer's disease

The presence of beta-amyloid in the brain is an early indicator of Alzheimer's disease. The photograph shows the brain of a patient with MCI (mild cognitive impairment), who shortly afterwards received an Alzheimer's diagnosis. The colour scale gives the concentration of beta-amyloid, red being the highest.

Text: Cecilia Odlind. Published in Medical Science, issue no. 3, 2009.