Scan Detects Alzheimer's

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Scientists have now come up with what appears to be a reliable non-invasive method of detecting these Alzheimer "markers" using a PET scan and a new tracer chemical called FDDNP that binds effectively to abnormal protein plaques and tangles.

PET stands for Positron Emission Tomography. A PET scan gives a three dimensional, computer enhanced and highly colourful "blurry-looking" image of the brain as it traces a positron emitting chemical (in this case FDDNP) after it is injected into the patient and travels through the tiny blood vessels in the brain. Any abnormal protein plaques and tangles show up because the FDDNP will stick to them.

Gary Small who led the study, and his team examined 83 volunteers who were psychiatrically evaluated and given cognitive tests (e.g. to detect memory and reasoning problems). 30 of the volunteers were classed as having no cognitive impairment (they were the "healthy controls"), 28 as having mild cognitive impairment, and 30 were classed as having Alzheimer's disease.

All of the volunteers underwent a PET scan using FDDNP, and they were also scanned using another PET method based on another chemical tracer called FDG. MRI (magnetic resonance imaging) scans were also performed on 72 of the volunteers.

The results showed that it was possible to tell which of the 83 volunteers was "healthy", which had Alzheimer's and which had the mild memory problems. The level of accuracy achieved was 98 per cent - significantly better than the FDG-PET method (87 per cent) and the MRI method (68 per cent accuracy).