July 14, 2015

Another test for Alzheimer’s?

The Herald (from the Telegraph) has a story today about a Google Science Fair contestant, under the headline “Has a 15-year-old found a way to test for Alzheimer’s?“. This is the sort of science story it’s good to see in the papers, but it would be better if it were more accurate.

Krtin Nithiyanandam’s research is impressive even if you ignore the fact that he was only 14. But claiming he

 has developed a “Trojan horse” antibody which can penetrate the brain and attach itself to the toxic proteins present in the disease’s early stages.

is a bit of an exaggeration.

The project write-up describes how he attached antibodies to fluorescent quantum dots. These, cleverly, fluoresce at a near-infrared wavelength which passes through tissue, skin, and bone.  If the project works, it would be possible to screen for Alzheimer’s without even a lumbar puncture.

That’s still ‘if’. Despite what the story says, Krtin hasn’t tested the antibody on any actual brains. Theoretically, it binds to a transporter protein in the right way to penetrate the brain, but it needs testing. It also needs testing for toxicity — if it’s going to be used for screening, it will be injected into large numbers of healthy people, so has to be safe. After all that, it would have to be tested for predictive accuracy: to be useful, the test would have to have a very low false-positive rate. And, on top of that, for testing to really be helpful there would need to be some treatment that showed some sign of actually working. We’re not there yet.

You might also wonder how this relates to the four other early Alzheimer’s tests the Herald has reported on in the past year or so, or the other two proposed by Google Science Fair finalists.  Testing for Alzheimer’s has been an area with a lot of recent research, which is going to be useful if we ever have promising drugs to test.



Thomas Lumley (@tslumley) is Professor of Biostatistics at the University of Auckland. His research interests include semiparametric models, survey sampling, statistical computing, foundations of statistics, and whatever methodological problems his medical collaborators come up with. He also blogs at Biased and Inefficient See all posts by Thomas Lumley »