Looking Inside the Brain
The study that gave rise to this new algorithm involved an analysis of brain scans taken of 236 people who were part of Alzheimer's studies at Washington University. The people's average age at the start of the research was 67 years old. All of the participants underwent two or more brain scans that, on average, were 4 1/2 years apart. The scans used were PET scans – positron emission tomography scans. This type of imaging uses radioactive dyes to take a picture of the brain and can reveal the presence of amyloid protein. As part of the investigation, the researchers included data from more than a thousand clinical assessments of 180 study subjects which included information about their cognitive health. According to researcher Suzanne Schindler, M.D., PhD, the study showed that there is a "tipping point" in the buildup of amyloid in the brain that signals a relatively rapid further accumulation of amyloid plaque and full-blown Alzheimer's disease. And after you reach that tipping point, you can predict how the disease will progress. “You may hit the tipping point when you’re 50; it may happen when you’re 80; it may never happen,” Dr. Schindler says. “But once you pass the tipping point, you’re going to accumulate high levels of amyloid that are likely to cause dementia. If we know how much amyloid someone has right now, we can calculate how long ago they hit the tipping point and estimate how much longer it will be until they are likely to develop symptoms.”Is this the Fool Proof Test We’ve Been Waiting For?
I have to tell you that what Dr. Schindler says gives me pause. First, she notes that accumulating high levels of amyloid is "likely" to cause dementia. That word right there indicates that this algorithm is not completely reliable – not yet anyway. Over and over again it's been shown that a lot of people carry around amyloid beta in their head and never develop Alzheimer's disease. Whether that’s because they haven’t hit the “tipping point” yet is a possibility. In an online discussion of this study, Murat Bilgel, PhD, a staff scientist with the National Institute on Aging, points out that "It is important to remember that not every individual who has elevated amyloid levels develops cognitive impairment or dementia. "Further analyses are necessary to provide insight into who among the amyloid accumulators might develop future cognitive impairment." 2 Another issue is the relatively small size of the study. The main part of the study only included 236 people. That's not a huge sample size. So the same results might not show up in a larger group of study subjects. Still, this research provides another potential step towards developing ways to predict Alzheimer's disease and potentially treat it before serious – and intractable – brain injury occurs. And that is welcome news.