“Early intervention is where it’s at,” Rao says. “If you can delay the onset of [the disease] by five years, you can cut the prevalence of the disease in half, and if you can delay it by 10 years, then you can virtually wipe it out because [those at risk] will die of other causes first.”
At present, researchers can identify people who are at risk for Alzheimer’s based on family history and genetic markers, but having these factors does not guarantee a person will get the disease. “The genetic markers aren’t going to tell the whole story, and you need to supplement it with something else,” says Morris Moscovitch, a neuropsychologist at the University of Toronto.
A promising approach that uses functional magnetic resonance imaging (fMRI) may help. In a study published Monday in the journal Neurology, researchers assess brain activity using fMRI as subjects distinguish between famous names (like Britney Spears) and unfamiliar names (like Thomas Fitzpatrick).
The test is simple and fast, with striking results—those at risk for Alzheimer’s based on genetic factors were nearly six times less efficient at performing the memory task was than those not at risk.
During the test, the subject lies down in an fMRI scanner with one of their hands on a keypad and listens to a randomly ordered list of famous and unfamiliar names. They press one button if the name is famous and another if it isn’t. Meanwhile, the machine is rapidly imaging the subject’s brain, logging the regions with increased blood flow (this serves as an indirect measure of brain activity) for later analysis. The whole process takes about five minutes.
Previous studies have used fMRI to detect the early brain changes that may ultimately lead to Alzheimer’s, but the memory tasks used were much more difficult. For instance, subjects might be read a list of words and asked to remember and repeat as many as possible—much more challenging than simply identifying whether a name is famous or not. The new method not only requires less effort on the part of the people being tested but allows researchers to track patients over time, even as they become more cognitively impaired.
The next step in the research is retesting the same individuals over time to see if those who showed less efficient brain activity during the initial fMRI test actually develop cognitive decline and symptoms of Alzheimer’s years later. Rao’s group has already retested the individuals who participated in the newly published study after 18 months, and plans to do so again after 5 years and 7.5 years.
Although all of the participants were cognitively intact initially, 35 percent showed symptoms of cognitive decline after 18 months, validating the initial fMRI test as a means of predicting future decline independently of a person’s genetic risk. Taken together, genetic risk factors combined with the result of an fMRI test may be the best predictor of future disease.
For now, the new method will probably be used to screen patients at risk for the disease for placement into clinical trials testing new treatments for Alzheimer’s. In the long run, this line of research could provide a means of predicting who will ultimately get Alzheimer’s early enough and with enough certainty that the disease can be markedly slowed down or stopped. And perhaps some future Nobel Prize winner will give a shout out to Britney.
