Even as I write this, I can feel the biological hallmarks of Alzheimer’s Disease building in my brain: the beta-amyloid plaques gumming it up, and the tau protein tangles snaking through the neurons. But a bit of paranoia is a small price to pay for the critical new understanding that scientists have gained about Alzheimer’s Disease in recent years: that the brain pathology begins long before the forgetfulness shows up. Early brain pathology means early detection is possible, and early detection means the potential for blocking the disease before it turns into the terrible dementia that affects millions.
Today is a landmark day for Alzheimer’s research: The first major new set of guidelines since 1984 on defining and diagnosing the disease has just been issued. The Alzheimer’s Association has posted them here, and both The New York Times and The Boston Globe do a nice job of summing them up. I spoke this morning with Dr. Reisa Sperling of Brigham & Women’s Hospital, lead author of today’s paper on the earliest, “pre-clinical” stage of Alzheimer’s Disease.
This is the first time in 27 years that the guidelines on Alzheimer’s have been re-issued. What are the biggest changes?
The biggest changes are that we’ve reconceptualized Alzheimer’s Disease as a continuum. The first criteria published in 1984 only dealt with Alzheimer’s Disease as a stage of dementia, which we now recognize to be at rather late stages of the disease process. The new criteria incorporate an earlier symptomatic stage called mild cognitive impairment due to Alzheimer’s Disease. And the earliest stage, which we have called pre-clinical Alzheimer’s Disease, is a new concept of the disease beginning in the brain prior to the clinical symptoms.
How would you sum up the state of the science on early detection of Alzheimer’s?
The pre-clinical stage is primarily detected through bio-markers. There have been tremendous advances over the past decade in being able to detect evidence of Alzheimer’s Disease in the brain during life. These include PET scans for amyloid, cerebrospinal fluid tests, and both functional and structural MRI scans.
Is there any one particular holy grail in terms of research on early detection of Alzheimer’s?
I don’t actually think it will be one thing. I think that we know from the autopsy data that there are actually several processes in the brain involved, and I suspect that we will need a combination of biomarkers to detect these processes. But the holy grail would be finding the combination of biomarkers in people who are still cognitively normal that accurately predicts who will progress to Alzheimer’s Disease dementia.
In terms of the existing ways for detecting Alzheimer’s Disease early, I gather none of them are ready for prime-time in the clinic? Continue reading