Would you want to know?
While we don’t currently have any medications or other approaches that effectively prevent or delay the progression of Alzheimer’s disease, it is heartening to know that research is being funded and that important discoveries are being made.
At a recent event of the BrightFocus Foundation, which funds research into glaucoma, macular degeneration and Alzheimer’s, I met some of those researchers and got a glimpse into some of the latest developments that hold promise.
Rather than try to explain any of that early research here, however, I want to address the topic in a broader way. There’s a debate afoot in the world of dementia research. The question is, how do researchers determine when a person has Alzheimer’s disease?
And there’s a related question not necessarily being asked: Do patients really want to know?
Only a post-mortem exam can definitively identify Alzheimer’s. In living persons, a diagnosis is generally made by ruling out other causes (such as other types of dementia), and is based on a thorough medical exam and history, investigating symptoms such as memory loss and neurological damage.
Brain scans and genetic tests can further aid diagnosis in some cases, and as these tests improve, momentum is building for using these more broadly, in hopes of identifying patients years before symptoms arise.
Why would we want to do that?
Since we don’t currently go looking for signs of Alzheimer’s until serious symptoms of dementia appear, we tend to diagnose people only after their brains show extensive signs of the plaques and tangles that characterize the disease.
It is now believed that defective tau protein tangles and amyloid plaques start forming in the brain decades before people show any symptoms. This means that by the time we start using the various drugs designed to postpone or halt the disease, it may be too late for them to work. Perhaps an earlier diagnosis would enable them to be more successful.
This is the thinking behind recent research guidelines issued by the National Institute on Aging and the Alzheimer’s Association that recommend identifying prospects for clinical trials based not on current symptoms, but rather on early biological markers that can be measured using current technology, such as brain scans and spinal taps.
This new proposed “research framework” is not being proposed for clinical use. In other words, doctors won’t start ordering these tests to try to identify potential Alzheimer’s patients. For one thing, they haven’t yet been validated as accurate diagnostic tools.
But even used solely in the context of research, this will vastly increase the number of people researchers consider to have Alzheimer’s, according to an interview published by the Associated Press:
“The numbers will increase dramatically,” said Dr. Clifford R. Jack, Jr., a Mayo Clinic brain imaging specialist who led the panel of experts who drafted the new guidelines. “There are a lot more cognitively normal people who have the pathology in the brain who will now be counted as having Alzheimer’s disease.”
Maybe that’s not a bad thing. If this enables people to enter a clinical trial possibly decades before any hint of a problem, it might lead to better treatments for them and those who come after them.
But there’s one problem with this logic. Jack also noted that “about one-third of people over 70 who show no thinking problems actually have brain signs that suggest Alzheimer’s.”
A similar statement appeared in our April edition in another AP article entitled “Why do some stay so sharp as they age?” Dr. Claudia Kawas of the University of California, Irvine, told a meeting of scientists that “About 40 percent of the oldest-old who showed no symptoms of dementia in life nonetheless have full-fledged signs of Alzheimer’s disease in their brains.”
So, on the one hand, we don’t really know when the presence of tangles and plaques in the brain will translate into the actual behavior of dementia we are trying to treat. This is good news for many of us, as it suggests the physical changes that occur fairly commonly do not necessarily have to cause the symptoms we so fear.
But at the same time, researchers are seeking to broaden the definition of who has Alzheimer’s to include those with the earliest biological signs associated with the disease.
Do we really foresee medicating 30 to 40 percent of the older population who are cognitively normal but have evidence of pathology in their brains when they may never exhibit any behaviors associated with dementia?
While we want to be able to find new and better treatments, we have to take into account the anxiety (and potentially many other problems) this new definition will cause for the people found to have these markers.
Yes, it’s important for our researchers to keep striving for more information, and for older adults to participate in clinical trials that help identify new drugs. But at the same time, we need to think ahead about the impact these developments will have on real people and their families.
I don’t have any answers today. Just questions. What do you think? I invite you to share your thoughts on this issue with us by sending a letter to the editor via mail, email or our website.
