This post may share a bit of ground with my last one (February 7th), but sometimes a little repetition is necessary.
The latest issue of JAMA Neurology is out (sorry folks, pay wall) with a study looking at “white matter hyperintensities” (WMH) in people’s brains. They have discovered a significant correlation between the amount of WMH and a diagnosis of Alzheimer’s Disease.
White matter hyperintensities are signs of small blood vessel disease in the brain that are seen on PET scans (positron emission tomography). While there has been inconsistent correlation to date between illness and amounts of amyloid in the brain, these cerebrovascular changes seem to be a better predictor of cognitive disability.
Let’s step WAY back for a moment. I am not as knowledgeable as the specialists on the details of brain pathology, but there are some basic considerations that keep popping out, that seem rather obvious to less sophisticated sorts like myself. Allow me to count them off on the fingers of my left hand, thus utilizing my right brain on this issue for a moment:
First, Alzheimer’s is not new. It was described by Dr. Alois Alzheimer over a century ago in a middle-aged woman, and no doubt has been around much longer than that. The population has skyrocketed in recent decades for three reasons: (1) better life expectancy, (2) more aging “Baby Boomers”, and (3) we are assigning the label to more people, as our testing becomes more sophisticated.
Second, we have found no easy answers to date–no clear causative factor(s) or effective treatments. And while younger people can develop Alzheimer’s, it is still by and large a condition of aging, and most people do not appear to have strong genetic factors in play.
Third, as I mentioned last time, there are many studies showing that “what’s good for the heart is good for the brain”, whether it be exercise, control of blood pressure, healthy diet, or avoidance of smoking.
Fourth, people with recurrent, clinically obvious strokes often develop dementia, so it makes sense that multiple tiny vascular lesions could also cause cognitive loss in a slower, more subtle manner.
Fifth, many people with amyloid plaques and tangles seen throughout their brains on autopsy never show evidence of dementia during their lives, suggesting that this hotbed of research may be less the cause and more the result of other changes. (There is a newer line of research looking at amyloid production within cells as a possible better avenue of investigation, but it still begs the question of what starts the whole process.)
So why does Alzheimer’s target certain areas of the brain most often? Maybe that’s where the vascular system is most susceptible to disruption. I don’t know if that’s true, but I am not sure anyone can fully explain why their proposed causative mechanisms might be targeting certain areas more than others.
I hate to be overly simplistic about this subject, but I was taught a principle in medical school called Occam’s Razor. Sir William of Ockham used this philosophy in the 14th century to discuss God and miracles, but it has since been co-opted by science, from Newton to the medical community. It means: Look for the simplest and most powerful answer to a problem, rather than introducing multiple factors that unnecessarily complicate a situation.
So at the risk of causing a few strokes among the research community, here’s a rather “naive” question: Is it possible that Alzheimer’s is the result of processes triggered by progressive vascular disease, as a consequence of aging, and that curing Alzheimer’s is difficult because we can neither cure aging nor the eventual deterioration of our cardiovascular apparatus?
And if that is the case, will there ever be a pill that can significantly reverse the process once these vascular changes take hold?
If these are valid questions, it would make our approach to prevention incredibly straightforward (healthy living and controlling risk factors) and also free up a lot of dollars to shift from dead-end avenues of research to improved systems of care for people living with cognitive disabilities.
Dangerous ideas, I know. A lot of people’s careers are hinging on all of this not being true. But maybe it’s time we confronted these questions more openly. It may be simpler than we would like to think.