Vascular Cognitive Decline

Washington DC

As I wrote in my last post, the background summary to my neuropsychological test results reported that my “recent brain MRI was read as showing generalized cerebral volume loss and small vessel occlusive disease.”  These findings are most consistent with vascular impairment.  Since I had been under the assumption that my previous MRIs were normal, this is a powerful indicator that my cognitive decline is due to vascular disease, which had previously been ruled out.  (I’ll be checking my conclusions with my neurologist in a few weeks, but I think my conclusions are correct.)

As I wrote in my post of Oct 30, “Letting Go of Alzheimer’s,” the false negative rate (the percentage of tests incorrectly indicating Alzheimer’s) for the PET brain scan I had is very low; I’ve since found out that it is under 3%.  Since I’ve had two of these scans, we can say with some confidence that the Alzheimer’s diagnosis I’ve been living with for the past sixteen months is almost certainly incorrect.  I do not have Alzheimer’s.  That has left me quite confused.  As I explained in my post of November 28, “The Elevator Version,” in brief conversations with others where I’ve had no opportunity to explain the ambiguity of the test results, I have continued to say that I probably had Alzheimer’s.  I can no longer say that.

What is vascular cognitive impairment?  It can most easily be described as many mini-strokes affecting tiny areas of the brain that cumulatively lead to a decline in mental function.  These strokes occur because tiny blood clots block (“occlude”) very small blood vessels (thus, the name “vascular”) sometimes without leaving a trace on MRI scans.  The occlusions then impair or kill multiple small areas of the brain.  Exactly what is impaired depends on where the mini-strokes are.  How great the impairment is depends on the number and size of the affected areas.  Symptoms early in the disease are sometimes indistinguishable from Alzheimer’s, which is why my neurologist said at my first visit that there was a small chance I did not have Alzheimer’s.

The eventual course of vascular impairment, however, is ultimately different.  Typical Alzheimer’s follows a continuous downward curve.  Although the steepness of the curve can vary, the gradual worsening is always the same: declining mental function, dementia, and death.

The downward course of vascular cognitive impairment, however, is not usually continuous.  Although not invariable, symptoms usually worsen in a step-wise function, that is, there is a period of stable plateau without new or worsening symptoms followed by a sudden decline of mental function (caused by a new shower of clots and occlusions) followed by another plateau.  This could explain why my symptoms have not changed much in the past ten months: I’ve been in a plateau period.

In vascular impairment, the frequency and seriousness of the sharp declines can vary enormously.  Sometimes small occlusions happen continuously, causing a steady downward course very similar to Alzheimer’s.  Other times the clots can be bigger or hit more important brain structures, leading to sudden major changes in cognition, the usual stroke symptoms or death.  And still other times the declines can be small and very far apart (or never happen).  You just don’t know.  I could remain this same way for a long time … or not.

The huge difference is that I can do something that might prevent further decline.  There is not treatment for Alzheimer’s, but vascular disease is the same process that causes heart attacks and strokes.  So the same preventative measures apply: reduce my blood pressure by a diet low in salt and reduce my bad cholesterol levels with aerobic exercise and a cholesterol-lowering diet, or, if necessary, medications to reduce both blood pressure and cholesterol.  I already exercise regularly and have normal blood pressure and cholesterol, but for both blood pressure and cholesterol, the lower the better.  So a low-salt, cholesterol-lowering diet may be helpful.

This is very good news.  I may be cognitively impaired, but the future is not predetermined.  As you might guess, this is causing a rather marked shift in my thinking, planning, and emotional state.  I’ll explore those changes here as I can better understand and name them.