Alzheimer's ... or not?

It was in March of 2015 when my local neurologist gave me a diagnosis of "early stage senile dementia, likely of the Alzheimer's type."  I then went to the Brain Wellness Center at the University of Washington's Harborview Medical Center where, after three hours of testing and an MRI, they said I had mild cognitive impairment, or MCI.  As we said in Beating the Dementia Monster, MCI is the last step in the disease process before dementia, and it usually lasts about five years.  They did not, however, write in my diagnosis the cause of the MCI.  Alzheimer's disease is the most common of about thirty possible causes of MCI.  It was in discussions that they indicated my MRI and test results were consistent with Alzheimer's disease.

Since then, I've been tested annually there in Seattle, and I've had about six more MRIs.  Some of these MRIs were associated with various studies I participated in where I also received lots of intensive cognitive testing.  After making aggressive lifestyle changes at the end of 2015, I showed steady improvement until about 2019.  After that, my cognition seemed to largely stabilize.

The MRI results are interesting.  The volume of my lateral ventricles has consistently been measured at >99 percentile for men my age, indicating significant atrophy of my brain.  Much more than most men my age.  (Or, perhaps, hydrocephalus has been pushing the ventricle walls outward.)  But the volume of my hippocampus is another matter.  The MRI in 2015 measured it at the 33 percentile for men my age, and a subsequent MRI in 2017 found it to be less than the one percentile.  The radiologist report for an MRI in 2018 reported no change from 2017.  But then in 2021, an MRI measured my hippocampus volume at the 52 percentile.  

This does mot mean that my hippocampus was growing, since these numbers are normalized for men my age.  All of our brains are atrophying as we age, and our hippocampi are all shrinking.  But from this data, it's fair to conclude that my hippocampus was atrophying faster than other men into 2018, but much less rapidly than other men into 2021.  This follows my personal experience with subjective changes in my memory and cognition, and it seems to be a consequence of the radical lifestyle changes I made, beginning in 2015.

Since 2015 the technology for diagnosing Alzheimer's disease has been advancing.  The final diagnosis is still the autopsy, but newer techniques are narrowing the probabilities of an accurate diagnosis in life.  One of those techniques is analysis of cerebrospinal fluid from a lumbar puncture, which I had on April 11 of this year.  The sample was analyzed at Mayo Clinic, and the results were returned a few days later.  My read of the results is that they were somewhat inconclusive, but it was clear that something is not right in my brain.  They did not support an Alzheimer's diagnosis, but they did support hydrocephalus.  The report said the results needed to be assessed in the context of other clinical findings.

So I saw my local neurologist yesterday to review the results.  Her assessment is that I do not have Alzheimer's disease but rather normal pressure hydrocephalus, or NPH.  We've said before that NPH is often misdiagnosed as Alzheimer's disease, primarily because it also causes cognitive decline and enlarged ventricles in the brain.  (It is not, however, known to affect the volume of the hippocampus.)  About a quarter or more of people with NPH are found also to have Alzheimer's disease.

We acknowledged in Beating the Dementia Monster that my Alzheimer's diagnosis was not certain, but it seemed highly probable.  It now seems less probable.

The hippocampus volume is a bit enigmatic.  I asked my local neurologist what that might mean, since there's no reason to believe that it was caused by hydrocephalus.  She said she didn't know.  But my improved cognition, which seemed to track with hippocampus volume changes, is surely due to my lifestyle changes.  So it seems to me that whatever caused the atrophy of my hippocampus and my cognitive decline has been countered by my lifestyle changes.

I will discuss this further with my regular neurologist in Seattle in June.  I expect her to agree with my local neurologist that it's now much less likely that my neurological issues were caused by Alzheimer's disease.  But I'd also like to know what she thinks about the anomaly of my hippocampus volume changes.