Hidden in the Dec. 1, 2022, issue of the New England Journal of Medicine was a small article on using deferiprone for Parkinson’s disease.
The idea behind it makes sense. A key factor in Parkinson’s disease is a loss of cells in the substantia nigra. The cells that have been lost have a build-up of iron content, suggesting that iron contributes to their demise. Therefore, maybe using an iron chelating agent to remove it may help.
Like I said, it makes sense.
Unfortunately, it didn’t quite work that way. In spite of a clear reduction of nigrostriatal iron, compared with the placebo group, the treated patients had worse MDS-UPDRS scores over 36 weeks than those on the placebo.
Back to the drawing board.
I’m not criticizing the people who did the study – it seemed like a reasonable hypothesis, and testing it is the only way we find out if it’s correct. We learn just as much, if not more, from a negative study as from a positive one, incrementally working toward the answer with each.
We face the same thing with the amyloid theory in Alzheimer’s disease. Getting rid of amyloid should fix the problem.
But it doesn’t, at least not completely. Even lecanemab, the latest-and-greatest of treatments, only shows a 27% slowing in disease progression. This is certainly meaningful – I’m not knocking it – but we’re still far from a cure. To date we haven’t even stopped disease progression, let alone reversed it.
Although the new drugs have a remarkable mechanism of action, the clinical results aren’t nearly as good as one would expect if amyloid was the whole issue.
Which, at this point, it probably isn’t, anymore than nigrostriatal iron deposition is the sole cause of Parkinson’s disease.
In medicine, as in so many other things, there’s simply a lot that we don’t know yet. Right now we’re better able to find planets 27,700 light years away (SWEEPS-11) than we are at knowing the cause of neuronal changes in the person sitting across the desk from us. That’s not saying we won’t have the answers someday, it just means we don’t have them now.
I was in my 3rd year of medical school in January of 1992, (surgery rotation at the Omaha VA, to be specific) when the first definitive planet outside our solar system was identified. Today, 31 years later, the number of exoplanets stands at 5,297.
But the laws of physics are generally a lot more predictable than those of biology.
That doesn’t mean we won’t find the answers, or more effective treatments, eventually. But it will take more time, work, and studies – with both positive and negative results – to get there.
Dr. Block has a solo neurology practice in Scottsdale, Ariz.
This article originally appeared on MDedge.com, part of the Medscape Professional Network.
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Image 1: Allan M. Block, MD
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Cite this: The Ongoing Search for Effective Treatments, More Answers - Medscape - Feb 07, 2023.