Saturday, October 22, 2011

31 for 21: Thoughts On Loss Of Neurons

A few weeks ago, there was some discussion on the Einstein-Syndrome list regarding statements made by the Changing Minds Foundation regarding the loss of neurons.

Because of this quote (namely the bolded portion) from the CMF website,

"Problem: Loss of neurons in the hippocampus:  Down syndrome loses 50% of their neuronal structure by 6 months old. This is an insurmountable problem.
The University Of Maryland School Of Medicine treated Down syndrome mice with prozac for 24 days (2006). It increased neurogenesis (the formation of new nerves) to a normal level.  This is like increasing the hardware on your computer. It allows you to run more complicated software. In fetuses with Down syndrome, neurons fail to show normal dendritic development, yielding a "tree in winter" appearance. This developmental failure is thought to result in mental retardation.""
I did some researching and wrote up a response to this, which I thought I would share below. From what I recall, CMF did change some of the wording on their site to make sure there was no confusion.

I am not a CMF protocol expert by any means, but I thought I would share what I could find in doing some researching on this.

This study, "Neurogenesis impairment and increased cell death reduce total neuron number in the hippocampal region of fetuses with Down syndrome" can be seen in full text here: If anyone would like a PDF of the full text, just let me know, as I have it downloaded and can email it.

A quote from the abstract: "Results show reduced neuron number in the DS hippocampal region and suggest that this defect is caused by disruption of neurogenesis and apoptosis, two fundamental processes underlying brain building."

While I don't understand all of the terminology in this study, here are a few interesting quotes:

"In all structures, however, DS fetuses had a significantly smaller number of neurons compared with controls (Figure 6D)."
"Comparison of the density of apoptotic cells, evaluated with either method, in control and DS fetuses showed that DS fetuses had a larger density of apoptotic cells both in the granule cell layer (Figure 8B,E) and in the ventricular zone of the hippocampus and PHG (Figure 8C,H) compared with control fetuses."
"The current study in DS fetuses demonstrates for the first time a severe hypocellularity in all areas forming the fetal hippocampal region and that neurogenesis impairment underlies this defect.
These findings allow us to trace back to early developmental stages the hippocampal hypotrophy of the adult DS brain. This precocious atrophy may explain the early impairment of hippocampus-related memory functions observed in children with DS (7, 50)."
"Although hypocellularity in the DS brain was previously documented in several studies, it was not known whether this defect was caused by a neurodegenerative processes or to decreased neuron production. With our investigations we demonstrate for the first time that in DS subjects neurogenesis is severely impaired during early phases of brain development. The ensemble of current and previous (10) data suggests that neurogenesis impairment may be a generalized feature of the DS brain and underlie the widespread brain hypotrophy that characterizes DS subjects starting from infancy."

Some of my thoughts: I can't find a study which says there is a 50% loss of neuronal structure by 6 months old either. I just did quite a bit of searching, although I'm sure I could've missed it if I didn't search for the right thing ;). I'd be glad to see it if it's there. Anyone have the reference for that?

From research I have done over the years, I know there is lack of neurogenesis (which some of the above quotes show) and increased apoptosis (programmed cell death) that starts from before the child is born. The above study also shows that there is a marked difference in the number of neurons babies with Down syndrome have. If the child starts out with 35%-55% less neurons than a non-T21 child (the above study mentioned those numbers in certain measurements/areas), then where is the idea of a 50% loss by the time the child is 6 months old? 

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Anonymous said...


I think that the idea behind the "50% reduction in neurons" may come from the study on "Dendrite Atrophy in Down Syndrome" and you have discussed this on Feb 20, 2007. I remember Teresa addressing this by e-mail, since I cannot read the entire article...I'm only going on recall.


Qadoshyah said...

Marsha, I think there may be something about that in that study. I think I read through that and couldn't find it exactly, but I will look at it again.

Mary Souter said...

Down Syndrome: From Understanding the Neurobiology to Therapy
by Mara Dierssen, Rafael de la Torre Fornell

New stuff in this book but its 250$ what do you think?

Qadoshyah said...

I haven't heard of that book, so I would not know if it was worth the $250 or not. I know Professor Dierssen is doing a lot of research right now with EGCG, so it might be a useful book.

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