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On 09/10/2012 21:09, Dave Sill wrote:
<blockquote
cite="mid:CAM5aL2fyJ9CAU4MMUatgVnDvahqkzGKoPX34YajurJSkH_qBog@mail.gmail.com"
type="cite">On Tue, Oct 9, 2012 at 2:45 PM, Anders Sandberg <span
dir="ltr"><<a moz-do-not-send="true"
href="mailto:anders@aleph.se" target="_blank">anders@aleph.se</a>></span>
wrote:<br>
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<div class="im"> On 09/10/2012 14:09, Dave Sill wrote:</div>
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<div><i>
<div>What’s new is the thought that while diabetes
doesn’t “cause” Alzheimer’s, they have the same
root: an over consumption of those “foods” that
mess with insulin’s many roles.</div>
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<br>
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Evidence please. It is not a bad hypothesis, but it takes
more than correlation to show anything. <br>
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<div><a moz-do-not-send="true"
href="http://www.ncbi.nlm.nih.gov/pubmed/16340083?dopt=Abstract">http://www.ncbi.nlm.nih.gov/pubmed/16340083?dopt=Abstract</a></div>
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<br>
Still not convinced. Abstract 1 and 2 show that AD brains have
disturbances in their IGF, insulin and glucose metabolism. But that
could easily be an effect of an underlying cause rather than the
cause. Practically anything that messes up the brain is bound to
change its energy profile.<br>
<br>
Abstract 3,<a
href="http://www.ncbi.nlm.nih.gov/pubmed/15750214?dopt=Abstract">
http://www.ncbi.nlm.nih.gov/pubmed/15750214?dopt=Abstract</a>
seemed more to the point:<br>
<br>
<blockquote type="cite"><i>Although no single model was determined
to be truly representative of AD, depletion of the neuronal
insulin receptor and intracerebroventricular injection of
Streptozotocin reproduce a number of important aspects of
AD-type neurodegeneration, and therefore provide supportive
evidence that AD may be caused in part by neuronal insulin
resistance, i.e. brain diabetes. </i></blockquote>
<br>
This is getting somewhere. Not an entirely convincing model (but no
model really is, you need intervention studies to get somewhere).<br>
<br>
<blockquote type="cite"><i>The extant literature did not resolve
whether the CNS insulin resistance in AD represents a local
disease process, or complication/extension of peripheral insulin
resistance, i.e. chronic hyperglycemia, hyperinsulinemia, and
Type 2 diabetes mellitus. The available epidemiological data are
largely inconclusive with regard to the contribution of Type 2
diabetes mellitus to cognitive impairment and AD-type
neurodegeneration.</i></blockquote>
<br>
This is the key point. More studies are needed, but fortunately this
issue is right at ground zero for plenty of funding (obesity *and*
alzheimers!) so more studies will be done. It is just that
epidemology is very hard to do for nutrition (at least so far).<br>
<br>
It is known that some saturated fatty acids reduce cognitive
performance somewhat, likely through effects on brain metabolism.
And the brain is a massive energy user in the body. So a link
between disturbances in energy allocation and bad things happening
in the brain is not too far fetched. These studies reinforce it. But
I don't think they provide much evidence for us to change diet
because we fear AD: rather, we should eat healthy because we should
fear *all* the known killers. Adding an extra is almost redundant,
unless we figure out some metabolic tweak that forces us to make
tradeoffs.<br>
<br>
<pre class="moz-signature" cols="72">--
Anders Sandberg,
Future of Humanity Institute
Philosophy Faculty of Oxford University </pre>
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