[ExI] The Dementia Plague

[Anders Sandberg]

On 09/10/2012 21:09, Dave Sill wrote:
> On Tue, Oct 9, 2012 at 2:45 PM, Anders Sandberg <anders at aleph.se 
> <mailto:anders at aleph.se>> wrote:
>
>     On 09/10/2012 14:09, Dave Sill wrote:
>
>>     /
>>     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.
>>     /
>
>     Evidence please. It is not a bad hypothesis, but it takes more
>     than correlation to show anything.
>
>
> http://www.ncbi.nlm.nih.gov/pubmed/16340083?dopt=Abstract

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.

Abstract 3,http://www.ncbi.nlm.nih.gov/pubmed/15750214?dopt=Abstract 
seemed more to the point:

> /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. /

This is getting somewhere. Not an entirely convincing model (but no 
model really is, you need intervention studies to get somewhere).

> /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./

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).

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.

-- 
Anders Sandberg,
Future of Humanity Institute
Philosophy Faculty of Oxford University

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