andrewmason at my-dejanews.com wrote:
> In article <3606977A.52D93633 at notarealaddr.ess>,
> Brian Manning Delaney <bmdelaney at notarealaddr.ess> wrote:
>>andrewmason at my-dejanews.com wrote:
>> > CR: possibly 50% greater life span, including a
>> > proportionally longer period of old age, complete
>> > with its problems of physical and mental impairment.
>> No. If you look at rodents on CR, their ratio of
>> "looking and acting young" time to time of
>> decrepitude is much greater than controls'.
> But is the actual period of decrepitude longer,
> shorter or the same as the controls?
There are many different aspects of decrepitude. Most
haven't been measured carefully, since most early CR studies
tended to look simply at mortality as the only endpoint, and
more recent ones have focussed on particular organs, or cell
types. Brain functioning seems to be robust until near the
end. But immune decrepitude is probably not shorter, and may
even be a bit longer (though the ratio of immune health to
ill-health is greater) than in controls.
> If it not
> shorter then we are not gaining a lot,...
Huh? Why not? Even if the period of decrepitude is a little
longer we're gaining a lot, 10-20 likely years of extra
healthy life. This is long enough that better interventions
will likely come along before we (those of us who aren't old
now) even have to worry about losing our health.
> particularly if, as has been suggested, the
> effectiveness of Calorie Restriction is reduced
> when it is started later in life.
It's only reduced a little.
> I do not doubt that CR works in lab animals up
> to primates, and may work in humans, however I
> am skeptical about a therapy becoming available (in
> our lifetimes anyway) that maintained acceptable
> quality of life.
This -- the justification for your skepticism -- depends on
what counts as an "acceptable quality" of life. I think
there will be two phases of CR-mimicking drugs. The first
will almost certainly be available in our lifetimes,
possibly even within a few years: effective appetite
suppressants that don't work against CR's beneficial effects
(I mean: something other than speed). Taking such a drug
would require attending to one's food, so that one is
following a "high/low" diet (so that one is doing CR, not
mere food restriction). So it's not precisely a CR-mimicking
drug. But it would allow someone to be on CR without
experiencing the hunger, which is the main reason people
don't want to try CR (once they've heard about it).
But this may not count as something that maintains an
acceptable quality of life, since for some people, eating
large amounts of food, or not being skinny, are requirements
for the good life.
So then we'll need the second phase, which is the sort of
drug that would be truly CR-mimicking in the way that others
here have been describing. This could take over ten years,
but probably not much longer than that.
> Issues of possible therapies aside, how long
> will it take just to prove conclusively that CR
> actually works in humans anyway? What is the
> strategy for demonstrating that it works in a
> controlled experiment of acceptable duration?
> And if a drug or therapy was proposed to mimic
> the effects of CR without hunger or physical
> weakness, how long would it take to prove it was
Same questions apply to any anti-aging drug. Without good
biomarkers of aging, you need a full human lifetime; with
good biomarkers, probably a few years (with "fairly" good
biomarkers, we prove it "fairly conclusively" within a few
Brian Manning Delaney
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