More on Spindler's Mice Study

[Guest guest]

Well folks, I know some of you will be a bit skeptical about the

contents of this post. And so you should be. But if you doubt it,

check for yourself ..............

There is an error in this study. While it is really a rather trivial

mistake, at the same time it has, in my opinion, an appreciable

impact on the report's conclusions.

The report considerably UNDERSTATES the benefits of CR to these

mice!!! Read on if it interests you.

The error is in the words: " After the second break point in the CR

survival curve (31 months of age), the mortality rate approximated

that of the control mice .......... " . [NOTE: Presumably mortality

rate is defined as deaths during a given month as a proportion of

those alive as of 12:01 am on the first day of that month.]

Absolutely not! The mortality rate of the CR mice is substantially

lower than that of the control mice continuously from age 22 months

until there are no more control mice alive to compare with. I think

the statement that the mortality rate approximated that of the

control mice was made based on looking at the survival curve rather

than from calculating mortality rates.

[The data for both series are rather erratic. For example in the

case of the control mice, lots of them died in months 28, 31 and 32,

but few in months 29 and 30. Obviously this is just a normal data

glitch in the nature of studies like this - there are sizeable

variations also in the number of deaths from month to month among the

CR mice. It helps if one smoothes out these erratic fluctuations in

the mortality data.]

Having done so, the mortality data for the period following month 31

(there is no dispute that the mortality rate of the CR mice is better

before age 31 months) look like this:

In the four months 32 through 35 the mortality rate of the control

mice was 72% higher than the CR mice.

In months 36 to 39 it was 40% higher.

In month 40 it was 93% higher.

In month 41 it was 135% higher.

In month 42 all remaining control mice died - mortality was 100%. By

comparison, among the CR mice only about one-fifth died and sixteen

percent of the original CR mice were still alive.

Although it may not appear to be the case when one looks at the

survival curve, the mortality rate for the CR mice was dramatically

better throughout the study from age 22 months onward.

First it was shown in fruit flies that even when initiated much later

in life, CR dramatically reduces mortality. Now Dr. Spindler et al.

has demonstrated it in older mice. We are all hoping it will

eventually be shown that something very similar is true of older

humans.

VIVA CR!!!

And thanks to Dr. Spindler et al. for doing all this work for all of

us to pore over, and smile about : ^ )))

Rodney.