Right, but that strikes me as a failure of n. (They started this study with 30 monkeys; what the hell were they thinking? They expanded it to 76, but it's still too small.) It is noteworthy that the hazard rate of 3 for age-related deaths becomes only 1.5 when you look at all deaths. But what hazard rate do they expect controls to have relative to CR? If it's around 1.5, then they should have expected from the beginning that even if this study gave the modal result, it would not be statistically significant. For comparison, smoking has a hazard rate in the neighborhood of 2- which this study would have been too small to detect most of the time (as p=.03 for the age-related death hazard rate of 3, just below the .05 level).
When you look at the individual age-related causes, the differences are dramatic. 5/38 of the controls were diagnosed with diabetes, and 11/38 were diagnosed as pre-diabetic. 0 of the experimental animals developed diabetes (and going from 40% to 0% is a big jump!). Heart disease and cancer were both reduced by 50%. Age at first age-related diagnosis was significantly later in experimental animals (p=.008). 20% of the control group had been diagnosed with an age-related condition by the time the first experimental subject was diagnosed, and at age 30, when half of the control group was dead, 66% of the experimental group had not been diagnosed with an age-related condition, compared to 23% of the control group.* Even age-related lean muscle mass deterioration was less among the CR group.
It would be nice to know about energy levels, fragility, and so on, but from reading the study it seems pretty clear something is better about the CR group than the control group, and reasonable to suspect CR is better overall than neutral or worse. It's actually not even clear the CR group was more susceptible to injury, because the higher rates of non-age death among CR monkeys (9 instead of 7) could just be due to there being more CR monkeys (since more of the controls are buried).
* I suspect that if an animal died from a non-age cause, it is recorded as never developing an age-related disease. If you assume the best for the control group- that everyone who died was old first- and the worst for the experimental group- everyone who died wasn't old first- then you get 23% unaged in the control and 30% unaged in the experimental group, which is still striking. If you assume things are more even, then CR wins by a large margin.
It would be nice to know about energy levels, fragility, and so on, but from reading the study it seems pretty clear something is better about the CR group than the control group, and reasonable to suspect CR is better overall than neutral or worse. It's actually not even clear the CR group was more susceptible to injury, because the higher rates of non-age death among CR monkeys (9 instead of 7) could just be due to there being more CR monkeys (since more of the controls are buried).
The age-related diseases was encouraging, yes, but we could've said as...