Aspirin is arguably a calorie restriction mimetic, able to spur some of the same beneficial cellular stress responses that are activated by low nutrient levels. Calorie restriction itself, practiced over the long term, does not have a very large effect on human life span. Given the existing demographic data, a gain of even five years of life would be very surprising. Further, it is well established that the life extension resulting from calorie restriction scales down as species life span scales up. Mice live up to 40% longer on calorie restricted diets, but we humans certainly don’t.
Aspirin has other effects besides increasing cellular stress responses, some good and some bad. Either no effect, a very small reduction, or a very small gain in life span are all plausible predictions for the outcome of a study on use of aspirin in older patients. The initial results from this study of aspirin cannot be used to discuss overall life span, but the data does show no gain in a common measure of healthy life span, free from disability. Nonetheless, this is a result that can be compared to studies in short-lived species in which it does modestly