"The researchers found that the mice exposed to radiation, or both radiation and simulated weightlessness, had sustained damage to their blood vessels. Namely,

"The researchers found that the mice exposed to radiation, or both radiation and simulated weightlessness, had sustained damage to their blood vessels. Namely, the mice had impaired vasodilation, or problems expanding their blood vessels to adjust for blood pressure. This can be a precursor to heart attacks and stroke. The mice that just experience simulated weightlessness, on the other hand, seemed normal." This is the main reason why its statistically significant. Sure, mice arent humans. But I say, with confidence, that many rats died to prove these statistics