The researchers investigated the anxiety levels of the mice by measuring a stress hormone called corticosterone in their faeces.The levels remained the same among the elderly mice in all three groups.

• 研究人员通过测量老鼠粪便中一种称为皮质酮（corticosterone）的调节紧张的激素，查验了它们的焦虑程度后发现，该激素在三组老龄鼠中均维持在相同的水平。