It depends on what kind of science it is. Mice are very very similar to humans at a chemical level. They have a similar genome, their bodies are basically the same as ours, they have the same organs, the same blood, the same cells, and the same chemical processes happen in those cells. They are just a bit smaller and arranged in a different way. That explains why scientists use mice as models for humans at all. However, with diseases that happen mostly in the elderly like Alzheimer's and cancer it's not so clear. Mice die at a young age, before those diseases really happen. Mice have to be genetically manipulated to develop those diseases. The development of those artificially caused diseases may not be the same as the development of those diseases in humans. The mice also still have a young body despite having the disease. This makes healing them a lot easier.