The young are the most creative, so multi-centenarians would be ossified
How do you know? What is it about young and old brains that generally (not universally, let's remember) makes old people less creative? I see three possibilities: it's something about the biological aging of the brain, it's a consequence of the amount of information in the brain, or it's an artefact of social pressures (older people have less time to do the rumination and daydreaming that are so intrinsic to creativity). In all cases, we are in the clear. if it's because the older brain has lost cells and synaptic connections, or the interstitial fluid is more oxidised, etc.: well, the idea is to fix all