The antonyms for "becomes demented" could include "remains lucid" or "maintains mental clarity". Other possible antonyms might include "maintains rationality", "retains cognitive function", or "stays mentally sharp". Each of these antonyms represents the opposite of "becomes demented", implying that the individual in question is able to think, reason, and remember with ease, rather than struggling with confusion, memory loss, or other symptoms of dementia. While dementia can be a devastating condition for those who are affected by it, understanding its antonyms can help us appreciate the importance of preserving our cognitive abilities over time.