acuity

noun

1. Sharpness or acuteness, as of a needle, wit, etc.
2. (figuratively)The ability to think, see, or hear clearly.

   “The old woman with dementia lost her mental acuity.”

   “And yet [Ray] Dalio’s acuity prompts an awkward question: how much of Bridgewater’s success comes not from the way it is organized, or any notion of “radical transparency,” but from the boss’s raw investment abilities?”

   “Donald Trump’s frequently bizarre public appearances[…] have once again raised questions about his mental acuity, experts say. […] During his presidency, Joe Biden was subjected to intense speculation over his mental acuity – including from Trump.”