A prior reply wrote after a diagnosis of dimentia they are no longer able the sign things legally, much less stress for LOs afraid of what they might get to into, including revoking POA. Looked it up in my state and it does not seem dimentia and being of legal sound mind are tied together? Not being of sound mind means not being able answer 4 questions, mostly about family connections.
Of legal sound mind has a slippery slope after the fact who knows if they could have answered the question at time of signing... Law must assume the default is they could have if asked the questions at the time of signing
A POA signed and witness by notary is only attesting that it is you, you present ID, and that is your signature. But an attorney can attest that you are mentally capable of understandind what you are signing. It is much less likely to be "questioned" by entities.
I would ask this question of an attorney in your area.
Rules surrounding PoA vary by state. I've not heard about "being able answer 4 questions" about family members as a test for their cognitive competency.