Two people have dementia one gives the other medical power attorney the other gives all their power of attorney to son. Who has medical POA?

Just a diagnosis of dementia does not make a person incapacitated. That could happen years after the initial diagnosis. As long as the person can understand "in the minute" what they are signing they can still assign the POA. MY mom was diagnosed about six years before she was considered unable to execute new documents.

Wait a minute. This is like one of those brain teaser math story problems I always used to flunk in school.

If A gave her son POA over herself, then son has her POA. If A now has dementia, I seriously doubt if she could execute her POA duties over B. She needs to be recused of her POA duties over B and a new POA over B needs to be found. One can not assign POA to anyone if one is found incompetent. I would think that one cannot remain POA for the same reason. In any case, consult with an attorney to make sure all this is done the right way.

(A) has POA over( B) medical ,( A) turn all of her POA over to son ,this was done about 5yrs when neither had dementia at the time of signing,but now the both of them have dementia,does( A )still have the power to( B) medical POA,

Are you asking if POA can be "inherited" so to speak? No. If the person appointed POA is unable to act, then the POA document should specify successor POA.

This is confusing. This is what I get from this. Person "A" has assigned their POA to person "B". Person "B" assigned their POA to their son. Son only has POA for person "B". If person "B" is not able to handle POA for person "A", then POA needs to be revolked and person "A" assigns a new POA. If "A" can no longer make informed decisions than guardianship is needed. A person with Dementia/ALZ cannot sign legal documents.

A person who has dementia is not considered competent and therefore cannot assign Power of Attorney to anyone, no matter who. If they were diagnosed with the disease at the time they appointed their POA, the forms are not valid. At that point, the only way to go is Guardianship. Are these forms that were drawn up by an attorney? If so, I’m surprised the attorney, if they knew about the dementia would go ahead with letting them sign the forms.

Are the two people with dementia competent to make these decisions?

Please restate your question. It is not clear.