Yes.  In early stages of Alzheimer's, a spouse can provide the encouragement and help that the afflicted partner may require.  But in final stages, there is nothing a spouse can do (other than visit and talk to the patient) that professional 24/7 care in a proper facility cannot do better.  

For example, the great singer and guitar player Glenn Campbell is now in such a care facility with 24/7 attention.  His devoted wife of some 25 years tried to continue to care for him herself as Glenn deteriorated but finally had to give up because he was a safety threat to himself, her and others and because he required 24/7 attention by shifts of trained staff. 

I have no doubt Ms. Raitt has discussed all of this with her husband and that he has urged her to run because she is so well qualified by education, experience, intelligence, industry and personality to serve our country.

I also have no doubt she will continue juggling her time as she does now and help her husband in The Long Goodbye..