I question Lisa's judgment. & sense of priorities.  Yes,  the dr said: he can still drive, fix things in his workshop, reheat food; those are TODAY statements.  Per Oct 2016 published research although the  SPEED of the decline and QUALITY OF LIFE is unique to each person, after diagnosis the average lifespan is 8-10 yrs  (up to 20 yrs).  

LEADERSHIP TIMLINE: Running for leader is a 9 yr commitment (as per others contenders' comments) with an election in 2019 + 2 terms, (you should give the party 1 yr to elect a new leader & enable them to brand/set direction).  -- or -- if she doesn't form gov't, it's expected the the leader will stay on for 1 more election) 
 
TESTING:  May I suggest that if you think a loved one has dementia symptoms, ask the GP in "writing"  to do the Mini Mental State Examination, MMSE so you request is on file.  TIP: if you don't know the dr name, look a pill bottle.   

CHERISH every moment. ASK lots of questions and capture the memories, NOW.