Why do we deny or look the other way when someone is diagnosed with AD?

Is there anyone that could possibly wrap there mind around the fact that you have AD? 
How difficult is it for a spouse or any family member to accept that fact?  We can tell you that it sometimes can be very difficult to accept.  There are too many questions about the disease to accept it readily.  It doesn't have a red rash that changes your face.  It doesn't make you limp, or bend over holding your belly in pain.  It doesn't make you talk funny or pull your face to one side.  You can't have your chest cut open and be repaired.  Your hair doesn't even fall out.  In the early years there is just no change that can be seen by casual encounters.  You can't visit once in a while and notice that your Dad, Brother, Son or Uncle has changed any.  He still cracks those silly little jokes that he always has.  He still loves playing with the children like he has all his life.  He still hands you a little bouquet of flowers or a pretty rock he found outside the exact same as he always has.  And yes he does get upset now and then as he always has.  The only reason that I saw any change in my husband was the fact that we were in our motor home traveling 24/7 and it was just the two of us and you notice everything.  I never thought that was the reason for our making a colossal change in 2008, but things have a way of working out.  If we had not chosen to live this way, who knows how long it might have been before I noticed the changes that were happening.  I feel certain that I would not have noticed for a long time. 
     We saw the changes that took place in his dear Uncle that was diagnosed around the same age as Gerry was at his diagnoses.  We didn't see him often but the times we did see him I noticed changes in him.  I think maybe I noticed what other people chose not to notice or admit it if they did.  I believed our Aunt when she told us that he has AD.  I noticed that he was still the same sweet, happy man that we always knew.  I noticed that when he saw people that he loved he reached out his arms and hugged them tightly and was so glad to see them,  but never called them by name.  I noticed that when he saw old friends or people from the church he smiled and shook their hand so warmly and patted their shoulder and told them he was so glad to see them, but he never called them by name.  I noticed that when we all were around eating and talking constantly he sat back and smiled and most of the time he would nod off and nap while everything went on around him.   He would sit and listen to the family talk about the old days and he would nod and smile and agree with anything they said, but he never had any story of his own to tell, he was happy just to be there among the people he knew that he loved and loved him.  I noticed how as time went on he clung to his wife and had to be near her no matter what. 
I wondered how she handled all the changes that she saw him go through during the 10 or so years since his diagnosis.  I know she loved him and clung to that love and to her faith in the Lord and had the support of her children and of the community.  What will I cling to as my husband goes down this road of living his life backward?  How will I deal with the changes that I will see in him?  That's what I need to learn - how to deal with the changes.
    So many people joke about it when they forget something or act silly and that's ok.  I just feel that to laugh it off when it is a serious matter is wrong.  We have found that a sense of humor helps in many instances.  I saw that too many family members denied the disease that took our Uncle.  Little did any of us know  just how many people in the family were going to be or already were affected by it.  We have learned that my husband's family has had this horrible disease afflict so many people, some we know had it, others we suspect had it by symptoms.  By now we do believe that it is a Genetic disease.  His Grandfather had 2 wives and 10 children by each wife.  Gerry is the only son of the eldest of the second 10 children.  From stories I've heard, Grandpa probably had AD, but was never diagnosed.  He lived to be 98 and suffered from Dementia for many years.  From the older set of children I only heard that one died from AD.  From the younger set, we know that a minimum of 3 have died from AD and there is a good possibility that 3 others may have. 
My husband's Mother has Dementia and has been on meds for seizures for several years.  AD has not been diagnosed but we spent 15 years living very close with her and I know that a lot of the symptoms of AD are present in her.  I've seen them first hand.  Of course those are also Dementia symptoms and I pray that is what it is.  Sadly we'll never know because Mom lives in a place that we can't visit and has been cut off from having contact with us.  This happened after my husbands diagnosis of AD.  I feel responsible for this and will share the blame, but will not carry it alone.  This is just as painful to my dear husband as it is for him to know that he is in a no win battle between himself and AD.