Traveling with a Demented Elder, diagnosis

I am glad to see that some are becoming aware of situations like this one. My father has been diagnosed with dementia. He's only 64 years old. My parents live in another country, they hold U.S. turist visas and have come visit many times since I moved to this country years ago. My Dad knows that there will be a time when he won't be able to visit anymore. The worst part is security at airports and immigration officers. I don't blame the extra security due to terrorism but the questions asked at the immigration desk are done is such a rude tone regardless of who they are taking to, that it disturbs my Dad and sometimes they ask things he doesn't remember or understand and they don't like my Mom intervining. My Dad is still able to function and travel. He only needs my Mom with him to help him when something confuses him but because of the lack of understanding by security and immigration officials, they might never again come visit my home. A letter from the doctor might help but my parents have gone through so uncomfortable situations in the past year when passing immigration that they might not want to do it again. I agree, they need a deeper understanding of dementia.