Nancy Vaughan is a charming and lively conversationalist, a friendly host, and at nearly 90, still has much of the sparkle and attractiveness that must have turned many heads when she was in her heyday as a model in New York.
But she also has trouble remembering her own name, or the fact that she is married (62 years and counting), or indeed, much of the time, some of the basics of the English language.
Nancy is in the advanced stages of Alzheimer's.
On a sunny late autumn day I visited Nancy and her husband, John, at their home in Phoenix, Arizona. We made friendly conversation in the kitchen and for moments I could have believed that she was mentally well.
Her smile is still engaging, she is physically fit, and she can sometimes carry on brief exchanges. When I asked if she had any problems with her memory, she said an emphatic "no".
He has also stuck a copy of their wedding photo up in the kitchen so that, in her confused moments, he can prove to her that they are married.
John cares for Nancy fulltime. They have no children, so there is no family help take the strain - and they are not in the financial position to have Nancy go into a care home.
Aged 88, John is the full-time carer for someone with many of the same needs as an adult-sized toddler.
It's reckoned that one in eight Americans aged 65 and over has Alzheimer's - the most common cause of dementia. Nearly half of the over 85s has the disease. As medical science has become better and better at prolonging our lives, the mental side of things hasn't kept pace.
Nowhere is this more in evidence than in Phoenix. For years Phoenix has been a mecca for America's elderly, who are attracted by the year-round sun and dry desert heat.
Now increasingly it is a kind of capital of the forgetful and the confused.
Not coincidentally, Phoenix is also pioneering the way dementia sufferers are cared for and treated.
One of the top destinations for people in need of round-the-clock care is Beatitudes, a gated retirement complex, which has, tucked among its many buildings, a memory support annex.
Most of the residents at Beatitudes have seriously impaired memories, to the point where they can no longer look after themselves, are quite often confused, and occasionally have delusions.
Click here to Read More:
BBC News - Louis Theroux on dementia: The capital of the forgetful