A Knowing Look

We go out to dinner once or twice a month. Quite often when we go to out favorite restaurant there is a woman there with her mother . At least I am pretty sure it is her mother as they have the same facial features. Last time we saw them I  really "saw" them. I recognized the "face" of Alzheimer's on her mother. The somewhat vacant stare that although fleeting was there. I looked at the daughter and saw the perceptible nod she gave me as she recognized it on Bob as well.
A silent  knowing look exchanged by us, and a feeling of  not being quite so alone. I wonder how long till others recognize that "look".