Mom's main problem is osteoporosis and arthritis. Lately she has started substituting words - "aisle" for "hallway", "truffle" for "toffee" - things like that, and she is WAY overdoing it on days she knows she has other things she wants to later on - which she has always been careful about conserving her energy for important events. Also, she has gotten irritable a couple of times, which in not like my sweet mother at all. Is this something I should be concerned about? How should I bring this up?