My mother-in-law has Alzheimer's, which was first diagnosed as dementia. The first signs we noticed was her failure to keep her checkbook up to date and then one day, while at our house, forgetting that my son had to go to the emergency room that day. Later it was discovered she was not taking her medicines properly because the number of pills in the various bottles did not match up with the dates. It starts out in a very subtle manner and can spread quickly. Today my mother-in-law has her long term memories, but gets some of old stories confused. She knows her family, but has trouble remembering simple tasks.