The first change that Marie noticed in her husband William's behavior that gave her cause for concern was his uncharacteristic impulsiveness and occasional rudeness to other people. Some 5 months after this apparent alteration in his personality, William found that he was having difficulty running or walking. He sometimes felt unsteady and dizzy on his feet and had the occasional fall when he moved too quickly. At about the same time, Marie noticed that his memory was beginning to deteriorate. William could remember things that had happened in the past, but his recall of events or conversations in his every day life was unreliable. He also developed a slight tremor in his right hand.