One thing one can be sure of when volunteering as a Respite provider for RSVP: the next dementia client is going to be different. Dementia is, of course, an umbrella term that includes Alzheimer's, Parkinson's and other diseases having to do with the brain. No two are truly alike, as one finds out quickly.Tom was my first, suffering from Alzheimer's. (Note: names herein are changed for privacy.) He was quick to talk, often repeating questions within minutes. After several months of staying with him while his wife went out to play bridge, he and I became modest friends. He disappeared …