I no this is a strang thing and not every one the same . I whent out over the weekend and a friend of mine was there I hadn't seen her for a few years we stop and chat.she was on abought her brother in law having dementia he was diagnosed 3 year ago .she said he was told that hehad it 3 years befor diagnosed as nothing would show up on skans till then .is this true or can you tell stray away if you get whot I mean