Hiya Duffer,
What an amazing time for you all and it has been interesting to hear you're dad's insight too. Obviously the longer this goes on the more interested the professionals will become. I am not sure if you are aware but there is a large dementia research centre at the University of Stirling, maybe they would be interested in what is happening, especially if things continue to improve. Here is their website
http://dementia.stir.ac.uk/.
I was interested in your dad saying it was like there was another version of him around as it gives another level of understanding, particularly as a psychiatrist had described dementia in a different way to us. He said to think about an old radiogram with a tuning dial. He said the brain can be damaged in different ways dependent upon what type of dementia that you have. So, back to the tuner, you turn the dial and all you hear is static, sometimes really bad.static, nothing is going to get through no matter what you try. These represent the bad days where it is difficult to communicate, practically no cognitive function. The tuning dial continues moving along and very occasionally you might pick up a hint of a feint radio station, difficult to hear it but you know it is there. These are thos little lucid moments when you get reminded that the person you know is still in there. Then as you move on you're back into the static again, bad day maybe, maybe you are sundowning. Then one day you arrive at RADIO 2 FM station (his choice not mine! LOL). Lots more clarity today. Big change. Everything seems clear and the person is alert and responsive. Does continue as there is more fine tuning improvements continue to be noticed and you can hang around RADIO 2 for a while and still hear it properly although the quality of the reception changes as you move away. Eventually though you start to hearthe crackle of the static coming back again. Things start to become more confused again, but you do have your odd lucid moments and occasionally you find you have reached RADIO 1 or Classic FM.
I can see how your dad's explanation could easily tie in with the psychiatrist's account. I am also interested in the infection scenario too and it will be interesting to find out if anyone sheds any light on this aspect too for you.
All very intriguing isn't it. Whatever is allowing this to happen I do hope your dad continues to improve and that perhaps this might be a very rare case of it not having been dementia at all but some sort of brain injury that can heal or improve over time.
Fiona