You could also look into the truehope suplements. www.truehope.com. I tried them, they worked better than my meds, but it was not enough. I don't use them anymore, because for one, they are expensive. They can heal brain damage though so it might be interesting to see what it does on your dad.
Just thought I'd mention here that I've started a thread of the same title in the journals area. Somewhere I expect to update regularly and document progress and changes, as well as somewhere to continue conversations about Alzheimer's and the potential of a paleo/primal approach.