Yeah, what do they think that a crop of stem cells could do about plaque on the brain? Zippo, that's what. And even if Alzheimer's was a problem involving the death of cells or damage to cells, we'd be using stem cells to replace them with brand new brain cells. A brand new neuron doesn't help you remember somebody's face, it's frickin' empty!
Of course, that's assuming that embryonic stem cells are useful at all, which we're not seeing with the data so far. Research in that area is simply killing kids on a wisp of a forlorn hope, or in other words, grant-money-a-rama.