I just got back from an asian market. There were stuff like pork tongue and brain and stuff there. I don't think digestive organs(ie liver...) are safe, but what about pork brain, or tongue? I would love to eat a pork brain, simply because it is so difficult nowadays, living in our society, to find that organ of any animal. However, the question is how safe is the brain? Since afterall, it's commercial poultry.
Personally, I would not take such risks. I would try to come in contact with a farmer who correctly raises pigs and see about acquiring one. The cost would likely be the same and the risk would be a tiny fraction. There are a lot of contaminants that deposit in the brain, in addition to things like prions, which may be present if, for example, the pigs are fed questionable beef.
I'm too scared to even eat wild brains... I like the idea... But media and modern diseases Terrify me. That said, with someone with knowledge of it, killed a wild animal with me on safari(away from civilization) I'd try it.
But commercial grain fed , you couldn't pay me.
Meanwhile you can get most of the fats and nutrients through other means
Tongue is just another muscle, so it shouldn't be any more dangerous than a porkchop. Brains, on the other hand -- not worth it unless you know where the animal comes from and the feeding practices of the ranch. Ideally you'll find a place which maintains a closed herd (no new animals have been introduced in some time) and uses safe feeding practices; for example, as Travis Culp says above, no brains from pigs which have been fed beef.
I wouldn't touch wild brains at all. Cervids in particular can have chronic wasting disease (the deer equivalent of BSE), and while it tends to be limited to small areas, it's still a good idea to leave the brain alone.