Antenna's can and do work OK in an attic.
If you have A/C Lines in attic that can be an issue - best to keep the wire/antenna as far away from them as you can.
That said they do not work quite as well as the same Antenna Outside.
The wires do not have to be "in attic" to cause a problem, the wiring in the rest of the house is close enough to be a potential problem. (The ceiling of the rest of the house below is not going to stop interference, in fact wiring there is going to just add to it. I think you knew all that and just slipped in your wording.
