If one of these two cards are attached to an investigator, is it no longer an investigator? (not talking about the powers the investigator has)

E.g. if Madness is attached to Pickman, is it still an investigator?

Madness: You cannot win if you have this unless conditions say otherwise. If you have any Investigator Keeps in play, you must choose one to attach this to. Any special powers of the Keeper become ignored. Both cards stay together until discarded.

Pickman: ???