mad: Showing that one has amanita illness which often causes them to behave in strange way.

　　crazy: (infl) Very strange or foolish.

　　psychotic: The most precise one. used by psychiatrists.

　　insane Not sound in mind. Used in scientific articles.

　　lunatic: (old derog) wildly foolish.

　　demented It indicates sb's mentality has degenerated from a precious level.

　　maniac: (n) A mad person who is violent and dangerous.