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.