He is touched―cracked―crack-brained―unsound in mind―not in his right mind―out of his mind―out of his wits―out of his senses―off his head―not right in his head―wrong in the upper story―His wits are wandering―His reason wanders.
気がすむ
気がさくい
気になるもの
気難しいさま
気懸りになる
to give heed to anything