Yosef Karo, Shulchan Aruch — Choshen Mishpat 35
“ Paragraph 9- One who often collapses from a disease that drives him out of his mind, is disqualified from testifying while collapsed, but is valid while healthy. This is true whether he collapses from time to time or consistently collapses without any set time, so long as his senses are not always distorted because there are those that often collapse and are out of their mind even while healthy. We must extensively evaluate the testimony of one who collapses often. ”
