St Veranus (or Vrain or Veran’) is counted as an intercessor for persons with mental illness.
For information on St. Veranus:
Here is a more extended, informative article from Wikipedia in Italian: http://it.wikipedia.org/wiki/Verano_di_Cavaillon .
An (awkward, imperfect) Google translation of this site into English: http://translate.google.com/translate?js=n&prev=_t&hl=en&ie=UTF-8&layout=2&eotf=1&sl=auto&tl=en&u=http%3A%2F%2Fit.wikipedia.org%2Fwiki%2FVerano_di_Cavaillon&act=url
Update: For an even better source, see the site from which the image above was found:
Image from Saint Véran de Jargeau
Google Translation: Saint Veran Jargeau