I read a book decades ago that said Finland ran out of wheat in WW1. That resulted in many mentally ill people becoming normal, who were then released from mental institutions.
Ok, historical facts. Partial facts are dangerous.
http://www.botany.hawaii.edu/faculty/wong/BOT135/LECT12.HTM
It as MORE likely they were released because the quality and quantity of food got better. The lack of good food meant they had to eat some pretty crappy stuff like ergot infested rye.
What I read took place in World War 1, not 1350.