If anyone doubts the power of the mind-body effect, look up Nocebo effects (opposite of placebo) where the mind manufactures "real" symptoms as side effects to

If anyone doubts the power of the mind-body effect, look up Nocebo effects (opposite of placebo) where the mind manufactures "real" symptoms as side effects to medication. I can't find the source(s) right now - but I have previously read about cases as extreme as blindness and paralysis with purely mind-induced and non-physical causes.