interpretation of it varies with culture. I think the notion that it is a disease of young teenage girls mired in self absorption is rapidly being discarded. Ten years ago families were blamed when their daughters developed anorexia; now it is recognized as a genetic disease.
As for Catherine, look at some of these details:
"From her earliest childhood Catherine began to see visions and to practice extreme austerities.
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Though always suffering terrible physical pain, living for long intervals on practically no food save the Blessed Sacrament
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Her strength was rapidly being consumed; she besought her Divine Bridegroom to let her bear the punishment for all the sins of the world, and to receive the sacrifice of her body for the unity and renovation of the Church; at last it seemed to her that the Bark of Peter was laid upon her shoulders, and that it was crushing her to death with its weight. After a prolonged and mysterious agony of three months, endured by her with supreme exultation and delight, from Sexagesima Sunday until the Sunday before the Ascension, she died."
http://www.newadvent.org/cathen/03447a.htmSt Catherine died of a stroke in Rome, the spring of 1380, at the age of thirty-three.
http://en.wikipedia.org/wiki/Catherine_of_SienaCompare that to what happened to Karen Carpenter!
The article in the Catholic Encyclopedia also mentions a three month episode that could have been brought on by starvation. The descriptions of her physical condition and the fact that she died so young of a stroke remind me of the way so many women struggle today. Now, I am not going to argue that her visions were hallucinations brought on by starvation. I have no way of knowing. Even if they were hallucinations, why did she see and hear what she did? I can see a woman of her era afflicted with anorexia interpreting it as a call to join her suffering with Christ. Where young woman explain their disease today as an attempt to be thin enough, Catherine experienced hers as a call to holiness. The important thing is she answered the call.
It doesn't mean that her writings are invalid. We all take what we are handed and make what we will of it. Hildegarde Von Bingen wrote of her visions of Hell, but some suggest today what she was seeing was migraine aura. IMO, it doesn't matter what inspired her writings, what matters is what she wrote. Again, I have to believe that Joan of Arc had some form of schizophrenia. Since she believed the voices were giving her instructions from God, and since she tried her best to follow those instructions, I still respect and honor her.