Assuming biofeedback can be classified as one of the suggestive
rememdies, like hypnosis, we have more evidence here of the
psychgenesis of autism:

http://www.eegspectrum.com/Applications/Autism/EEGandAutism/

In the late 1800's, Jean Charcot demonstrated that some forms of
paralysis and blindness can be temporarily cured through hypnosis.
People with total paralysis of the legs, so bad that they couldn't
even feel needles being stuck into their legs, could be made to walk
again under hypnosis. Upon awakening, however, they collapsed.

Likewise, people who were so blind they didn't blink when a lighted
candle was thrust towards their eyes, were able to see perfectly well
under the influence of hypnotic suggestion--only to be blinded again
upon awakening!

It's a good test of whether or not a condition is mental or
physical. The above link should be a wakeup call for those who
insist that autism is "neurobiological" rather than psychological.
There is a reason for this to be included in the DSM IV, which is a
manual for *mental* disorders.