I don't know any more than is at the end of that link; someone who knew the subject could doubtless say much more. There's a remark about cryonics and Alzheimer's in this Ralph Merkle article:

Most people suffer legal death because of a heart attack or cancer. Deterioration of the brain prior to legal death from neurodegenerative diseases (e.g., Alzheimer's or Parkinson's disease), accidental damage to the brain (e.g., as in the case of Phineas Gage) or other causes would adversely influence this risk.