An article in Annals of Neurology in February of 2012 showed that in mice the anesthetic Forane caused impaired cognitive function that were much like the changes in Alzheimer's disease. Previous studies have documented that patients undergoing general anesthesia may increase the risk of Alzheimer's disease. Transient cognitive dysfunction is common after general anesthesia.
Forane showed increased mitochondrial permeability, reduced ATP production, and increased levels of the cell-death enzyme, caspase in tissue culture experiments. None these changes was found with either spinal anesthesia or with Suprane anesthesia.
The authors recommended against using Forane with the elderly or with patients with Alzheimers. I can't imagine why anyone would want to use Forane when other drugs are possible. It is very important to interview the person doing one's anesthesia as well as learn about the drugs planned for usage during surgery.