Free Will doesn't pertain to ones disposition or feeling so you're not really dealing with Free will. Free will is the innate power or capacity to be able to cause ones own actions, and be able to do otherwise. Just ilike you're able to type a reply back, is an example of you excesizing your free will. Insanity may be influenced by things external to the mind, it is a condition or state of the mind, not necessarily of the brain. The brain isnt the mind.