How To Treat Small Vessel Disease Of Brain With Severe Emotional And Physical Disabilities?

I have diffuse chronic small vessel disease of the brain and already have severe (I'm home bound) emotional, cognitive and physical disabilities. My father was diagnosed at age 52, but lived to age 85, much in a vegetative state. None of my doctors will give me a life expectancy estimate. (Wayne State University docs, mostly.)Cleveland Clinic diagnosed (or misdiagnosed???) Multi-system Atrophy 3 1/2 yrs ago with a life expectancy of 1 to 7 years. I really don't want to live until 85 as a vegetable. I am now 62 years old. Will you level with me. When will I cast off this mortal coil?????