Hello @tarazkp,
I am sorry about your father. It is a difficult situation. Each person has a particular condition, but I will dare to share the case of the mother of a friend of ours. Our friend is a chemist by profession and her mother was a nurse for much of her life, she is now 95 years old and suffers from Alzheimer's. She tried many treatments with her mother, but the last one has been almost miraculous.
She gives her mother a teaspoon of coconut oil on an empty stomach and a pill of Ginkgo Biloba with breakfast. Now her mother has improved markedly. I don't know if it will serve your father, but what they would lose by trying. Obviously, check with your brother @galenkp first and ask his treating doctor what he thinks about it.
Thank you for the tip about the coconut oil and Ginkgo Biloba... logged for future reference
You're welcome.