These are the Rebbe's letters to individuals about their own situations. Throughout, the Rebbe instructed people to consult an expert doctor and follow his guidance; anyone facing a medical question should do the same.
The Rebbe's guidance on old age and caring for elderly parents:
For an elderly parent, the environment matters most. In deciding where an elderly person should live, give priority to a place rich in community and spiritual connection, where they are surrounded by warmth and Yiddishkeit (IK 1240).
Old age is a time to grow, not to withdraw. Reaching older age is an opportunity to increase in Torah, mitzvos and spreading Yiddishkeit (IK 8591). Retirement from a position need not mean retiring from public service; continue to contribute to the community (IK 10296). Both youth and old age depend on Hashem's help, and the Rebbe blessed people with the Tehillim verses about strength and freshness in old age (IK 3032, 4920).
Reaching out to the elderly with Chassidus and mitzvos carries great merit (IK 3858).
See also: כיבוד אב ואם.