The author of this New York Times blog post argues that the MD of a patient with dementia or other serious medical condition should occasionally ask the family caregiver if the caregiver is eating properly, sleeping enough, depressed, etc. See:
newoldage.blogs.nytimes.com/2014/11/17/seeing-the-invisible-patient/
The New Old Age: Caring and Coping
Seeing the ‘Invisible Patient’
The New York Times
By Jane Gross
November 17, 2014
In my mind, this does not seem realistic given time constraints or appropriate since the family caregiver is probably not the MD’s patient as well.
Indeed, a neurologist I spoke to about this said:
I think it is unethical to ask questions about specific health problems or indirectly treat a family member, particularly in regards to mental health like depression. Asking general questions or general statements like ‘make sure you are taking care of yourself as well’ or encouraging them to see their own doctor regularly, or telling them about caregiver services and support groups is fine and should be encouraged. The problem is always time of course. We don’t have enough time to ask the patient everything necessary, let alone the family.
Robin