Nurse Practitioner teaching professor. He knows a lot and is highly respected by MDs.

@barjoe i like him! Very clear! But the "Dr" in this context seems a bit.......something......

@AnneWimsey Didn't we go offer this worth Jill Biden? While a doctor may refer a patient for specialized care, such as to a neurologist, the physician has a well-rounded education that overlaps with all specialties. An NP is a nurse practitioner. Whereas the RN cannot prescribe medications, the nurse practitioner is licensed to do so, as well as diagnose conditions. The Phd makes him a highly educated man in the medical field. [solvhealth.com].

@barjoe some did, not I. I do understand the enormous work & time involved in getting a PhD in anything. But it is So easy to indicate what your degree has been earned in, using abbreviation(s) after the "PhD", there is a entire recognized way to do it.
One assumes, because he is giving medical information with Doctor in front of his name...well, what would the average reader assume? Where in actuality his PhD is in Philosophy.
I just find it unnecessary for such a well-rounded, articulate, yea, popular, man to allow such assumptions when it is so easy to avoid.