There's another option that I don't think anyone has suggested...
Rather than going back to school for another degree, why not try to get a job as a post-doc in someone's psychology research group?
Here are my reasons for suggesting this:
1. On a first-impression basis it's a more fitting path for someone with an MD.
2. Some schools will allow post-docs to audit/enroll in classes, so you could get some of the didactic education that you want.
3. You wouldn't have to take part in some of the PhD stuff that you don't want to do. (I'm sure not all of the classes appeal to you.)
4. You'd still get the research experience that it sounds like you're looking for.
5. You wouldn't be tied to a 4+ year experience.
6. Schools wouldn't have to use up one of their training slots that they'd really like to give out to someone who's taking a more traditional path.
Last point... sort of a part-A, part-B thing:
7A - If you're getting another degree, in the best-case scenario it will be a funded position but you'll be barely making any money. You'll just be delaying your real income. Worst case: unfunded, you'll be racking up more debt.
7B - If you're doing research as a post-doc you'd be eligible for NIH loan repayment programs to pay off your med school debt (google "nih loan repayment").
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In the end, however, I don't recommend this path if you want to practice medicine like you say you do.
If you're really serious about practicing medicine, don't forget that your skills are likely to get rusty whether you do a post-doc or go to graduate school. All those things you learn in residency will start slipping away if you're busy doing research full time.
I think you're trying to do too much. Neurology AND psychiatry AND clinical psychology, with equal emphasis on clinical theory AND research? Too much stuff!
You say you don't want your research to be viewed as coming from one distinct theoretical paradigm. But psychology and psychiatry are pretty similar. Maybe you should do a Doctor of Social Work program after your PhD, that way no one will accuse you of ignoring the social work approach. Something to consider? And if you get a PhD in psychology from a school that emphasizes cognitive-behavioral type stuff, maybe you should add on a PsyD from a school that teaches Jungian psychology.
Ed Smith, MD, PhD, DSW, PsyD... nice ring to it, right? Now no one would dare question your credentials... (Joking
point is, people are always going to think your work is influenced by your training!)
You say you want the two degrees to be considered an expert, but generalization is not how experts are usually made. Experts are usually highly specialized, not highly generalized.
Also, it usually takes a looooonnnnggg time before anyone will start thinking of you as an expert, and taking a guess about your age this plan sounds like you'll be in your mid-40's by the time you finish... you'll have spent so much time working on your credentials that you won't have the time you need to do the work that makes you an expert.
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Do what makes you happy, but this sounds like you're biting off more than you can chew. Good luck!