Top tier schools (because they had the research I was interested in) NYU, Columbia, Mt Sinai, UChicago, Northwestern, WashU, UCLA, UCSD, USC, UCSF. My current PI and my former PI at BU both wrote me recommendations, as well as a professor from BU who is a co director of the Alzheimer's research group at BU and a Harvard and BU medical school professor.
I had several people (both in science and not) read over my statement of purpose.
That is mainly been my problem, just being able to find the research I want at lower tier schools. Most PIs I have spoken to have basically told me to give up on doing a PhD in neurodegenerative diseases and look for another topic, but that's what I'm passionate about. I don't think I want to compromise on that. Is that being selfish? Should I suck it up and just get the degree where ever I can?