I had a double major in psychology and studio art. (Fulfilled two majors... not an interdisciplinary major.) I graduated over 10 years ago and OT was not on my radar at the time.
As it turns out, this seems to be a great background for OT. I also managed to do most of the OT prereqs, since most OT prereqs are psych classes (including stats.) And I'm really glad that I did the psych courses at my small liberal arts college, rather than majoring in something else and taking the psych classes elsewhere later, since our psych dept. was great. Classes were all discussion-based and largely based on original journal articles rather than textbooks. I think I better learned how to think critically and analytically within the psychology field than I would have in a large lecture-based class, plus we had labs and a practicum where I got to work with psychiatric patients. As far as prereqs went, I only later needed to take Adult Development, and A&P I/II. I'd say you should take a general bio class while in college, because it gives you a necessary foundation for A&P (although if necessary you could read up on it before A&P.) And if A&P is offered (which is often not the case at liberal arts colleges), you could take those while still in college, too. Then you'd be pretty much set.
That said, as another commenter posted, people picking a major with an eye towards later studying OT should look at what's strong at their particular college.