I think that bipolar disorder is diagnosed more often than BPD -- i always assumed that it was because BiPolar is something that is medicated (more cash flow for the drug companies) and Borderline is not a sentence for medication. When working for a dr, office years ago it seemed like everyone was suddenly diagnosed as BiPolar, and then as time passed, some of those were being re-addressed as BPD. My doctor said that BPD isnt a diagnosis anyone wants to receive when dealing with MI, soo... not sure.