The reason this diagnosis has become murky is our old friend the pharmaceutical industry, which often gets patents extended on older
drugs by getting FDA approval to use them for
OCD, which leads to more diagnoses of OCD where it doesn't exist. I know this not just from research but from personal experience -- anxiety gave me obsessive thoughts and so did antidepressants, but after Paxil withdrawal I developed OCD, and it's quite a different bird.