Question: Can people with developmental disabilities have bipolar disorder?
Answer: Absolutely, people with developmental disabilities can have bipolar disorder. The challenge there is to diagnose them, because often they are not able to convey their history or their feelings as well as people who have normal intelligence.
It's best, I think, to understand the developmental disabilities as being an entirely separate category from the mood disorder. And there's nothing that prevents a person with development disabilities from having a superimposed or a simultaneous mood problem.