There are multiple ways to get involved with neuropsychiatry. There are some of residencies that combine psychiatry and neurology and the majority of these are listed on FREIDA (at least the ones officially approved). You can also do a fellowship in either neuropsychiatry or behavioral (or "cognitive") neurology. Neither of these are official ACGME sub-boards, so you will not find them on FREIDA. As someone already mentioned, there is a certifying body that recently started for neurological sub-specialties (UCNS) and it is recognized by that, though the significance of that recognition is still unclear.
From your question, I suspect you are already in residency, so the combined programs are not options for you. These are more rigorous and if done at one of the better places (UMass or NYU) are certainly the most comprehensive options. The fellowships are good too but more limited in scope. I would look carefully at any fellowship you are considering since they all have different focuses and few are particularly comprehensive. In fact, many of the fellowships focus more on dementia then general neuropsychiatry.