By straightforward, I mean following the way that we make a diagnosis. Clinically, there is a textbook where there's very clear criteria about how to make a diagnosis of a major depressive disorder or schizophrenia. When the presentation is not consistent with one of the criteria or the set of criteria, what we call the differential diagnosis is complex. When it's not clear that this was a depressive episode with psychosis or schizophrenia, then a referral is typically made for diagnostic clarification. That's when the clinical presentation does not fit in one category, a simple category.
On February 3rd, 2016. See this statement in context.