Just to make the detection and diagnosis of depression a little more complicated, there are two disorders that have depressive symptoms as an integral part of their course: dysthymia and bipolar disorder. A better way to understand it is to think of these two disorders as subtypes of depression. While many of their symptoms are exactly alike, there are distinct differences that separate them. A definitive diagnosis should be left to a professional. For now, you need to understand the differences to help that process along.