What is the difference between bipolar disorder and depression? Are they related? Are their similarities in their biological basis? What makes someone switch from manic to depressive states? Does the brain of a bipolar patient that is going through a depressed episode exhibit the same patterns as a person diagnosed with unipolar depression? These are just some of the questions that I have about the relationship between depression and bipolar disorder. Sitting in class I could not help but think that there must be similarities between these two disorders since bipolar disorder is often marked by long periods of depression. If they are exhibiting similar symptoms are their biological symptoms the same?
In my search for answers to this question I realized that as little is known about depression, even less seems to be known about bipolar disorder. I found many articles explaining that behaviorally there is a difference between depression and bipolar disorder, but they weren’t recognized as separate disorders until 1966! The articles that initially discussed the differences cited differences in genetics, gender, clinical course, and premorbid personality. All of these seem to be reasonable support for defining depression and bipolar as different disorders, but what about the biological component?
The article I read, “Are Depression and Bipolar Disorder the Same Illness” reviewed work done by Frazier et al. who found several interesting biological components to this disorder (but the article I read didn’t cite it, so I can’t find it anywhere!). But his research found differences in the limbic systems of prepubescent children with bipolar. Frazier also found that the hippocampus volume decreased in children with bipolar disorder, but this was not found in adults with bipolar disorder. This brings up two questions: Is bipolar in childhood fundamentally different from adult bipolar disorder? And is the decrease in hippocampal volume of bipolar patients similar to the same symptom found in depressed patients? In the research I did it felt like I came up with more questions than I got answers. There is still so much to understand when it comes to Bipolar disorder!