ABSTRACT
Mood disorders have been documented for over 4000 years. What we think of today as “depression” was described by ancient Greek physicians (who regarded these disorders as related to imbalances in bodily fluids) to be “melancholia.” Aristotle was the first to document a relationship between alternating states of sadness and cheerfulness. It was then recognized that there existed a single phenomenon characterized by the cycling of these mood states: this condition came to be known as “bipolar disorder.” The conceptualization of bipolar disorder as a single disorder came to be known as the “unitary hypothesis,” articulated by the German psychiatrist Emil Kraepelin, and was incorporated into the first major diagnostic compendium of mental health in the mid-twentieth century. But Kraepelin’s idea was challenged by Karl Leonhard, who argued that depression was a distinct disease entity from bipolar disorder. This resulted in revisions to our current diagnostic nosology, which now distinguishes unipolar depression from bipolar depression, a distinction increasingly viewed as problematic by leaders in the field. One might argue it obscures symptom recognition and poses problematic treatment implications for those with mood dysregulation.
