Why did the disease name "manic depression" change to "bipolar disorder"? It's a good question, and for the answer we'll look back at the roots and the history of the terms.

First, the phrase "manic depression" has its origins rooted in ancient Greece, where the coupling of the words was used as early as the first century to describe symptoms of mental illness. In her book Bipolar Expeditions: Mania and Depression in American Culture, author Emily Martin writes, "The Greeks believed that mental derangement could involve imbalance among the humors, as when melancholy, heated by the fluxes of the blood, became its opposite, mania."

In the late 1800s, Jean-Pierre Falret, a French psychiatrist, identified "folie circulaire" or circular insanity - manic and melancholic episodes that were separated by symptom-free intervals. It is through his work that the term manic-depressive psychosis became the title of this psychiatric disorder. It's noteworthy that "psychosis" was included, thus excluding all types of what we know as bipolar disorder that don't include psychotic features.

In 1902, Emil Kraepelin organized and classified what used to be thought of as unitary psychosis into two categories. Manic-depression was the term he used to describe mental illnesses centered in emotional or affective problems. Dementia praecox (literal meaning "premature madness," later renamed to schizophrenia) was his title for mental illnesses derived from thought or cognitive problems.

In the early 1950s, Karl Leonhard introduced the term bipolar to differentiate unipolar depression (Major Depressive Disorder) from bipolar depression.

And in 1980, with the publication of the third edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM), the term manic depression was officially changed in the classification system to bipolar disorder.

In the last few decades the medical profession (psychiatry specifically) has made a concerted effort to shift the vernacular to the official DSM diagnostic term of bipolar disorder.