Falret then found that this link between depression and mania differed from the symptoms of pure depression. In 1875, he came up with the term "manic-depressive psychosis" for his new findings and listed it as a psychiatric disorder. Through his studies, he believed that the disorder was genetic because it existed in specific families. Many at the time were unable to see the differences between bipolar disorder and many other mental disorders. Francois Baillarger was able to site many differences between bipolar disorder and schizophrenia which lead to bipolar disorder being classified as a mental disorder by its own. Emil Krapelin formally established the term "manic-depressive" in 1913 due to his studies of the effects of depression along with mania. In 1952, "The Journal of Nervous and Mental Disorder" published an article stating the genetic factors of manic-depression, stating that it "ran in families". Around this time however, this disorder was still not gaining much acceptance and those diagnosed with it were merely institutionalized without treatment. The government rejected this disorder as a "legitimate illness" and did not support it financially. During the 1970's, certain laws were implemented in order to provide better care for those with manic-depression. The National Association of Mental Health (NAMI) was established in 1979 thus giving better governing over the illness. The term manic-depressive disorder was replaced with "bipolar disease" in 1980. Research has been carried out from then to the present concerning this disease. In the 1980's, researchers were able to find a difference between adult and child bipolar disease. The search for the causes and cure still remains. ("Brief History").
Many theories have been brought up concerning why people have bipolar disorder. However, every theory is merely an observation without conclusive proof that it holds true in all cases.