The form of the disorder that Jackson has, called bipolar II depression, is a treatable one that afflicts many Americans who are still able to live successful, fruitful lives in spite of it, the clinic says.
The Chicago congressman, eldest son of civil rights pioneer the Rev. Jesse Jackson -- is "responding well to the treatment and regaining his strength," according to the Mayo Clinic statement.
Jackson has been on medical leave from his U.S. House seat since June 10, and until recently it was not even publicly known where he was, until his family announced he was undergoing medical treatment at the Mayo Clinic, according to USA Today.
The Mayo Clinic provided several paragraphs of information about Jesse Jackson Jr.'s health as well as the diagnosis itself. Bipolar depression disorder is an oft-misunderstood ailment unfamiliar to many Americans.
"Bipolar II disorder is a treatable condition that affects parts of the brain controlling emotion, thought and drive and is most likely caused by a complex set of genetic and environmental factors. Congressman Jackson underwent gastric bypass surgery in 2004. This type of surgery is increasingly common in the US and can change how the body absorbs food, liquids, vitamins, nutrients and medications," the Mayo Clinic wrote in its statement.
"Congressman Jackson has asked Mayo Clinic to distribute this information on his behalf. He and his family remain grateful for support and prayers offered and received on his behalf. Note: No time frame is specified for another update on Congressman Jackson's condition."
WebMD describes bipolar II disorder as less crippling than bipolar I disorder:
"Bipolar II is similar to bipolar I disorder, with moods cycling between high and low over time. However, in bipolar II disorder, the 'up' moods never reach full-on mania. The less-intense elevated moods in bipolar II disorder are called hypomanic episodes, or hypomania," WebMD explains.
"A person affected by bipolar II disorder has had at least one hypomanic episode in life. Most people with bipolar II disorder also suffer from episodes of depression. This is where the term 'manic depression' comes from. In between episodes of hypomania and depression, many people with bipolar II disorder live normal lives."
The effects of a hypomanic episode often include rapid, forceful and loud speech, a quick flitting between disparate ideas and increased energy, hyperactivity and lack of need for sleep, according to WebMD.
Treatments for bipolar II disorder are mainly medication-based, and can include the administration of mood stabilizers, antipsychotics, benzodiazepines, antidepressants, according to WebMD.