Understanding Bipolar I Disorder

A More Severe Form of Manic-Depressive Illness

Bipolar Disorder
Gerard Fritz Collection/Photographer's Choice/Getty Images

When we talk about bipolar disorder, we tend to think of it as one thing and one thing alone. But there are, in fact, different forms of the disorder which can vary by the frequency of mood swings and the severity of symptoms.

These differences are important as they help us determine the best form of treatment for the specific type of disorder. In some cases, it can be managed by support and counseling alone.

In others, it may require medication to help control the symptoms of the disease.

Bipolar I disorder is the most severe form of manic-depressive illness. It accounts a large proportion of disability claims in the U.S. and is currently the sixth leading cause of disability worldwide. All told, around 1.1 percent of the population meets the diagnostic criteria for bipolar I disorder compared to 2.4 percent for all other types.

Other types include bipolar II disorder (a milder form of the illness), cyclothymic disorder, and mixed features bipolar disorder.


While the exact cause of bipolar I disorder remains unclear, genetics is believed to play a major role. This is evidenced, in part, by studies of twins in which one or both had a bipolar I diagnosis. In 40 percent of maternal twins (those with identical gene sets), both twins were found to be bipolar compared to only five percent of fraternal twins (who had individual gene sets).

Other contributing factors include abnormalities in a person’s brain circuitry, irregularities in dopamine production, and environmental factors such as childhood trauma or abuse.


Bipolar disorder cannot be diagnosed like physiological illnesses where a blood test, X-ray, or physical exam can provide a definitive diagnosis.

Rather, diagnosis is based on a set of criteria that a person must meet in order to be considered bipolar.

Bipolar I disorder is characterized by the occurrence of at least one manic episode, usually in an association with one or more depressive episodes. One episode of mania without depression can be enough to make a diagnosis so long as there are no other causes for the symptoms (such as substance abuse, neurological problems, or other mood disorders like post-traumatic stress disorder). 

An informed diagnosis would include specific tests to exclude all other causes. This may involve a drug screen, imaging tests (CT scan, ultrasound), electroencephalogram (EEG), and a full battery of diagnostic blood tests.

Challenges of Bipolar I Diagnosis

While specific, the review of bipolar criteria is also highly subjective. As such, cases are often missed. One study, presented at the Royal College of Psychiatry’s Annual Meeting in 2009, reported that more than 25 percent of people with bipolar disorder were incorrectly diagnosed and treated when seeking help from a mental health professional.

On the flip side, over-diagnosis of bipolar disorder is also a concern, particularly if exclusionary tests have not been performed.

A 2013 review of clinical studies demonstrated that bipolar disorder was incorrectly diagnosed in:

  • 42.9 percent of substance abuse treatment centers
  • 40 percent of patients with borderline personality disorder
  • 37 percent of cases where a clinician inexperienced in bipolar disorder made the call

Without an exclusionary diagnosis, the likelihood of misdiagnosis and abuse is strong. A study released in 2010 showed that, of 528 people receiving Social Security disability for a bipolar disorder, only 47.6 percent met the diagnostic criteria.


Treatment of bipolar I disorder is highly individualized and based on the types and severity of symptoms a person may be experiencing.

Mood stabilizers are most often part of the treatment process and may include:

  • lithium, a mainstay of bipolar therapy
  • anticonvulsives used to stabilize mood swings
  • antipsychotics used to control psychotic symptoms such as delusions, hallucinations, and severe manic features
  • antidepressants (less commonly prescribed as they can trigger a manic episode)

In more severe cases, electroconvulsive therapy (ECT) may be used to create minor seizures which can help relieve mania or severe depression.


Culpepper, L. "The Diagnosis and Treatment of Bipolar Disorder: Decision-Making in Primary Care." Primary Care Companion CNS Disorders. 2014; 16(3): PCC.13r01609.

Datto, C. "Bipolar II compared with bipolar I disorder: baseline characteristics and treatment response to quetiapine in a pooled analysis of five placebo-controlled clinical trials of acute bipolar depression." Annals of General Psychiatry. 2016; 15:1–12.

Ghouse, A.; Sanches, M.; Zunta-Soares, G. "Overdiagnosis of Bipolar Disorder: A Critical Analysis of the Literature." Scientific World Journal. 2013; 2013:297087.