An Overview of Bipolar Disorder

Explore key differences between the types

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difference between bipolar i and bipolar ii
Illustration by Hugo Lin. © Verywell, 2018.

Bipolar disorder is a mental health condition defined by periods (better known as episodes) of extreme mood disturbances. Bipolar affects a person's mood, thoughts, and behavior. 

There are two distinct types of bipolar: bipolar I and bipolar II. According to the Diagnostic and Statistical Manual of Mental Disorders, bipolar I disorder involves episodes of mania and depression.

Bipolar II disorder involves a less severe form of mania called hypomania.


Despite the major difference when it comes to mania in the two types of bipolar disorder, there are quite a few similarities in symptoms.

Depressive Episodes

In bipolar I disorder, a major depressive episode (one or more) usually occurs, but it is not required. Bipolar II disorder involves one or more major depressive episodes. Common symptoms that occur in a major depressive episode include:

  • Insomnia or hypersomnia
  • Unexplained or uncontrollable crying
  • Severe fatigue
  • Loss of interest in things the patient enjoys during euthymia
  • Recurring thoughts of death or suicide

Both disorders include periods of euthymia—symptom-free or "normal" states.


Manic episodes last at least seven days. An individual experiencing a manic episode may experience:

  • Feelings of euphoria
  • Less need for sleep
  • Increased sexual desire
  • Hallucinations or delusions
  • Marked increase in energy

During a manic episode, individuals may engage in risky or reckless behavior. For example, someone may indulge in risky sexual behavior, spend excessive amounts of money, or make impulsive decisions.

It's important to note that experiencing mania does not automatically mean a person will become violent or dangerous.

Sometimes people assume a "manic episode" means someone turns into a "maniac." That's not true.


An individual experiencing a hypomanic episode may experience similar symptoms but their functioning won't be markedly impaired. Many individuals who experience hypomania associated with bipolar II enjoy the increased energy and decreased need for sleep.

An episode of hypomania does not escalate to a point that a person needs hospitalization, which may happen with a person experiencing mania—especially if he or she is becoming a danger to others and/or themselves.


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.


When diagnosing bipolar disorder (regardless of the type), a physician or clinician must rule out other illnesses such as schizoaffective disorderschizophrenia, delusional disorder, or schizophreniform disorder.

Bipolar disorder cannot be diagnosed like physiological illnesses where a blood test, X-ray, or physical exam can provide a definitive diagnosis. The diagnosis is based on a set of criteria that a person must meet in order to be considered bipolar.

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.


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:

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

Both Types Should Be Properly Treated

Since hypomania is less severe than the mania that occurs in bipolar I disorder, bipolar II is often described as "milder" than bipolar I—but this is not completely accurate. Certainly, people with bipolar I can have more serious symptoms during mania, but hypomania is still a serious condition that can have life-changing consequences and so should be properly addressed.

In addition, research suggests that bipolar II disorder is dominated by longer and more severe episodes of depression. In fact, over time, people with bipolar II become less likely to return to fully normal functioning between episodes.

One study specifically concluded that bipolar type II was linked to a poorer health-related quality of life compared to type I. This remained true even during long periods of euthymia.

Thus, experts tend to believe that bipolar II disorder is equally (if not more) disabling as bipolar I disorder because they are ill more often, have more lifetime days spent depressed, and don't do as well overall between episodes. Proper treatment should be determined for these situations.


As with many mental health conditions, bipolar disorder is associated with a certain stigma in society, which may make coping with the condition more difficult for you or a loved one. Know that stigma very often develops because of lack of knowledge—those who make comments or discriminate are usually ignorant or have fear based on what they think they know about the disorder.

Whether or not someone with bipolar faces stigma directly, know that the best way to cope with the condition is to connect with others who are experiencing it and get professional help. You can also fight stigma to help you cope better, and read up on your rights.

In Kids

Bipolar disorder can occur in kids of any age. It's important for parents and caregivers to be aware of the unique signs—they should pay attention to a child's functioning, feelings, and any family history of the disorder. With a timely diagnosis, a treatment plan for symptom management can be better established.

A Word From Verywell

Bipolar disorder is a complex mood disorder. If you are worried that you or a loved one has symptoms of a bipolar episode, seek medical attention for a proper evaluation.

Although bipolar is not curable, it is treatable. With the right medication and support, symptoms can be managed to the point where quality of life isn't drastically affected.


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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.

Swartz HA, Thase ME. Pharmacotherapy for the treatment of acute bipolar II depression: current evidence. J Clin Psychiatry. 2011 Mar;72(2):356-66.