Bipolar Disorder vs. Depression: What’s the Difference?

These mood disorders are similar, but a key symptom sets them apart.

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Bipolar disorder might be known for causing two “extremes” of the mood spectrum—mania and depression—yet recognizing symptoms of bipolar disorder can still be challenging. Manic episodes often occur infrequently, and some types of manic symptoms (like impulsive spending) may fly under the radar to friends and family. In fact, to an outsider, someone’s bipolar disorder may seem indistinguishable from depression.

One possible reason for the confusion? Americans are more familiar with what depression looks like. Approximately 6.7 percent of adults in the United States have had at least one major depressive episode, while only 2.8 percent of U.S. adults have had bipolar disorder in the past year, according to the National Institute of Mental Health (NIMH).

“Bipolar disorder is a mental illness that involves both having had an experience of a manic episode, as well as experiencing depressive episodes,” says Susan Samuels, MD, psychiatrist at New York-Presbyterian Hospital, Weill Cornell Medicine. Learn more about the types of bipolar disorder here.

How Bipolar Differs from Depression

Since bipolar disorder and depression both include depressive symptoms, the difference really boils down to mania. It only takes one manic episode to classify someone as having bipolar disorder instead of depression.

“The difference between bipolar disorder and depression is [the] presence of a manic episode,” says Ben Michaelis, PhD, a psychologist in New York City. “Once you have a manic episode, [the diagnosis] moves immediately from a depressive disorder to a bipolar disorder.”

Manic episodes can fall on a spectrum of severity. What most people consider a manic episode is actually on the severe end of the spectrum. Here are symptoms of a severe manic episode, according to Dr. Samuels:

  • Extreme distractibility

  • Impulsivity

  • Speaking fast

  • Not needing sleep

  • Feeling invincible and on top of the world

But someone with bipolar depression may also experience hypomanic episodes, which are much less severe and may be less obvious to outsiders—or even to the person experiencing them. Being easily agitated, having trouble with budgeting, racing thoughts, or poor sleep habits are all signs of a hypomanic episode.

Someone with depression, on the other hand, doesn’t flip to mania. “Depression is unipolar depression, meaning you only go to the one pole of low mood,” says Gail Saltz, MD, psychiatrist at New York-Presbyterian Hospital, Weill Cornell Medicine. Learn more about the symptoms of depression here.

Why Knowing the Difference Really Matters

Despite the similarities in the two mood disorders, recognizing bipolar disorder is critical and even lifesaving. Severe manic episodes can be destructive and dangerous, and dealing with them can be exhausting.

Among those with bipolar disorder, more than 80 percent experience “serious impairment” that affects their personal and professional lives, according to the NIMH, which is the highest among all mood disorders. This means treating bipolar disorder demands careful methods and targeted medication.

“Medications that you choose that might treat the depressive episode can cause one to move into a hypomanic state if you are not aware that you have bipolar disorder,” explains Dr. Saltz. Instead of antidepressants, doctors may prescribe mood stabilizers or antipsychotic drugs for someone with bipolar disorder.

If you have depression or bipolar disorder and are experiencing thoughts of self-harm or suicide, call 911, go to the emergency room, or call the National Suicide Prevention Lifeline: 1-800-273-8255.