What Is Bipolar Disorder Not Otherwise Specified (NOS)?

A diagnosis suggestive rather than indicative of bipolarity

Young woman reclining on couch, psychologist looking at her in background.
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Bipolar disorder not otherwise (NOS) is one of those psychiatric terms that can cause more confusion than clarity, especially to the person being diagnosed. Like schizoaffective disorder (a condition that falls somewhere in between schizophrenia and bipolar disorder), bipolar disorder NOS is not really even a presumptive diagnosis but rather one that suggests you are at risk of developing bipolar disorder.

What Not Otherwise Specified Means

Bipolar disorder NOS is more of a catch-all category than an actual type of bipolar disorder. Your doctor may use the classification to document symptoms which are consistent with bipolar disorder but fall short of the criteria needed to make a definitive diagnosis.

In general, NOS is most commonly ascribed when a mood disorder is characterized by depression alternating with short episodes of hypomania (a milder form of mania). Oftentimes, the mood swings are rapid, occurring within days of each other. By and large, children and adolescents are most frequently diagnosed with NOS as they will be least likely to have a previous history of mood dysfunction.

From a psychiatric standpoint, bipolar disorder NOS is taken just as seriously as any other form of mood disorder. At its very heart, it presumes that there is a problem and that it will be likely be definitively diagnosed in the future. By assigning the NOS diagnosis now, the person will be less likely to slip through the cracks should another mood episode occur.

With that being said, there remains contention in the psychiatric community as to whether bipolar disorder NOS is a valid and diagnosis or if it may lead to the premature treatment or overtreatment of an otherwise presumptive illness.

As such, the American Psychiatric Association (APA) prefers the term unspecified bipolar disorder and unspecified depressive disorder to better reflect the uncertainty of the diagnosis.

Diagnostic Criteria for Bipolar Disorder NOS

There are no specific criteria as to when a doctor should make a bipolar NOS diagnosis. With that being said, the Diagnostic and Statistical Manual of Mental Disorders (DSM) issued by the APA does provide examples as to when it may be appropriate:

  • The person has experienced alternating manic or depressive symptoms, but the episodes are too short to meet the criteria for inclusion.
  • The person has experienced both hypomania and depression, but the episodes are too short to qualify as a cyclothymic disorder.
  • The person may have had multiple episodes of hypomania but no depressive episode.
  • The person has had a manic or mixed episode after having been previously diagnosed with either schizophrenia or a psychotic episode.
  • The person meets the criteria for bipolar disorder, but the doctor is concerned that the symptoms may be caused by recreational drugs, alcohol, or a neurological disorder.

Differential Diagnoses

Any informed diagnosis of bipolar disorder NOS would involve a review of all other possible causes.

In the event that substance abuse or an undiagnosed medical condition is suspected, further investigations may be ordered, including blood tests, a drug screen, neurological imaging, or other diagnostic techniques to identify an infection, injury, or malignancy.

The doctor should also consider other psychiatric conditions that closely mimic bipolar disorder NOS. One such example is a severe mood dysregulation (SMD), a condition seen in children and adolescents which is characterized by a persistently irritable or angry mood accompanied by frequent temper outbursts that are disproportionate to the situation.

Unlike bipolar disorder NOS, SMS does not have distinct manic episodes but is rather defined by the persistence of irritability and temper. Current research strongly suggests that SMD is, in fact, not a form of bipolar disorder and that children with SMD are not at high risk of developing bipolar disorder as they get older.

By contrast, bipolar NOS is commonly regarded as a precursor to either bipolar I or bipolar II disorder.

Treatment of Bipolar Disorder NOS

There is no established treatment plan for bipolar disorder NOS. As such, the treatment would be largely based on a doctor's clinical experience and the appropriate use of medications (including mood stabilizers and atypical antipsychotics) and psychotherapy.

Currently, there is little evidence on how to appropriately treat bipolar disorder NOS or whether treatment would offer any benefit compared to a watch-and-wait approach. With that being said, most experts agree that psychotherapy can be beneficial to anyone deemed at risk of developing full-blown symptoms of bipolar disorder, ideally start early.

A Word From Verywell

While the NOS diagnosis can be frustrating for anyone looking for a definitive cause of their mood symptoms, it's important to remember that it is often better to monitor a condition than rush into treatment that could expose a person to drugs he or she may not need.

It is a situation commonly seen when someone with bipolar disorder is misdiagnosed with depression. When this happens, the person may be wrongly treated with antidepressants and experience an acute manic episode.

In the end, when it comes to offering a bipolar diagnosis, it is always better to take a conservative approach until you have a clearer sense of what you are dealing with.

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