Bipolar Disorder Not Otherwise Specified (NOS)

Bipolar disorder not otherwise specified (NOS) is one of those psychiatric terms that can cause more confusion than clarity, especially to the person being diagnosed. Bipolar disorder NOS is usually diagnosed when a patient shows some symptoms of bipolar disorder but doesn't necessarily meet all the criteria as outlined in the Diagnostic and Statistical Manual of Mental Disorders.

The term bipolar disorder NOS was used in the fourth edition of the DSM (DSM-IV); however, the DSM-5 actually uses the terms "unspecified bipolar and related disorder" or "other specified bipolar and related disorder" to diagnose conditions that were previously called bipolar disorder NOS.

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.

By assigning the NOS diagnosis now, the person will be less likely to slip through the cracks should another mood episode occur.

Still, there remains contention in the psychiatric community as to whether bipolar disorder NOS is a valid diagnosis or if it may lead to the premature treatment or over-treatment of an otherwise presumptive illness.

Unspecified vs. Specified Bipolar Disorder

As mentioned, the American Psychiatric Association (APA) prefers the terms unspecified or other specified for bipolar disorder to better reflect the uncertainty of the diagnoses. (The terms unspecified and other specified are also used for types of depressive disorders in the DSM-5).

Other specified bipolar disorder may be diagnosed when a person displays specific symptoms of bipolar (such as manic and/or depressive episodes), but the full criteria for those symptoms aren't met.

Unspecified bipolar may be the diagnosis when a person's symptoms resemble the symptoms of bipolar disorder, but the clinician chooses not to specify the reason the criteria are not met for a specific bipolar disorder, such as in an emergency room where there is insufficient information to make a more specific diagnosis.

Diagnostic Criteria

The Diagnostic and Statistical Manual of Mental Disorders (DSM) issued by the APA does provide examples as to when it may be appropriate to diagnose bipolar disorder NOS (or other specified/unspecified):

• 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.

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 disruptive mood dysregulation disorder (DMDD), 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, DMDD does not have distinct manic episodes but is rather defined by the persistence of irritability and temper. Current research strongly suggests that DMDD is, in fact, not a form of bipolar disorder and that children with DMDD are not at a particularly high risk of developing bipolar disorder as they get older.

Treatment

Specific treatments for bipolar disorder NOS are not as well researched. However, they are generally the same as for other bipolar and related disorders—including mood stabilizers and psychotherapy.

Most experts agree that psychotherapy can be beneficial to anyone deemed at risk of developing symptoms of bipolar disorder, ideally starting early.

A Word From Verywell

While the NOS diagnosis can be frustrating for anyone looking for a more definitive diagnosis for their mood symptoms, it is often about your clinician trying to be precise in the application of established diagnostic criteria for particular disorders. Often, the diagnosis will become clearer over time. For example, it is not uncommon that someone initially diagnosed with a depressive disorder may ultimately turn out to have a bipolar and related disorder diagnosis at some point down the road.