Understanding Bipolar II Disorder and Bipolar Disorder NOS

Bipolar II disorder and bipolar disorder not otherwise specified (NOS) are subtypes of bipolar disorder, a mental health condition marked by recurring episodes of depression and elevated mood states such as hypomania or mania. Each subtype presents with distinct patterns of symptoms and levels of severity. Understanding their differences, common causes, diagnostic criteria, and treatment options is essential for accurate diagnosis and effective care.

Bipolar II Disorder and Bipolar Disorder NOS

Bipolar disorder is a type of mood disorder involving significant shifts in energy, functional ability, and mood. The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) lists three main subtypes of bipolar disorder: bipolar I, bipolar II, and cyclothymic disorder. It also notes several less common subtypes: ^[1]

• Substance/medication-induced bipolar and related disorder
• Bipolar and related disorder due to another medical condition
• Other specified bipolar and related disorder
• Unspecified bipolar and related disorder

The two final subtypes in the list above were previously referred to as “bipolar disorder not otherwise specified” or “bipolar disorder NOS” in earlier editions of the DSM. They are sometimes collectively called “other specified and unspecified bipolar and related disorders.”

Distinctions Between Bipolar Disorder Subtypes

Each of the subtypes of bipolar disorder involves both depressive episodes and manic or hypomanic episodes. However, each subtype has its distinct characteristics.

Bipolar I is characterized by manic and major depressive episodes, while bipolar II involves hypomanic and major depressive episodes. Cyclothymic disorder is viewed as a milder form of bipolar disorder, with less severe fluctuations between mild depression and hypomania.^[2]

Bipolar disorder not otherwise specified, now split into two diagnoses called “other specified bipolar and related disorder” and “unspecified bipolar and related disorder,” can be diagnosed when a person has bipolar disorder symptoms that don’t meet the full criteria for any of the other subtypes. These disorders are most frequently diagnosed in children and can serve as placeholders while more information about symptoms is gathered.

What Is Bipolar II Disorder?

Bipolar II, which people sometimes refer to as “bipolar 2” or “bipolar type 2,” consists of alternating depressive and hypomanic episodes. The primary difference between bipolar I and bipolar II is that bipolar I involves manic episodes that impact a person’s ability to function in daily life, and bipolar II involves less severe hypomanic episodes. Those with bipolar II also tend to spend more time in episodes of depression than those with bipolar I. To be diagnosed with bipolar II, a person must have experienced both a hypomanic episode and a major depressive episode ^[1]. 

Most people with bipolar II seek professional help during a depressive episode. They may view hypomanic symptoms positively or fail to recognize that they are signs of a mental health condition. However, the loved ones of individuals with bipolar II may have concerns about their erratic or impulsive behavior during hypomanic episodes.

The DSM-5 states that the international 12-month prevalence of bipolar II is 0.3%. In the United States, this number rises to 0.8%. Most people with bipolar II develop the disorder in their mid-20s ^[1]. 

Symptoms of Bipolar II Disorder

People with bipolar II disorder experience alternating episodes of depression and hypomania—an elevated mood state that is less intense than full mania. These mood shifts can disrupt daily functioning, relationships, and overall well-being, even if the hypomanic episodes don’t require hospitalization.

Hypomanic Symptoms

A hypomanic episode must last at least four consecutive days and is characterized by noticeable changes in mood and behavior. Common symptoms include: ^[3]

• Elevated or irritable mood
  
• Increased energy or restlessness
  
• Inflated self-esteem or grandiosity
  
• Decreased need for sleep
  
• Talking more than usual or feeling pressure to keep talking
  
• Racing thoughts or flight of ideas
  
• Easily distracted
  
• Increase in goal-directed activity (social, occupational, educational)
  
• Engaging in impulsive or risky behavior, such as overspending, unsafe sex, or reckless driving
  

It’s important to distinguish hypomania from mania. Hypomania does not involve psychotic symptoms (like delusions or hallucinations), does not lead to hospitalization, and generally does not cause severe impairment in social or work life. The presence of psychosis or a need for hospitalization would instead suggest a diagnosis of bipolar I disorder ^[1]. 

Individuals with bipolar II disorder often experience major depressive episodes that last at least two weeks. These episodes can be deeply disruptive, affecting daily life, relationships, and overall functioning ^[3]. Common symptoms include:

• Persistent low mood, including feelings of sadness, emptiness, or hopelessness
  
• Anhedonia, or a loss of interest and pleasure in activities once enjoyed
  
• Significant changes in appetite, which may result in weight loss or gain
  
• Sleep disturbances, including insomnia or oversleeping
  
• Physical restlessness or noticeable slowing of speech and movement
  
• Fatigue or low energy
  
• Feelings of worthlessness, guilt, or self-blame
  
• Difficulty focusing, remembering details, or making decisions
  
• Recurrent thoughts of death or suicide*
  

Some individuals may also experience “mixed episodes,” where features of both depression and hypomania occur simultaneously. In between episodes, individuals often return to a neutral or baseline mood. Those who experience four or more mood episodes in a year may be diagnosed with “bipolar II disorder with rapid cycling” ^[1]. 

*If you or someone you know is struggling, the Suicide and Crisis Lifeline is available 24/7 at 988.

Bipolar Disorder Not Otherwise Specified (NOS)

The most recent edition of the DSM changed the diagnosis of bipolar disorder not otherwise specified or bipolar NOS. It was replaced with the subtypes “other specified bipolar and related disorder” and “unspecified bipolar and related disorder.” Both of these disorders involve symptoms associated with bipolar disorder that do not meet the full criteria for bipolar I, bipolar II, or cyclothymic disorder.

Other specified bipolar and related disorders are diagnosed when the clinician identifies the reason that the individual’s symptoms do not meet the criteria for other types of bipolar disorder. For example, they might determine that their client has experienced short-duration hypomanic and depressive episodes (less than four days and less than two weeks, respectively) or that they have experienced a hypomanic episode but haven’t experienced a depressive episode ^[1]. 

With unspecified bipolar and related disorder, the clinician does not specify why the individual’s symptoms do not meet the criteria for other types of bipolar disorder. This subtype is often diagnosed in emergency room settings where the clinician may not have enough information to provide a more specific diagnosis ^[1]. 

For both of these diagnoses, individuals experience symptoms characteristic of bipolar disorder that lead to significant distress and impairment. It’s common for people who are initially given these diagnoses to receive later a diagnosis of bipolar I, bipolar II, or cyclothymia. For instance, in a 2014 study, one-third of participants converted from a diagnosis of bipolar NOS to bipolar I or bipolar II over 18 months ^[4]. 

Causes of Bipolar II and Bipolar NOS

While specific causes of bipolar II and bipolar NOS (now called “other specified and unspecified bipolar and related disorders”) have not yet been identified, several risk factors appear to increase a person’s chance of developing these disorders.

Biological factors, such as having a close relative with bipolar disorder, tend to increase a person’s risk of developing bipolar disorder themselves. Around 80% to 90% of those with bipolar disorder have a relative with either depression or bipolar disorder. A family history of other mood disorders, psychotic disorders, or substance use disorders can also increase a person’s risk ^[5].  

Environmental factors also play a role in the development of bipolar II and other specified and unspecified bipolar and related disorders, particularly in individuals who are already genetically vulnerable. Environmental factors include stress, substance use, sleep disruptions, and childhood trauma. Certain variations in brain structure and function are also thought to contribute to bipolar disorder ^[3][6]. 

Having these risk factors does not mean a person is guaranteed to develop bipolar disorder. Instead, it increases their chance of developing the disorder.

Diagnosing Bipolar Disorder

The diagnostic processes for bipolar II disorder and other specified and unspecified bipolar and related disorders are similar. In most cases, a doctor performs a physical exam and runs tests to rule out any physical health problems that could be contributing to a person’s mental health symptoms. A licensed mental health specialist then asks about the individual’s mental health history, family history, and past and current symptoms.

Differential Diagnosis

Mental health professionals typically use the diagnostic criteria in the DSM-5 to conduct a differential diagnosis, meaning that they rule out other mental health disorders that have symptoms in common with bipolar disorder.

For bipolar II, clinicians must consider whether their client’s symptoms more closely match the diagnostic criteria for the following mental health conditions: 

• Bipolar I disorder
• Cyclothymic disorder
• Major depressive disorder
• Schizophrenia and other psychotic disorders
• Panic disorder and other anxiety disorders
• Substance use disorders
• Attention-deficit/hyperactivity disorder (ADHD)
• Personality disorders

Co-Occurring Disorders

It’s not uncommon for individuals with bipolar II disorder to experience other mental health conditions at the same time, a phenomenon known as comorbidity or co-occurring disorders. These overlapping diagnoses can complicate both diagnosis and treatment, requiring a more comprehensive and individualized approach to care.

Common co-occurring conditions include anxiety disorders, such as generalized anxiety disorder (GAD), panic disorder, and social anxiety. These can intensify the emotional instability associated with bipolar II, potentially increasing the risk of depressive episodes. Substance use disorders are also prevalent, as individuals may turn to drugs or alcohol to manage difficult moods, leading to cycles of self-medication and worsened symptoms.

Eating disorders, such as bulimia or binge eating disorder, and attention-deficit/hyperactivity disorder (ADHD) may also co-occur with bipolar II. These additional diagnoses can impact concentration, impulse control, and self-esteem, making mood regulation even more challenging.

Effective treatment plans should address all co-occurring conditions simultaneously to improve overall outcomes and reduce the risk of relapse or complications ^[7].

Diagnosing Other Specified and Unspecified Bipolar and Related Disorders

When a person’s symptoms are characteristic of bipolar disorder but don’t meet the specific criteria for any of the subtypes, they may be given a diagnosis of other specified bipolar and related disorder (if the clinician determines the reason why their symptoms don’t meet diagnostic criteria) or unspecified bipolar and related disorder (if the clinician does not specify their reasoning).

Individuals who are given these diagnoses, which previously fell under the bipolar NOS umbrella, are often diagnosed with other disorders over time as clinicians gain more information about their symptoms and history.

Treatment for Bipolar II and Bipolar NOS

The primary approach to treating bipolar II disorder and bipolar disorder not otherwise specified (NOS) involves a combination of medication and psychotherapy. This dual approach addresses both mood stabilization and the development of coping strategies to manage symptoms effectively ^[8].

Medication for Bipolar II and Bipolar NOS

Medication is typically the first line of treatment for both bipolar II disorder and bipolar disorder NOS, as it plays a critical role in stabilizing mood and preventing future episodes ^[7]. Common pharmacological interventions include:

Mood stabilizers: For example, lithium, have been widely used for decades to reduce the frequency and severity of mood swings. Lithium is especially effective at preventing depressive episodes and reducing the risk of suicide.

Anticonvulsants: Lamotrigine and valproate, are also prescribed as mood stabilizers. These medications are often used when lithium is not well tolerated or ineffective. Lamotrigine, in particular, is considered beneficial for bipolar II, as it may be more effective in preventing depressive episodes than hypomanic ones.

Atypical antipsychotics: Quetiapine or lurasidone, are sometimes used alone or in combination with mood stabilizers. These medications help manage both mood symptoms and accompanying anxiety or sleep issues.

Antidepressants: These may be prescribed during depressive episodes, but with caution. When used alone, antidepressants can trigger hypomanic symptoms. To mitigate this risk, they are typically paired with a mood stabilizer or antipsychotic to prevent a switch to a hypomanic state.

Medication plans are highly individualized and often require ongoing adjustments. Regular follow-up with a psychiatrist is essential to monitor effectiveness, manage side effects, and maintain long-term stability.

Talk Therapy for Bipolar II and Bipolar NOS

Psychotherapy is a vital component of a comprehensive treatment plan for bipolar disorders. It helps individuals manage symptoms, build coping skills, and improve overall functioning ^[8]. Several evidence-based approaches are particularly effective:

• Cognitive Behavioral Therapy (CBT): CBT focuses on identifying and challenging unhelpful thought patterns that contribute to emotional distress. It teaches individuals how to change these thoughts and develop healthier behavioral responses to mood shifts.
  
• Dialectical Behavior Therapy (DBT): Originally developed for borderline personality disorder, DBT has shown benefits for bipolar disorder by teaching skills for managing distress, regulating emotions, and improving interpersonal relationships.
  
• Interpersonal and Social Rhythm Therapy (IPSRT): IPSRT emphasizes the importance of maintaining consistent daily routines, including sleep, meals, and activity levels. Stabilizing these rhythms can reduce the likelihood of mood episodes.
  
• Family-Focused Therapy (FFT): FFT involves both the individual and their family members. It educates loved ones about bipolar disorder and helps improve communication and problem-solving within the family unit, fostering a supportive home environment.
  

These therapies not only provide emotional support but also equip individuals with practical tools to navigate the challenges of living with bipolar disorder.

​​Other Treatment Options for Bipolar II and Bipolar NOS

Beyond medication and talk therapy, several additional treatment options may be used to manage bipolar disorder symptoms, particularly when traditional approaches are not fully effective.

• Electroconvulsive Therapy (ECT): ECT involves brief electrical stimulation of the brain while the patient is under anesthesia. It is generally reserved for individuals with severe depression or treatment-resistant bipolar disorder. ECT can be highly effective, especially when rapid symptom relief is needed or when medications are not tolerated well ^[7].
  
• Repetitive Transcranial Magnetic Stimulation (rTMS): rTMS is a noninvasive procedure that uses magnetic fields to stimulate nerve cells in the brain. It is typically used for depression and offers a less invasive alternative to ECT with fewer side effects, making it a viable option for some individuals with bipolar depression.
  
• Light Therapy: While commonly associated with seasonal affective disorder (SAD), light therapy may also benefit individuals with bipolar depression that worsens during specific times of the year. It involves exposure to a light box that mimics natural sunlight to help regulate mood-related biological rhythms.
  

These alternative treatments can complement traditional therapy and medication, especially in complex or hard-to-treat cases.

Living Well with Bipolar II or Bipolar NOS

Although bipolar disorder is a lifelong condition, individuals with bipolar II, other specified, and unspecified bipolar and related disorders can manage their symptoms effectively and lead fulfilling, productive lives. With a combination of medical treatment, therapy, and healthy lifestyle habits, long-term stability is achievable.

The Importance of Ongoing Treatment

Consistent adherence to treatment is essential, even during symptom-free periods. Medications should be taken as prescribed, and regular therapy sessions should continue to help monitor and manage mood changes. If a particular medication or therapy isn’t providing relief, it’s important to consult a healthcare provider rather than discontinuing treatment. Many therapeutic options are available, and adjustments can be made to better suit individual needs.

Lifestyle Strategies for Mood Stability

Healthy habits support overall well-being and can enhance the effectiveness of treatment. Key lifestyle modifications include:

• Maintaining a consistent sleep schedule, aiming for 7–9 hours nightly
  
• Eating balanced, nutritious meals
  
• Reducing or eliminating caffeine and alcohol
  
• Staying hydrated and physically active
  
• Spending time outdoors
  
• Engaging in hobbies that bring joy and relaxation
  

Support Systems and Self-Compassion

Strong support networks can make a meaningful difference. Spending time with trusted friends and family and seeking support when needed can ease emotional burdens. Mood tracking may also help individuals identify early warning signs of mood shifts and maintain better control over symptoms.

Above all, practicing self-compassion is essential. Progress may come gradually and unevenly, but help is available, and recovery is possible. With the right support and strategies, those living with bipolar II and related conditions can thrive.

Understanding and Managing Bipolar II and Bipolar NOS

Bipolar II disorder and bipolar disorder not otherwise specified (NOS) are complex mental health conditions that require accurate diagnosis and individualized treatment. Distinguishing between these subtypes is essential for appropriate intervention, as untreated symptoms can significantly impair daily functioning and may lead to complications such as rapid cycling or heightened suicidal risk.

Effective management of these disorders typically involves a combination of medication, psychotherapy, and lifestyle adjustments. Regular collaboration with healthcare professionals ensures treatment plans remain responsive to the individual’s evolving needs. Early intervention and consistent care play a critical role in symptom stabilization and long-term well-being.

For individuals experiencing signs of bipolar disorder, timely consultation with a mental health professional can provide the guidance and support needed for recovery. With comprehensive care and ongoing support, those living with bipolar II and bipolar NOS can achieve stability and lead fulfilling, meaningful lives.