What are the DSM-5 (Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition) criteria and treatment options for a patient suspected of having bipolar type II disorder?

DSM-5 Bipolar II Disorder Diagnostic Criteria

Core Diagnostic Requirements

Bipolar II disorder requires at least one major depressive episode AND at least one hypomanic episode, with no history of full manic episodes. 1, 2, 3

Hypomanic Episode Criteria

A hypomanic episode must include:

• Elevated, expansive, or irritable mood lasting at least 4 consecutive days, representing a clear departure from baseline functioning 2, 3
• At least three associated symptoms (four if mood is only irritable): grandiosity, decreased need for sleep, increased talking, racing thoughts, distractibility, increased goal-directed activity, psychomotor agitation, and excessive involvement in risky activities 2
• Observable change in functioning that is uncharacteristic of the person when not symptomatic, but NOT severe enough to cause marked impairment or require hospitalization 2
• Absence of psychotic features - the presence of psychosis automatically upgrades the diagnosis to Bipolar I disorder 2, 4

Major Depressive Episode Criteria

• At least 2 weeks of depressed mood or loss of interest, plus additional depressive symptoms meeting full DSM criteria 2, 3
• Depression is the dominant feature of Bipolar II, with depressive episodes outnumbering hypomanic episodes by approximately 39:1 3
• Mixed features (depressive symptoms with concurrent subsyndromal hypomanic symptoms like racing thoughts or increased energy) are common and should raise suspicion for bipolarity 5, 2

Critical Diagnostic Distinctions

Differentiating Hypomania from Mania

The key distinction between Bipolar I and Bipolar II centers on severity:

• Hypomania often increases functioning, whereas mania causes marked impairment requiring hospitalization 2
• Psychotic features are absent in hypomania but may be present in mania 2, 4
• Duration differs: hypomania requires 4 days minimum, mania requires 7 days 5

Hallmark Features to Assess

Focus screening on decreased need for sleep (feeling rested after only 2-4 hours), distinct episodic mood changes, and psychomotor activation - these differentiate bipolar disorder from other conditions 5, 1

• Grandiosity and irritability must represent marked changes from baseline, not reactions to situations or temperamental traits 5, 1
• Symptoms must occur in distinct episodes with clear periods of elevation alternating with baseline or depressed mood, not chronic irritability 5

Essential Diagnostic Assessment Components

Historical Information Required

• Document past psychiatric diagnoses and any prior misdiagnoses, particularly unipolar depression 5
• Antidepressant response history is critical - antidepressant-induced mood elevation or agitation strongly suggests underlying bipolarity, with approximately 20% of youths with major depression eventually developing manic episodes 5, 6
• Family psychiatric history, particularly of mood disorders, as first-degree relatives have a 4-6 fold increased risk 5
• Substance use history with toxicology screening to rule out substance-induced mood disorder 5

Longitudinal Assessment

• Create a life chart mapping symptom patterns, episode duration, severity, and treatment responses over time 5, 1
• Obtain collateral information from family members, as patients often lack insight during mood episodes and family can describe behavioral changes more objectively 5
• Document age of onset - symptoms must have some manifestation before age 12 per DSM-5 criteria, though full syndrome may emerge later 7

Screening for Comorbidities

• Assess suicidality thoroughly - Bipolar II has suicide completion rates at least equivalent to Bipolar I disorder 5, 3
• Screen for anxiety disorders and substance use disorders, which are highly comorbid 5, 3
• Evaluate for ADHD, PTSD, and disruptive behavior disorders, as manic symptoms must be differentiated from these conditions 5, 1
• Rule out borderline personality disorder - both share emotional dysregulation, affective instability, and impulsivity, but decreased need for sleep is hallmark of bipolar disorder whereas sleep problems in BPD relate to emotional distress 5

Medical Evaluation

• Complete medical workup including thyroid function tests, complete blood count, and comprehensive metabolic panel to exclude organic causes 5
• Vital signs and neurologic examination to identify medical conditions causing or exacerbating symptoms 5

Common Diagnostic Pitfalls

• Misdiagnosis as unipolar depression is extremely common because depressive episodes dominate the clinical picture and patients rarely seek treatment during hypomania 2, 3
• Overlooking hypomania when it increases functioning - patients and families may not report these periods as problematic 2
• Confusing chronic irritability (as in DMDD) with episodic mood changes - bipolar disorder manifests as distinct episodes, not persistent irritability 5
• Missing substance-induced presentations - always obtain toxicology and assess temporal relationship between substance use and mood symptoms 5
• Diagnostic caution in very young children (under age 6) - validity has not been established in this age group 5

Treatment Implications Following Diagnosis

First-Line Pharmacotherapy

• Quetiapine or lamotrigine are first-line treatments for bipolar depression 6
• Lithium has strong long-term evidence and is FDA-approved for bipolar disorder maintenance, reducing frequency and intensity of episodes 6, 8, 9
• Valproate is FDA-approved for acute mania and can be used as initial therapy 6

Critical Treatment Principles

• Antidepressant monotherapy is contraindicated in bipolar depression - if antidepressants are necessary for severe depression, they must be combined with a mood stabilizer 6, 2
• Treat hypomania even if associated with improved functioning, as depression often follows hypomania in the hypomania-depression cycle 2
• Continue mood stabilizer indefinitely given the chronic recurrent nature of bipolar disorder 6

Psychosocial Interventions

• Psychoeducation about symptoms, course, treatment options, impact on functioning, and heritability 1
• Relapse prevention education focusing on medication compliance, recognition of emergent symptoms, and factors precipitating relapse (sleep deprivation, substance abuse) 1
• Family-focused therapy and interpersonal/social rhythm therapy have demonstrated benefit 1