What is bipolar disorder?

Bipolar Disorder: Definition and Clinical Features

Bipolar disorder is a recurrent and sometimes chronic mood disorder characterized by distinct episodes of mania or hypomania alternating with depression, with marked changes in mood, energy, behavior, and sleep patterns that represent a significant departure from the individual's baseline functioning. 1, 2

Types of Bipolar Disorder

• Bipolar I Disorder:

  • Requires at least one manic episode lasting ≥7 days (or any duration if hospitalization is required)
  • Characterized by euphoria, grandiosity, irritability, racing thoughts, and decreased need for sleep
  • Depressive episodes are common but not required for diagnosis 1, 2

• Bipolar II Disorder:

  • Requires periods of major depression and hypomania (episodes lasting ≥4 days)
  • No history of full manic or mixed episodes
  • Hypomania is similar to mania but less severe and doesn't cause marked impairment 1, 3

• Bipolar Disorder Not Otherwise Specified (NOS):

  • Used for cases that don't meet full criteria for other bipolar diagnoses
  • Often used to describe atypical presentations, particularly in youth 1

Clinical Manifestations

Manic Episodes

• Elevated, expansive, or irritable mood
• Increased energy and activity
• Decreased need for sleep (considered pathognomonic in adults)
• Racing thoughts and pressured speech
• Grandiosity and poor judgment
• Distractibility and flight of ideas
• Increased goal-directed activity or psychomotor agitation
• Excessive involvement in pleasurable activities with high potential for painful consequences 1, 4

Mixed Episodes

• Periods lasting ≥7 days where symptoms of both manic and depressive episodes are present
• Often characterized by irritability, agitation, and emotional lability 1, 2

Cycling Patterns

• Rapid cycling: ≥4 mood episodes in a year
• Ultrarapid cycling: 5-364 cycles per year (brief, frequent episodes lasting hours to days)
• Ultradian cycling: >365 cycles per year (repeated brief cycles occurring daily) 1

Epidemiology and Course

• Affects approximately 2% of the world's population 5
• Life expectancy is reduced by 12-14 years 2
• 1.6-2 fold increased risk of cardiovascular mortality 2
• Peak age of onset typically ranges from 15-30 years 1
• Approximately 20% of adult cases show evidence of illness before age 19 1
• Early-onset cases (before age 13) are predominantly male 2
• Approximately 75% of symptomatic time consists of depressive episodes or symptoms 2
• Strong genetic component with approximately 70% heritability 2
• Four to sixfold increased risk in first-degree relatives 2

Diagnostic Challenges

• Diagnosis is often delayed by approximately 9 years following initial episode 2
• Frequently misdiagnosed, particularly in adolescents with psychotic features who may be incorrectly diagnosed with schizophrenia 2
• Presentation in youth often differs from classic adult presentation:
  • More chronic difficulties regulating mood, emotions, and behavior
  • Erratic and explosive outbursts rather than clearly demarcated phases
  • Mixed episodes and irritability more common than euphoria
  • High rates of comorbid disruptive disorders 1
  • Less prominent sleep disturbance compared to adults 1

Treatment Implications

• Pharmacotherapy is the primary treatment for acute mania in bipolar I disorder
• First-line medications include lithium, valproate, and atypical antipsychotics 2
• Lithium is indicated for both acute manic episodes and maintenance treatment 4
• Lithium may produce normalization of symptoms within 1-3 weeks during manic episodes 4
• Monotherapy with antidepressants is contraindicated during mixed episodes, manic episodes, and in bipolar I disorder 6
• Psychotherapy is a useful adjunct to pharmacotherapy 6, 7

Comorbidities and Complications

• Higher rates of other mental health disorders and substance use disorders 6
• Increased risk of suicide, particularly during depressive and mixed episodes 5
• Childhood-onset cases are often more chronic and treatment-resistant 2
• Environmental factors like seasonal light changes and circadian disruption can trigger episodes 6

Bipolar disorder represents a complex and variable condition that requires careful diagnosis and comprehensive management to reduce the frequency and severity of episodes and improve long-term outcomes.