Notes on Major Depressive Disorder and Bipolar Disorders

Major Depressive Disorder (MDD)

  • Definition: MDD is a mood disorder characterized by changes in cognition, behavior, and physical functioning.
  • Symptoms:
    • Depressed mood
    • Sadness and hopelessness
    • Sleep disturbances
    • Changes in appetite and weight
    • Loss of interest
    • Suicidal ideation
    • Difficulty concentrating
  • Prevalence: Affects approximately 151 million people worldwide, with a lifetime prevalence of 20.6% among U.S. adults (Hasin et al., 2018).
  • Treatment Gap: 80% to 90% can be treated effectively, but only one-third seek treatment.

Causes of MDD

  • Multifactorial nature involving physiological, social, genetic, environmental, and biochemical factors.
  • Genetic Risk: First-degree relatives have 2.8 times higher risk.
  • History of depression increases risk for future episodes significantly.

Pathophysiology of MDD

  • Focus on neurochemical aspects and neurotransmitters: serotonin and norepinephrine.
  • Theories:
    • Serotonin Hypothesis: Deficiency of serotonin.
    • Norepinephrine Hypothesis: Deficiency of norepinephrine.
    • Permissive Hypothesis: Low serotonin creates a context for depression.
    • Beta-Adrenergic Receptor Hypothesis: Increased sensitivity leads to depression.

Diagnostic Criteria (DSM-5)

  • At least five symptoms present during the same 2-week period, including:
    1. Depressed mood or irritability (in children/adolescents)
    2. Loss of interest
    3. Significant weight change
    4. Sleep disturbances
    5. Fatigue or loss of energy
    6. Feelings of worthlessness or guilt
    7. Difficulty concentrating
    8. Suicidal thoughts
  • Symptoms must cause clinically significant distress or impairment in functioning.

Types of Depression

  • Persistent Depressive Disorder (Dysthymia): Symptoms lasting 2 years but less severe.
  • Postpartum Depression: Onset within 6 weeks of childbirth, lasting from 3 to 14 months (5.2% to 74% prevalence).
  • Seasonal Affective Disorder (SAD): Recurrent episodes coincide with seasonal changes.
  • Melancholic Features: Severe impairment, harder to treat, but responds well to medication.
  • Psychotic Features: Depression with delusions or hallucinations.

Non-Pharmacologic Therapy

  • Psychotherapy:
    • Cognitive-Behavioral Therapy (CBT): Most common and effective, focusing on changing negative thoughts.
    • Interpersonal Therapy (IPT): Addresses social issues.
    • Problem-Solving Therapy: Identifying personal problems and formulating solutions.
  • Electroconvulsive Therapy (ECT): Used for severe cases unresponsive to other therapies.

Initiating Drug Therapy

  • Guideline Considerations: Severity, patient's history, comorbid conditions, and previous response to treatments.
  • Goals of Therapy: Promote full remission and minimize residual symptoms.
    • A response is defined as a 50% reduction in scores, while full remission means scoring less than 7 on the HAM-D.

Monitoring Patient Response

  • Phases of Treatment: Acute (8-12 weeks), Continuation (4-6 months post-remission), Maintenance (3-5 years or longer for high-risk patients).
  • Drug Modifications: Increase dosage, switch drugs, or augment with additional therapies if initial drugs are ineffective.

Antidepressant Drugs

  • Classes:
    • SSRIs: Selective Serotonin Reuptake Inhibitors; e.g., Fluoxetine, Sertraline.
    • SNRIs: Serotonin-Norepinephrine Reuptake Inhibitors; e.g., Venlafaxine, Duloxetine.
    • TCAs: Tricyclic Antidepressants; e.g., Amitriptyline, Nortriptyline.
    • MAOIs: Monoamine Oxidase Inhibitors; e.g., Phenelzine.
    • Atypicals: Bupropion, Mirtazapine.

Bipolar Disorder Overview

  • Definition: Characterized by manic and depressive episodes. Mania consists of elevated mood and activity; depression includes sadness and low energy.
  • Types:
    • Bipolar I: At least one manic episode.
    • Bipolar II: At least one major depressive episode and one hypomanic episode.
    • Cyclothymic Disorder: Subsyndromal depressive and hypomanic episodes lasting for at least 2 years.

Pharmacotherapy for Bipolar Disorder

  • Combination of mood stabilizers, anticonvulsants, antipsychotics, and antidepressants necessary for management.
  • Common Medications:
    • Lithium: First-line treatment.
    • Anticonvulsants: Carbamazepine, Lamotrigine.
    • Atypical Antipsychotics: Quetiapine, Olanzapine.
  • Considerations: Efficacy, tolerability, adverse effects, patient-specific needs.