Mood Disorders

Must know

• MDD Diagnostic CriteriaDiagnostic Timeline and Threshold: Diagnosis requires 5 or more of 9 symptoms present nearly every day during the same 2-week period, representing a distinct change from previous functioning.

  • Diagnostic Timeline and Threshold: Diagnosis requires 5 or more of 9 symptoms present nearly every day during the same 2-week period, representing a distinct change from previous functioning.
  • Core Symptom Requirement: At least 1 of the 5 required symptoms must be either depressed mood or anhedonia (loss of interest or pleasure).
  • Key Mnemonic: The SIG E CAPS mnemonic summarizes the 9 diagnostic criteria: Sleep changes, Interest loss, Guilt or worthlessness, Energy loss, Concentration impairment, Appetite or weight changes, Psychomotor retardation or agitation, and Suicidal ideation.
  • Epidemiology Metrics: Lifetime prevalence is 12 percent, with a 2 to 1 female-to-male ratio. Prevalence in young adults aged 18 to 29 is 3 times higher than in adults over 60, with a mean onset between 20 and 35 years.
  • Heritability and Inpatient Risk: Heritability is 40 percent with a 2 to 4 times higher risk in first-degree relatives. Medical inpatients carry a 15 percent higher risk of major depressive disorder than the general population.
  • Prognosis and Bipolar Conversion: Untreated episodes last 6 to 13 months, and 50 percent of hospitalized patients recover within 1 year. Crucially, 5 to 10 percent of patients initially diagnosed with major depressive disorder develop a manic episode 6 to 10 years later.
• Core Symptom Logic and ScreeningThe initial evaluation relies on screening for depressed mood and anhedonia.

  • The initial evaluation relies on screening for depressed mood and anhedonia.
  • Using the PHQ-2 screening tool, if a patient denies both depressed mood and loss of interest or pleasure, major depressive disorder is ruled out.
  • A patient can deny feeling sad, down, or blue, but if anhedonia is present along with 4 other qualifying criteria, the full diagnostic threshold for a major depressive episode is satisfied.
• SIG E CAPS Criteria BreakdownSleep: Insomnia or hypersomnia where sleep fails to feel restorative.

  • Sleep: Insomnia or hypersomnia where sleep fails to feel restorative.
  • Interest: Depressed mood or anhedonia. Mood often shows a marked diurnal variation, presenting worst in the morning and improving as the day progresses. In children and adolescents, irritability serves as a diagnostic depression equivalent.
  • Guilt: Feelings of worthlessness or excessive, inappropriate, and potentially delusional guilt.
  • Energy: Severe fatigue, lack of ambition, or feeling physically drained.
  • Concentration: Diminished ability to think clearly, indecisiveness, or memory complaints that can mimic pseudodementia in older adults.
  • Appetite: Significant weight loss or weight gain, loss of food enjoyment, or failure to achieve expected weight gain in pediatric patients.
• Clinical SignpostsScreen every patient presenting with depressive symptoms for a past history of mania or hypomania to rule out bipolar disorder before starting treatment.

  • Screen every patient presenting with depressive symptoms for a past history of mania or hypomania to rule out bipolar disorder before starting treatment.
  • Continuously assess for suicidal ideation and active plans. Passive thoughts of death are most common, but active intent requires immediate safety planning and potential inpatient admission.
  • Bereavement is not an automatic exclusion for a major depressive episode, nor is altered mood from bereavement a diagnostic criterion itself. Clinical judgment is required to distinguish normal grief from a major depressive episode.

  Board trap. Bereavement is not an automatic exclusion for a major depressive episode, nor is altered mood from bereavement a diagnostic criterion itself. Clinical judgment is required to distinguish normal grief from a major depressive episode.

  Safety. Continuously assess for suicidal ideation and active plans. Passive thoughts of death are most common, but active intent requires immediate safety planning and potential inpatient admission.

• Epidemiology and Clinical CoursePrevalence: Lifetime prevalence is 12 percent. Women are affected at twice the rate of men.

  • Prevalence: Lifetime prevalence is 12 percent. Women are affected at twice the rate of men.
  • Age Dynamics: Prevalence in adults aged 18 to 29 is 3 times higher than in adults over age 60. The mean age of onset is between 20 and 35 years.
  • Medical Comorbidity: Medical inpatients have a 15 percent higher prevalence of major depressive disorder than the general population. Common psychiatric comorbidities include ADHD, anxiety disorders, PTSD, conduct disorder, learning disabilities, and substance use disorders.
  • Genetics: Heritability is estimated at 40 percent. First-degree relatives face a 2 to 4 times higher risk than the general population.
  • Prognosis: Untreated episodes last 6 to 13 months. Following hospitalization, 50 percent of patients recover within 1 year. Between 5 and 10 percent of patients with major depressive disorder will experience a manic episode 6 to 10 years after their initial depressive event.
• Rating Scales and Disability MetricsPHQ-9: Scores of 1 to 4 reflect minimal depression, 5 to 9 reflect mild depression, 10 to 14 reflect moderate depression, 15 to 19 reflect moderately severe depression, and 20 to 27 reflect severe depression.

  • PHQ-9: Scores of 1 to 4 reflect minimal depression, 5 to 9 reflect mild depression, 10 to 14 reflect moderate depression, 15 to 19 reflect moderately severe depression, and 20 to 27 reflect severe depression.
  • WHODAS: The World Health Organization Disability Assessment Schedule is a self-administered tool measuring functional disability across cognition, mobility, self-care, getting along with people, life activities, and participation in society. It replaces the obsolete Global Assessment of Functioning score.
• Differential DiagnosisMedical and Substance Rule-Outs: Always rule out direct physical causes such as hypothyroidism, cerebrovascular accidents, or Parkinson's disease, as well as substance-induced mood changes from alcohol, stimulants, or prescribed medications like steroids.

  • Medical and Substance Rule-Outs: Always rule out direct physical causes such as hypothyroidism, cerebrovascular accidents, or Parkinson's disease, as well as substance-induced mood changes from alcohol, stimulants, or prescribed medications like steroids.
  • Bipolar Spectrum: Differentiate unipolar depression from bipolar I disorder, bipolar II disorder, and cyclothymic disorder.
  • Other Depressive Conditions: Consider persistent depressive disorder (dysthymia, requiring depressed mood plus 2 symptoms for at least 2 years in adults or 1 year in children without symptom-free periods exceeding 2 months), adjustment disorder with depressed mood (symptoms within 3 months of an identifiable stressor not meeting full MDD criteria), premenstrual dysphoric disorder (luteal phase symptoms remitting around menses), and schizoaffective disorder.
• Which of the following statements is false regarding the diagnosis of major depression?A. More likely to occur in men than women

  • A. More likely to occur in men than women
  • B. Higher prevalence for whites than blacks
  • C. Lifetime prevalence is 12%
  • D. Risk factors include genetics and low education
• Which of the following is not a DSM-5-TR criterion for major depressive episode?B. Loss of food enjoyment

  • B. Loss of food enjoyment
  • D. Altered mood associated with bereavement
• Mnemonic: SIG E CAPSMajor depressive disorder diagnosis requires at least 5 of 9 criteria present nearly every day during a minimum 2-week timeline, with at least 1 core criterion being depressed mood or anhedonia.

  • Major depressive disorder diagnosis requires at least 5 of 9 criteria present nearly every day during a minimum 2-week timeline, with at least 1 core criterion being depressed mood or anhedonia.
  • The lifetime prevalence of major depressive disorder is 12%, with a 2-fold higher risk in women compared to men, and a 3-times higher prevalence in adults aged 18 to 29 compared to those over 60.
  • First-line screening utilizes the PHQ-2 (evaluating depressed mood and anhedonia) followed by the PHQ-9, where severity is scored as 5 to 9 for mild, 10 to 14 for moderate, 15 to 19 for moderately severe, and 20 to 27 for severe depression.
  • The SIG E CAPS mnemonic memory hook links the Latin prescription direction "sig" with "energy capsules" to systematically recall all 8 symptom domains.
  • Medical inpatients carry a 15% higher risk of major depressive disorder than the general population, and first-degree relatives have a 2-to-4 times higher genetic risk with a 40% heritability rate.
  • Screening for prior manic or hypomanic episodes is mandatory before confirming unipolar major depressive disorder or initiating psychotropics, as 5% to 10% of patients diagnosed with depression experience a manic episode 6 to 10 years later.

  Board trap. Assuming a patient cannot have major depressive disorder if they deny feeling sad or blue is a common error; meeting criteria through anhedonia plus 4 other symptoms satisfies the diagnosis.

  Safety. Screening for prior manic or hypomanic episodes is mandatory before confirming unipolar major depressive disorder or initiating psychotropics, as 5% to 10% of patients diagnosed with depression experience a manic episode 6 to 10 years later.

• Breakdown of the SIG E CAPS Symptom DomainsS - Sleep: Disturbance presenting as insomnia (difficulty falling asleep, middle awakening, or early morning awakening) or non-restful hypersomnia where the patient sleeps excessively but wakes unrefreshed.

  • S - Sleep: Disturbance presenting as insomnia (difficulty falling asleep, middle awakening, or early morning awakening) or non-restful hypersomnia where the patient sleeps excessively but wakes unrefreshed.
  • I - Interest: Anhedonia, defined as a marked loss of interest or pleasure in almost all daily activities. This domain also encompasses depressed mood, which often exhibits a distinct diurnal variation where patients feel most severe depression upon waking in the morning with slight improvement as the day progresses.
  • G - Guilt: Pathologic feelings of worthlessness, self-reproach, or excessive and inappropriate guilt that may reach near-delusional or frank delusional proportions.
  • E - Energy: Chronic fatigue, loss of energy, or a total lack of ambition to complete routine tasks.
  • C - Concentration: Diminished ability to think, concentrate, or make simple decisions. Patients frequently report inability to finish reading a single page and may express fear that they are developing dementia or organic cognitive decline.
  • A - Appetite: Unintended weight loss or weight gain, or significant decrease or increase in appetite. It also includes loss of food enjoyment. In pediatric patients, this criterion includes failure to achieve expected developmental weight gains.
• Diagnostic Timelines and Differential SignpostsFirst-line assessment: Administer the PHQ-2 screening tool. Because depressed mood or anhedonia must be present to establish the diagnosis, a negative PHQ-2 effectively rules out a major depressive episode. If positive, proceed immediately to the PHQ-9.

  • First-line assessment: Administer the PHQ-2 screening tool. Because depressed mood or anhedonia must be present to establish the diagnosis, a negative PHQ-2 effectively rules out a major depressive episode. If positive, proceed immediately to the PHQ-9.
  • Confusing bereavement with a major depressive episode. Uncomplicated grief fluctuates in waves tied to thoughts of the deceased, whereas major depressive disorder involves persistent unremitting depressed mood and pervasive self-loathing. Bereavement alone is not a DSM-5-TR criterion for major depressive disorder.
  • Always rule out bipolar disorder, substance-induced mood disruption, and general medical conditions (such as hypothyroidism or cerebrovascular accidents) before confirming unipolar major depressive disorder. Initiating antidepressant monotherapy in unrecognized bipolar disorder can precipitate acute mania.

  Board trap. Confusing bereavement with a major depressive episode. Uncomplicated grief fluctuates in waves tied to thoughts of the deceased, whereas major depressive disorder involves persistent unremitting depressed mood and pervasive self-loathing. Bereavement alone is not a DSM-5-TR criterion for major depressive disorder.

  Safety. Always rule out bipolar disorder, substance-induced mood disruption, and general medical conditions (such as hypothyroidism or cerebrovascular accidents) before confirming unipolar major depressive disorder. Initiating antidepressant monotherapy in unrecognized bipolar disorder can precipitate acute mania.

• Table 8-1: MDD Epidemiology and RiskLifetime prevalence: Major depressive disorder carries a lifetime prevalence of 12%, making it one of the most frequently tested psychiatric conditions on national board certification exams.

  • Lifetime prevalence: Major depressive disorder carries a lifetime prevalence of 12%, making it one of the most frequently tested psychiatric conditions on national board certification exams.
  • Gender risk: Women face a 2 times higher risk for major depressive disorder than men (a 2 to 1 female to male ratio), whereas bipolar I disorder affects men and women equally.
  • Age distribution: Major depressive disorder is primarily a younger person's illness with a mean age of onset between 20 and 35 years. Prevalence in young adults aged 18 to 29 is 3 times higher than in adults over 60 years of age.
  • Medical inpatient risk: Medical inpatients experience a 15% higher risk of major depressive disorder than the general population, highlighting the critical role of screening in consultation-liaison settings.
  • Heritability and genetics: Major depressive disorder has a heritability of approximately 40%. First-degree relatives of affected individuals have a 2 to 4 times higher risk of developing the disorder compared to the general population.
  • High-yield comorbidities: Major depressive disorder frequently co-occurs with non-mood conditions including ADHD, PTSD, anxiety disorders, conduct disorder, learning disabilities, and substance use disorders.
• Clinical Settings, Comorbidities, and SignpostsThe initial step in managing major depressive disorder is establishing and maintaining a therapeutic alliance. Diagnostic confirmation requires identifying at least 5 SIGECAPS criteria for a minimum duration of 2 weeks, with at least one required cardinal symptom being depressed mood or loss of interest or pleasure (anhedonia).

  • Medical inpatients carry a 15% higher risk of major depressive disorder than the general population. On inpatient consultation-liaison units, always evaluate medical inpatients presenting with apathy, fatigue, or low mood for active suicidal ideation and rule out organic medical causes before assuming symptoms are merely expected grief or physical illness.
  • Exam items frequently present patients with non-mood primary conditions and ask if depression screening is necessary. Major depressive disorder has high comorbidity with non-mood psychiatric conditions such as ADHD, PTSD, anxiety disorders, conduct disorder, learning disabilities, and substance use disorders. Never attribute depressive symptoms solely to a co-occurring disorder without formally screening with standardized tools like the PHQ-9.
  • The initial step in managing major depressive disorder is establishing and maintaining a therapeutic alliance. Diagnostic confirmation requires identifying at least 5 SIGECAPS criteria for a minimum duration of 2 weeks, with at least one required cardinal symptom being depressed mood or loss of interest or pleasure (anhedonia).

  Board trap. Exam items frequently present patients with non-mood primary conditions and ask if depression screening is necessary. Major depressive disorder has high comorbidity with non-mood psychiatric conditions such as ADHD, PTSD, anxiety disorders, conduct disorder, learning disabilities, and substance use disorders. Never attribute depressive symptoms solely to a co-occurring disorder without formally screening with standardized tools like the PHQ-9.

  Safety. Medical inpatients carry a 15% higher risk of major depressive disorder than the general population. On inpatient consultation-liaison units, always evaluate medical inpatients presenting with apathy, fatigue, or low mood for active suicidal ideation and rule out organic medical causes before assuming symptoms are merely expected grief or physical illness.

• Course and PrognosisUntreated major depressive episodes typically last 6 to 13 months, with 50 percent of hospitalized patients recovering within the first year.

  • Untreated major depressive episodes typically last 6 to 13 months, with 50 percent of hospitalized patients recovering within the first year.
  • A unipolar depression diagnosis carries a 5 to 10 percent risk of converting to Bipolar Disorder, as patients develop a manic episode 6 to 10 years after their initial depressive event.
  • Recurrence is common: 20 percent of patients experience a relapse within 6 months of remission, and 50 to 85 percent suffer at least one lifetime recurrence.
  • Continuation phase treatment requires keeping the patient on full therapeutic antidepressant doses for 4 to 9 months post-remission to prevent immediate relapse.
  • Maintenance phase pharmacotherapy is indicated indefinitely for patients with 3 or more lifetime major depressive episodes or severe co-occurring risk factors.
  • Discontinuation of antidepressant therapy requires a 6-week gradual taper to avoid withdrawal symptoms, followed by a mandatory clinic evaluation at 2 months post-cessation.
• Recurrence Risk Factors and Longitudinal DynamicsA history of 3 or more prior major depressive episodes.

  • A history of 3 or more prior major depressive episodes.
  • Persistent residual mild depressive symptoms rather than complete symptom remission.
  • High severity of past episodes, including past suicidal attempts or psychotic features.
  • Early age of onset, particularly during adolescence or early adulthood.
  • Co-occurring non-affective psychiatric disorders, such as generalized anxiety disorder, panic disorder, ADHD, or substance use disorders.
  • Co-occurring general medical conditions, such as type 1 diabetes mellitus, cerebrovascular accidents, or chronic pain.