Seasonal Affective Disorder

Background

• Seasonal affective disorder is a seasonal pattern of depressive episodes associated with bipolar or major depressive disorder.
• The most common type is "winter type," in which symptom onset occurs during autumn or winter, followed by spontaneous recovery in spring and summer, but "summer type" also occurs occasionally.
• Hypothesized to be caused by desynchronization between biological clock and natural day-night cycle due to seasonal changes in daylight, leading to depressive symptoms.
• Estimated prevalence is 1%-10% of the general population, most often occurring among women, persons living at northern latitudes, and persons who do shift work that limits exposure to sunlight.

Evaluation

• Symptom severity may vary, but clinical presentation usually includes a combination of emotional symptoms such as depressed mood and irritability, ideational symptoms such as negativity and hopelessness, and somatic symptoms such as excessive sleepiness and carbohydrate cravings.
• Conduct a clinical interview and consider using standardized questionnaires to assess severity and seasonality of depressive symptoms; options include
  • Structured Interview Guide for the Hamilton Rating Scale - Seasonal Affective Disorder (SIGH-SAD)
  • Seasonal Health Questionnaire (SHQ)
  • Seasonality Assessment Form
  • Seasonal Pattern Assessment Questionnaire (SPAQ)
• Diagnose clinically according to Diagnostic and Statistical Manual of Mental Disorders, 5th ed. (DSM-5) criteria for the "seasonal pattern" specifier for major depressive disorder or bipolar disorder (but note "seasonal affective disorder" is not a distinct entity in the DSM-5):
  • ≥ 2 episodes of mood disorder, with onset within the same time of the year (usually fall or winter) for ≥ 2 consecutive years, excluding cases caused by obvious psychosocial stressor, such as being unemployed every winter
  • full remissions occur within distinct period of the year, usually spring or summer
  • seasonal episodes substantially outnumber any nonseasonal episodes in lifetime

Management

• Offer light therapy as the first-line treatment (Strong Recommendation).
  • It involves exposure to bright light to simulate lengthening of the daylight period.
  • The standard regimen is bright light with intensity 10,000 lux for 20-60 minutes per day, administered in the morning from early fall until spring.
  • It is typically administered at home with a commercially available fluorescent light box.
• Consider counseling, such as with cognitive behavioral therapy (CBT), alone or in combination with light therapy to help patients work through depressive episodes.
• Consider medications to improve depressive symptoms but note that evidence supporting efficacy for seasonal affective disorder is limited; options include:
  • antidepressants, including
    • sertraline
    • fluoxetine
  • other medications and supplements which may improve mood such as tryptophan, vitamin D, and St. John's Wort
• Consider modifying activity as a conservative management strategy; examples include increasing physical exercise, ensuring good sleep hygiene, and occasionally walking outside during daytime to increase sunlight exposure.
• Consider starting bupropion before a depressive episode begins in wintertime to prevent a recurrence of symptoms.