Educational Disclaimer: This case study is for educational and informational purposes only. It does not constitute medical advice, clinical guidance, or a substitute for professional psychiatric evaluation. All diagnostic criteria referenced are from the DSM-5-TR (APA, 2022). Clinicians should rely on their professional training, direct patient assessment, and current evidence-based guidelines when making diagnostic and treatment decisions.

Clinical Vignette

Patient: "Mr. F," 42-year-old high school teacher in Minnesota, presenting in mid-January with his fourth consecutive winter of depressive symptoms.

Chief Concern: "Every November through March I turn into a different person. I sleep 12 hours, gain 15 pounds from carb cravings, can't focus enough to grade papers, and just want to hibernate. Then spring comes and I'm fine within 2 weeks."

History of Present Illness: Mr. F reports a consistent pattern over 4 consecutive years: depressive symptoms begin in early November, worsen through December and January, and remit by late March. During winter months, he reports hypersomnia (sleeping 11-12 hours vs. his usual 7), increased appetite with specific carbohydrate cravings (bread, pasta, sweets), resulting in 12-15 pound weight gain per winter (which he loses by mid-summer). He describes low energy, difficulty concentrating (leading to delayed paper grading), social withdrawal, and depressed mood. He has no suicidal ideation. When asked about summer months, he reports feeling 'great' — high energy, productive, social, and active. He denies any history of summer depressive episodes. He moved from Florida to Minnesota 5 years ago. He had no depressive episodes while living in Florida. No prior psychiatric history before the Minnesota move.

Past Psychiatric History: No psychiatric history prior to 4 years ago. No prior medication trials. No mania or hypomania history.

Family History: Sister diagnosed with seasonal depression. Mother has recurrent MDD.

Mental Status Exam: Overweight (15-pound seasonal gain). Slightly slowed speech. Mood 'lethargic and low.' Affect constricted but reactive to positive stimuli (smiles when discussing summer plans). No psychotic symptoms. No suicidal ideation. Cognition intact. Insight excellent.

Step 1: Confirming MDE and Seasonal Pattern Specifier

Major Depressive Episode criteria

Depressed mood, hypersomnia, weight gain/increased appetite, low energy, concentration difficulty, social withdrawal. 6 symptoms present for 4-5 months per year. MDE criteria met. MDE CONFIRMED.

Seasonal Pattern Specifier — Criterion A: Regular temporal relationship between onset of MDEs and a particular time of year.

Onset consistently in early November for 4 consecutive years. MET.

Seasonal Pattern — Criterion B: Full remissions at a characteristic time of year.

Full remission by late March for 4 consecutive years. Completely asymptomatic May through October. MET.

Seasonal Pattern — Criterion C: In the last 2 years, two MDEs occurred demonstrating the seasonal temporal pattern, with no non-seasonal MDEs in the same period.

Four consecutive winters of seasonal depression. No non-seasonal episodes. No summer depressive episodes. MET.

Seasonal Pattern — Criterion D: Seasonal MDEs substantially outnumber non-seasonal MDEs over the lifetime.

Four seasonal MDEs. Zero non-seasonal MDEs. Ratio is 4:0. MET.

Step 2: Noting the Atypical Features of Seasonal Depression

MDD with seasonal pattern frequently presents with atypical features rather than melancholic features. This distinguishes it from non-seasonal MDD:

Feature Seasonal (Atypical) Pattern Non-Seasonal (Melancholic) Pattern This Patient
Sleep Hypersomnia Insomnia (terminal) Hypersomnia: 11-12 hours
Appetite Increased, carbohydrate craving Decreased, anorexia Increased: carb cravings, 15-lb gain
Mood reactivity Partially reactive Non-reactive Reactive: smiles discussing summer
Energy 'Leaden' heaviness Psychomotor retardation Low energy, 'want to hibernate'
Time course Predictable onset/offset Variable or persistent November onset, March remission
Geographic pattern Worse at higher latitudes Not latitude-dependent No symptoms in Florida; onset after move to Minnesota

Clinical Significance

The atypical symptom profile (hypersomnia, hyperphagia, mood reactivity) and the clear latitude-dependent pattern (symptoms began after relocating from Florida to Minnesota) are classic for seasonal depression. The atypical features profile also has treatment implications: light therapy is first-line for SAD, and SSRIs (particularly fluoxetine) are the preferred pharmacological intervention.

Diagnostic Formulation

Diagnostic Conclusion

Major Depressive Disorder, Recurrent, Moderate, with Seasonal Pattern (F33.1): Recurrent MDD (4 episodes). Seasonal pattern specifier confirmed (all 4 criteria met). Atypical features (hypersomnia, hyperphagia, mood reactivity). Geographic correlation (onset after latitude change). Treatment: bright light therapy (10,000 lux for 30 minutes each morning), consider SSRI (bupropion or fluoxetine) for prophylactic use beginning October.

Teaching Points

  • The seasonal pattern specifier requires a consistent temporal relationship between depressive episode onset and a specific season over at least 2 years, with seasonal episodes substantially outnumbering non-seasonal episodes over the patient's lifetime. The specifier is not applied when seasonal depression is explained by seasonal psychosocial stressors (e.g., holiday-related stress, unemployment patterns).
  • Bright light therapy (10,000 lux for 20-30 minutes each morning) is a first-line treatment for seasonal depression. The light must be administered in the morning to phase-advance the circadian clock. Evening light is less effective and may worsen insomnia.
  • Latitude is a risk factor for seasonal depression: prevalence increases at higher latitudes where winter daylight hours are shorter. Mr. F's symptom onset following relocation from a lower-latitude (Florida) to a higher-latitude (Minnesota) location is a textbook presentation.
  • Bupropion XL has FDA approval for preventive treatment of seasonal MDD when initiated in autumn before symptom onset. This prophylactic approach can prevent the winter episode entirely in some patients.
  • Clinicians should screen for Bipolar II when evaluating seasonal depression. Some patients with seasonal depressive episodes also experience spring/summer hypomanic episodes (increased energy, decreased sleep need, elevated mood). This pattern would indicate Bipolar II with seasonal pattern rather than recurrent MDD.