Atypical Depression and Bipolar Screening
A 34-year-old woman presents with a 2-year history of depressed mood, hypersomnia (10-11 hours nightly), increased appetite with 8-kg weight gain, and leaden paralysis. She reports feeling rejected 'at the slightest criticism' and has stopped socializing. She has no manic or hypomanic episodes. Her PHQ-9 score is 18. TSH, CBC, and vitamin B12 are normal. She has tried two SSRIs at adequate doses for 8 weeks each with partial response. She asks about 'another antidepressant.' She also reports that her mood often worsens in the evening and that she has been drinking two glasses of wine nightly to sleep. She has no suicidal ideation. She denies any history of elevated mood, decreased need for sleep, or impulsive spending, but her mother has bipolar I disorder.
1. What is the most likely diagnosis, and what features support it? What differential diagnoses must be considered?
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Reasoning: The most likely diagnosis is major depressive disorder, single episode, with atypical features. The supporting features are hypersomnia, hyperphagia with weight gain, leaden paralysis, and rejection sensitivity, plus a 2-year depressed mood and functional impairment. Atypical depression is not a separate DSM diagnosis but a specifier. The differential includes bipolar II disorder, which can present with atypical depression and a family history of bipolar I; thyroid disease, which is made less likely by normal TSH; substance-induced mood disorder from nightly wine; and seasonal affective disorder if the pattern is seasonal. The absence of reported hypomania is reassuring but not sufficient, because patients often underreport elevated periods. The PHQ-9 score of 18 indicates moderately severe depression but is not diagnostic by itself.
2. What pharmacologic and psychologic options are supported? Why might an SSRI alone be insufficient?
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Reasoning: SSRIs remain first-line for atypical depression, and CBT or interpersonal therapy is appropriate. However, atypical features-especially hypersomnia, hyperphagia, and rejection sensitivity-have historically been associated with a poorer response to tricyclics and a better response to MAOIs; more recent evidence is mixed. If two adequate SSRI trials have produced only partial response, the next step is to verify adherence and dose, then consider augmentation or a switch. Bupropion may help with hypersomnia and weight gain but can worsen anxiety; mirtazapine can worsen weight gain. The nightly alcohol is a target: it disrupts sleep and can worsen mood. I would not start an MAOI without first ruling out bipolar disorder and addressing alcohol use.
3. How would you screen for bipolar disorder before adjusting treatment, and why does it matter?
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Reasoning: Use a structured screen such as the MDQ or a clinical interview covering distinct periods of elevated or irritable mood, decreased need for sleep, increased goal-directed activity, pressured speech, and impulsive spending. Ask specifically about hypomania, because patients often experience it as a 'good period' and not as illness. Family history of bipolar I is a risk factor. It matters because antidepressant monotherapy can trigger mania or hypomania and accelerate cycling in bipolar disorder. If the screen is positive, the plan should shift toward mood stabilization rather than another antidepressant alone. If negative, document the screen and proceed with atypical depression treatment while monitoring.