One-liner#

MDD management centers on SSRI first-line therapy (sertraline or escitalopram), titrated to therapeutic dose over 4-6 weeks, with treatment duration of 6-12 months for first episode and indefinite maintenance for recurrent episodes, while monitoring for response (PHQ-9 ≤4), suicidality, and treatment-resistant cases requiring augmentation or psychiatry referral.

Quick nav#

Definition and epidemiology#

Diagnostic criteria#

DSM-5 criteria for Major Depressive Episode:

≥5 of the following symptoms present during the same 2-week period, representing a change from previous functioning. At least one symptom must be (1) or (2):

  1. Depressed mood most of the day, nearly every day
  2. Markedly diminished interest or pleasure (anhedonia)
  3. Significant weight change (>5% in a month) or appetite change
  4. Insomnia or hypersomnia nearly every day
  5. Psychomotor agitation or retardation (observable by others)
  6. Fatigue or loss of energy nearly every day
  7. Feelings of worthlessness or excessive/inappropriate guilt
  8. Diminished concentration or indecisiveness
  9. Recurrent thoughts of death, suicidal ideation, or suicide attempt

Additional criteria:

  • Symptoms cause clinically significant distress or functional impairment
  • Episode not attributable to substance use or medical condition
  • Not better explained by schizophrenia spectrum or other psychotic disorder
  • No history of manic or hypomanic episode (rules out bipolar)

Severity classification by PHQ-9:

SeverityPHQ-9 ScoreTreatment Approach
Minimal0-4No treatment; monitor
Mild5-9Psychotherapy; consider medication
Moderate10-14Medication + psychotherapy
Moderately severe15-19Medication + psychotherapy; close monitoring
Severe20-27Medication + psychotherapy; consider psychiatry

MDD specifiers (document when present):

  • With anxious distress (very common; ~60%)
  • With melancholic features (severe anhedonia, worse in morning, early waking)
  • With atypical features (mood reactivity, hypersomnia, hyperphagia, leaden paralysis)
  • With psychotic features (mood-congruent delusions/hallucinations—requires psychiatry)
  • With seasonal pattern (recurrent episodes at specific time of year)
  • With peripartum onset (during pregnancy or within 4 weeks postpartum)

Epidemiology#

Lifetime prevalence is 16-20% in the US; 12-month prevalence is ~7%. Female:male ratio is 2:1. Median age of onset is 32 years, but can occur at any age. Peak incidence is in the 20s-30s. Risk factors include female sex, family history (2-3x increased risk with first-degree relative), prior depressive episode (50-60% recurrence after first episode; 70-80% after second; 90% after third), childhood trauma/adverse experiences, chronic medical illness, substance use, and social isolation.

Comorbidity rates:

  • Anxiety disorders: 60%
  • Substance use disorders: 30%
  • Chronic pain: 30-50%
  • Cardiovascular disease: bidirectional relationship
  • Diabetes: 2x increased risk

Pathophysiology#

Mechanism (clinical understanding)#

MDD is a heterogeneous disorder with multiple contributing mechanisms. No single theory fully explains the condition, which is why treatment response varies and multiple approaches may be needed.

Monoamine hypothesis (classic theory): Deficiency in serotonin, norepinephrine, and/or dopamine neurotransmission. This explains why SSRIs, SNRIs, and dopaminergic agents (bupropion) are effective. However, monoamine levels increase within hours of starting medication, yet clinical response takes 4-6 weeks—suggesting downstream effects are more important than simple neurotransmitter levels.

Neuroplasticity and BDNF: Chronic stress and depression are associated with decreased brain-derived neurotrophic factor (BDNF) and reduced neuroplasticity, particularly in the hippocampus and prefrontal cortex. Antidepressants increase BDNF over weeks, promoting neurogenesis and synaptic remodeling. This explains the delayed onset of action and why continued treatment is needed to maintain benefits.

HPA axis dysregulation: The hypothalamic-pituitary-adrenal axis is often hyperactive in depression, with elevated cortisol levels. Chronic cortisol elevation damages hippocampal neurons and impairs neuroplasticity. This connects depression to chronic stress and explains the bidirectional relationship with medical illness.

Inflammation: Elevated inflammatory markers (IL-6, TNF-α, CRP) are found in a subset of depressed patients. Inflammation may impair neurotransmitter synthesis and neuroplasticity. This explains why depression is common in inflammatory conditions and why some patients respond to anti-inflammatory approaches.

Neural circuit dysfunction: Functional imaging shows altered activity in the prefrontal cortex (decreased—impaired executive function), amygdala (increased—heightened negative emotion), and default mode network (increased rumination). These changes normalize with successful treatment.

Clinical relevance: Understanding these mechanisms helps explain to patients why:

  • Medication takes weeks to work (neuroplasticity changes)
  • Stress management matters (HPA axis)
  • Exercise helps (increases BDNF, reduces inflammation)
  • Treatment must continue after feeling better (maintaining neuroplastic changes)

How to explain to patients#

Depression is a medical condition that affects how your brain works—it’s not a character flaw or something you can just “snap out of.”

Think of your brain like a garden. When you’re healthy, the garden grows and thrives. But depression is like a drought—the plants stop growing, connections wither, and everything slows down. The medications we use are like watering and fertilizing the garden. It takes time—usually 4-6 weeks—for the garden to start growing again. That’s why you won’t feel better right away.

Stress hormones also play a role. When you’re under chronic stress, your body releases hormones that can actually damage parts of the brain involved in mood and memory. This is why managing stress, getting enough sleep, and exercising all help—they reduce these harmful stress hormones.

The good news is that with treatment, your brain can heal and grow new connections. But just like a garden needs ongoing care, you need to continue treatment even after you feel better to keep those healthy connections strong.

Clinical presentation#

Characteristic symptoms#

Core symptoms (at least one required for diagnosis):

  • Depressed mood: sadness, emptiness, hopelessness, tearfulness
  • Anhedonia: loss of interest or pleasure in previously enjoyed activities

Neurovegetative symptoms:

  • Sleep disturbance: insomnia (75%) or hypersomnia (15-25%)
    • Terminal insomnia (early morning awakening) classic for melancholic depression
    • Hypersomnia more common in atypical depression
  • Appetite/weight changes: decreased (more common) or increased (atypical)
  • Fatigue: “no energy,” “exhausted,” even with adequate sleep
  • Psychomotor changes: retardation (slowed movements, speech) or agitation (restlessness, pacing)

Cognitive symptoms:

  • Difficulty concentrating: “can’t focus,” “brain fog”
  • Indecisiveness: difficulty making even simple decisions
  • Memory problems: often subjective; can mimic dementia in elderly (“pseudodementia”)

Psychological symptoms:

  • Worthlessness: “I’m a burden,” “I’m useless”
  • Excessive guilt: often inappropriate or disproportionate
  • Hopelessness: “nothing will ever get better”
  • Thoughts of death: passive (“wish I wouldn’t wake up”) to active suicidal ideation

Symptom patterns by subtype:

SubtypeKey FeaturesTreatment Implications
MelancholicSevere anhedonia; worse in morning; early waking; weight loss; excessive guiltOften needs higher doses; may respond better to SNRIs or TCAs
AtypicalMood reactivity; hypersomnia; hyperphagia; leaden paralysis; rejection sensitivityMAOIs historically preferred; SSRIs effective; avoid TCAs
AnxiousProminent anxiety, tension, restlessness; worry about futureStart SSRI at lower dose; may need longer to respond
With psychotic featuresMood-congruent delusions (guilt, worthlessness, nihilism) or hallucinationsRequires antipsychotic + antidepressant; refer to psychiatry

Physical exam findings#

General appearance:

  • Poor grooming, hygiene (severe cases)
  • Psychomotor retardation: slow movements, delayed responses
  • Psychomotor agitation: restlessness, hand-wringing, pacing
  • Downcast gaze, poor eye contact
  • Slumped posture

Vital signs:

  • Usually normal
  • May have elevated heart rate if anxious
  • Weight change (document and track)

Mental status exam findings:

  • Speech: slow rate, low volume, monotone, increased latency
  • Mood: “sad,” “empty,” “numb,” “hopeless” (patient’s words)
  • Affect: flat, constricted, tearful; congruent with depressed mood
  • Thought content: hopelessness, worthlessness, guilt, suicidal ideation
  • Cognition: impaired concentration; may have difficulty with serial 7s or spelling backward

Physical exam (to rule out medical causes):

  • Thyroid: goiter, nodules (hypothyroidism)
  • Skin: pallor (anemia), dry skin (hypothyroidism)
  • Neurologic: focal findings (stroke, tumor), tremor (Parkinson’s)

Red flags#

Psychiatric emergencies (ED immediately):

  • Active suicidal ideation with plan and intent
  • Suicide attempt (recent or ongoing)
  • Homicidal ideation with specific target
  • Psychotic symptoms (hallucinations, delusions)
  • Catatonia (immobility, mutism, posturing)
  • Unable to care for self (not eating, drinking, severe neglect)

Urgent evaluation (same-day or next-day):

  • Suicidal ideation without plan but with risk factors:
    • Prior suicide attempt (strongest predictor)
    • Access to lethal means (firearms)
    • Recent loss or stressor
    • Substance intoxication
    • Social isolation
  • Severe functional impairment (can’t work, can’t care for children)
  • Suspected mania (do not start antidepressant—may trigger full mania)

Suicide risk factors to assess:

  • Prior suicide attempt (most important)
  • Family history of suicide
  • Access to firearms or other lethal means
  • Recent loss (job, relationship, loved one)
  • Chronic pain or terminal illness
  • Substance use (especially alcohol)
  • Social isolation
  • Male sex (higher completion rate)
  • Age >65 or adolescent

Diagnostic workup#

Initial evaluation#

PHQ-9 (administer at every visit):

  • Validated screening and monitoring tool
  • 9 items scored 0-3; total 0-27
  • Question 9 specifically asks about suicidal ideation
  • Track scores over time to assess treatment response

Baseline labs for new MDD diagnosis:

TestRationaleInterpretation
TSHRule out hypothyroidism (mimics depression)TSH >4.5 mIU/L: evaluate for hypothyroidism
CBCRule out anemia (causes fatigue)Hgb <12 (women) or <14 (men): evaluate anemia
BMPBaseline before medications; electrolytesHyponatremia can occur with SSRIs (SIADH)

Additional labs based on presentation:

TestWhen to OrderRationale
Vitamin B12Elderly, vegetarian/vegan, cognitive symptomsDeficiency causes depression, cognitive impairment
FolatePoor nutrition, alcohol useDeficiency associated with depression; needed for neurotransmitter synthesis
Vitamin DFatigue, seasonal pattern, limited sun exposureLow levels associated with depression
HbA1c or fasting glucoseObesity, risk factors for diabetesDiabetes and depression are bidirectionally related
Lipid panelStarting medication; cardiovascular riskSome antidepressants affect weight/metabolism
LFTsHeavy alcohol use, starting duloxetineDuloxetine contraindicated in hepatic impairment
Urine drug screenSuspected substance useSubstance-induced depression requires different approach

Confirmatory testing#

Bipolar screening (critical before starting antidepressant):

  • Ask about prior manic/hypomanic episodes:
    • “Have you ever had periods of unusually high energy, decreased need for sleep, racing thoughts, or doing risky things?”
    • “Have you ever felt so good or hyper that others thought you weren’t your normal self?”
  • Family history of bipolar disorder
  • Early age of onset (<25 years)
  • Multiple failed antidepressant trials
  • History of antidepressant-induced mania or hypomania

If bipolar suspected: Do NOT start antidepressant monotherapy—can trigger mania. Refer to psychiatry.

MDQ (Mood Disorder Questionnaire): Screening tool for bipolar; sensitivity ~70%, specificity ~90%. Positive screen warrants psychiatry referral.

Structured diagnostic interviews (if diagnosis unclear):

  • MINI (Mini International Neuropsychiatric Interview)
  • SCID (Structured Clinical Interview for DSM)
  • Usually performed by psychiatry or psychology

When to refer for specialist workup#

  • Suspected bipolar disorder
  • Psychotic features
  • Diagnostic uncertainty (is it depression, anxiety, ADHD, personality disorder?)
  • Comorbid substance use disorder requiring specialized treatment
  • Treatment-resistant depression (failed 2+ adequate trials)
  • Complex comorbidities requiring medication expertise

What NOT to order#

  • Brain imaging (CT, MRI): Not indicated for typical MDD; only if focal neurologic findings or atypical presentation suggesting structural cause
  • EEG: Not indicated unless seizure suspected
  • Genetic testing for antidepressant selection: Pharmacogenomic testing (CYP2D6, CYP2C19) has limited evidence for improving outcomes; not routinely recommended; may consider after multiple failed trials
  • Extensive autoimmune or infectious workup: Only if clinical suspicion based on history/exam
  • Repeat PHQ-9 more than monthly: More frequent testing doesn’t improve outcomes and can be burdensome

Treatment#

Goals of therapy#

Primary goals:

  • Remission: PHQ-9 ≤4 (not just response/improvement)
  • Resolution of suicidal ideation
  • Return to baseline functioning (work, relationships, self-care)

Why remission matters:

  • Residual symptoms predict relapse
  • Partial response associated with ongoing functional impairment
  • Push for remission, not just “feeling better”

Timeline expectations:

  • Initial response: 2-4 weeks (some improvement)
  • Full response: 6-8 weeks at therapeutic dose
  • Remission: may take 8-12 weeks or longer
  • If no response by 4-6 weeks at adequate dose: reassess, consider change

Treatment targets:

ParameterTargetTimeline
PHQ-9≤4 (remission)8-12 weeks
Suicidal ideationResolvedOngoing monitoring
SleepNormalized2-4 weeks
Energy/fatigueImproved4-6 weeks
ConcentrationImproved4-8 weeks
Functional statusReturn to baseline8-12 weeks

Non-pharmacologic management#

Psychotherapy (evidence-based):

Therapy TypeDescriptionEvidenceAccess
CBT (Cognitive Behavioral Therapy)Identifies and changes negative thought patterns and behaviorsStrong; as effective as medication for mild-moderate; combination bestTherapist; some apps (e.g., Woebot)
IPT (Interpersonal Therapy)Focuses on relationships and social functioningStrong; particularly for interpersonal issuesTherapist
Behavioral ActivationIncreases engagement in positive activitiesStrong; can be delivered brieflyTherapist; self-directed
Problem-Solving TherapyStructured approach to addressing life problemsModerate; good for primary care settingCan be delivered by PCP

Recommend psychotherapy for:

  • All patients with MDD (combination with medication most effective)
  • Mild depression (may be sufficient alone)
  • Patient preference for non-medication approach
  • Pregnancy/breastfeeding (first-line)
  • History of recurrence (reduces relapse risk)

Exercise:

  • Strong evidence for antidepressant effect (NNT ~4 for mild-moderate depression)
  • Recommend: 150 minutes/week moderate aerobic exercise (30 min x 5 days)
  • Any exercise is better than none; start where patient is
  • Mechanism: increases BDNF, reduces inflammation, improves sleep
  • Counsel: “Exercise is as effective as medication for mild depression. Even a 10-minute walk helps.”

Sleep hygiene:

  • Depression disrupts sleep; poor sleep worsens depression
  • Consistent sleep/wake times (even weekends)
  • Avoid screens 1 hour before bed
  • Limit caffeine after noon
  • Address sleep disorders (screen for OSA if indicated)

Social activation:

  • Social isolation worsens depression
  • Encourage maintaining social connections even when not feeling like it
  • Behavioral activation: schedule pleasant activities, social contact

Lifestyle factors:

  • Limit alcohol (depressant; interferes with sleep and medication)
  • Healthy diet (Mediterranean diet associated with lower depression risk)
  • Sunlight exposure (especially for seasonal pattern)
  • Stress reduction techniques (mindfulness, relaxation)

Pharmacologic management#

First-line: SSRIs

DrugDoseContraindicationsMonitoringCostNotes
Sertraline (Zoloft)Start 50 mg daily; titrate by 50 mg q2-4 weeks; max 200 mgMAOIs; concurrent pimozideNone routine; weight$First choice for most; good for comorbid anxiety; GI side effects initially; safe in cardiac disease
Escitalopram (Lexapro)Start 10 mg daily; max 20 mg (10 mg if >65)MAOIs; QT prolongationECG if cardiac history$Well-tolerated; fewest drug interactions; QT prolongation at high doses
Fluoxetine (Prozac)Start 20 mg daily; titrate by 20 mg q4 weeks; max 80 mgMAOIsNone routine$Long half-life (no discontinuation syndrome); activating; many drug interactions (CYP2D6)
Paroxetine (Paxil)Start 20 mg daily; titrate by 10 mg q2-4 weeks; max 50 mgMAOIsWeight$Sedating; weight gain; anticholinergic; worst discontinuation syndrome; avoid in elderly (Beers)
Citalopram (Celexa)Start 20 mg daily; max 40 mg (20 mg if >60)MAOIs; QT prolongationECG if cardiac history$Similar to escitalopram; QT prolongation limits dose

Second-line: SNRIs and others

DrugDoseContraindicationsMonitoringCostNotes
Venlafaxine XR (Effexor XR)Start 37.5-75 mg daily; titrate by 75 mg q2-4 weeks; max 225 mgMAOIs; uncontrolled HTNBP at higher doses$SNRI; good for comorbid pain, anxiety; can raise BP; severe discontinuation syndrome
Duloxetine (Cymbalta)Start 30 mg daily; increase to 60 mg after 1-2 weeks; max 120 mgMAOIs; hepatic impairment; heavy alcohol; CrCl <30LFTs if hepatic concerns$$SNRI; FDA-approved for pain; nausea common
Bupropion XL (Wellbutrin XL)Start 150 mg daily; increase to 300 mg after 1-2 weeks; max 450 mgSeizure disorder; eating disorders; MAOIsNone routine$NDRI; no sexual dysfunction; no weight gain; activating; avoid if prominent anxiety
Mirtazapine (Remeron)Start 15 mg at bedtime; titrate by 15 mg q2-4 weeks; max 45 mgMAOIsWeight$Sedating; increases appetite/weight; good for insomnia, poor appetite; less sexual dysfunction

Medication selection by clinical scenario:

  • First episode, no comorbidities: sertraline or escitalopram
  • Comorbid anxiety: sertraline, escitalopram, or venlafaxine (start low)
  • Comorbid chronic pain: duloxetine or venlafaxine
  • Insomnia prominent: mirtazapine
  • Poor appetite/weight loss: mirtazapine
  • Fatigue/low energy: bupropion
  • Sexual dysfunction concern: bupropion
  • Prior good response: same agent
  • Elderly: escitalopram or sertraline (avoid paroxetine)
  • Cardiac disease: sertraline
  • Pregnancy: sertraline

Augmentation agents (after 1-2 failed adequate trials):

DrugDoseContraindicationsMonitoringCostNotes
Bupropion (add to SSRI/SNRI)150-300 mg XL dailySeizure disorder; eating disordersNone routine$Most common PCP augmentation; addresses fatigue, sexual dysfunction
Buspirone (add to SSRI)5 mg TID, titrate to 15-30 mg TIDMAOIsNone routine$Anxiolytic; takes 2-4 weeks; no dependence
Aripiprazole (Abilify)2-5 mg daily; max 15 mgNone absoluteWeight; glucose; lipids$$$FDA-approved augmentation; akathisia common; usually psychiatry-initiated
Quetiapine (Seroquel)50-150 mg at bedtimeNone absoluteWeight; glucose; lipids$$Sedating; metabolic effects; usually psychiatry-initiated

Treatment algorithm:

  1. Start SSRI (sertraline 50 mg or escitalopram 10 mg)
  2. Week 2-4: Assess tolerability; if tolerated, continue
  3. Week 4-6: Assess response (PHQ-9)
    • If improving: continue; optimize dose if not at target
    • If no response: increase to max tolerated dose
  4. Week 8-12: Assess for remission
    • If remission (PHQ-9 ≤4): continue maintenance
    • If partial response: optimize dose; consider augmentation
    • If no response: switch to different class or augment
  5. After 2 failed adequate trials: Consider augmentation or psychiatry referral

What constitutes an adequate trial:

  • Therapeutic dose (not just starting dose)
  • Duration of 6-8 weeks at therapeutic dose
  • Confirmed adherence

Patient counseling points#

When starting medication:

  • “This medication works by helping your brain chemistry rebalance. It takes 4-6 weeks to feel the full effect—don’t give up if you don’t feel better right away.”
  • “You may feel a bit more anxious or jittery in the first week or two. This usually goes away. If it’s too uncomfortable, call us.”
  • “Common side effects include nausea, headache, and sleep changes. These usually improve after the first 1-2 weeks.”
  • “Sexual side effects (decreased libido, difficulty with orgasm) can occur. Let me know if this is a problem—we have options.”
  • “Take it every day, even when you start feeling better. Stopping suddenly can cause withdrawal symptoms and your depression may come back.”

About treatment duration:

  • “For a first episode, we typically continue medication for 6-12 months after you feel better, then slowly taper off.”
  • “If you’ve had depression before, you may need to stay on medication longer—sometimes indefinitely—to prevent it from coming back.”
  • “When it’s time to stop, we’ll do it gradually over weeks to months. Never stop suddenly.”

About side effects:

  • “If you have thoughts of hurting yourself, especially in the first few weeks, call us right away or go to the ED. This is rare but important.”
  • “Don’t drink alcohol while taking this medication—it can make depression worse and increase side effects.”

Monitoring and follow-up#

Initial treatment phase:

TimepointAssessmentAction
Week 1-2Phone or portal check-inAssess tolerability, side effects, safety
Week 2-4Office visitPHQ-9; safety assessment; adjust dose if needed
Week 6-8Office visitPHQ-9; assess response; optimize dose or switch if no response
Week 10-12Office visitPHQ-9; assess for remission; plan maintenance

Maintenance phase:

  • Every 1-3 months until stable
  • Then every 3-6 months
  • PHQ-9 at every visit
  • Safety assessment at every visit

What to monitor:

ParameterFrequencyAction if Abnormal
PHQ-9Every visitAdjust treatment if not improving
Suicidal ideation (PHQ-9 Q9)Every visitSafety assessment; increase monitoring; consider hospitalization
Side effectsEvery visitManage or switch medication
WeightEvery visitAddress if significant change
Blood pressureBaseline; with venlafaxineReduce dose or switch if elevated
SodiumIf symptoms of hyponatremia (confusion, falls)Hold SSRI; evaluate

Patient education#

What is this condition?#

Depression is a medical condition that affects your brain and how you feel, think, and handle daily activities. It’s not a sign of weakness or something you can just “snap out of.”

When you have depression, the chemicals in your brain that control mood are out of balance. This affects the parts of your brain that control emotions, thinking, sleep, appetite, and energy. That’s why depression affects so many different parts of your life.

Depression is very common—about 1 in 6 people will experience it at some point in their lives. It can happen to anyone, regardless of age, race, or background. Having depression doesn’t mean you did anything wrong.

The good news is that depression is very treatable. With the right treatment—usually a combination of medication and therapy—most people get significantly better.

What you can do#

Take your medication every day at the same time, even when you start feeling better. The medication needs to build up in your system to work, and stopping suddenly can cause problems.

Try to get some exercise, even if it’s just a short walk. Exercise has been shown to help depression almost as much as medication. Start small—even 10 minutes helps.

Keep a regular sleep schedule. Go to bed and wake up at the same time every day, even on weekends. Avoid screens (phone, TV, computer) for an hour before bed.

Stay connected with people. Depression makes you want to isolate, but being around others helps. Even if you don’t feel like it, try to spend time with family or friends.

Limit alcohol. Alcohol is a depressant and can make your symptoms worse. It also interferes with your medication.

Be patient with yourself. Recovery takes time. You may have good days and bad days. This is normal.

When to seek care#

Call your doctor’s office if:

  • Your symptoms are getting worse instead of better
  • You’re having side effects that bother you
  • You’re having trouble taking your medication
  • You’re thinking about stopping your medication

Call 988 (Suicide & Crisis Lifeline) or go to the emergency room if:

  • You’re having thoughts of hurting yourself or ending your life
  • You have a plan to hurt yourself
  • You feel like you can’t keep yourself safe
  • You’re hearing or seeing things that aren’t there

Questions to ask your doctor#

  • What is my PHQ-9 score, and what does it mean?
  • How long will it take for the medication to work?
  • What side effects should I watch for?
  • How long will I need to take this medication?
  • Should I also see a therapist?
  • What should I do if I miss a dose?
  • Are there any foods, drinks, or other medications I should avoid?
  • When should I come back for a follow-up?
  • What should I do if I start feeling worse?

Prognosis and monitoring#

Expected course#

With treatment:

  • 60-70% respond to first antidepressant trial
  • 30% achieve remission with first trial
  • With sequential trials, ~70% eventually achieve remission
  • Most improvement occurs in first 6-8 weeks
  • Full remission may take 3-6 months

Without treatment:

  • Episodes typically last 6-12 months
  • Spontaneous remission occurs but takes longer
  • Higher risk of recurrence
  • Greater functional impairment
  • Increased suicide risk

Recurrence risk:

  • After 1st episode: 50-60% will have another
  • After 2nd episode: 70-80% will have another
  • After 3rd episode: 90% will have another
  • Each episode increases risk of future episodes
  • Residual symptoms increase recurrence risk

Factors predicting poorer outcome:

  • Incomplete remission (residual symptoms)
  • Comorbid anxiety or substance use
  • Chronic medical illness
  • Longer duration of episode before treatment
  • More severe initial episode
  • History of childhood trauma
  • Poor social support

Monitoring parameters#

ParameterFrequencyTarget
PHQ-9Every visit≤4 (remission)
Suicidal ideationEvery visitAbsent
Functional statusEvery visitReturn to baseline
Side effectsEvery visitTolerable
AdherenceEvery visitTaking as prescribed
WeightEvery visitStable (±5%)
Sleep qualityEvery visitNormalized

Complications to watch for#

Treatment-related:

  • Serotonin syndrome: rare; agitation, hyperthermia, hyperreflexia, tremor; usually with drug interactions (MAOIs, tramadol, triptans)
  • Hyponatremia (SIADH): especially elderly; confusion, falls, seizures; check sodium if symptoms
  • Bleeding risk: SSRIs inhibit platelet function; caution with NSAIDs, anticoagulants
  • QT prolongation: citalopram, escitalopram at high doses; avoid in cardiac disease
  • Discontinuation syndrome: flu-like symptoms, dizziness, “brain zaps”; taper slowly

Disease-related:

  • Suicide: highest risk in first weeks of treatment and during transitions
  • Progression to bipolar: 10-20% of MDD eventually diagnosed with bipolar
  • Chronic/treatment-resistant depression: ~30% don’t achieve remission with standard treatment
  • Functional impairment: work disability, relationship problems
  • Medical comorbidities: cardiovascular disease, diabetes (bidirectional)

Special populations#

Elderly/geriatric#

Presentation differences:

  • May present with somatic complaints rather than mood symptoms
  • Cognitive symptoms prominent (“pseudodementia”)
  • Apathy may be more prominent than sadness
  • Higher risk of psychotic features
  • Often comorbid with medical illness, chronic pain

Treatment considerations:

  • Start at half the usual dose; titrate slowly
  • Escitalopram max 10 mg (QT prolongation)
  • Citalopram max 20 mg (QT prolongation)
  • Avoid paroxetine (anticholinergic; Beers list)
  • Avoid TCAs (anticholinergic, cardiac effects; Beers list)
  • Mirtazapine good choice if insomnia, poor appetite
  • SSRIs increase fall risk (monitor)
  • Higher risk of hyponatremia (monitor sodium)

Beers criteria considerations:

  • Paroxetine: avoid (highly anticholinergic)
  • TCAs: avoid (anticholinergic, cardiac)
  • SSRIs: use with caution (hyponatremia, falls, GI bleeding)

Polypharmacy concerns:

  • Review all medications for interactions
  • SSRIs inhibit CYP450 enzymes (fluoxetine, paroxetine worst)
  • Escitalopram and sertraline have fewest interactions
  • Watch for serotonin syndrome with tramadol, triptans

Cognitive impairment:

  • Depression can cause reversible cognitive impairment (“pseudodementia”)
  • Treat depression; reassess cognition after remission
  • If cognitive symptoms persist after depression treated, evaluate for dementia
  • Depression and dementia often coexist

Chronic kidney disease#

Dosing adjustments:

DrugCKD Stage 3 (eGFR 30-59)CKD Stage 4-5 (eGFR <30)
SertralineNo adjustmentNo adjustment
EscitalopramNo adjustmentNo adjustment
FluoxetineNo adjustmentNo adjustment
ParoxetineNo adjustmentStart low; titrate slowly
VenlafaxineReduce dose 25%Reduce dose 50%
DuloxetineAvoid if CrCl <30Avoid
BupropionReduce frequency (every other day)Reduce frequency; use with caution
MirtazapineNo adjustmentUse with caution; clearance reduced

Monitoring:

  • Standard monitoring applies
  • Higher risk of hyponatremia
  • Duloxetine contraindicated if eGFR <30 (accumulates)

Other populations#

Pregnancy:

  • Untreated depression carries risks: preterm birth, low birth weight, postpartum depression, impaired bonding
  • Weigh risks of untreated depression vs medication exposure
  • Psychotherapy first-line for mild-moderate depression
  • If medication needed: sertraline preferred (most safety data)
  • Avoid paroxetine in first trimester (cardiac defects)
  • Third trimester exposure: neonatal adaptation syndrome (usually mild, self-limited)
  • Continue effective medication through pregnancy if severe/recurrent depression
  • Close monitoring; may need dose adjustment (increased metabolism)
  • Refer to psychiatry or MFM for complex cases

Postpartum:

  • Screen at postpartum visits (Edinburgh Postnatal Depression Scale)
  • Breastfeeding: sertraline preferred (low milk levels)
  • Paroxetine also acceptable for breastfeeding
  • Avoid fluoxetine if possible (long half-life, accumulates in infant)
  • Severe postpartum depression: consider brexanolone (IV, specialist only)

Adolescents and young adults:

  • Black box warning: increased suicidal thinking/behavior in patients <25
  • Risk of untreated depression generally outweighs medication risk
  • Close monitoring in first 4 weeks (weekly contact)
  • Fluoxetine FDA-approved for pediatric depression
  • Escitalopram FDA-approved for adolescents ≥12
  • Document informed consent discussion
  • Involve family in monitoring

Cardiac disease:

  • Depression common after MI (20-30%); worsens cardiac outcomes
  • Sertraline has best cardiac safety data (SADHART trial)
  • Avoid TCAs (arrhythmogenic)
  • Citalopram/escitalopram: QT prolongation at higher doses; use lower doses
  • SSRIs may have cardioprotective effects (antiplatelet)

Chronic pain:

  • Depression and chronic pain highly comorbid
  • Duloxetine FDA-approved for fibromyalgia, diabetic neuropathy, chronic musculoskeletal pain
  • Venlafaxine also effective for pain
  • TCAs effective for pain but more side effects
  • Treating depression often improves pain perception

Substance use disorder:

  • Very common comorbidity (30%)
  • Treat both conditions simultaneously
  • SSRIs safe in substance use
  • Avoid bupropion if stimulant use (lowers seizure threshold)
  • Mirtazapine may help with alcohol cravings
  • Address substance use; may need specialized treatment

When to refer#

Specialist referral criteria#

Psychiatry referral:

  • Suspected bipolar disorder (do not start antidepressant alone)
  • Psychotic features (hallucinations, delusions)
  • Treatment-resistant depression (failed 2+ adequate trials)
  • Severe depression with high suicide risk
  • Complex comorbidities (multiple psychiatric diagnoses)
  • Pregnancy with severe depression
  • Need for ECT, TMS, or esketamine
  • Patient request for specialized care
  • Diagnostic uncertainty

Psychology/therapy referral:

  • All patients (combination treatment most effective)
  • Patient preference for non-medication approach
  • Mild depression (therapy may be sufficient)
  • History of trauma (trauma-focused therapy)
  • Personality factors contributing to depression
  • Relationship issues contributing to depression

Emergency department:

  • Active suicidal ideation with plan and intent
  • Recent suicide attempt
  • Homicidal ideation
  • Psychotic symptoms
  • Unable to care for self
  • Catatonia

Urgency levels#

ScenarioUrgencyAction
New mild-moderate MDDRoutineStart treatment; f/u 2-4 weeks
New severe MDD, safeUrgent (within 1 week)Start treatment; close f/u; consider psychiatry
Suicidal ideation without planUrgent (within 1-2 days)Safety assessment; safety plan; close f/u
Suicidal ideation with plan/intentEmergentED for psychiatric evaluation
Suspected bipolarUrgent (within 1 week)Do not start antidepressant; psychiatry referral
Psychotic featuresEmergentED or urgent psychiatry
Treatment-resistant (2+ failed trials)RoutinePsychiatry referral
Pregnancy with depressionUrgent (within 1-2 weeks)Psychiatry/MFM co-management

Smartphrase snippets#

MDD, new diagnosis, starting treatment: Major depressive disorder, new diagnosis, PHQ-9 [X]. Safety assessment negative. Starting sertraline 50 mg daily; counseled on 4-6 week onset. Psychotherapy referral placed; follow-up in 2 weeks.

MDD, stable on treatment: MDD on [medication, dose], PHQ-9 today [X] consistent with remission. No suicidal ideation; tolerating medication well. Continue current regimen; follow-up in 3 months.

MDD, not responding, dose increase: MDD on [medication, dose] for [X weeks], PHQ-9 [X] showing partial response. Increasing to [new dose]; discussed 4-6 week timeline for full effect. Follow-up in 4 weeks.

MDD, switching medication: MDD, inadequate response to [prior medication] at [dose] for [duration]. Switching to [new medication]; cross-taper over 2 weeks. Follow-up in 2 weeks to assess tolerability.