Types of depression: DSM-5 and ICD-11 classification, screening tools for each type

Why "depression" is not one diagnosis

"Depression" in everyday language is often one state: low mood, loss of interest, fatigue. In clinical literature it is a family of conditions with different trajectories, causes, and approaches. DSM-5 (American Psychiatric Association, 2013) defines eight main categories of depressive disorders plus a set of specifiers that refine the picture. ICD-11 (WHO, 2018) uses a similar structure with minor differences.

Why this classification matters beyond academic interest. Different depression types respond to different interventions, have different prognoses, and require different screening tools. PHQ-9 separates classical MDD well but captures atypical features (increased appetite and sleep instead of decreased) poorly. BDI-II is more sensitive in the severe range. EPDS is specialized for perinatal contexts and excludes somatic confounders of normal pregnancy. CES-DC is adapted for adolescents. A single screening tool for all types does not exist.

MDD: classical Major Depressive Disorder

MDD is the most common and most researched type. DSM-5 frames criteria around at least five of nine symptoms over a minimum two-week period, where at least one symptom is depressed mood or loss of interest (anhedonia). The list covers weight/appetite changes, sleep disturbance, psychomotor changes, fatigue, feelings of worthlessness, concentration impairment, and suicidal ideation. Duration ≥ 2 weeks and significant functional impairment are mandatory conditions.

Epidemiology. Lifetime MDD prevalence in the US is 20.6% (Hasin et al. 2018, NESARC-III, n=36,309). 12-month prevalence is 10.4%. The female-to-male ratio in most samples is roughly 2:1. Modal age of onset is late adolescence and the early 20s, but real onset is broadly distributed across the lifespan. Cross-cultural prevalence varies — in the WMH Surveys, lifetime MDD ranges from 6.6% (Japan) to 21% (US), with a median ~12% in high-income countries.

Screening for MDD. PHQ-9 (Spitzer et al. 1999) is the standard in primary care and MBC. Its 9 items map directly onto the 9 DSM-5 criteria. Levis et al. (2019, *BMJ*) in an individual participant data meta-analysis (n=17,357 across 58 studies) confirmed sensitivity 0.88 and specificity 0.85 at cutoff ≥ 10 against a structured clinical interview. BDI-II (Beck 1996) has 21 items and is more sensitive in the severe range (≥ 15) due to broader coverage of cognitive and somatic symptoms; Cronbach α ≥ 0.90 in most samples. HAM-D (Hamilton 1960) is clinician-rated, the gold standard in RCT antidepressant trials.

• MDD: episode ≥ 2 weeks with ≥ 5 of 9 DSM-5 symptoms
• Lifetime prevalence 20.6% (Hasin 2018, NESARC-III)
• 12-month prevalence 10.4%
• Female:male ratio ~2:1, modal onset late adolescence
• Screening: PHQ-9 (fast, primary care), BDI-II (severity, atypical features), HAM-D (clinician-rated)

PDD and subthreshold: the "quiet" chronic depression

PDD (Persistent Depressive Disorder, formerly dysthymia) is low-grade depression lasting ≥ 2 years. DSM-5 merged dysthymia and chronic MDD into the single PDD category. Symptoms may fall short of a full MDD episode at any given moment, but persistent chronicity produces substantial functional impact. Lifetime PDD prevalence is a methodologically variable estimate, typically cited in the ~3–6% range in the general population. The subset with PDD + episodic MDD episodes ("double depression") is a distinct clinical category with a worse prognosis than pure MDD.

Subthreshold (or subclinical) depression is the collective term for people who do not meet DSM-5 MDD criteria (fewer than 5 symptoms or less than 2 weeks duration) but have clinically meaningful symptoms. Buntrock et al. (2024, *Lancet Psychiatry*) in an IPDMA on ≥ 6,000 participants showed that psychological interventions in people with subthreshold depression reduce the incidence rate ratio of full MDD to IRR = 0.57 over 12-month follow-up. In other words — almost twice as few people with subthreshold depression progress to full MDD when they receive early psychological intervention.

Screening for PDD and subthreshold depression. PHQ-9 captures both categories through scores 5–9 (mild) and 10–14 (moderate). A critical methodological condition: one measurement is not enough. PDD requires confirmation of a chronic pattern through a series of PHQ-9 measurements over 6+ months. So the MBC approach (repeated measurements every 4–6 weeks) is the standard for differentiating MDD from PDD. Subthreshold tracking is not "didn't meet criteria, forgot about it" — it is active monitoring with an opportunity for early intervention to roughly halve the progression risk.

Specifiers: atypical, melancholic, psychotic, anxious

DSM-5 does not split MDD into "subtypes" in the strict sense — it uses specifiers (modifiers) that describe episode features. Hasin 2018 reported general-population prevalence: anxious/distressed — 74.6% of MDD cases, mixed features — 15.5%. Other specifiers are less common but clinically meaningful.

Melancholic features — anhedonia, non-reactivity to positive events, morning worsening of symptoms, early morning awakening, marked psychomotor agitation or retardation, significant weight loss. Melancholic MDD has historically been viewed as a more "biological" subtype with stronger response to pharmacotherapy and ECT. Screening: PHQ-9 captures well via somatic items; BDI-II is more sensitive in the severe range.

Atypical features — reactive mood, significant weight or appetite increase, increased sleep (hypersomnia), leaden paralysis, chronic sensitivity to interpersonal rejection. Atypical MDD differs conceptually from melancholic — it is a "mirror" picture of somatic symptoms. Screening: PHQ-9 works less well (its items are oriented to "eat less, sleep poorly"); BDI-II or specialized scales (e.g., the Atypical Depression Diagnostic Scale) work better.

Psychotic features — depression + delusions or hallucinations (usually mood-congruent — guilt, worthlessness, nihilism). A severe category. Maj (2007, *J Clin Psychiatry*) indicates that roughly 20% of MDD patients show psychotic features. Self-report screening does not work here — psychotic depression requires a structured psychiatric interview, not PHQ-9 / BDI-II.

• Anxious/distressed — 74.6% of MDD cases (dominant specifier)
• Mixed features — 15.5% (Hasin 2018)
• Melancholic — somatic pattern, stronger response to pharmacotherapy
• Atypical — "mirror" somatic pattern (eat more, sleep more)
• Psychotic — ~20% of severe MDD cases (Maj 2007), requires psychiatric interview

Postpartum, seasonal, perinatal — context-bound types

Three categories defined by context, each with its own screening tools.

Peripartum / postpartum depression. DSM-5 "with peripartum onset" — depression beginning during pregnancy or in the first 4 weeks after delivery (ICD-11 extends to 6 months). Shorey et al. (2018, *Journal of Psychiatric Research*) in a meta-analysis reported pooled postpartum depression prevalence of 17% among mothers, with substantial cross-cultural spread (Europe ~8%, Middle East ~26%). Differs from "baby blues" (a normal reaction in the first 2 weeks that resolves spontaneously) in duration and intensity. Screening: EPDS (Edinburgh Postnatal Depression Scale, Cox 1987) is the standard. 10 items specialized for perinatal context (excluding somatic symptoms typical of normal pregnancy).

Seasonal pattern (SAD). DSM-5 "with seasonal pattern" specifier — depression with a recurring seasonal pattern (usually fall–winter). Prevalence 1–5% in northern latitudes with sharp inter-seasonal contrast, higher in Northern Europe and Canada (Axelsson et al. 2002 showed significant cross-cultural variation in Arctic regions). Bright light therapy is first-line treatment with strong evidence: Golden et al. (2005, *American Journal of Psychiatry*) in a meta-analysis found an effect size d = 0.84 for bright light therapy in SAD patients vs controls. Screening: PHQ-9 + SPAQ (Seasonal Pattern Assessment Questionnaire) for seasonal pattern confirmation.

Premenstrual Dysphoric Disorder (PMDD). Not technically a "depression type", but a related category in the DSM-5 chapter on depressive disorders. Lifetime prevalence ~3–8% among women of reproductive age. Screening: DRSP (Daily Record of Severity of Problems) — prospective tracking across ≥ 2 cycles is required for diagnosis. Retrospective self-report scales systematically overestimate here.

Which scale for which type — instrument selection

A consolidated map of which screening tool fits which depressive situation. All instruments mentioned are in the Soveria catalog.

• Primary care, fast screening: PHQ-9 — 9 items, ~5 min, public domain. Sensitivity 88% / specificity 85% at cutoff ≥ 10 (Levis 2019 IPDMA, n=17,357)
• Severe or atypical MDD: BDI-II — 21 items, more sensitive at ≥ 15, includes atypical features via cognitive items. Cronbach α ≥ 0.90
• Adolescents 13–17: CES-DC or PHQ-A. PHQ-9 is validated from age 13; CES-DC is specifically adapted for the adolescent sample
• Postpartum / peripartum: EPDS — excludes somatic confounders of normal pregnancy, sensitivity 0.86 at cutoff ≥ 13 (Levis 2020 meta n=5,398)
• Clinician-rated, RCT, fundamental research: HAM-D — interview-based, gold standard in RCT antidepressant trials
• Russian clinical practice, classic: Zung Self-Rating Depression Scale — 20 items, traditional Russian adaptation
• Multi-dimensional screen for comorbid presentation: SCL-90-R — 9 subscales, GSI as primary outcome, better for broad assessment than for depression-specific (see SCL-90-R deep dive)

The core methodological principle: one screening tool repeated over time, not "a battery of different tests in a single moment". The MBC approach — choose one scale appropriate to the clinical context, fix a baseline, and repeat every 4–6 weeks. Trajectory beats snapshot. The Reliable Change Index for PHQ-9 is around 5 points; for BDI-II — 8–9 points (Jacobson & Truax 1991 methodological foundation; exact figure depends on the sample). Change below RCI is statistical noise; above is clinically meaningful movement.

How to use in practice with the MBC frame

Five typical workflows for working across the depressive spectrum.

• First visit with depressive symptoms: PHQ-9 + GAD-7 (for anxiety comorbidity — present in 40–60% of cases; see PHQ-9/GAD-7). High PHQ-9 without a clear MDD pattern → repeat after 2 weeks to differentiate episodes vs PDD
• MDD vs PDD differentiation: PHQ-9 every 4 weeks across 3–6 months. PDD requires confirmation of a chronic pattern, not a single measurement
• Subthreshold tracking: PHQ-9 every 4–6 weeks. Buntrock 2024 showed: early psychological interventions in subthreshold roughly halve 12-month MDD incidence (IRR 0.57). Ignoring "doesn't meet criteria" is a methodological error
• Pregnancy / postpartum period: EPDS at 28 weeks of pregnancy + EPDS at 6–8 weeks postpartum (NICE 2014 guideline; see EPDS). A high score → specialized perinatal mental health follow-up
• Monitoring treatment response: the same scale as the baseline, every 4–6 weeks. PHQ-9 Reliable Change Index ≈ 5 points; BDI-II ≈ 8–9 points

Does not replace: a structured clinical interview for type confirmation, medical evaluation (ruling out thyroid dysfunction, anemia, vitamin D deficiency — common "masked" causes of depressive symptoms), or suicide risk assessment (BHS + C-SSRS where indicated).