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Epidemiology and burden

TL;DR — The only large study that has measured DSM-5 GAD in the general population across countries is the WHO World Mental Health series: 147,261 adults in 26 countries, combined lifetime prevalence 3.7% (SE 0.1), 12-month 1.8%, 30-day 0.8%, with lifetime prevalence 5.0% in high-income, 2.8% in middle-income and 1.6% in low-income countries (Ruscio 2017, PMID 28297020). Those numbers are criterion artefacts as much as epidemiological facts: dropping the excessiveness requirement raises the global lifetime figure from 2.6% to 4.0% in the same data (Ruscio 2024, PMID 39364896), and dropping the 6-month duration rule to one month raises the developed-country lifetime figure from 4.1% to 7.5% (Lee 2009, PMID 19091158). GAD is disabling at population scale — severe role impairment in 50.6% of lifetime cases, and lifetime comorbidity 81.9% (Ruscio 2017, PMID 28297020) — but no GBD estimate exists for GAD specifically; GBD models "anxiety disorders" as one cause, 359.2 million prevalent cases in 2021 with an age-standardised DALY rate up 18.2% since 1990 (Zhang 2026, PMID 40935255). Treatment gaps are the most consistent finding in the whole literature: 75.7% in India (Jayasankar 2023, PMID 38298878), only 3.9% of Bangladeshi cases seeking professional help (Sarkar 2025, PMID 41061374), and roughly half of WMH cases seeking any treatment (Ruscio 2017, PMID 28297020).

Prevalence: never quote a number without its definition

Source Population Criteria / instrument Lifetime 12-month Note
Ruscio 2017 (PMID 28297020) 147,261 adults, 26 countries (WMH) DSM-5, CIDI 3.7% (SE 0.1) 1.8% (SE 0.1) 30-day 0.8%; the only cross-national DSM-5 estimate
Ruscio 2017, by income band (PMID 28297020) as above DSM-5, CIDI HIC 5.0% / MIC 2.8% / LIC 1.6% — Later onset and more persistent course in lower-income countries
Ruscio 2024 (PMID 39364896) 133,614 adults, 28 surveys (WMH) DSM-5 without excessiveness 4.0% (vs 2.6% with it) — Increase larger in LMICs
Lee 2009 (PMID 19091158) 85,052, 17 countries DSM-IV at varying durations Developed 7.5% (1 mo) / 5.2% (3 mo) / 4.1% (6 mo) / 3.0% (12 mo); developing 2.7 / 1.8 / 1.5 / 1.2% — Clinical profile essentially unchanged across durations
Szuhany 2022 (PMID 36573969) US Review of US estimates 6.2% — Quoted alongside social anxiety 13%, panic 5.2%
Weisberg 2009 (PMID 19371500) US DSM-IV ~5% ~2–3% current Review-level
Wittchen 2001 (PMID 11414546) General population + primary care DSM-III/III-R ~5%; 10% in women ≥40 — Primary care attenders ~8%
Lee 2016 (PMID 27969075) 6,616 adults, Singapore DSM-IV, CIDI 3.0 0.9% 0.4% Among the lowest published; authors invoke cultural reporting
Jayasankar 2023 (PMID 38298878) India NMHS 2016, 12 states DSM/MINI 6.0 — 0.57% current Treatment gap 75.7%
Sarkar 2025 (PMID 41061374) 7,270 adults, Bangladesh DSM-5, psychiatrist interview after SRQ screen 3.5% (95% CI 2.9–4.2) — Women 4.2% vs men 2.7%; rural 3.7% vs urban 2.8%
Mohammadi 2020 (PMID 32470794) 29,709 children/adolescents 6–18, Iran K-SADS-PL 2.6% (95% CI 2.4–2.8) — 57.6% comorbid with another anxiety disorder
Mackenzie 2011 (PMID 21427639) 12,312 US adults ≥55 (NESARC-2) DSM-IV — 2.80% past-year Only 0.53% had GAD with no Axis I or II comorbidity
Yu 2018 (PMID 29524751) China NHWS, urban Self-report 5.3% diagnosed+undiagnosed — Only 0.5% of respondents reported a diagnosis
Druet-Cabanac 2025 (PMID 40611531) 1,086,618 US insured adults, Optum claims Diagnostic codes — 1-year prevalence 2.1% (2012) → 7.4% (2022); incidence 0.8% → 2.4% Administrative, not interview-based
Shevlin 2023 (PMID 36215152) 2,058 UK-representative ICD-11 algorithm, IAQ self-report — 7.1% meeting algorithm Instrument and system both differ from the CIDI estimates

The spread — 0.4% to 7.4% "current" GAD — is not measurement noise. It tracks four decisions: which manual, which duration, which instrument (lay-administered structured interview vs clinician interview vs self-report algorithm vs billing code), and which country. The methodological hazard is comparing across rows of this table as if they estimated the same quantity.

Age, sex and time

  • Onset is late for an anxiety disorder. Meta-analysis of 24 general-population studies places mean age of onset for GAD, panic, agoraphobia, OCD and PTSD between 21.1 and 34.9 years, versus <15 years for separation anxiety, specific and social phobia; no sex difference in onset was detected (Lijster 2017, PMID 27310233). Across ICD-11 diagnostic blocks, anxiety/fear-related disorders have a median onset of 17 (IQR 9–25) with peak 5.5 years — but that block is dominated by childhood phobias, not GAD (Solmi 2022, PMID 34079068). GAD is the anxiety disorder whose onset most resembles a mood disorder's.
  • Incidence rises through midlife. In the prospective Zurich cohort the annual incidence of DSM-III GAD increased considerably between ages 20 and 40, although mean age at symptom onset was 15.6 years with 75% before age 20 (Angst 2009, PMID 18575915). Wittchen's primary-care data put prevalence in women over 35 at ~10% (Wittchen 2001, PMID 11414546).
  • Female predominance is consistent but not extreme. 66.5% female in a 1.09-million US claims cohort (Druet-Cabanac 2025, PMID 40611531); 4.2% vs 2.7% in Bangladesh (OR 1.62, p=0.012) (Sarkar 2025, PMID 41061374); higher female age-standardised rates in GBD 2021 for anxiety disorders overall (Fan 2025, PMID 40375174).
  • Symptom-level prevalence is far higher than disorder-level. In the 2022 US National Health Interview Survey, 18.2% of adults reported any past-two-week anxiety symptoms on the GAD-7, up from 15.6% in 2019; symptoms were highest at ages 18–29 and declined with age, higher in women, in those with less than high-school education, below the federal poverty level, and in rural areas (Terlizzi 2024, PMID 39591466). This is a screening-scale figure, roughly an order of magnitude above interview-based 12-month GAD, and is routinely mis-cited as a GAD prevalence.
  • Expression changes with age, not just severity. In 375 clinical participants matched for GAD status and severity, older adults showed differential item functioning for distress/interference (higher) and fatigue (lower), and worried more about world affairs and their own health and less about work and school (Correa 2019, PMID 31938010) — so age differences in symptom counts are partly measurement artefacts (special populations).

Burden: what is measured, and what is not

GBD does not model GAD. It models "anxiety disorders" as a single cause. Everything in this section is therefore a pooled anxiety figure unless stated otherwise.

Metric Value Source
Global prevalent cases, anxiety disorders, 2021 359.2 million Zhang 2026, PMID 40935255
Anxiety + depression as share of all mental-disorder burden 63.1% of mental-health disorder cases; 9.1% of all disease Zhang 2026, PMID 40935255
Change in age-standardised DALY rate, anxiety disorders, 1990–2021 +18.2% (depression +13.4%); driven mainly by population growth Zhang 2026, PMID 40935255
Projected anxiety cases by 2040 >515 million Zhang 2026, PMID 40935255
Mental disorders as share of global DALYs 3.1% (1990) → 4.9% (2019); 80.8M → 125.3M DALYs GBD 2019 Mental Disorders Collaborators, PMID 35026139
Anxiety disorders in GBD 2021 rankings Second-highest age-standardised DALY rate among 12 mental disorders (524.33 per 100,000) after major depression (557.87); the largest increase of any subtype Fan 2025, PMID 40375174
COVID-19 effect, 2020 Anxiety-disorder prevalence rose with SARS-CoV-2 infection rate and reduced mobility in a 204-country meta-regression COVID-19 Mental Disorders Collaborators, PMID 34634250
Adolescents/young adults 10–24, 1990–2021 Anxiety-disorder incidence +52%, sharpest 2019–2021; bullying victimization a significant risk factor Bie 2024, PMID 39691785

GAD-specific burden, where it has been measured directly:

Metric Value Source
Severe role impairment, lifetime DSM-5 GAD 50.6% (SE 1.2), higher in high-income countries Ruscio 2017, PMID 28297020
Lifetime comorbidity 81.9% (SE 0.7); mood 63.0%, other anxiety 51.7% Ruscio 2017, PMID 28297020
Any treatment sought 49.2% overall; 59.4% with severe role impairment; 59.0% in high-income countries Ruscio 2017, PMID 28297020
HRQoL impairment Comparable to depression or panic disorder; GAD plus depression significantly worse than either alone Revicki 2012, PMID 22154706
Median annual medical cost US $2,375 (GAD) vs $1,448 (primary-care patients without GAD); mean annual cost $2,138 higher than other anxiety disorders (mean $6,475) Revicki 2012, PMID 22154706
Adequately treated 20–32% of GAD patients in the reviewed studies Revicki 2012, PMID 22154706
Role impairment, pure GAD Similar in magnitude to pure MDD in large representative samples Hoffman 2008, PMID 17146763
Suicidal ideation Threshold and subthreshold GAD independently associated with 12-month suicidal ideation after adjusting for comorbidity (Canada, n=24,785); 32.0% of men and 21.2% of women with threshold GAD reported past-year ideation Gilmour 2016, PMID 27849314

The treatment gap

Setting Gap measure Value Source
26 countries (WMH) Any treatment sought, lifetime GAD 49.2% Ruscio 2017, PMID 28297020
India (NMHS 2016) Overall treatment gap, current GAD 75.7% Jayasankar 2023, PMID 38298878
Bangladesh Sought professional help 3.9% (OR 8.32 if family history of mental illness) Sarkar 2025, PMID 41061374
Urban China Reported having a diagnosis 0.5% of respondents, against 5.3% self-reported GAD Yu 2018, PMID 29524751
US older adults ≥55 Sought professional help in past year 18% (no comorbidity) / 28.3% (with comorbid Axis I) Mackenzie 2011, PMID 21427639
US primary care Anxiety-disorder patients reporting no current treatment 41% Kroenke 2007, PMID 17339617
Singapore Substantial non-treatment-seeking despite self-reported impairment qualitative in the source Lee 2016, PMID 27969075
Europe/North America "Adequately treated" 20–32% Revicki 2012, PMID 22154706

The gradient — worse in lower-income countries, worse in older adults, worse without comorbidity — is consistent across every study above. It is also the strongest argument that prevalence differences between countries are partly detection differences: lifetime prevalence is 3× higher in high-income than low-income countries in the same instrument and protocol (Ruscio 2017, PMID 28297020), while help-seeking is also highest there.

Special-population signals

  • Veterans: 7.9% (95% CI 6.7–9.3) screened positive for probable GAD and a further 22.1% for mild anxiety symptoms in a nationally representative US veteran sample, with a dose–response relation to suicidal thoughts and functional impairment (Macdonald-Gagnon 2024, PMID 38325107). Screener-based, and veterans overlap heavily with PTSD.
  • University students: in 72,288 first-year students across 18 countries, 57.4% screened positive for any 12-month disorder; internalizing disorders were more prevalent in females and among non-heterosexual and transgender students (Mason 2025, PMID 40010072). Weighted response rate 20.8%, so these are upper bounds.
  • Children and adolescents: lifetime GAD 2.6% in 29,709 Iranian 6–18-year-olds, with 57.6% anxiety-disorder comorbidity (Mohammadi 2020, PMID 32470794). See special populations.
  • Subthreshold GAD is roughly twice as prevalent as threshold GAD and carries measurable morbidity and cost (Haller 2014, PMID 24886240); in Canada, 2.6% threshold vs 2.3% subthreshold (Gilmour 2016, PMID 27849314).

Open questions

  • Why is DSM-5 GAD three times more prevalent in high-income than low-income countries under an identical protocol (Ruscio 2017, PMID 28297020)? Detection, expression, and criterion fit are all candidate explanations and none has been isolated.
  • What would a GAD-specific GBD estimate look like? Anxiety disorders are modelled as one cause, so the disorder with 50.6% severe role impairment is invisible in the burden accounts (Ruscio 2017, PMID 28297020; Zhang 2026, PMID 40935255).
  • Is the US administrative-claims increase from 2.1% to 7.4% between 2012 and 2022 (Druet-Cabanac 2025, PMID 40611531) incidence, coding practice, or screening deployment? NHIS symptom data rose over a comparable period but by far less (15.6%→18.2%; Terlizzi 2024, PMID 39591466).
  • Does the female excess in GAD survive measurement-invariance checks? GAD-7 studies found partial strong invariance across sex in young adults (Af Winklerfelt Hammarberg 2025, PMID 39880312) and invariance in 165,872 treatment seekers (Saunders 2023, PMID 37118684). Those results make simple scale non-invariance an unlikely complete explanation in those samples, but they do not establish invariance for diagnostic interviews or every culture.

References

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