Cited by 108Treatment of Major DepressionElectroconvulsive Therapy StudiesTryptophan and brain disorders

The DOI matches its Crossref record; 223 of the 227 references it cites were found in a registry or an index; 119 of the 231 sources its claims cite were checked for support.

Ketamine in neuropsychiatric disorders: an update

Open access

Abstract

The discovery of ketamine as a rapid-acting antidepressant led to a new era in the development of neuropsychiatric therapeutics, one characterized by an antidepressant response that occurred within hours or days rather than weeks or months. Considerable clinical research supports the use of-or further research with-subanesthetic-dose ketamine and its (S)-enantiomer esketamine in multiple neuropsychiatric disorders including depression, bipolar disorder, anxiety spectrum disorders, substance use disorders, and eating disorders, as well as for the management of chronic pain. In addition, ketamine often effectively targets symptom domains associated with multiple disorders, such as anxiety, anhedonia, and suicidal ideation. This manuscript: 1) reviews the literature on the pharmacology and hypothesized mechanisms of subanesthetic-dose ketamine in clinical research; 2) describes similarities and differences in the mechanism of action and antidepressant efficacy between racemic ketamine, its (S) and (R) enantiomers, and its hydroxynorketamine (HNK) metabolite; 3) discusses the day-to-day use of ketamine in the clinical setting; 4) provides an overview of ketamine use in other psychiatric disorders and depression-related comorbidities (e.g., suicidal ideation); and 5) provides insights into the mechanisms of ketamine and therapeutic response gleaned from the study of other novel therapeutics and neuroimaging modalities.

Overview

AI snapshot

Written from the paper’s full text.

TL;DR

This narrative review updates the evidence for subanesthetic ketamine and esketamine across neuropsychiatric disorders, emphasizing rapid antidepressant and transdiagnostic effects alongside mechanistic and clinical-practice issues. It concludes that efficacy is broad but often supported by small or preliminary studies, with long-term safety and misuse data still limited.

Key findings

  • Subanesthetic ketamine/esketamine can produce rapid effects in depression and bipolar disorder, often within hours, peaking near 24 h and declining over 10–12 days; intranasal esketamine received FDA approval for treatment-resistant depression in 2019 and for major depression with acute suicidal ideation or behavior in 2020.
  • Real-world effectiveness estimates include a meta-analytic mean response rate of 55.3% and remission rate of 28.9%, community-practice response/remission of roughly 50%/30%, and 6-month intranasal esketamine response/remission of 47.8%/37%; a telehealth sublingual ketamine trial (n = 1247) reported PHQ-9 remission of 32.6% and GAD-7 remission of 31.3%.
  • For suicidal ideation, meta-analyses show reductions from one day up to six weeks, partly independent of mood effects; one crossover trial (n = 37) found 69% complete remission after six infusions maintained with weekly maintenance, and an emergency-department RCT (n = 18) reported 88% remission between 90 and 180 min after treatment.
  • Evidence in other conditions is mixed: a multicenter PTSD trial (n = 158) found no effect on PTSD symptoms despite reduced depressive symptoms; OCD trials are mostly positive but one open-label study (n = 10) found no OCD effect; alcohol-use trials suggest increased abstinence, while cocaine self-administration fell by 67% at 24 h but the effect faded; (R)-ketamine did not separate from placebo at 24 h in a Phase 2a trial (n = 102).

Methods

  • Narrative review synthesizing pharmacology, hypothesized mechanisms, clinical use, and recent clinical findings (2019–2023) across psychiatric disorders, with Table 1 summarizing selected studies.
  • Draws on preclinical work, meta-analyses, randomized controlled trials, open-label pilots, case series, and neuroimaging modalities including EEG, MEG, MRS, fMRI, and PET; neurological conditions such as Alzheimer’s, Huntington’s, and Parkinson’s disease are excluded.
  • No primary data collection or formal systematic meta-analysis is reported.

Limitations

  • The authors state that many trials are pilot studies or case series, often uncontrolled or with small samples, and that larger, more rigorous trials are needed; efficacy for several conditions rests on few trials and participants.
  • The authors also note high placebo response rates in depression and suicidality research, outcome measures such as MADRS being designed for longer intervals than rapid-acting effects, and scarce long-term safety, relapse, and misuse-liability data.
  • Evident from the text: as a narrative review without a systematic search or risk-of-bias assessment, study selection and synthesis may be non-exhaustive, and heterogeneity in dose, route, frequency, and formulation complicates comparisons.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1038/s41386-023-01632-1

Cites

223 of 223 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Verification

Claims the paper makes

86 No full text of the sources · 57 Partly supported · 40 Supported · 31 Own interpretation · 28 No basis given · 5 Sources not found · 4 Not checked yet · 2 Supported so far · 1 Not supported · 1 Couldn’t confirm · accuracy not yet measured

Show all 160 claims

  • It may state two separate claims as one. 76
  • Probably not a substantial claim. 29
  • The quote only partly states this claim. 1
95 of 95
  • The paper relies on this without support.

    Alcohol and substance misuse are highly prevalent, and current treatments have long-term relapse rates, so novel therapeutic approaches are needed.

    “Alcohol and substance misuse are highly prevalent, and current treatments have long-term relapse rates, necessitating novel therapeutic approaches.”
  • The paper relies on this without support.

    Substance use disorders are often resistant to traditional pharmacotherapy and behavioral interventions.

    “Substance use disorders are often resistant to traditional pharmacotherapy and behavioral interventions.”
  • The paper relies on this without support.

    Glutamatergic dysregulation is implicated across multiple substance use disorders.

    “Glutamatergic dysregulation has been implicated across multiple substance use disorders, leading to interest in the putative therapeutic impact of ketamine.”
3 of 3

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

7 of 7

Citations

Cites

Items 201–223 of 223

Cited by

Sorted by citations

See all 108

Metadata

Authors
Johnston, J. N., Kadriu, B., Kraus, C., Henter, I. D., & Zarate, C. A.
Affiliations
National Institutes of Health (US)
Corresponding author
Johnston, Jenessa N.
Venue
Neuropsychopharmacology
Published
2023-06-20
Volume
49
Issue
1
Pages
23-40
ISSN
  • 0893-133X (ISSN-L)
  • 1740-634X
OpenAlex
W4381334012
Cited by
108
References
227
Citations by year
2026: 28 · 2025: 41 · 2024: 36 · 2023: 3
FWCI
3.90
Type
journal article
Language
en
Open access
Locations
  • Neuropsychopharmacology (publishedVersion)
  • PubMed Central (publishedVersion)
  • PubMed (publishedVersion)
Funders
U.S. Department of Health & Human Services | NIH | National Institute of Mental Health (ZIAMH002857)
Topics
  • Health Sciences › Medicine › Pharmacology (medical) › Treatment of Major Depression
  • Health Sciences › Medicine › Psychiatry and Mental health › Electroconvulsive Therapy Studies
  • Life Sciences › Neuroscience › Biological Psychiatry › Tryptophan and brain disorders
Keywords
ketamine, esketamine, subanesthetic ketamine, rapid-acting antidepressants, depression, bipolar disorder, anxiety disorders, substance use disorders, eating disorders, chronic pain, hydroxynorketamine, enantiomers, suicidal ideation, anhedonia, mechanism of action, neuroimaging
MeSH terms
Antidepressive Agents, Anxiety Disorders, Bipolar Disorder, Depression, Humans, Ketamine, Anhedonia

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

A language model drew the claims from the paper on 2026-09-28, under version 3 of the claim definition (model deepseek-v4.1-flash, prompt extract-v3).

A second model labelled each claim on 2026-09-28 (model jev-1.13-20260917, definition revision gold-guideline-v0.2).

Cited sources are checked with a language model’s help (gpt-6-sol).

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

What counts as a claim ›How we measure confidence ›How we check this ›

Are you an author, or do you see a problem with this page? Request a review