Definition and research guide
This page combines a MeSH definition, publication statistics and selected research abstracts. It is a starting point for reading the literature, not a medical textbook or a systematic evidence review.
Content available: 3 complete abstracts (664 words), 9 references. Full article text is not stored or reproduced here; follow the PMID, DOI or PMC links to read the original sources and their access terms.
Definition
Psychiatric illness or diseases manifested by breakdowns in the adaptational process expressed primarily as abnormalities of thought, feeling, and behavior producing either distress or impairment of function.
Definition: NLM Medical Subject Headings (MeSH) scope note (Public domain (U.S. National Library of Medicine); attribution requested). View the MeSH record.
Also known as: Mental Disorder; Psychiatric Disorders; Psychiatric Disorder; Psychiatric Diseases; Psychiatric Disease; Psychiatric Illness; Psychiatric Illnesses; Mental Illness.
Where it fits in the MeSH classification
- Broader topics
- Psychiatry and Psychology Category
- Narrower topics
- Anxiety Disorders; Disruptive, Impulse Control, and Conduct Disorders; Dissociative Disorders; Elimination Disorders; Feeding and Eating Disorders; Mood Disorders; Motor Disorders; Neurocognitive Disorders; Neurodevelopmental Disorders; Neurotic Disorders; Paraphilic Disorders; Personality Disorders; Schizophrenia Spectrum and Other Psychotic Disorders; Sexual Dysfunctions, Psychological
- See also
- Persons with Psychiatric Disorders
Research landscape
PubMed indexes 1,633,087 records tagged with the MeSH heading “Mental Disorders” (counts retrieved 2026-10-31). 380,971 of them (23.3%) were published from 2020 onward, and the busiest period so far is 2010-2019 with 480,052 records.
Reviews account for 235,666 records (14.4%) and meta-analyses for 24,702. Randomized controlled trials number 62,958 (3.9%) as a share of all records on the topic.
Show the data
| Period | Records |
|---|---|
| through 1999 | 466,431 |
| 2000-2009 | 305,633 |
| 2010-2019 | 480,052 |
| 2020 onward | 380,971 |
Publication-type chart data
| Type | Records | Share |
|---|---|---|
| Reviews | 235,666 | 14.4% |
| Meta-analyses | 24,702 | 1.5% |
| Randomized controlled trials | 62,958 | 3.9% |
Method: PubMed query "Mental Disorders"[MeSH Terms] with publication-type and date filters, retrieved 2026-10-31.
Reading the evidence in psychiatry and psychology
Research on mental health and behaviour relies on questionnaires, interviews and rating scales rather than physical measurements, so how a condition was defined and measured shapes every result. Many studies are observational or small, placebo responses can be large, and findings in one group or culture may not carry over to another. Nothing on this page is advice about diagnosis or treatment; anyone worried about their mental health should talk to a qualified clinician. Check how outcomes were measured, who took part and how long they were followed.
Evidence from open-access studies
These open-access studies come from PubMed’s best-match results for this heading (papers whose main topic it is), ranked here by citation count, with one recent addition. Each abstract is reproduced in full under its recorded open licence so that you can read the authors’ own words. They illustrate the literature; they are not a systematic summary of it. Citation counts measure attention, not reliability or clinical benefit.
| Study / authors | Year | Source label / design | Europe PMC citations | Licence / source |
|---|---|---|---|---|
| UK Medical Cannabis Registry: A Two-Year Prospective Observational Cohort Study of Clinical Outcomes in Insomnia | 2026 | Research article Design not recorded in structured metadata | 0 | cc by PMID 42935025 · DOI · PMC13710906 |
| Psychometric Properties of the Choosing Wisely Questions in a Large Psychiatric Sample | 2026 | Research article Design not recorded in structured metadata | 0 | cc by PMID 42929188 · DOI · PMC13697498 |
| Time, Trust and Participation: A Nationwide Quantitative Study of Person-Centred Care in Forensic Mental Health Settings | 2026 | Research article Design not recorded in structured metadata | 0 | cc by PMID 42947530 · DOI · PMC13714552 |
UK Medical Cannabis Registry: A Two-Year Prospective Observational Cohort Study of Clinical Outcomes in Insomnia [1]
Abstract reading summary — source excerpts
- Opening excerpt
- BackgroundInsomnia disorder affects approximately 10% of people.
- Closing excerpt
- As an uncontrolled, observational study of a self-selected and predominantly cannabis-experienced cohort, placebo effects, regression to the mean, and selection bias cannot be excluded.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (210 words)
BackgroundInsomnia disorder affects approximately 10% of people. The persistence of insomnia, despite treatment, remains high. Cannabis-based medicinal products (CBMPs) have been proposed as a potential treatment for insomnia. This study aims to use data from the UK Medical Cannabis Registry to analyze changes in self-reported sleep quality in patients prescribed CBMPs for insomnia.MethodsA prospective cohort study of patients treated with CBMPs for insomnia was completed. The primary outcome was the Single-Item Sleep Quality Scale (SQS). This was assessed at baseline and at 1, 3, 6, 12, 18, and 24 months from baseline. Secondary outcomes included change in anxiety and general health-related quality of life. p-values ResultsTwo hundred and eleven participants met the inclusion criteria. Over half (n = 126; 59.72%) were users of cannabis at baseline. At the primary endpoint of 24 months, mean SQS improved from 2.46 ± 2.10 (mean ± standard deviation (SD)) at baseline to 5.14 ± 2.75 (mean difference +2.68; 95% confidence interval (CI) 2.23-3.14; p ConclusionInitiation of CBMPs was associated with improvements in self-reported sleep quality across 2 years, with the largest associations observed in those with the most severe impairment. As an uncontrolled, observational study of a self-selected and predominantly cannabis-experienced cohort, placebo effects, regression to the mean, and selection bias cannot be excluded.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 42935025 · DOI · PMC13710906
Psychometric Properties of the Choosing Wisely Questions in a Large Psychiatric Sample [2]
Abstract reading summary — source excerpts
- Opening excerpt
- ObjectivesThe Choosing Wisely Questions (CWQ) support shared decision-making and aim to reduce low-value care, but their psychometric properties remain unclear.
- Closing excerpt
- Patients reported more information on benefits than on risks, alternatives, or no treatment (p ConclusionThe Swedish CWQ show good validity, reliability, and item performance, supporting their use as a unidimensional measure of perceived information in psychiatric shared decision-making.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (203 words)
ObjectivesThe Choosing Wisely Questions (CWQ) support shared decision-making and aim to reduce low-value care, but their psychometric properties remain unclear. This study evaluated the structural validity, reliability, and item characteristics of the Swedish CWQ in a psychiatric sample.MethodsIn this cross-sectional study, adult patients at a Swedish university psychiatric clinic (early 2025) completed four CWQ items on perceived information about their medication (benefits, risks, alternatives, and no treatment). Structural validity was assessed using exploratory and confirmatory factor analyses. Internal consistency was measured with Cronbach's alpha, and item characteristics were examined using a graded response model.ResultsA total of 666 patients (57.2% women; median age 35.0 years) were included. The majority had multiple ICD F-diagnoses. EFA supported a one-factor solution explaining 53.8% of the variance. CFA demonstrated excellent model fit (CFI = 0.998, TLI = 0.995, RMSEA = 0.032, SRMR = 0.015). Internal consistency was good (α = 0.81, 95% CI 0.79-0.83). In the item response analysis, all items showed high discrimination (a = 1.94-2.72) and ordered thresholds. Patients reported more information on benefits than on risks, alternatives, or no treatment (p ConclusionThe Swedish CWQ show good validity, reliability, and item performance, supporting their use as a unidimensional measure of perceived information in psychiatric shared decision-making.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 42929188 · DOI · PMC13697498
Time, Trust and Participation: A Nationwide Quantitative Study of Person-Centred Care in Forensic Mental Health Settings [3]
Abstract reading summary — source excerpts
- Opening excerpt
- Person-centred care emphasises the uniqueness of individuals through partnerships, the co-creation of care plans and coordinated health care.
- Closing excerpt
- Among those who reported having a written care plan, involvement in and understanding of the plan were rated positively, whereas broader involvement in decision-making, use of patients' own resources and relatives' participation received lower ratings, indicating areas for further improvement in person-centred practice.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (251 words)
Person-centred care emphasises the uniqueness of individuals through partnerships, the co-creation of care plans and coordinated health care. Its implementation in forensic mental health services is challenged by legal coercion and restrictive practices. Person-centred principles are embedded in legislation; however, national data on patients' perspectives on person-centred care are lacking. This study aimed to map person-centred care as perceived by patients and to identify areas for improvement. A nationwide survey included 329 patients across 13 forensic psychiatric hospitals in Sweden using the Generic Person-Centred Care Questionnaire supplemented with contextual background questions. The median Generic Person-Centred Care Questionnaire score was 70 (range 19-95). Length of stay was associated with perceived person-centred care; patients hospitalised for 2-5 years reported higher total scores than those hospitalised for more than 10 years, although the pairwise difference did not remain significant after correction for multiple comparisons. Trust in staff differed by length of stay, with patients hospitalised for > 10 years reporting significantly lower trust than those hospitalised for 0-1 and 2-5 years. Communicative safety showed a similar pattern, although pairwise differences were not significant after correction. No significant differences in total scores were found by gender, age, ethnicity, diagnosis, or hospital type. Overall, patients reported positive experiences of respect and emotional support. Among those who reported having a written care plan, involvement in and understanding of the plan were rated positively, whereas broader involvement in decision-making, use of patients' own resources and relatives' participation received lower ratings, indicating areas for further improvement in person-centred practice.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 42947530 · DOI · PMC13714552
Key reviews and meta-analyses
The most cited review-type papers among PubMed’s best-match results for this heading, listed with bibliographic details only. Follow the links for the full text and access terms.
- Research article Self-administered single-session interventions for mental health in young people: A systematic review and meta-analysis [4]
- Research article Domain-specific physical activity levels and risk of dementia: a systematic review and meta-analysis [5]
- Research article Tree Imagery in Drawing Tests for Screening Mental Disorders: A Systematic Review and Meta-Analysis [6]
- Research article Genome wide association study meta-analysis of neuropathologic lesions of Alzheimer's disease and related dementias in a multi-site autopsy cohort [7]
- Research article Prevalence and severity of mental health problems in early-career researchers: a systematic review and meta-analysis [8]
- Research article Baseline omega-3 nutritional status and supplementation response in pediatric attention-deficit/hyperactivity disorder: a systematic review and biomarker-stratified meta-analysis [9]
Full-text reviews on EvidenceLib
Open-access review articles about this topic, reproduced in full with authors, licence and references.
Research progress on the mechanisms of comorbidity between functional gastrointestinal disorders and mental disorders: A review
Ruirui Tan, Chao Han, Dongwei Sun et al. · Medicine 2025 · CC BY 4.0
Glymphatic System and Psychiatric Disorders: A Rapid Comprehensive Scoping Review
Tommaso Barlattani, Paolo Grandinetti, Alexsander Di Cintio et al. · Current Neuropharmacology 2024 · CC BY 4.0
Complement Dependent Synaptic Reorganisation During Critical Periods of Brain Development and Risk for Psychiatric Disorder
Laura J. Westacott, Lawrence S. Wilkinson · Frontiers in Neuroscience 2022 · CC BY 4.0
Anomalous brain gyrification patterns in major psychiatric disorders: a systematic review and transdiagnostic integration
Daiki Sasabayashi, Tsutomu Takahashi, Yoichiro Takayanagi et al. · Translational Psychiatry 2021 · CC BY 4.0
Prevalence and factors associated with common mental disorders in young people living with HIV in sub‐Saharan Africa: a systematic review
Ezra K Too, Amina Abubakar, Carophine Nasambu et al. · Journal of the International AIDS Society 2021 · CC BY 4.0
References
- Koye A, Erridge S, Clarke E, McLachlan K, Coomber R, Rucker JJ, et al.. UK Medical Cannabis Registry: A Two-Year Prospective Observational Cohort Study of Clinical Outcomes in Insomnia. . 2026. PMID 42935025 · DOI · PMC13710906
- Bengtsson J, Andersson A, Forss Lilja N, Hultgren Farsani I, Lissbrant E, Wettermark B, et al.. Psychometric Properties of the Choosing Wisely Questions in a Large Psychiatric Sample. . 2026. PMID 42929188 · DOI · PMC13697498
- Vidaurrázaga Aras V, Wolf A, Nilsson T, Alexiou E, Olausson S. Time, Trust and Participation: A Nationwide Quantitative Study of Person-Centred Care in Forensic Mental Health Settings. . 2026. PMID 42947530 · DOI · PMC13714552
- Ball J, Meiser-Stedman R, Thompson Z, Chiu K. Self-administered single-session interventions for mental health in young people: A systematic review and meta-analysis. J Child Psychol Psychiatry. 2026. PMID 42318615 · DOI · PMC13647095
- Feter N, Iso-Markku P, Markarian T, Luong DM, Gunnink J, Schröder N, et al.. Domain-specific physical activity levels and risk of dementia: a systematic review and meta-analysis. Lancet Public Health. 2026. PMID 42612650 · DOI · PMC13532401
- Guo H, Feng B, Liu T, Zhao R, Fan H, Dong Z, et al.. Tree Imagery in Drawing Tests for Screening Mental Disorders: A Systematic Review and Meta-Analysis. Depress Anxiety. 2026. PMID 42437128 · DOI · PMC13355497
- Cholerton B, Godrich D, Pasteris J, Rivero J, Martin ER, Kunkle BW, et al.. Genome wide association study meta-analysis of neuropathologic lesions of Alzheimer's disease and related dementias in a multi-site autopsy cohort. PLoS Genet. 2026. PMID 42371968 · DOI · PMC13340787
- Dreisoerner A, Goetz V, Frohnmayer D, Tran US, Voracek M, Nater UM. Prevalence and severity of mental health problems in early-career researchers: a systematic review and meta-analysis. Nat Hum Behav. 2026. PMID 42373822 · DOI · PMC13590413
- Fu X, Feng L, Jiang M, Li J. Baseline omega-3 nutritional status and supplementation response in pediatric attention-deficit/hyperactivity disorder: a systematic review and biomarker-stratified meta-analysis. Front Public Health. 2026. PMID 42433395 · DOI · PMC13353153
About this article
- Sources
- NLM Medical Subject Headings (definition, synonyms); NCBI PubMed (counts, identifiers); Europe PMC (open-access abstracts and citation counts).
- Verification
- Every reference was resolved against PubMed on 2026-11-04; title, year and DOI matched.
- Review state
- automated source verified; no human expert review has been recorded yet.
- Version
- 1, last updated 2026-11-04.
See how EvidenceLib is built. Spotted an error? Email support@evidencehelix.com.
Evidence strength
EvidenceHelix's computed view of the study designs behind this topic: how common meta-analyses, randomized trials and reviews are, how recent the literature is, and a plain-language reading. It describes the design mix of the literature. It is not a quality appraisal of any study, and it is not medical advice.