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 (665 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
The feeling-tone accompaniment of an idea or mental representation. It is the most direct psychic derivative of instinct and the psychic representative of the various bodily changes by means of which instincts manifest themselves.
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: Affects; Mood; Moods.
Where it fits in the MeSH classification
- Broader topics
- Emotions
- Narrower topics
- Irritable Mood
Research landscape
PubMed indexes 40,539 records tagged with the MeSH heading “Affect” (counts retrieved 2026-10-31). 7,131 of them (17.6%) were published from 2020 onward, and the busiest period so far is 2010-2019 with 13,990 records.
Reviews account for 3,585 records (8.8%) and meta-analyses for 418. Randomized controlled trials number 4,661 (11.5%) as a share of all records on the topic. Randomized trials make up a comparatively large share of this literature, which means many treatment questions have been tested directly.
Show the data
| Period | Records |
|---|---|
| through 1999 | 7,454 |
| 2000-2009 | 11,964 |
| 2010-2019 | 13,990 |
| 2020 onward | 7,131 |
Publication-type chart data
| Type | Records | Share |
|---|---|---|
| Reviews | 3,585 | 8.8% |
| Meta-analyses | 418 | 1.0% |
| Randomized controlled trials | 4,661 | 11.5% |
Method: PubMed query "Affect"[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 |
|---|---|---|---|---|
| Marked sex differences are observed in heroin acquisition and affective states in rats but converge to similar levels of footshock stress-induced reinstatement | 2026 | Research article Design not recorded in structured metadata | 7 | cc by PMID 41182352 · DOI · PMC12951745 |
| From Food to Mood: Psychological and Psychiatric Impact of Diet in Bipolar Disorder | 2025 | Review article Design not recorded in structured metadata | 6 | cc by PMID 41374018 · DOI · PMC12694245 |
| The Gut Microbiome and Its Impact on Mood and Decision-Making: A Mechanistic and Therapeutic Review | 2025 | Review article Design not recorded in structured metadata | 4 | cc by PMID 41228422 · DOI · PMC12609437 |
Marked sex differences are observed in heroin acquisition and affective states in rats but converge to similar levels of footshock stress-induced reinstatement [1]
Abstract reading summary — source excerpts
- Opening excerpt
- RationaleNegative affective states, particularly those driven by stress, are known to trigger the development of opioid addiction and relapse.
- Closing excerpt
- ConclusionsThese findings indicate sex-specific vulnerabilities to development of heroin use disorders.
- 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 (256 words)
RationaleNegative affective states, particularly those driven by stress, are known to trigger the development of opioid addiction and relapse. Previous preclinical research has identified sex differences in vulnerability to stress and resulting compulsion to consume drugs.ObjectivesTo investigate sex differences in heroin self-administration, stress-induced reinstatement, and related affective state in rats.Methods22- and 50-kHz ultrasonic vocalizations (USVs), reflecting negative and positive affective state, respectively, were recorded during a heroin self-administration and footshock stress-induced reinstatement model in Sprague-Dawley rats. We hypothesized that females would display increased vulnerability towards heroin use disorder-like profiles.ResultsFemales showed elevated acquisition of heroin self-administration, but behavioral patterns were not linked to gonadal hormone levels. During heroin acquisition, males emitted significantly more 50 kHz calls compared to females, suggesting positive reinforcement-driven intake. We observed successful stress-induced reinstatement in both sexes, with males and females reaching similar overall numbers of active lever presses by the end of the reinstatement session. However, they appear to do so via different strategies, with females displaying "frontloading", rapidly lever pressing in the first 20 min of the behavioral session, perhaps indicating differential stress vulnerability or differences in underlying neural encoding of stressor/reward value. Successful stress-induced reinstatement in both sexes is accompanied by a distinct pattern of USVs, whereby a high number of anticipatory 50 kHz calls are emitted prior to the onset of reinstatement sessions, followed by 22 kHz call production by males during reinstatement sessions, perhaps reflecting drug seeking to relieve negative affect or negative affective responses to drug unavailability.ConclusionsThese findings indicate sex-specific vulnerabilities to development of heroin use disorders.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 41182352 · DOI · PMC12951745
From Food to Mood: Psychological and Psychiatric Impact of Diet in Bipolar Disorder [2]
Abstract reading summary — source excerpts
- Opening excerpt
- Bipolar disorder (BD) is a severe psychiatric illness characterized by recurrent mood episodes and significant psychosocial impairment.
- Closing excerpt
- Future perspectives should include interdisciplinary, personalized interventions that incorporate nutritional strategies into standard care for BD.
- 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 (171 words)
Bipolar disorder (BD) is a severe psychiatric illness characterized by recurrent mood episodes and significant psychosocial impairment. Emerging evidence supports a bidirectional link between diet and mental health, with growing interest in nutritional psychiatry. This narrative review examines the psychological and psychiatric impact of diet in BD, focusing on biological mechanisms (gut-brain axis, neuroinflammation, oxidative stress, neurotransmitter synthesis, and HPA axis dysregulation) and the role of specific dietary patterns, including Western, Mediterranean, ketogenic, and anti-inflammatory diets. Key micronutrients such as omega-3 fatty acids, B-vitamins, magnesium, and vitamin D are explored in relation to mood regulation. This review also addresses psychological factors, including emotional eating, disordered eating behaviors, and the symbolic meaning of food in BD. Furthermore, it highlights the integration of nutritional psychoeducation into psychotherapy, the impact of comorbidities (e.g., obesity, metabolic syndrome), and the role of lifestyle factors such as sleep and physical activity. Despite promising findings, current research is limited by methodological heterogeneity. Future perspectives should include interdisciplinary, personalized interventions that incorporate nutritional strategies into standard care for BD.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 41374018 · DOI · PMC12694245
The Gut Microbiome and Its Impact on Mood and Decision-Making: A Mechanistic and Therapeutic Review [3]
Abstract reading summary — source excerpts
- Opening excerpt
- Background/Objectives: The gut microbiome is increasingly recognized as a key modulator of central nervous system function through the gut-brain axis.
- Closing excerpt
- Microbiome-based interventions represent a promising frontier in neuropsychiatric care, although further translational research is needed to define optimal therapeutic strategies and address individual variability.
- 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 (238 words)
Background/Objectives: The gut microbiome is increasingly recognized as a key modulator of central nervous system function through the gut-brain axis. Dysbiosis has been associated with neuropsychiatric disorders such as depression, anxiety, impulsivity, cognitive decline, and addiction. This review aims to synthesize mechanistic insights and therapeutic perspectives on how gut microbiota influence mood regulation, decision-making, and cognitive processes. Methods: A comprehensive narrative review was conducted using peer-reviewed articles retrieved from PubMed, Scopus, and Web of Science up to August 2025. Studies were included if they explored microbiota-related effects on behavior, mood, cognition, or decision-making using human or animal models. Emphasis was placed on molecular mechanisms, microbiome-targeted therapies, and multi-omics approaches. Results: Evidence indicates that gut microbiota modulate neurochemical pathways involving serotonin, dopamine, GABA, and glutamate, as well as immune and endocrine axes. Microbial imbalance contributes to low-grade systemic inflammation, impaired neuroplasticity, and altered stress responses, all of which are linked to mood and cognitive disturbances. Specific microbial taxa, dietary patterns, and interventions such as probiotics, prebiotics, psychobiotics, and fecal microbiota transplantation (FMT) have shown promise in modulating these outcomes. The review highlights methodological advances including germ-free models, metagenomic profiling, and neuroimaging studies that clarify causal pathways. Conclusions: Gut microbiota play a foundational role in shaping emotional and cognitive functions through complex neuroimmune and neuroendocrine mechanisms. Microbiome-based interventions represent a promising frontier in neuropsychiatric care, although further translational research is needed to define optimal therapeutic strategies and address individual variability.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 41228422 · DOI · PMC12609437
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 The benefits of frequent positive affect: does happiness lead to success? [4]
- Research article Meditation programs for psychological stress and well-being: a systematic review and meta-analysis [5]
- Research article The Microbiota-Gut-Brain Axis: From Motility to Mood [6]
- Research article On the universality and cultural specificity of emotion recognition: a meta-analysis [7]
- Research article Negative symptoms of schizophrenia: new developments and unanswered research questions [8]
- Research article The Brain Basis of Positive and Negative Affect: Evidence from a Meta-Analysis of the Human Neuroimaging Literature [9]
Full-text reviews on EvidenceLib
Open-access review articles about this topic, reproduced in full with authors, licence and references.
Pre-Analytical Factors that Affect Metabolite Stability in Human Urine, Plasma, and Serum: A Review
Victoria L Stevens, Elise Hoover, Ying Wang et al. · Metabolites 2019 · CC BY 4.0
References
- Deckers C, Ahmed Z, Li C, Kirby LG. Marked sex differences are observed in heroin acquisition and affective states in rats but converge to similar levels of footshock stress-induced reinstatement. . 2026. PMID 41182352 · DOI · PMC12951745
- Marano G, Boggio G, Abate F, Caroppo E, Traversi G, Mazza O, et al.. From Food to Mood: Psychological and Psychiatric Impact of Diet in Bipolar Disorder. . 2025. PMID 41374018 · DOI · PMC12694245
- Diotaiuti P, Misiti F, Marotta G, Falese L, Calabrò GE, Mancone S. The Gut Microbiome and Its Impact on Mood and Decision-Making: A Mechanistic and Therapeutic Review. . 2025. PMID 41228422 · DOI · PMC12609437
- Lyubomirsky S, King L, Diener E. The benefits of frequent positive affect: does happiness lead to success?. Psychol Bull. 2005. PMID 16351326 · DOI
- Goyal M, Singh S, Sibinga EM, Gould NF, Rowland-Seymour A, Sharma R, et al.. Meditation programs for psychological stress and well-being: a systematic review and meta-analysis. JAMA Intern Med. 2014. PMID 24395196 · DOI · PMC4142584
- Margolis KG, Cryan JF, Mayer EA. The Microbiota-Gut-Brain Axis: From Motility to Mood. Gastroenterology. 2021. PMID 33493503 · DOI · PMC8634751
- Elfenbein HA, Ambady N. On the universality and cultural specificity of emotion recognition: a meta-analysis. Psychol Bull. 2002. PMID 11931516 · DOI
- Galderisi S, Mucci A, Buchanan RW, Arango C. Negative symptoms of schizophrenia: new developments and unanswered research questions. Lancet Psychiatry. 2018. PMID 29602739 · DOI
- Lindquist KA, Satpute AB, Wager TD, Weber J, Barrett LF. The Brain Basis of Positive and Negative Affect: Evidence from a Meta-Analysis of the Human Neuroimaging Literature. Cereb Cortex. 2016. PMID 25631056 · DOI · PMC4830281
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.
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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.