-
1.
Ultra-Processed Food Consumption and Mental Health: A Systematic Review and Meta-Analysis of Observational Studies.
Lane, MM, Gamage, E, Travica, N, Dissanayaka, T, Ashtree, DN, Gauci, S, Lotfaliany, M, O'Neil, A, Jacka, FN, Marx, W
Nutrients. 2022;14(13)
-
-
-
Free full text
Plain language summary
Poor dietary quality is well established as a potentially modifiable risk factor for mental disorders. The NOVA food classification system was recently developed to enable the categorisation of food items based on distinctive levels of processing. The aim of this study was to synthesise and provide quantitative analyses of the most up-to-date evidence assessing associations between consumption of ultra-processed food, as defined by the NOVA food classification system, and mental disorders. This study is systematic review and meta-analysis of 17 studies with a total of 385,541 participants. The studies were 15 cross-sectional and 2 prospectively designed studies. Results show that ultra-processed food consumption is bidirectionally associated with adverse mental health. In fact, greater intake of ultra-processed food was associated with increased odds of depressive and anxiety symptoms, both when these outcomes were assessed together as well as separately. Authors conclude that further prospective and experimental studies are required to better determine directionality and causality and ensure that global preventative and treatment strategies are efficacious and appropriate.
Abstract
Since previous meta-analyses, which were limited only to depression and by a small number of studies available for inclusion at the time of publication, several additional studies have been published assessing the link between ultra-processed food consumption and depression as well as other mental disorders. We aimed to build on previously conducted reviews to synthesise and meta-analyse the contemporary evidence base and clarify the associations between the consumption of ultra-processed food and mental disorders. A total of 17 observational studies were included (n = 385,541); 15 cross-sectional and 2 prospective. Greater ultra-processed food consumption was cross-sectionally associated with increased odds of depressive and anxiety symptoms, both when these outcomes were assessed together (common mental disorder symptoms odds ratio: 1.53, 95%CI 1.43 to 1.63) as well as separately (depressive symptoms odds ratio: 1.44, 95%CI 1.14 to 1.82; and, anxiety symptoms odds ratio: 1.48, 95%CI 1.37 to 1.59). Furthermore, a meta-analysis of prospective studies demonstrated that greater ultra-processed food intake was associated with increased risk of subsequent depression (hazard ratio: 1.22, 95%CI 1.16 to 1.28). While we found evidence for associations between ultra-processed food consumption and adverse mental health, further rigorously designed prospective and experimental studies are needed to better understand causal pathways.
-
2.
A Low-FODMAP Diet Provides Benefits for Functional Gastrointestinal Symptoms but Not for Improving Stool Consistency and Mucosal Inflammation in IBD: A Systematic Review and Meta-Analysis.
Peng, Z, Yi, J, Liu, X
Nutrients. 2022;14(10)
-
-
-
-
Free full text
Plain language summary
The low-FODMAP diet eliminates carbohydrates that cannot be easily digested in order to reduce functional gastrointestinal symptoms associated with irritable bowel disease (IBD). The symptoms of irritable bowel disease include abdominal pain and bloating. This systematic review and meta-analysis aimed to evaluate whether a low-FODMAP diet can alleviate functional gastrointestinal symptoms in individuals with inflammatory bowel disease. In comparison with a regular diet, a low-FODMAP diet significantly reduced symptoms of bloating, wind, flatulence, abdominal pain, fatigue, and lethargy in patients with IBD. In addition, patients with Crohn's disease have achieved remission or reduced symptoms after following a low-FODMAP diet. Healthcare professionals can use this study to understand better the effects of a low-FODMAP diet on patients with IBD who have functional gastrointestinal symptoms. Further robust studies are, however, required to evaluate the evidence's robustness and identify the mechanism behind the improvement of symptoms.
Expert Review
Conflicts of interest:
None
Take Home Message:
- LFD use in IBD improved symptoms of bloating, wind or flatulence, borborygmi, abdominal pain, and fatigue or lethargy, but not nausea and vomiting.
Evidence Category:
-
X
A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
-
B: Systematic reviews including RCTs of limited number
-
C: Non-randomized trials, observational studies, narrative reviews
-
D: Case-reports, evidence-based clinical findings
-
E: Opinion piece, other
Summary Review:
Introduction
This meta-analysis assesses the efficacy of a low fermentable oligosaccharides, disaccharides, monosaccharides, and polyols diet (LFD) in inflammatory bowel disease [IBD: ulcerative colitis (UC) and Crohn’s disease (UC)] participants with functional gastrointestinal symptoms (FGSs).
Methods
A search was performed on PubMed, Web of Science, EMBASE, Cochrane Central Register of Controlled Trials, Chinese National Knowledge Infrastructure (CNKI), WanFang (Chinese) Database up to March 2022. Quality assessment of all included studies was performed.
Results
9 studies (4 randomised controlled trials, 5 non-randomised studies) with a total of 351 participants diagnosed with IBD were included, and compared LFD with a placebo diet or normal diet (ND), overall and individual
LFD Effects of FGS:
- Overall 9 studies: an improvement (0.47, 0.33–0.66, p = 0.0000)
- No difference in the subgroup classified by disease type
- CD and UC: no improvement
Individual improvement:
- Bloating (0.37, 0,24-0,57, p=0.0000); wind or flatulence (0.38, 0,28-0,51, p=0.0000); borborygmi (0.48, 0,26-0,89, p=0.0000), abdominal pain (0.5, 0,37-0,68, p=0.0000), fatigue/lethargy (0.71, 0,61-0,82, p=0.0000)
- No difference in nausea and vomiting (0.54, 0,22-1,32, p=018)
IBS Quality of Life Score:
- 2 studies: reduced Short IBD Questionnaire (SIBDQ) score (11.24, 6.61-15.87, p=0.0000)
Bristol Stool Form Chart:
- 2 studies: normal stool consistency (type 3-4); no difference (5.99, 0.17-216.51, p=0.33)
- 2 other studies: no difference (-0.17, 0.48 - 0.15, p=0.30)
Diseases activity (Harvey-Bradshaw index):
- 2 studies using the Mayo score: no difference (-32, -1,09-0.45, p=0.41)
- 3 studies using BHi score: reduction (-1.09, -1,77-0.42, p=0.002)
Faecal calprotectin:
- 2 studies: no change (-16.03, -36,78-4.73, p=0.13)
Limitations
- Comparison diets were not standardised, suggesting the potential of different dietary habits to bias results..
- Heterogeneity of included studies, and the relatively small sample size of the studies can reduce the reliability of the results.
Conclusion
While the study found inconsistent definition standards for FGS, all the nine studies showed that LFD was associated with an improvement in some symptoms.
Clinical practice applications:
- This study suggests that IBD patients with FGSs may benefit from LFD treatment with the assistance of a healthcare professional.
Considerations for future research:
- This study has shown that LFD can improve FGSs in IBD, but further research with a larger sample size and more comprehensive analysis is warranted to replicate the results.
- The description of the findings and Quality of Life data are a little unclear. The impact on Quality of Life warrants further investigation, as clinicians need to consider the impact of following a restrictive diet on Quality of Life.
Abstract
BACKGROUND A low fermentable oligosaccharides, disaccharides, monosaccharides, and polyols diet (LFD) is claimed to improve functional gastrointestinal symptoms (FGSs). However, the role of LFD in inflammatory bowel disease (IBD) patients with FGSs remains unclear. OBJECTIVE To systematically assess the efficacy of LFD in IBD patients with FGSs. METHODS Six databases were searched from inception to 1 January 2022. Data were synthesized as the relative risk of symptoms improvement and normal stool consistency, mean difference of Bristol Stool Form Scale (BSFS), Short IBD Questionnaire (SIBDQ), IBS Quality of Life (IBS-QoL), Harvey-Bradshaw index (HBi), Mayo score, and fecal calprotectin (FC). Risk of bias was assessed based on study types. A funnel plot and Egger's test were used to analyze publication bias. RESULTS This review screened and included nine eligible studies, including four randomized controlled trials (RCTs) and five before-after studies, involving a total of 446 participants (351 patients with LFD vs. 95 controls). LFD alleviated overall FGSs (RR: 0.47, 95% CI: 0.33-0.66, p = 0.0000) and obtained higher SIBDQ scores (MD = 11.24, 95% CI 6.61 to 15.87, p = 0.0000) and lower HBi score of Crohn's disease (MD = -1.09, 95% CI -1.77 to -0.42, p = 0.002). However, there were no statistically significant differences in normal stool consistency, BSFS, IBS-QoL, Mayo score of ulcerative colitis, and FC. No publication bias was found. CONCLUSIONS LFD provides a benefit in FGSs and QoL but not for improving stool consistency and mucosal inflammation in IBD patients. Further well-designed RCTs are needed to develop the optimal LFD strategy for IBD.
-
3.
Use of Meditation and Cognitive Behavioral Therapies for the Treatment of Stress, Depression and Anxiety in Students. A Systematic Review and Meta-Analysis.
González-Valero, G, Zurita-Ortega, F, Ubago-Jiménez, JL, Puertas-Molero, P
International journal of environmental research and public health. 2019;16(22)
-
-
-
Free full text
Plain language summary
Research in the field of the mind is increasing, with students becoming key objects of study in the field of social sciences and health. The main aim of this study was to review the scientific literature in order to analyze the effect produced by cognitive-behavioural programs and meditation strategies on stress, anxiety, and depression in students. A secondary aim was to identify the determinants of treatment success. This study is a systemic review and meta-analysis of 34 articles which included 3296 participating students. A total of 22 effect sizes were calculated for stress treatment, 28 for anxiety and 28 for depression. Results show that interventions based on cognitive-behavioural programs, self-reflection, and mindfulness-based approaches produce satisfactory and significant results in relation to the reduction of stress, anxiety, and depression in students. Furthermore, taking into consideration the theoretical foundations of the studies analysed, meditation (mindfulness, yoga and tai chi), muscle relaxation and breathing, coaching, and cognitive-behavioural therapy are strategies that have shown effectiveness in improving mental health. Authors conclude that it is essential to focus attention on how to improve the mental health of students, including an increase in the number of interventions in the classroom.
Abstract
The prevalence of mental health problems within students due to high academic demands and learning difficulties is a current challenge the field of education. The aim of this study is to review the scientific literature in order to analyze the effect produced by cognitive-behavioral programs and meditation strategies on stress, anxiety, and depression in students. A further aim is to identify the determinants of treatment success. The bibliographic search was carried out using Web of Science, specifically in the categories of "Education and Educational Research" and "Psychology", obtaining a sample of 122 articles published between 2007 and 2018. Studies were included which had a pre-experimental or quasi-experimental design and included pre-test and post-test phases. Following application of inclusion criteria, 34 articles were selected for inclusion in a meta-analysis of the random effects of each variable. This obtained an average effect size of -0.41 for stress, -0.37 for anxiety, and -0.30 for depression. Three moderating variables were analyzed, with significant correlations being found for the type of treatment relating to stress (Q = 11.01, df = 2, p = 0.004, R2 = 0.294) and depression (Q = 6.14, df = 2, p = 0.048; R2 = 0.436). The stage of education of the individuals was also found to impact upon anxiety intervention success (Q = 13.093 df = 2, p = 0.0009, R2 = 0.196). Interventions mainly addressed the importance of meditation strategies, mindfulness programs, and cognitive-behavioral therapy to reduce stress, anxiety, and depression in students. This supports the need to increase research at an early age, considering the treatment of mental health as a key factor influencing academic performance and quality of life.
-
4.
The anxiolytic effect of probiotics: A systematic review and meta-analysis of the clinical and preclinical literature.
Reis, DJ, Ilardi, SS, Punt, SEW
PloS one. 2018;13(6):e0199041
-
-
-
-
Free full text
Plain language summary
The microbiome-gut-brain axis in general and the possibility of altering the microbiome through administration of probiotics to support physical and mental health has received much attention in recent years. Here, a systematic review and meta-analysis were carried out to evaluate the clinical and preclinical evidence for the use of probiotics in anxiety. 22 preclinical (rodent) studies were included in the meta-analysis and showed an overall significant anxiolytic effect of probiotics in diseased, but not healthy, animals. Studies were heterogenous with regards to species and strains of probiotic used. Subgroup analysis showed that only Lactobacillus rhamnosus significantly reduced anxiety-like behaviour. 14 human studies were included in the meta-analysis and overall no anxiolytic effect was observed. Only three out of the 14 studies showed a positive effect (vs 12 out of the 22 animal studies), one of which used L. rhamnosus. Due to the small number of trials no subgroup analysis could be performed. Apart from the small number and heterogeneity of human studies, the authors discuss further possible reasons for the discrepancy between animal and human studies: • Dose: Dosages were typically 100 times higher (per kg) in animals than in humans. • Diseased vs healthy subjects: In animal studies, only those which investigated animals displaying anxiety related behaviour improved with probiotic administration. None of the human studies specifically recruited anxious individuals, eight of the studies included healthy subjects, the other six selected participants for other disorders, including four for irritable bowel syndrome. The authors conclude that more research into an anxiolytic effect of probiotics in humans is warranted, especially using L. rhamnosus, studying patients with anxiety, and using higher dosages and longer study duration.
Expert Review
Conflicts of interest:
None
Take Home Message:
- While preclinical animal studies suggest that probiotics may help reduce anxiety, such findings have not yet translated to clinical research in humans.
- Further investigation of probiotic treatment for clinically relevant anxiety is warranted, particularly with respect to the probiotic species L. rhamnosus.
Evidence Category:
-
X
A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
-
B: Systematic reviews including RCTs of limited number
-
C: Non-randomized trials, observational studies, narrative reviews
-
D: Case-reports, evidence-based clinical findings
-
E: Opinion piece, other
Summary Review:
This review highlights how important it is for future studies to focus on clinically anxious patients and also to consider exploring the effects of differing doses of probiotics in this population.
Clinical practice applications:
Anxiety disorders affect as many as 3 in 10 people at some point during their lifetime. On that basis, it would be great to have a viable non-pharmaceutical option to help with some of the symptoms.
Considerations for future research:
If the results from the pre-clinical studies can be corroborated in human populations, this could have widespread clinical implications.
Abstract
BACKGROUND Probiotics have generated intensive research interest in recent years as a novel mode of treatment for physical and mental illness. Nevertheless, the anxiolytic potential of probiotics remains unclear. The present systematic review and meta-analysis aimed to evaluate the clinical and preclinical (animal model) evidence regarding the effect of probiotic administration on anxiety. METHODS The PubMed, PsycINFO, and Web of Science databases were reviewed for preclinical and clinical studies that met the defined inclusion and exclusion criteria. The effects of probiotics on anxiety-like behavior and symptoms of anxiety were analyzed by meta-analyses. Separate subgroup analyses were conducted on diseased versus healthy animals, specific preclinical probiotic species, and clinical versus healthy human samples. RESULTS Data were extracted from 22 preclinical studies (743 animals) and 14 clinical studies (1527 individuals). Overall, probiotics reduced anxiety-like behavior in animals (Hedges' g = -0.47, 95% CI -0.77 --0.16, p = 0.004). Subgroup analyses revealed a significant reduction only among diseased animals. Probiotic species-level analyses identified only Lactobacillus (L.) rhamnosus as an anxiolytic species, but these analyses were broadly under-powered. Probiotics did not significantly reduce symptoms of anxiety in humans (Hedges' g = -0.12, 95% CI -0.29-0.05, p = 0.151), and did not differentially affect clinical and healthy human samples. CONCLUSIONS While preclinical (animal) studies suggest that probiotics may help reduce anxiety, such findings have not yet translated to clinical research in humans, perhaps due to the dearth of extant research with clinically anxious populations. Further investigation of probiotic treatment for clinically relevant anxiety is warranted, particularly with respect to the probiotic species L. rhamnosus.
-
5.
Yoga for anxiety: A systematic review and meta-analysis of randomized controlled trials.
Cramer, H, Lauche, R, Anheyer, D, Pilkington, K, de Manincor, M, Dobos, G, Ward, L
Depression and anxiety. 2018;35(9):830-843
-
-
-
Free full text
-
Plain language summary
While temporary anxiety is a natural response, excessive and prolonged anxiety can lead to a wide range of physical symptoms and behavior changes. Current treatment options include psychological approaches and medication, however many individuals experiencing anxiety choose to self-manage their condition. Yoga has become a popular approach to improve emotional well-being, and based on a recent study, yoga practitioners have reported managing stress and anxiety as one of the main reasons for practicing. The aim of this meta-analysis was to review the effectiveness and safety of yoga for anxiety. Eight studies with 319 participants were included in this systematic review. Among these studies, no effects were found for patients with anxiety disorders diagnosed by the Diagnostic and Statistical Manual (DSM) criteria, only for patients without a formal diagnosis. Based on these results, the authors conclude yoga may be beneficial in the short-term for individuals with elevated levels of anxiety, however there was no conclusive evidence for individuals when only DSM-diagnosed anxiety disorders were considered. These findings warrant further studies to better understand the connection between mindfulness practices and anxiety.
Abstract
Yoga has become a popular approach to improve emotional health. The aim of this review was to systematically assess and meta-analyze the effectiveness and safety of yoga for anxiety. Medline/PubMed, Scopus, the Cochrane Library, PsycINFO, and IndMED were searched through October 2016 for randomized controlled trials (RCTs) of yoga for individuals with anxiety disorders or elevated levels of anxiety. The primary outcomes were anxiety and remission rates, and secondary outcomes were depression, quality of life, and safety. Risk of bias was assessed using the Cochrane tool. Eight RCTs with 319 participants (mean age: 30.0-38.5 years) were included. Risk of selection bias was unclear for most RCTs. Meta-analyses revealed evidence for small short-term effects of yoga on anxiety compared to no treatment (standardized mean difference [SMD] = -0.43; 95% confidence interval [CI] = -0.74, -0.11; P = .008), and large effects compared to active comparators (SMD = -0.86; 95% CI = -1.56, -0.15; P = .02). Small effects on depression were found compared to no treatment (SMD = -0.35; 95% CI = -0.66, -0.04; P = .03). Effects were robust against potential methodological bias. No effects were found for patients with anxiety disorders diagnosed by Diagnostic and Statistical Manual criteria, only for patients diagnosed by other methods, and for individuals with elevated levels of anxiety without a formal diagnosis. Only three RCTs reported safety-related data but these indicated that yoga was not associated with increased injuries. In conclusion, yoga might be an effective and safe intervention for individuals with elevated levels of anxiety. There was inconclusive evidence for effects of yoga in anxiety disorders. More high-quality studies are needed and are warranted given these preliminary findings and plausible mechanisms of action.
-
6.
Cognitive Behaviour Therapy for Health Anxiety: A Systematic Review and Meta-Analysis.
Cooper, K, Gregory, JD, Walker, I, Lambe, S, Salkovskis, PM
Behavioural and cognitive psychotherapy. 2017;45(2):110-123
-
-
-
Free full text
-
Plain language summary
Hypochondriasis is characterised by preoccupation with the belief that one has, or could acquire, a serious illness, emanating from “anxiety about the meaning, significance or cause” of their symptoms. The main aim of this study was to investigate the efficacy of cognitive behaviour therapy (CBT) for clinical and subclinical health anxiety (HA) relative to control conditions, focusing on measures of HA, depression and anxiety pre and post intervention, and assessing the quality of the randomized control trials. This study is a systemic review and meta-analysis which included 14 studies in the final analysis with a total of 1544 participants. Results provide evidence supporting CBT treatment of HA, in people with and without medical problems, and in people with subclinical as well as clinical levels of HA. Authors conclude that further investigation is required in order to delineate the active treatment elements.
Abstract
BACKGROUND Health anxiety (HA), or hypochondriasis, is a psychological problem characterized by a preoccupation with the belief that one is physically unwell. A 2007 Cochrane review (Thomson and Page, 2007) found cognitive behavioural therapy (CBT) to be an effective intervention for individuals with HA. Similar findings were reported in a recent meta-analysis (Olatunji et al., 2014), which did not employ a systematic search strategy. The current review aimed to investigate the efficacy of CBT for HA, and to update the existing reviews. METHOD A systematic search was conducted following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidance, including randomized controlled trials that compared CBT with a control condition for people with HA. Five hundred and sixty-seven studies were found in the original search, of which 14 were included in the meta-analysis. RESULTS Meta-analysis was conducted on 21 comparisons and a large effect size for CBT compared with a control condition was found at post therapy d = 1.01 (95% confidence interval 0.77-1.25), as well as at 6- and 12-month follow-up. CONCLUSIONS This systematic review and meta-analysis provides support for the hypothesis that CBT is an effective intervention for HA when compared with a variety of control conditions, e.g. treatment-as-usual, waiting list, medication, and other psychological therapies.
-
7.
Therapist-supported Internet cognitive behavioural therapy for anxiety disorders in adults.
Olthuis, JV, Watt, MC, Bailey, K, Hayden, JA, Stewart, SH
The Cochrane database of systematic reviews. 2016;3:CD011565
-
-
-
Free full text
-
Plain language summary
Previous research has supported the use of cognitive behavioural therapy (CBT) in the treatment of anxiety disorders, which is aimed at changing negative or unhealthy thinking patterns. Many individuals with anxiety find it challenging to get to CBT appointments and so an internet-based programme, with telephone and email support, has been developed. This systematic review of 38 randomised controlled trial studies aimed to assess the effects of internet CBT (ICBT) on anxiety symptoms and severity. The results showed that there was a clinically important improvement in anxiety alongside reductions in symptom severity and an increase in the patient’s quality of life (QoL) when following ICBT compared to no treatment or online support group discussions. When comparing supported ICBT and self-guided CBT there were no differences between anxiety symptom severity and QoL. When comparing ICBT and face to face therapist-supported CBT, no differences were reported in anxiety symptoms and QoL. It was concluded that ICBT is more beneficial than no treatment or online discussion groups and may be just as useful as face-to-face CBT. The number of studies that compared ICBT to self-guided CBT was limited and so specific conclusions were difficult to ascertain. This study could be used by healthcare professionals to understand that people suffering from anxiety may not be receiving the treatment they need for fears of new situations or leaving the house. In this instance ICBT is an alternative treatment that is just as beneficial as face-to-face therapy.
Abstract
BACKGROUND Cognitive behavioural therapy (CBT) is an evidence-based treatment for anxiety disorders. Many people have difficulty accessing treatment, due to a variety of obstacles. Researchers have therefore explored the possibility of using the Internet to deliver CBT; it is important to ensure the decision to promote such treatment is grounded in high quality evidence. OBJECTIVES To assess the effects of therapist-supported Internet CBT (ICBT) on remission of anxiety disorder diagnosis and reduction of anxiety symptoms in adults as compared to waiting list control, unguided CBT, or face-to-face CBT. Effects of treatment on quality of life and patient satisfaction with the intervention were also assessed. SEARCH METHODS We searched the Cochrane Depression, Anxiety and Neurosis Review Group Specialised Register (CCDANCTR) to 16 March 2015. The CCDANCTR includes relevant randomised controlled trials from MEDLINE, EMBASE, PsycINFO and CENTRAL. We also searched online clinical trial registries and reference lists of included studies. We contacted authors to locate additional trials. SELECTION CRITERIA Each identified study was independently assessed for inclusion by two authors. To be included, studies had to be randomised controlled trials of therapist-supported ICBT compared to a waiting list, attention, information, or online discussion group; unguided CBT (that is, self-help); or face-to-face CBT. We included studies that treated adults with an anxiety disorder (panic disorder, agoraphobia, social phobia, post-traumatic stress disorder, acute stress disorder, generalized anxiety disorder, obsessive compulsive disorder, and specific phobia) defined according to the Diagnostic and Statistical Manual of Mental Disorders III, III-R, IV, IV-TR or the International Classification of Disesases 9 or 10. DATA COLLECTION AND ANALYSIS Two authors independently assessed the risk of bias of included studies and judged overall study quality. We used data from intention-to-treat analyses wherever possible. We assessed treatment effect for the dichotomous outcome of clinically important improvement in anxiety using a risk ratio (RR) with 95% confidence interval (CI). For disorder-specific and general anxiety symptom measures and quality of life we assessed continuous scores using standardized mean differences (SMD). We examined statistical heterogeneity using the I(2) statistic. MAIN RESULTS We screened 1736 citations and selected 38 studies (3214 participants) for inclusion. The studies examined social phobia (11 trials), panic disorder with or without agoraphobia (8 trials), generalized anxiety disorder (5 trials), post-traumatic stress disorder (2 trials), obsessive compulsive disorder (2 trials), and specific phobia (2 trials). Eight remaining studies included a range of anxiety disorder diagnoses. Studies were conducted in Sweden (18 trials), Australia (14 trials), Switzerland (3 trials), the Netherlands (2 trials), and the USA (1 trial) and investigated a variety of ICBT protocols. Three primary comparisons were identified, therapist-supported ICBT versus waiting list control, therapist-supported versus unguided ICBT, and therapist-supported ICBT versus face-to-face CBT.Low quality evidence from 11 studies (866 participants) contributed to a pooled risk ratio (RR) of 3.75 (95% CI 2.51 to 5.60; I(2) = 50%) for clinically important improvement in anxiety at post-treatment, favouring therapist-supported ICBT over a waiting list, attention, information, or online discussion group only. The SMD for disorder-specific symptoms at post-treatment (28 studies, 2147 participants; SMD -1.06, 95% CI -1.29 to -0.82; I(2) = 83%) and general anxiety symptoms at post-treatment (19 studies, 1496 participants; SMD -0.75, 95% CI -0.98 to -0.52; I(2) = 78%) favoured therapist-supported ICBT; the quality of the evidence for both outcomes was low.One study compared unguided CBT to therapist-supported ICBT for clinically important improvement in anxiety at post-treatment, showing no difference in outcome between treatments (54 participants; very low quality evidence). At post-treatment there were no clear differences between unguided CBT and therapist-supported ICBT for disorder-specific anxiety symptoms (5 studies, 312 participants; SMD -0.22, 95% CI -0.56 to 0.13; I(2) = 58%; very low quality evidence) or general anxiety symptoms (2 studies, 138 participants; SMD 0.28, 95% CI -2.21 to 2.78; I(2) = 0%; very low quality evidence).Compared to face-to-face CBT, therapist-supported ICBT showed no significant differences in clinically important improvement in anxiety at post-treatment (4 studies, 365 participants; RR 1.09, 95% CI 0.89 to 1.34; I(2) = 0%; low quality evidence). There were also no clear differences between face-to-face and therapist supported ICBT for disorder-specific anxiety symptoms at post-treatment (7 studies, 450 participants; SMD 0.06, 95% CI -0.25 to 0.37; I(2) = 60%; low quality evidence) or general anxiety symptoms at post-treatment (5 studies, 317 participants; SMD 0.17, 95% CI -0.35 to 0.69; I(2) = 78%; low quality evidence).Overall, risk of bias in included studies was low or unclear for most domains. However, due to the nature of psychosocial intervention trials, blinding of participants and personnel, and outcome assessment tended to have a high risk of bias. Heterogeneity across a number of the meta-analyses was substantial, some was explained by type of anxiety disorder or may be meta-analytic measurement artefact due to combining many assessment measures. Adverse events were rarely reported. AUTHORS' CONCLUSIONS Therapist-supported ICBT appears to be an efficacious treatment for anxiety in adults. The evidence comparing therapist-supported ICBT to waiting list, attention, information, or online discussion group only control was low to moderate quality, the evidence comparing therapist-supported ICBT to unguided ICBT was very low quality, and comparisons of therapist-supported ICBT to face-to-face CBT were low quality. Further research is needed to better define and measure any potential harms resulting from treatment. These findings suggest that therapist-supported ICBT is more efficacious than a waiting list, attention, information, or online discussion group only control, and that there may not be a significant difference in outcome between unguided CBT and therapist-supported ICBT; however, this latter finding must be interpreted with caution due to imprecision. The evidence suggests that therapist-supported ICBT may not be significantly different from face-to-face CBT in reducing anxiety. Future research should explore heterogeneity among studies which is reducing the quality of the evidence body, involve equivalence trials comparing ICBT and face-to-face CBT, examine the importance of the role of the therapist in ICBT, and include effectiveness trials of ICBT in real-world settings. A timely update to this review is needed given the fast pace of this area of research.