The evidence base of Acceptance and Commitment Therapy (ACT) in psychosis: A systematic review

Relations between psychosis and emotion regulation in daily life: A systematic review and meta-analyses of studies using experience sampling methods

Research has shown that heightened emotionality often precedes psychotic experiences. Understanding how individuals cope with these emotions is crucial for psychosis. While prior studies on emotion regulation (ER) and psychosis have mainly relied on self-report questionnaires, recent research has increasingly utilised daily life methods. This systematic review and meta-analysis seek to examine the relationship between daily ER and psychotic experiences. In total, 15 studies were included in the meta-analysis (21 in the systematic review). The results of Experience Sampling Methods (ESM) studies indicated that ER strategies of avoidance, reappraisal, repetitive thinking, and emotional suppression are not associated with psychotic experiences in daily life. The effect was not moderated by type of sample (clinical vs non-clinical), symptom (hallucination vs delusions), relation (contemporaneous vs perspective), or other methodological variables. Acceptance was found to be negatively associated with psychotic experiences, but the effect was small. These results indicate that ER in daily life might not impact directly on psychotic experiences. The results are discussed in light of conceptual and methodological limitations in the field.

Acceptance and Commitment Therapy-based Lifestyle Counselling Program for people with early psychosis on physical activity: A pilot randomized controlled trial

OBJECTIVE

To evaluate the feasibility, acceptability and efficacy of an Acceptance and Commitment Therapy-based Lifestyle Counselling Program (ACT-LCP) on health outcomes of individuals with early psychosis.

METHODS

In this assessor-blinded, parallel-group pilot randomized controlled trial, 72 early psychosis patients (mean age [SD] = 30.51 [8.02], 58.3 % female) were randomized to either the ACT-LCP group or a control group. The ACT-LCP group underwent a five-week group program focusing on ACT-based motivation for healthy lifestyles, a booster session, and two follow-up calls. The control group received standard care, one lifestyle education session, and three follow-up calls. Outcomes including physical activity, autonomous motivation, psychological flexibility, mental status, and quality of life were measured at baseline, 1-week, and 12-week post-intervention. Recruitment, retention, and adherence rates were evaluated. Focus group interviews explored participants' experiences.

RESULTS

Generalized estimating equation models demonstrated that when compared to the Control group, the ACT-LCP group showed a sixfold likelihood of engaging in at least 150 min of moderate to vigorous physical activity per week (adjusted prevalence ratio = 6.28, 95 % CI [2.09-18.93], P ≤ 0.001) at 12-week post-intervention. Improvements at 12-week also included autonomous motivation (adjusted mean difference, aMD = 4.74; P < .001), psychological inflexibility (aMD = -7.69; P < .001), mental status (aMD = -6.83; P < .001), and quality of life (aMD = 0.46; P = .006). Recruitment was successful at 55.8 %, retention at 89 %, and adherence at 80.6 %. Engagement challenges were noted in focus groups.

CONCLUSIONS

The ACT-LCP is feasible and acceptable, demonstrating initial efficacy in individuals with early psychosis. Further research should refine the intervention and explore long-term impacts.

CLINICALTRIAL

gov Identifier: NCT04916496.

ACTing Spiritually: Integrating Spiritual Care and Mental Health Care within a US Department of Veterans Affairs Inpatient Psychiatric Unit

As a part of the VA's interprofessional fellowship in psychosocial rehabilitation, the authors developed an 8-week spirituality group manual, ACTing Spiritually, which incorporates principles of acceptance and commitment therapy (ACT) into a spirituality group protocol. The group, administered weekly as possible for 28 weeks on an inpatient psychiatric unit at a veterans affairs (VA) medical center in West Haven, CT, aimed to incorporate veterans' spirituality into their mental health treatment through concepts of acceptance, values, mindfulness, and committed action. ACTing Spiritually ran in tandem with a basic ACT group and the two groups had comparable average group sizes, suggesting interest in ACTing Spiritually similarly compares to interest in a basic ACT group in this context. In addition, development of the group yielded several qualitative findings, including a discussion of the similarities and differences between ACT and spiritual care, clinical gains for chaplains conducting the group, and clinical tensions that arose through the process of integration. The study provided preliminary evidence of the potential feasibility and acceptability of ACTing Spiritually. Next steps should include a formal evaluation of its potential efficacy.

Effectiveness of Acceptance and Commitment Therapy on Psychotic Severity Among Inpatients With Primary Psychoses: A Randomized Controlled Trial

This study investigated the effectiveness of acceptance and commitment therapy (ACT) compared to treatment as usual in managing psychotic symptoms, emotional dysregulation, recovery and psychological flexibility in inpatients with primary psychoses. The Primary outcome assessed the positive and negative syndrome scale, while the secondary outcomes were to assess difficulties in the emotion regulation scale, recovery assessment scale and acceptance and action questionnaire. An open-label, two-arm parallel randomized controlled trial was conducted. Participants diagnosed with primary psychoses were randomly assigned to either the ACT (n = 33) or treatment-as-usual (n = 32) group. The intervention included six structured sessions of ACT. ACT significantly reduced psychotic symptoms from 128 to 104 (Z = 5.01) compared to treatment as usual from 130 to 117 (Z = 4.88). Emotional regulation improved significantly in the ACT group from 73 to 55 (Z = 4.835) compared to treatment as usual from 73 to 70 (Z = 2.406). Recovery increased in the ACT group from 50 to 88 (Z = 5.01) compared to treatment as usual from 51 to 61 (Z = 4.93). Psychological flexibility improved in the ACT group from 33 to 25 (Z = 4.98) compared to treatment as usual from 33 to 31 (Z = 4.75). Between-group differences after intervention were significant for psychotic symptoms, emotional regulation, recovery and psychological flexibility (Z = 2.356, 4.652, 3.881 and 4.453, respectively). Accordingly, the current study demonstrates the effectiveness of ACT in reducing psychotic symptoms and improving emotional regulation, recovery and psychological flexibility in patients with primary psychoses. Integrating ACT into standard care protocols can enhance treatment outcomes, offering a comprehensive approach to managing complex mental health conditions. Trial Registration: ClinicalTrials.gov identifier: NCT06160869.

Reducing self-stigma in psychosis: A systematic review and meta-analysis of psychological interventions

The burden of self-stigma in psychosis has been widely studied, leading to the development and implementation of self-stigma reduction programmes to ameliorate its impact. In order to successfully improve self-stigma in psychosis, we must evaluate the effect of available interventions to help clinicians select the most appropriate approach for their patients. This systematic review and meta-analysis aimed to evaluate the effect of self-stigma reduction interventions in people with psychosis while considering the interventions' characteristics as an important moderator of their effect. The results from this systematic review suggest that interventions involving more than one component, particularly those combining psychoeducation, social skills training and cognitive approaches, were most effective at reducing self-stigma in people with psychosis. Additionally, shorter interventions were found best reduced self-stigma at post-treatment evaluation. A meta-analysis mirrored these results, finding an overall favourable effect of interventions but high heterogeneity in the sample. Subgroup analyses found larger self-stigma reductions following multi-component interventions compared to single-component interventions. An analysis of risk of bias revealed a trend suggesting studies with lower risk of bias produced smaller effects. The results of this review can inform practitioners select and develop interventions to reduce self-stigma in psychosis.

Let's fail better: Using philosophical tools to improve neuroscientific research in psychiatry

Despite predictions that neuroscientific discoveries would revolutionize psychiatry, decades of research have not yet led to clinically significant advances in psychiatric care. For this reason, an increasing number of researchers are recognizing the limitations of a purely biomedical approach in psychiatric research. These researchers call for reevaluating the conceptualization of mental disorders and argue for a non-reductionist approach to mental health. The aim of this paper is to discuss philosophical assumptions that underly neuroscientific research in psychiatry and offer practical tools to researchers for overcoming potential conceptual problems that are derived from those assumptions. Specifically, we will discuss: the analogy problem, questioning whether mental health problems are equivalent to brain disorders, the normativity problem, addressing the value-laden nature of psychiatric categories and the priority problem, which describes the level of analysis (e.g., biological, psychological, social, etc.) that should be prioritized when studying psychiatric conditions. In addition, we will explore potential strategies to mitigate practical problems that might arise due to these implicit assumptions. Overall, the aim of this paper is to suggest philosophical tools of practical use for neuroscientists, demonstrating the benefits of a closer collaboration between neuroscience and philosophy.

Ultra-brief acceptance & commitment therapy for inpatients with psychosis - a single-case experimental design investigating processes of change

People with primary psychosis are among the most seen in inpatient psychiatry. Treatment guidelines recommend both pharmacological and psychological treatments. However, psychological treatments are not routinely offered in many settings. There is also a lack of research on psychological treatments for this vulnerable population in the inpatient setting. The first aim of the current study was to examine treatment effects of a brief form of Acceptance and Commitment Therapy on outcomes valued by the treatment recipients. The second aim was to explore hypothetical processes of change in relation to outcomes over time. Three people with primary psychosis were treated for two to four sessions. A replicated single-case experimental design with multiple baselines across subjects (Clinical Trials registration number ID NCT04704973) was employed to examine treatment effects. The Personal Questionnaire (PQ) was used as primary outcome, symptom believability and preoccupation as proposed processes of change. Data were analyzed using visual inspection, calculation of Tau-U values, and cross-lagged correlation. All participants improved significantly on PQ and the symptom preoccupation measure. Two improved significantly on the symptom believability measure. Cross-lagged correlation analyses showed no clear mediation. Change in proposed processes of change and primary outcome predominantly happened concomitantly, although patterns of results reflected individual differences.

Acceptance and commitment therapy for psychosis: Current status, lingering questions and future directions

PURPOSE

Acceptance and Commitment Therapy for psychosis (ACTp) is a contextual behavioural intervention that promotes psychological flexibility by fostering active acceptance, cognitive defusion, values construction and committed action to enhance well-being and recovery. Multiple studies have shown that ACTp is acceptable and efficacious, but questions remain as to its distinction from similar approaches and the conditions under which it would be implemented most effectively.

METHODS

We present the current evidence for processes and outcomes of ACTp and summarise the qualitative findings of experiences of service users in ACT programmes. We compare ACTp with other cognitive behavioural therapies and mindfulness-informed interventions for psychosis.

RESULTS

Acceptance and commitment therapy for psychosis is promising as a pragmatic, process-driven intervention model. Further efforts are needed to investigate psychological flexibility in the context of psychosis with observational, experimental and intervention studies that will inform model scope and treatment refinement. Additionally, implementation research is the necessary next step, including how support persons can be trained in ACTp. Lower intensity and technology-assisted approaches have the potential to reduce barriers to accessing ACTp and extend impact.

CONCLUSIONS

Over the last 20 years, ACTp has demonstrated meaningful effects in individual and group formats in a range of settings, targeting outcomes such as rehospitalisation, depression, psychotic symptom distress and impact. Future work should focus on how best to integrate ACTp with other current evidence-based interventions for psychosis.

Effectiveness of acceptance and commitment therapy for inpatients with psychosis: Implementation feasibility and acceptability from a pilot randomized controlled trial

OBJECTIVE

Acceptance and Commitment Therapy for Inpatients (ACT-IN) with psychosis has been found to be efficacious in previous trials, but its effectiveness has not been studied when implemented by frontline clinicians in routine settings.

METHOD

In this pilot randomized controlled effectiveness trial, inpatients with schizophrenia-spectrum disorders were randomized to ACT-IN plus treatment as usual (TAU) (n = 23) or a time/attention matched (TAM) supportive condition plus TAU (n = 23) delivered by routine hospital staff. Both conditions received individual and group therapy during inpatient care and completed follow-up phone sessions during the first month post-discharge. Patients were assessed through 4 months post-discharge (blinded to condition) to determine feasibility, acceptability, and preliminary effectiveness of ACT-IN.

RESULTS

ACT-IN was feasible to deliver with fidelity by frontline staff when integrated into an acute care setting. At post-treatment, patients reported significantly greater treatment satisfaction in ACT-IN relative to TAM. Overall, results showed significant but similar improvements for both conditions through 4-month follow-up in psychiatric symptoms, functioning, and mindfulness. Only ACT-IN improved over time in distress. Furthermore, patients receiving TAM had a 3.76 times greater risk of rehospitalization over 4 months compared with ACT-IN.

CONCLUSIONS

ACT-IN is feasible and acceptable for patients with psychosis, can be implemented by hospital staff when integrated into acute treatment, and may result in decreased rehospitalization compared to alternative therapies. A future full-scale randomized-controlled implementation trial is warranted.

CLINICALTRIALS

gov Identifer: NCT02336581.

Safety Planning in Context: A Case Study Integrating DBT Techniques and ACT for Overlapping Suicide and Psychosis Risk

Suicide risk is markedly higher for clients at clinical high risk for psychosis (CHR-p) compared to the general population. Dialectical behavior therapy (DBT) has a strong evidence base supporting its utility for managing suicide risk. Meanwhile, acceptance and commitment therapy (ACT) has been shown to effectively treat individuals with psychosis symptoms, as well as comorbid anxiety and mood disorders in CHR-p clients. Despite the robust evidence for each of these modalities in addressing concerns around suicidality and psychosis risk independently, there is a paucity of literature on how to support clients experiencing co-occurring suicide and psychosis risk. Such overlapping risk is often central to presenting concerns in CHR-p clients. Our manuscript presents a case example of an integrated DBT-ACT approach to managing risk surrounding both suicide and psychosis symptoms in an outpatient setting. We highlight how an integrated approach may help outpatient providers to implement and modify effective treatment that promotes continued outpatient care focused on goals beyond immediate risk management of both suicide and emerging psychosis. We provide specific examples of DBT techniques and ACT interventions used by a supervised doctoral-level student clinician in treatment with a CHR-p client and discuss implications for future clinical research.

Effectiveness of Acceptance and Commitment Therapy on the Positive and Negative Symptoms and Emotion Regulation of Patients with Schizophrenia Spectrum Disorders: A Single-case Clinical Trial Study

Background: The literature suggests the increasing application of acceptance and commitment therapy (ACT) for people with schizophrenia spectrum disorders (SSD). Objectives: This study aimed to determine the effectiveness of ACT on the positive and negative symptoms and emotion regulation of patients with SSD. Methods: The experimental design of the current study was an AB (baseline and intervention phases) along with the follow-up phase, in addition to Treatment-As-Usual (TAU), ACT sessions were held for the participants. Among the 20 participants who had inclusion criteria to the study, five participant (three men and two women in the age range of 32 - 43 years) were randomly allocated to participate in the intervention through drawing and evaluated using the Positive and Negative Syndrome Scale (PANSS) and Difficulties in Emotion Regulation Scale (DERS) in three phases of baseline, intervention, and follow-up. For data analysis, non-overlapping indices and Cohen's d effect size were measured, and visual diagrams were plotted for interpretation. Results: The present results showed that the effect sizes of psychotic symptoms in the first to fifth participants were 1.7, 1.9, 0.6, 4, and 1.4, respectively in the intervention phase relative to the baseline; the effect size was only large for the fourth participant. Also, the effect sizes of emotion regulation in the first to fifth participants were 0.8, 1.6, 1.5, 1.2, and 2.7, respectively; the effect size was only large for the fifth participant. Conclusions: The results of data analysis showed that ACT is effective in reducing psychotic symptoms and improving emotion regulation. The effect size of ACT was the largest for the fourth participant; medium for the first, second, and fifth participants; and small for the third participant.

Acceptance and Commitment Therapy for Patients with a First Psychotic Episode

The search for the most effective methods of therapy for mental disorders is a priority for modern psychiatry. An approach to the early diagnostics and rehabilitation of patients experiencing psychotic episodes for the first time is proposed in the present article. The proposed approach is based on the combination of drug therapy and acceptance and commitment therapy (ACT) characterized by the development of the patient's psychological flexibility, rather than controlling the disease symptoms. The article describes the main processes of the ACT model: acceptance, cognitive defusion, contact with the present moment, understanding of the inner world, awareness of significant values, and the regulation of purposeful behaviour for the implementation of these values. Recommendations for different stages of treatment were also developed by specialists of the First Psychotic Episode Clinic at the Mental Health Clinic No.1 named after N.A. Alexeev. The psychological rehabilitation of patients with the use of ACT in the case of psychotic disorders with both negative and positive symptoms was elaborated. The application of acceptance and commitment therapy in the early diagnostics and treatment of patients experiencing a first psychotic episode results in fewer readmissions and improved psychosocial functioning in both inpatient and outpatient care.

Ensuring Effective Public Health Communication: Insights and Modeling Efforts From Theories of Behavioral Economics, Heuristics, and Behavioral Analysis for Decision Making Under Risk

Public health (PH) messaging can have an enormous impact on shaping how individuals within society behave, and can ensure it is in a safe and responsible way, consistent with up-to-date evidence-based PH guidelines. If done effectively, messaging can save lives and improve the health of those within society. However, unfortunately, those within Government PH bodies typically have little training about how to effectively represent PH messages in a way that is consistent with psychological theories of cognitive bias, in order to avoid cognitively biasing the public through their messages. As a result of this, inadequate representation of PH messages can result, which can often lead to cognitive bias in those from the public who read or listen to the message information. This can lead to poor decision making of the pubic as a whole, which can then further lead to harm and even death of public members as a result of these poor decisions. One way to minimize the problem of bias in decision making is to explore psychology theories that model how bias can occur from PH messaging, and identify ways in which PH agencies can utilize such approaches to improve the effectiveness of their messages. Previous focus has been largely on behavioral economic theories, however, here, other accounts are offered in addition to these. These include theories of heuristics and theories from the behavior analysis domain, which may increase the predictive power of modeling bias, and have applications for how best to represent PH message information which minimize bias.

Paranoia and negative schema about the self and others: A systematic review and meta-analysis

Negative self and negative other schema have been implicated in the development of paranoia. The current study provides a meta-analysis, narrative review and quality appraisal of quantitative studies investigating the relationship between negative self and negative other schema and paranoia across the paranoia continuum. A systematic search identified 43 eligible studies; 25 were included in the meta-analysis. Meta-analytic findings demonstrated a medium to large relationship between paranoia and negative self-schema (r = 0.46, 95% CI 0.39 to 0.53) and negative other schema (r = 0.48, 95% CI 0.38 to 0.56). The magnitude of associations was similar across people with and without psychosis. Findings demonstrated that associations between negative self-schema and paranoia were not always statistically significant when controlling for confounding variables, particularly depression. The association between negative other schema and paranoia tended to remain significant when controlling for confounding variables. Findings also demonstrated that negative schema may mediate relationships between adverse experiences in childhood and paranoia. Overall, findings support theoretical proposals that both negative self and negative other schema are associated with paranoia. Longitudinal studies are required to confirm the direction of effects. Findings provide support for incorporating and targeting negative self and negative other schema in psychological formulations and therapeutic work.

Effectiveness of Acceptance and Commitment Therapy for Patients with Psychosis Being Monitored at a Community Mental Health Center: A Six-Month Follow-up Study

OBJECTIVE

This study aimed to examine the long-term efficacy of a short-term acceptance and commitment therapy-based (ACT) group psychotherapy on patients with psychosis in a community mental health center (CMHC).

METHODS

A total of 6 group-based ACT sessions were applied to 16 people diagnosed with psychotic disorders who met the inclusion criteria. They were evaluated at the start of, end of, and 6 months after the therapy using the acceptance and action questionnaire, the psychotic symptom rating scales, and the quality-of-life scale.

RESULTS

At the end of the 6 session group therapy and 6-month follow-up, a statistically significant decrease was found in patients' psychotic symptoms and experiential avoidance as well as a statistically significant increase in their quality of life (P < .001).

CONCLUSION

According to the results, ACT can be said to be an effective method for managing psychotic symptoms, reducing experiential avoidance, and improving the quality of life in patients diagnosed with psychotic disorders in CMHCs.

The safety and efficacy of acceptance and commitment therapy against psychotic symptomatology: a systematic review and meta-analysis

OBJECTIVE

Acceptance and commitment therapy (ACT) is a third-wave psychological intervention that has attracted considerable clinical and research attention. A previous meta-analysis of ACT trials in psychosis reported a large effect size of ACT against overall psychotic symptomatology. However, there were critical methodological issues in the review that justify replication.

METHODS

Systematic review and meta-analysis of randomized controlled trials (RCTs) testing ACT vs. any comparator condition in a sample of adults with psychosis. The outcome of interest was overall psychotic symptomatology.

RESULTS

The search identified seven published and eight unpublished trials (of which we were able to obtain data from one). Data on symptomatology were extracted from six trials that involved 274 participants. The summary effect size (Hedge's G) for overall symptomatology was small and not significant (-0.21, 95%CI -0.60-0.18). Trials were generally rated as having a high risk of bias. Safety reporting was inadequate across included trials.

CONCLUSIONS

Our observed effect size contrasted with that reported in a previous meta-analysis; differences were likely explained by errors in data extraction. The findings of this review suggest that there is currently inadequate evidence to conclude that ACT is a safe and effective treatment against psychotic symptomatology.

SYSTEMATIC REVIEW REGISTRATION

CRD42018097200.

Why are some drought-affected farmers less distressed than others? The association between stress, psychological distress, acceptance, behavioural disengagement and neuroticism

OBJECTIVE

To identify the modifiable psychological and behavioural coping strategies associated with low levels of psychological distress, independent of more stable personality and demographic factors, in a sample of farmers who reported being exposed to a recent stressful event during an extended drought.

DESIGN/SETTING/PARTICIPANTS

Three hundred and nine South Australian, drought-affected grain, sheep and/or cattle farmers completed printed or online questionnaires. Only those who reported experiencing a stressful event in the past month that they rated ≥7 on a scale ranging from 1 (not stressful at all) to 10 (extremely stressful) were included in the analyses (n = 175, 65.06%). Participants ranged in age from 24 to 85 years and 40% were female.

MAIN OUTCOME MEASURES

Psychological distress was measured using the Kessler Psychological Distress Scale, and coping strategies were measured using a situational version of the COPE inventory. Five personality factors (extraversion, neuroticism, openness, conscientiousness and agreeableness) were assessed using the Quickscales-R.

RESULTS

In the final multivariable model, distress was elevated among individuals reporting higher neuroticism and behavioural disengagement, and lower in individuals reporting greater use of acceptance. These 3 variables explained 44% of the variance in distress.

CONCLUSION

Farmers recently exposed to a significant stressor, who used acceptance as a coping strategy, did not engage in behavioural disengagement and scored low on neuroticism, were least likely to experience distress. Given the stability of personality factors, interventions that foster farmers' use of acceptance and prevent behavioural disengagement as coping strategies might assist them with the management of future stressors, particularly in times of drought.

The Effectiveness of a Mindfulness-Based Psychoeducation Programme for Emotional Regulation in Individuals with Schizophrenia Spectrum Disorders: A Pilot Randomised Controlled Trial

BACKGROUND

Emotion dysregulation has emerged as a transdiagnostic factor that potentially exacerbates the risk of early-onset, maintenance, and relapse of psychosis. Mindfulness is described as the awareness that emerges from paying attention to the present moment without judgment. It gently pulls the mind out of the negative emotions induced by the disparity between expectation and reality by focusing on the present moment, instead of worrying about the future or regretting the past. However, only a few research has ever focused on the efficacy of using a mindfulness-based intervention to improve emotion regulation in schizophrenia spectrum disorders.

PURPOSE

The purpose of this study was to examine the effectiveness of a Mindfulness-Based Psychoeducation Programme (MBPP) on the emotion regulation of individuals with schizophrenia, in particular, to access emotion regulation strategies. The objective of this study was to find out whether MBPP is feasible for improving emotion regulation strategies, in terms of rumination, cognitive reappraisal, and expressive suppression, with a sustainable effect at a three-month follow-up.

PATIENTS AND METHODS

A single-blinded pilot randomised controlled trial with repeated-measures designs was adopted. Forty-six participants diagnosed with schizophrenia and its subtypes were randomised in either the 8-week mindfulness-based psychoeducation programme or treatment-as-usual (control) group.

RESULTS

The results of the Generalised Estimating Equations test indicated that the MBPP group showed a significant improvement in reappraisal at a three-month follow-up (β = -6.59, Wald's χ ²=4.55, p=0.033), and a significant reduction in rumination across time. However, the Generalised Estimating Equations indicated no significant difference in rumination and expressive suppression in the MBPP group. Two participants reported having unwanted experiences, including feelings of terror and distress during the mindfulness practice.

CONCLUSION

The MBPP appeared to be effective for improving emotion regulation, which will contribute to future large-scale RCT to confirm the treatment effects in more diverse groups of schizophrenic patients.

Safety and Efficacy of Acceptance and Commitment Therapy (ACT) in Schizophrenia Spectrum and Other Psychotic Disorders: Protocol for a Systematic Review and Meta-Analysis

Acceptance and commitment therapy (ACT) has been reported to be effective in the treatment of some psychiatric disorders. It remains uncertain, however, whether ACT is safe and effective in treating schizophrenia spectrum and other psychotic disorders (e.g., psychosis). This protocol describes the methodology for a systematic review and meta-analysis of the safety and efficacy of ACT in the treatment of psychosis. The review will be guided by the standards set by the Cochrane Collaboration. We will search the Allied and Complementary Medicine Database (AMED), Cumulative Index to Nursing and Allied Health Literature (CINAHL), Cochrane Central Register of Controlled Trials (CENTRAL), Excerpta Medica database (EMBASE), EMCARE, Education Resources Information Center (ERIC), MEDLINE, and PsycINFO databases for randomized controlled trials, whose arms are ACT and any comparator, as well as ClinicalTrials.gov, Australian New Zealand Clinical Trials Registry (ANZCTR), and Current Controlled Trials (ISRCTN), for unpublished and ongoing trials. The primary outcome will be any standard (or surrogate) measure of psychotic pathology. The meta-analysis will summarize short-term and long-term effects and different control conditions with or without treatment as usual or comparative to other interventions. In cases where heterogeneity is detected (via χ² and I²), we will adopt the random effects model for computation.