Exposure to green spaces and schizophrenia: a systematic review.

The mental health benefits of exposure to green spaces are well known. This systematic review summarizes the evidence of green space exposure for people with schizophrenia spectrum disorders (SSDs), focusing on incidence and mental health outcomes, including mental health symptoms and health service use. The study was pre-registered (PROSPERO ID: CRD42023431954), and conducted according to PRISMA guidelines. Seven databases, reference lists, and gray literature sources were searched. Methodological quality was assessed using The Quality Assessment Tool for Quantitative Studies. 126 studies were screened, and 12 studies were eligible for inclusion. Seven studies found that exposure to green space was associated with a reduced risk of schizophrenia (lowest to highest green space exposure: HRs = 0.62-0.37; IRRs = 1.52-1.18), with five studies reporting a dose-response relationship. Of these studies, four examined childhood exposure and the remainder examined adult exposure. Regarding health service use, proximity to green space was not significantly associated with length of hospital admission, though greater green space exposure was associated with reduced hospital admission rates. Three studies found reduced symptoms of anxiety (d = -0.70-2.42), depression (d = -0.97-1.70) and psychosis (d = -0.94) with greater green space exposure. Exposure to green space reduces the risk of schizophrenia, and there is emerging evidence of the potential benefits of green space for reducing symptoms and health service use among people with SSDs. Future research using experimental and longitudinal designs will provide more robust evidence of the benefits of green space for people with SSDs.

Cross-cultural validation of the revised Green et al., paranoid thoughts scale.

BACKGROUND: With efforts increasing worldwide to understand and treat paranoia, there is a pressing need for cross-culturally valid assessments of paranoid beliefs. The recently developed Revised Green et al., Paranoid Thoughts Scale (R-GPTS) constitutes an easy to administer self-report assessment of mild ideas of reference and more severe persecutory thoughts. Moreover, it comes with clinical cut-offs for increased usability in research and clinical practice. With multiple translations of the R-GPTS already available and in use, a formal test of its measurement invariance is now needed. METHODS: Using data from a multinational cross-sectional online survey in the UK, USA, Australia, Germany, and Hong Kong (N = 2510), we performed confirmatory factory analyses on the R-GPTS and tested for measurement invariance across sites. RESULTS: We found sufficient fit for the two-factor structure (ideas of reference, persecutory thoughts) of the R-GPTS across cultures. Measurement invariance was found for the persecutory thoughts subscale, indicating that it does measure the same construct across the tested samples in the same way. For ideas of reference, we found no scalar invariance, which was traced back to (mostly higher) item intercepts in the Hong Kong sample. CONCLUSION: We found sufficient invariance for the persecutory thoughts scale, which is of substantial practical importance, as it is used for the screening of clinical paranoia. A direct comparison of the ideas of reference sum-scores between cultures, however, may lead to an over-estimation of these milder forms of paranoia in some (non-western) cultures.

Intolerance of uncertainty and psychosis: A systematic review.

OBJECTIVES: Intolerance of uncertainty, the tendency to interpret and react negatively to uncertainty, is a transdiagnostic risk factor for anxiety, depression and eating-related disorders. Given the high comorbidity between anxiety, depression and schizophrenia-spectrum diagnoses (SSDs), there is potential for intolerance of uncertainty to play a role in modulating psychosis symptoms. To address this gap in our understanding, we conducted the first prospectively registered systematic review on intolerance of uncertainty and psychotic symptoms in both people with SSDs and in the general population. METHODS: Four databases were searched (PsycINFO, Medline, Web of Science and PubMed), which identified ten studies with a total of 1503 participants that measured intolerance of uncertainty and psychosis symptoms. RESULTS: Key findings suggest the following: (1) Intolerance of uncertainty was associated with total negative psychotic symptoms with small-medium effect sizes; (2) intolerance of uncertainty was higher in individuals with an 'at-risk' mental state for psychosis compared to controls; (3) higher intolerance of uncertainty was associated with more individual psychotic symptoms related to delusions and paranoia within clinical and nonclinical samples; and (4) there was mixed evidence for a relationship between intolerance of uncertainty and auditory hallucinations and intolerance of uncertainty and total positive symptoms in clinical samples. CONCLUSIONS: Overall, these findings highlight that intolerance of uncertainty may be an important transdiagnostic dimension and potential treatment target for psychotic symptoms such as delusions and paranoia in people with SSDs.

Experimental studies of paranoid thinking in clinical and nonclinical populations: a systematic review and meta-analysis.

Paranoia is common in clinical and nonclinical populations, consistent with continuum models of psychosis. A number of experimental studies have been conducted that attempt to induce, manipulate or measure paranoid thinking in both clinical and nonclinical populations, which is important to understand causal mechanisms and advance psychological interventions. Our aim was to conduct a systematic review and meta-analysis of experimental studies (non-sleep, non-drug paradigms) on psychometrically assessed paranoia in clinical and nonclinical populations. The review was conducted using PRISMA guidelines. Six databases (PsycINFO, PubMed, EMBASE, Web of Science, Medline and AMED) were searched for peer-reviewed experimental studies using within and between-subject designs to investigate paranoia in clinical and nonclinical populations. Effect sizes for each study were calculated using Hedge's g and were integrated using a random effect meta-analysis model. Thirty studies were included in the review (total n = 3898), which used 13 experimental paradigms to induce paranoia; 10 studies set out to explicitly induce paranoia, and 20 studies induced a range of other states. Effect sizes for individual studies ranged from 0.03 to 1.55. Meta-analysis found a significant summary effect of 0.51 [95% confidence interval 0.37-0.66, p < 0.001], indicating a medium effect of experimental paradigms on paranoia. Paranoia can be induced and investigated using a wide range of experimental paradigms, which can inform decision-making about which paradigms to use in future studies, and is consistent with cognitive, continuum and evolutionary models of paranoia.

Pandemic paranoia in the general population: international prevalence and sociodemographic profile.

BACKGROUND: The term 'pandemic paranoia' has been coined to refer to heightened levels of mistrust and suspicion towards other people specifically due to the COVID-19 pandemic. In this study, we examine the international prevalence of pandemic paranoia in the general population and its associated sociodemographic profile. METHODS: A representative international sample of general population adults (N = 2510) from five sites (USA N = 535, Germany N = 516, UK N = 512, Australia N = 502 and Hong Kong N = 445) were recruited using stratified quota sampling (for age, sex, educational attainment) and completed the Pandemic Paranoia Scale (PPS). RESULTS: The overall prevalence rate of pandemic paranoia was 19%, and was highest in Australia and lowest in Germany. On the subscales of the PPS, prevalence was 11% for persecutory threat, 29% for paranoid conspiracy and 37% for interpersonal mistrust. Site and general paranoia significantly predicted pandemic paranoia. Sociodemographic variables (lower age, higher population size and income, being male, employed and no migrant status) explained additional variance and significantly improved prediction of pandemic paranoia. CONCLUSIONS: Pandemic paranoia was relatively common in a representative sample of the general population across five international sites. Sociodemographic variables explained a small but significant amount of the variance in pandemic paranoia.

Dispositional forgiveness buffers paranoia following interpersonal transgression.

OBJECTIVE: To test a novel proposition that dispositional forgiveness has the unrecognized benefit of buffering feelings of paranoia following negative interpersonal experiences and interpersonal transgressions. METHODS: In Study 1 (N = 128), we used an experimental paradigm, the Prisoner's Dilemma Game (PDG), to test the premise that an interpersonal transgression increases state paranoia. Study 2 (N = 180) used a longitudinal design to test the central proposition that dispositional forgiveness buffers state paranoia following naturally occurring difficult (vs pleasant) interpersonal events. Study 3 (N = 102) used a novel experimental paradigm to determine the causal effect of manipulating forgiveness on paranoia. RESULTS: In Study 1, interpersonal transgressions in the PDG increased paranoia. In Study 2, paranoia was higher following difficult (rather than pleasant) events, and higher levels of dispositional forgiveness moderated the negative effect of difficult events on paranoia. In Study 3, there was a causal effect of forgiveness on (reduced) paranoia. CONCLUSIONS: This is the first evidence that (1) interpersonal transgressions increase paranoia, (2) high dispositional forgiveness moderates the deleterious effect of interpersonal transgression on paranoia, and (3) dispositional forgiveness is causally related to less paranoia.

Are they out to get me? Individual differences in nonclinical paranoia as a function of narcissism and defensive self-protection.

OBJECTIVE: Three studies tested a novel model of the narcissism-paranoia link, whereby narcissism (primarily its socially maladaptive facets) is associated with paranoia via over-use of defensive self-protection and/or under-use of self-affirmation. METHODS: In Study 1, 245 online volunteers (87% female; MAGE  = 20.92; 44% White-British) completed trait measures of narcissism, self-enhancement/protection strategies and paranoia. In Study 2, 116 students (82% female; MAGE  = 20.23; 70% White-British) completed baseline measures, then reported state reactions and paranoia following two difficult and two pleasant interpersonal events after 3-10 days. In Study 3, 517 online volunteers (64% female; MAGE  = 22.76; 77% White/Caucasian) completed baseline measures, experienced a standardized social exclusion (vs. neutral) manipulation (Cyberball), then reported state reactions and paranoia. RESULTS: In Study 1, narcissism was associated with higher paranoia via defensiveness. In Study 2, this was replicated in difficult but not pleasant events, and was driven by the Entitlement/Exploitativeness facet of narcissism. In Study 3, narcissistic rivalry and vulnerable narcissism, but not admiration, were associated with Cyberball-related paranoia via general defensiveness and denigration of others. CONCLUSIONS: Individuals high in narcissism-especially its socially maladaptive facets-who over-rely on defensive self-protection strategies in response to threat, are particularly vulnerable to paranoia. Findings help to understand individual differences in paranoia.

Recommendations for monitoring and reporting harm in mindfulness for psychosis research.

There is increasing interest in potential harmful effects of mindfulness-based interventions. In relation to psychosis, inconsistency and shortcomings in how harm is monitored and reported are holding back our understanding. We offer eight recommendations to help build a firmer evidence base on potential harm in mindfulness for psychosis.

A dimensional summation account of polymorphous category learning.

Polymorphous concepts are hard to learn, and this is perhaps surprising because they, like many natural concepts, have an overall similarity structure. However, the dimensional summation hypothesis (Milton and Wills Journal of Experimental Psychology: Learning, Memory and Cognition, 30, 407-415 2004) predicts this difficulty. It also makes a number of other predictions about polymorphous concept formation, which are tested here. In Experiment 4, we confirm the theory's prediction that polymorphous concept formation should be facilitated by deterministic pretraining on the constituent features of the stimulus. This facilitation is relative to an equivalent amount of training on the polymorphous concept itself. In further experiments, we compare the predictions of the dimensional summation hypothesis with a more general strategic account (Experiment 2), a seriality of training account (Experiment 3), a stimulus decomposition account (also Experiment 3), and an error-based account (Experiment 4). The dimensional summation hypothesis provides the best account of these data. In Experiment 5, a further prediction is confirmed-the single feature pretraining effect is eliminated by a concurrent counting task. The current experiments suggest the hypothesis that natural concepts might be acquired by the deliberate serial summation of evidence. This idea has testable implications for classroom learning.

Can cognitive insight predict symptom remission in a first episode psychosis cohort?

BACKGROUND: The outcome of first episode psychosis (FEP) is highly variable and difficult to predict. Cognitive insight measured at illness onset has previously been found to predict psychopathology 12-months later. The aims of this study were to examine whether the prospective relationship between cognitive insight and symptom severity is evident at four-years following FEP and to examine some psychological correlates of cognitive insight. METHODS: FEP participants (n = 90) completed the Beck Cognitive Insight Scale (BCIS) at illness onset, and associations between BCIS scores with symptom severity outcomes (4-years after FEP) were assessed. The BCIS scales (self-reflectiveness and self-certainty) were examined as a composite score, and individually compared to other cognitive measures (IQ and jumping to conclusions (JTC) bias). RESULTS: Regression analyses revealed that the cognitive insight composite did not predict 4-year symptom remission in this study while the self-reflection subscale of the BCIS predicted severity of symptoms at 4-years. Self-certainty items of the BCIS were not associated with symptom severity. Significant correlations between the JTC bias, self-certainty and IQ were found, but self-reflection did not correlate with these other cognitive measures. CONCLUSIONS: Self-reflective capacity is a more relevant and independent cognitive construct than self-certainty for predicting prospective symptom severity in psychosis. Improving self-reflection may be a useful target for early intervention research.

Distress, omnipotence, and responsibility beliefs in command hallucinations.

OBJECTIVES: Command hallucinations are considered to be one of the most distressing and disturbing symptoms of schizophrenia. Building on earlier studies, we compare key attributes in the symptomatic, affective, and cognitive profiles of people diagnosed with schizophrenia and hearing voices that do (n = 77) or do not (n = 74) give commands. METHODS: The study employed a cross-sectional design, in which we assessed voice severity, distress and control (PSYRATs), anxiety and depression (HADS), beliefs about voices (BAVQ-R), and responsibility beliefs (RIQ). Clinical and demographic variables were also collected. RESULTS: Command hallucinations were found to be more distressing and controlling, perceived as more omnipotent and malevolent, linked to higher anxiety and depression, and resisted more than hallucinations without commands. Commanding voices were also associated with higher conviction ratings for being personally responsible for preventing harm. CONCLUSIONS: The findings suggest key differences in the affective and cognitive profiles of people who hear commanding voices, which have important implications for theory and psychological interventions. PRACTITIONER POINTS: Command hallucinations are associated with higher distress, malevolence, and omnipotence. Command hallucinations are associated with higher responsibility beliefs for preventing harm. Responsibility beliefs are associated with voice-related distress. Future psychological interventions for command hallucinations might benefit from focussing not only on omnipotence, but also on responsibility beliefs, as is done in psychological therapies for obsessive compulsive disorder. Limitations The cross-sectional design does not assess issues of causality. We did not measure the presence or severity of delusions.

Anger and Paranoia in Mentally Disordered Offenders.

Previous studies have identified a positive relationship between aggression and paranoia, yet the relationship between the emotion of anger and paranoia in forensic populations has not been examined. Possible confounding variables, such as social desirability and mood, should also be considered. Sixty-six participants who had a violent conviction and mental disorder completed self-report questionnaires that measured anger, paranoid ideation, socially desirable responding, anxiety, and depression. The findings indicated that increased anger was associated with increased paranoia. Partial correlations showed that anger remained significantly associated with paranoia after socially desirable responding, anxiety, depression, gender, and violence history were controlled, suggesting anger and paranoia were not associated due to indirect relationships with these constructs. This could suggest that integrative psychological interventions that consider experiences of both anger and paranoia may be beneficial with forensic populations.

Paranoia in the therapeutic relationship in cognitive behavioural therapy for psychosis.

BACKGROUND AND AIMS: This study explored therapists' and clients' experiences of paranoia about the therapist in cognitive behaviour therapy. METHOD: Ten therapists and eight clients engaged in cognitive behaviour therapy for psychosis were interviewed using a semi-structured interview. Data were analyzed using thematic analysis. RESULTS: Clients reported experiencing paranoia about their therapist, both within and between therapy sessions. Therapists' accounts highlighted a number of dilemmas that can arise in responding to clients' paranoia about them. CONCLUSIONS: The findings highlight helpful ways of working with clients when they become paranoid about their therapist, and emphasize the importance of developing a therapeutic relationship that is radically collaborative, supporting a person-based approach to distressing psychotic experience.

Naturalistic change in nonclinical paranoid experiences.

BACKGROUND: Numerous studies have shown that paranoia is common in the nonclinical population; however, little research has examined whether nonclinical paranoid beliefs change over time, or considered potential reasons for change. AIMS: The aim of the present study was therefore to examine naturalistic change in nonclinical paranoid experiences. METHOD: 60 participants described an idiosyncratic experience of paranoia, including when it occurred, and rated their experience along four key belief dimensions: preoccupation, impact, distress and conviction. Participants provided two ratings for each dimension, retrospective recall at the time of the occurrence of the paranoid event, and again at the time of the interview. Participants were also asked to provide qualitative descriptions of reasons for change in belief dimensions. RESULTS: Participants described paranoid experiences that had occurred over a large timeframe (1 day-25 years). Reductions across all four belief dimensions were found, and seven key themes emerged following qualitative analysis of the participants' reason for change in response to the paranoid event. CONCLUSIONS: The findings highlight a number of factors associated with reported naturalistic changes in belief dimensions of conviction, distress, preoccupation and impact, which might be useful in enhancing interventions for clinical and nonclinical paranoia, and in helping to build models to account for why people showing clear paranoid ideation do, or do not, go on to develop clinical paranoia.

Mindfulness for psychosis: Current evidence, unanswered questions and future directions.

PURPOSE & METHOD: Mindfulness for psychosis research has grown exponentially over the last 15 years. In this paper, a brief overview of mindfulness for psychosis is provided followed by a summary of the findings from a systematic search of meta-analyses dated up to February 2023. Current issues in the field are discussed and a future research agenda is presented. RESULTS: Ten meta-analyses published between 2013 and 2023 were identified. Reported effect sizes on reductions in psychotic symptoms ranged from small-large across reviews. Four key issues in the field are identified and discussed - (1) is mindfulness for psychosis safe? (2) is home practice essential and related to clinical outcomes? (3) what is the impact of mindfulness practice versus metacognitive insights derived from practice, on clinical outcomes? (4) do the benefits translate into routine clinical practice? CONCLUSIONS: Mindfulness is a promising intervention that is emerging as being both safe and effective for people with psychosis. Future research focused on evaluating mechanisms of change and implementation in routine clinical practice should be prioritised.

Systematic review of the safety of mindfulness-based interventions for psychosis.

Harmful outcomes of psychological interventions are under-researched, including in mindfulness-based interventions (MBI) for psychosis. This systematic review summarizes reporting and prevalence of 8 harm indices (death, adverse events, hospitalisation, study drop out, noncompletion of therapy, side effects of therapy, symptom deterioration and crisis service use) in Randomised Controlled Trials (RCTs) of MBIs for psychosis. Meta-analyses of risk differences were also calculated for each harm index. The review included 39 studies, with a total n of 2684 participants across studies. The percentage of studies reporting on each index of harm, and the prevalence of harm, varied greatly across each index. 0% of studies reported on side effects of interventions compared to 92% of studies reporting on study dropout. Meta-analyses of risk differences (RD) found a higher risk of hospitalisation (RD (95% CI) = -0.136 (-0.23 to -0.05), p = 0.003) and crisis service use (RD (95% CI) = -0.160 (-0.299, -0.024), p = 0.02) in control arms compared to intervention arms, and no significant difference in adverse events, death, symptom deterioration, noncompletion of therapy, drop out and side effects of therapy. Overall, reporting of harm was inconsistent across studies and the quality of data collection and reporting varied. MBIs for psychosis appear to be safe and may reduce the risk of hospitalisation and use of crisis services. However, the absence of thorough reporting on harm precludes a balanced analysis of benefits versus harms. Future research into the effectiveness of MBIs should consistently operationalise, monitor and report data on harm.

The Apple Doesn't Fall Far from the Tree? Paranoia and Safety Behaviours in Adolescent-Parent-Dyads.

Paranoia is a common experience in adolescence that may entail the use of safety behaviours (e.g. avoidance), which are assumed to maintain paranoia in the long run. As the development of paranoia and related safety behaviours in youth may be influenced by their caregivers, we aimed to investigate the associations of paranoia and safety behaviours in adolescents and their parents. Adolescents from the general population aged 14-17 and one of their parents (N = 142 dyads) were recruited via Qualtrics to complete online surveys including measures of paranoia, safety behaviour use, anxiety, and demographics. We fitted an Actor-Partner-Interdependence Model (APIM) for testing dyadic parent-child interaction by using structural equation modelling and controlled for adolescents' and parents' anxiety. Results indicated that paranoia positively predicted safety behaviour use in adolescents and in parents. There were significant positive intra-dyad (i.e. parent-adolescent) correlations for both paranoia and safety behaviour use. One partner effect was significant: parental paranoia positively predicted the safety behaviour use of their adolescent child. Conversely, adolescents' paranoia did not predict their parents' safety behaviour use. Our findings corroborate prior research demonstrating an association between paranoia and safety behaviours among adults, and extend this association to adolescents. Children of parents experiencing paranoia are at increased risk of developing paranoia and safety behaviours, which indicates the need for interventions that target paranoia and safety behaviours in family systems.

Pandemic Paranoia Scale for Adolescents (PPS-A): An Initial Psychometric Evaluation and Prevalence Study of Adolescents in the United States and United Kingdom.

Paranoid thoughts have been reported in 20-30% of adolescents, and preliminary research has shown that paranoia and psychotic-like experiences have increased during the COVID-19 pandemic. However, previous research has typically used general measures to assess paranoia, rather than those specific to COVID-19, which may overlook particular facets of paranoia related to the pandemic and result in an under-reporting of paranoia prevalence rates during this time. Therefore, this study aimed to examine the psychometric properties of the Pandemic Paranoia Scale for Adolescents (PPS-A), which was adapted from the original scale to be appropriate for younger respondents, and to assess the prevalence of pandemic paranoia among adolescents. Adolescents (N = 462) recruited on Qualtrics from the United States (US) and United Kingdom (UK) completed an online survey consisting of the PPS-A and measures of general paranoia and negative affect. A subset of adolescent's parents (N = 146) also completed an online survey providing dyadic data. Findings showed that the PPS-A shared the same three factor structure as the adult PPS (i.e., persecutory threat, paranoid conspiracy, and interpersonal mistrust) and across participant nationality, race, gender, and mental health diagnosis. It also demonstrated strong psychometric properties. The overall prevalence rate of pandemic-related paranoia among adolescents was 21% and prevalence rates were higher among US participants than UK participants. This study provides the most comprehensive psychometric evaluation of a pandemic paranoia scale designed for adolescents and highlights the continued prevalence of pandemic paranoia in this age-group nearly two years after COVID-19 began.

Perception of peer group rank of individuals with early psychosis.

OBJECTIVES: Social rank theory has been applied to psychosis, in particular the relationship between an individual and their voices. However, perceived peer group rank has not been empirically tested in an early psychosis group. The purpose of the study was to test the prediction that individuals with early psychosis will have lower perceived social status, engage in submissive behaviours more frequently, and will feel more entrapped by external events compared to a healthy control group. DESIGN: The study employed a cross-sectional design, comparing individuals with early psychosis and healthy controls. METHODS: A total of 24 participants with early psychosis and 24 matched controls completed self-report measures of social rank, including social comparison, submissive behaviours and entrapment, measures of depression, anxiety and psychotic symptoms, and measures of peer network size and peer relationship quality. RESULTS: Individuals with early psychosis viewed themselves as being of lower social rank and inferior in relation to matched controls, and also reported engaging in submissive behaviours more frequently and felt more entrapped by external events. CONCLUSIONS: Perception of lower social rank and inferiority amongst individuals with early psychosis may impact on engagement in peer relationships and impact on the social decline in early psychosis, which could have significant implications for interventions and recovery.

A paradigm for the study of paranoia in the general population: the Prisoner's Dilemma Game.

A growing body of research shows that paranoia is common in the general population. We report three studies that examined the Prisoner's Dilemma Game (PDG) as a paradigm for evaluation of non-clinical paranoia. The PDG captures three key qualities that are at the heart of paranoia--it is interpersonal, it concerns threat, and it concerns the perception of others' intentions towards the self. Study 1 (n=175) found that state paranoia was positively associated with selection of the competitive PDG choice. Study 2 (n=111) found that this association was significant only when participants believed they were playing the PDG against another person, and not when playing against a computer. This finding underscores the interpersonal nature of paranoia and the concomitant necessity of studying paranoia in interpersonal context. In Study 3 (n=152), we assessed both trait and state paranoia, and differentiated between distrust- and greed-based competition. Both trait and state paranoia were positively associated with distrust-based competition (but not with greed-based competition). Crucially, we found that the association between trait paranoia and distrust-based competition was fully mediated by state paranoia. The PDG is a promising paradigm for the study of non-clinical paranoia.