Risk Factor For Psychotic Disorders Research Articles

Lost in translation? Deciphering the role of language differences in the excess risk of psychosis among migrant groups.

Migration is a well-established risk factor for psychotic disorders, and migrant language has been proposed as a novel factor that may improve our understanding of this relationship. Our objective was to explore the association between indicators of linguistic distance and the risk of psychotic disorders among first-generation migrant groups. Using linked health administrative data, we constructed a retrospective cohort of first-generation migrants to Ontario over a 20-year period (1992-2011). Linguistic distance of the first language was categorized using several approaches, including language family classifications, estimated acquisition time, syntax-based distance scores, and lexical-based distance scores. Incident cases of non-affective psychotic disorder were identified over a 5- to 25-year period. We used Poisson regression to estimate incidence rate ratios (IRR) for each language variable, after adjustment for knowledge of English at arrival and other factors. Our cohort included 1 863 803 first-generation migrants. Migrants whose first language was in a different language family than English had higher rates of psychotic disorders (IRR = 1.08, 95% CI 1.01-1.16), relative to those whose first language was English. Similarly, migrants in the highest quintile of linguistic distance based on lexical similarity had an elevated risk of psychotic disorder (IRR = 1.15, 95% CI 1.06-1.24). Adjustment for knowledge of English at arrival had minimal effect on observed estimates. We found some evidence that linguistic factors that impair comprehension may play a role in the excess risk of psychosis among migrant groups; however, the magnitude of effect is small and unlikely to fully explain the elevated rates of psychotic disorder across migrant groups.

Examining the association between prenatal and perinatal adversity and the psychotic experiences in childhood.

Prenatal and perinatal complications are established risk factors for psychotic disorder, but far less is known about these measures and psychotic experiences (PEs). We investigated the longitudinal effect of prenatal risk factors (maternal behavior, medication complications) and perinatal risk factors (birth weight, medical complications) on frequency of PEs. We also examined the cumulative risk of prenatal/perinatal risk factors, and differences between transient PE, persistent PE, and controls. The Adolescent Brain Cognitive Development study is a large child cohort (age 9-10 at baseline; n = 11 872 with PE data). PEs were measured longitudinally using the Prodromal Questionnaire-Brief, Child version, and included only if reported as distressing. Mixed-effects models were used for analysis, controlling for random effects, and a substantial number of fixed-effects covariates. Urinary tract infection (β = 0.11, 95% confidence interval [CI] 0.03-0.19) and severe anemia (β = 0.18, 95% CI 0.07-0.29) increased frequency of distressing PEs in childhood. Number of prenatal complications increased frequency of PEs (β = 0.03, 95% CI 0.01-0.06) and risk of persistent PEs (odds ratio [OR] = 1.08, 95% CI 1.01-1.15). Maternal smoking was associated with an increased frequency of PEs (β = 0.11, 95% CI 0.04-0.18) and persistent PEs (OR = 1.31, 95% CI 1.04-1.66). Maternal substance use was a risk factor for a 48% increased risk of persistent PEs (OR = 1.48, 95% CI 1.08-2.01). Perinatal complications showed no effect on PEs. This study provides evidence that certain prenatal medical complications (severe nausea, severe anemia), cumulative number of prenatal medical complications, and maternal behaviors (smoking during pregnancy), increased frequency of distressing PEs in childhood. Maternal smoking and substance use, as well as cumulative number of prenatal complications increased risk of persistent PEs.

The risk of hospitalization for psychotic disorders following hospitalization for COVID-19: a French nationwide longitudinal study.

COVID-19, like other infectious diseases, may be a risk factor for psychotic disorders. We aimed to compare the proportions of hospitalizations for psychotic disorders in the 12 months following discharge from hospital for either COVID-19 or for another reason in the adult general population in France during the first wave of the pandemic. We conducted a retrospective longitudinal nationwide study using the national French administrative healthcare database. Psychotic disorders were first studied as a whole, and then chronic and acute disorders separately. The role of several adjustment factors, including sociodemographics, a history of psychotic disorder, the duration of the initial hospitalization, and the level of care received during that hospitalization, were also analyzed. Between 1 January 2020 and 30 June 2020, a total of 14,622 patients were hospitalized for psychotic disorders in the 12 months following discharge from hospital for either COVID-19 or another reason. Initial hospitalization for COVID-19 (vs. another reason) was associated with a lower rate of subsequent hospitalization for psychotic disorders (0.31% vs. 0.51%, odds ratio (OR) = 0.60, 95% confidence interval (CI) [0.53-0.67]). This was true for both chronic and acute disorders, even after adjusting for the various study variables. Importantly, a history of psychotic disorder was a major determinant of hospitalization for psychotic disorders (adjusted OR = 126.56, 95% CI [121.85-131.46]). Our results suggest that, in comparison to individuals initially hospitalized for another reason, individuals initially hospitalized for COVID-19 present a lower risk of hospitalization for first episodes of psychotic symptoms/disorders or for psychotic relapse in the 12 months following discharge. This finding contradicts the hypothesis that there is a higher risk of psychotic disorders after a severe COVID-19.

Air pollution, climate conditions and risk of hospital admissions for psychotic disorders in U.S. residents

BackgroundThe physical environmental risk factors for psychotic disorders are poorly understood. This study aimed to examine the associations between exposure to ambient air pollution, climate measures and risk of hospitalization for psychotic disorders and uncover potential disparities by demographic, community factors. MethodsUsing Health Cost and Utilization Project (HCUP) State Inpatient Databases (SIDs), we applied zero-inflated negative binomial regression to obtain relative risks of hospitalization due to psychotic disorders associated with increases in residential exposure to ambient air pollution (fine particulate matter, PM2.5; nitrogen dioxide, NO2), temperature and cumulative precipitation. The analysis covered all-age residents in eight U.S. states over the period of 2002–2016. We additionally investigated modification by age, sex and area-level poverty, percent of blacks and Hispanics. ResultsOver the study period and among the covered areas, we identified 1,211,100 admissions due to psychotic disorders. For each interquartile (IQR) increase in exposure to PM2.5 and NO2, we observed a relative risk (RR) of 1.11 (95% confidence interval (CI) = 1.09, 1.13) and 1.27 (95% CI = 1.24, 1.31), respectively. For each 1 °C increase of temperature, the RR was 1.03 (95% CI = 1.03, 1.04). Males were more affected by NO2. Older age residents (≥30 yrs) were more sensitive to PM2.5 and temperature. Population living in economically disadvantaged areas were more affected by air pollution. ConclusionsThe study suggests that living in areas with higher levels of air pollutants and ambient temperature could contribute to additional risk of inpatient care for individuals with psychotic disorders.

Polygenic risk for schizophrenia as a moderator of associations between childhood trauma and schizotypy

Recent evidence shows that genetic and environmental risk factors for psychotic disorders are associated with higher levels of schizotypy (or psychosis proneness) in the general population. However, little is known about how these risk factors interact. We specifically examined whether genetic loading for schizophrenia moderates the association between childhood trauma severity and schizotypy. Schizotypy was measured using the Schizotypal Personality Questionnaire (SPQ), and childhood trauma severity was measured with the Childhood Trauma Questionnaire (CTQ) among a total of 168 participants (comprising 51 healthy individuals, 56 diagnosed with schizophrenia, and 61 with bipolar disorder). Polygenic risk scores (PRS) for schizophrenia were calculated for all participants and examined as a potential moderator of associations between total scores on the CTQ and schizotypy total scores and dimensions (i.e., cognitive-perceptual, interpersonal, disorganised). Multiple linear regression models revealed associations between childhood trauma and all dimensions of schizotypy, but no associations between PRS and schizotypy. A significant interaction between PRS and childhood trauma was evident for the interpersonal and disorganised dimensions of schizotypy, as well as the total score, reflecting positive associations between childhood trauma severity and these two schizotypal dimensions, only for individuals with low or average PRS for schizophrenia. This suggests that trauma may be able to increase risk for psychosis independently of any genetic vulnerability. The present findings are consistent with the idea of several risk pathways for the development of psychotic disorders.

Comparing Risk Factors for Non-affective Psychotic Disorders With Common Mental Disorders Among Migrant Groups: A 25-Year Retrospective Cohort Study of 2 Million Migrants.

Although migration is a well-established risk factor for psychotic disorders, less is known about factors that modify risk within migrant groups. We sought to assess whether socio-demographic, migration-related, and post-migration factors were associated with the risk of non-affective psychotic disorders (NAPD) among first-generation migrants, and to compare with estimates for common mental disorders (CMD) to explore specificity of the effect. We constructed a retrospective cohort of first-generation migrants to Ontario, Canada using linked population-based health administrative data (1992-2011; n = 1 964 884). We identified NAPD and CMD using standardized algorithms. We used modified Poisson regression models to estimate incidence rate ratios (IRR) for each factor to assess its effect on the risk of each outcome. Nearly 75% of cases of NAPD met the case definition for a CMD prior to the first diagnosis of psychosis. Our findings suggest that younger age at migration, male sex, being of African-origin, and not having proficiency in national languages had a specificity of effect for a higher risk of NAPD. Among migrants who were over 19 years of age at landing, higher pre-migratory education and being married/common-law at landing showed specificity of effect for a lower risk of NAPD. Migrant class, rurality of residence after landing, and post-migration neighborhood-level income showed similar effects across disorders. Our findings help identify high-risk groups to target for intervention. Identifying factors that show specific effects for psychotic disorder, rather than mental disorders more broadly, are important for informing prevention and early intervention efforts.

Characterizing sustained social anxiety in individuals at clinical high risk for psychosis: trajectory, risk factors, and functional outcomes.

While comorbidity of clinical high-risk for psychosis (CHR-P) status and social anxiety is well-established, it remains unclear how social anxiety and positive symptoms covary over time in this population. The present study aimed to determine whether there are more than one covariant trajectory of social anxiety and positive symptoms in the North American Prodrome Longitudinal Study cohort (NAPLS 2) and, if so, to test whether the different trajectory subgroups differ in terms of genetic and environmental risk factors for psychotic disorders and general functional outcome. In total, 764 CHR individuals were evaluated at baseline for social anxiety and psychosis risk symptom severity and followed up every 6 months for 2 years. Application of group-based multi-trajectory modeling discerned three subgroups based on the covariant trajectories of social anxiety and positive symptoms over 2 years. One of the subgroups showed sustained social anxiety over time despite moderate recovery in positive symptoms, while the other two showed recovery of social anxiety below clinically significant thresholds, along with modest to moderate recovery in positive symptom severity. The trajectory group with sustained social anxiety had poorer long-term global functional outcomes than the other trajectory groups. In addition, compared with the other two trajectory groups, membership in the group with sustained social anxiety was predicted by higher levels of polygenic risk for schizophrenia and environmental stress exposures. Together, these analyses indicate differential relevance of sustained v. remitting social anxiety symptoms in the CHR-P population, which in turn may carry implications for differential intervention strategies.

The role of aberrant salience in the association between cannabis use frequency and psychotic experiences among racial and ethnic minoritized youth

Prior studies have shown cannabis use is correlated with psychotic symptoms, but few have explored potential underlying mechanisms. The present study examined whether aberrant salience explains the association between cannabis use frequency and psychotic experiences (PE) while accounting for the mediating role of anxiety in this association. A US urban undergraduate sample of 816 racial and ethnic minorities contributed data used in linear regression models to determine associations between recent (3 months) cannabis use frequency, aberrant salience, anxiety, positive subscale Prodromal Questionnaire (PQ) items, and distressing positive PQ items. Results from hierarchical linear regression and mediation models using Hayes PROCESS application indicated the association between cannabis use frequency and PE was significantly explained by higher aberrant salience and anxiety. Furthermore, anxiety's indirect association with cannabis use frequency and PE significantly occurred through aberrant salience's indirect association with cannabis use frequency and PE (i.e., serial mediation). A similar pattern emerged for distressing PE. We also found earlier age of cannabis use onset (age 12–14) was associated with a higher number of PE and distressing PE and that this was partially explained by higher aberrant salience. Anxiety's indirect association between earlier age of onset and PE/distressing PE only occurred through aberrant salience (i.e., serial mediation). Aberrant salience may be the part of psychosis proneness most directly connected to why earlier initiation of cannabis use is a risk factor for psychotic disorders. This should be explored further in future longitudinal work with clinical high-risk populations and among minoritized youth.

Genetic risk for bipolar disorder and schizophrenia predicts structure and function of the ventromedial prefrontal cortex.

Background:Bipolar disorder is highly heritable and polygenic. The polygenic risk for bipolar disorder overlaps with that of schizophrenia, and polygenic scores are normally distributed in the population. Bipolar disorder has been associated with structural brain abnormalities, but it is unknown how these are linked to genetic risk factors for psychotic disorders.Methods:We tested whether polygenic risk scores for bipolar disorder and schizophrenia predict structural brain alterations in 98 patients with bipolar disorder and 81 healthy controls. We derived brain cortical thickness, surface area and volume from structural MRI scans. In post-hoc analyses, we correlated polygenic risk with functional hub strength, derived from resting-state functional MRI and brain connectomics.Results:Higher polygenic risk scores for both bipolar disorder and schizophrenia were associated with a thinner ventromedial prefrontal cortex (vmPFC). We found these associations in the combined group, and separately in patients and drug-naive controls. Polygenic risk for bipolar disorder was correlated with the functional hub strength of the vmPFC within the default mode network.Limitations:Polygenic risk is a cumulative measure of genomic burden. Detailed genetic mechanisms underlying brain alterations and their cognitive consequences still need to be determined.Conclusion:Our multimodal neuroimaging study linked genomic burden and brain endophenotype by demonstrating an association between polygenic risk scores for bipolar disorder and schizophrenia and the structure and function of the vmPFC. Our findings suggest that genetic factors might confer risk for psychotic disorders by influencing the integrity of the vmPFC, a brain region involved in self-referential processes and emotional regulation. Our study may also provide an imaging–genetics vulnerability marker that can be used to help identify individuals at risk for developing bipolar disorder.

T123. RISK FACTORS FOR PSYCHOTIC DISORDERS WITHIN MIGRANT GROUPS IN CANADA

BackgroundAlthough there is a large evidence base suggesting elevated rates of psychotic disorder for some migrant groups, relative to the non-migrant host population, less is known about factors that modify the risk of psychosis within migrant groups. Our objective was to assess whether pre-migration, migration-related, and post-migration factors were associated with an elevated risk of psychotic disorder among first-generation migrants in Ontario, Canada.MethodsUsing linked population-based health administrative data, we constructed a retrospective cohort of first-generation migrants to Ontario over a 20-year period between 1992 and 2012. We identified first onset non-affective psychotic disorders using a validated algorithm. Pre-migration factors included sex, country of origin, education, occupation, marital status, and language. Migration-related factors included age at migration, year of migration, duration of residence, and migrant class. Post-migration factors included rural place of residence and neighbourhood-level indicators of marginalization. We used Poisson regression models to compute incidence rate ratios for each pre-migration, migration-related, and post-migration factor to assess its magnitude of effect on the risk of developing psychosis, relative to migrants who did not develop psychotic disorder.ResultsOur cohort included over two million first-generation migrants over the 20-year period. Preliminary findings suggest that males, refugees, and people who set up residence in urban centres have higher rates of psychotic disorder, and people who are older at the time of migration and those who set up residence in high-income areas have lower rates of psychotic disorder. Full results for pre-migration, migration-related, and post-migration risk factors will be presented.DiscussionMigrant status is one of few well-established risk factors for psychotic disorder, yet we have limited understanding of the underlying etiology. The findings from this study help to identify high-risk groups to target for intervention. Improving our understanding of key risk factors for psychotic disorders within migrant groups is crucial for informing prevention and early intervention efforts.

T67. TRAUMA IN AFFECTIVE AND NONAFFECTIVE PSYCHOSIS: ASSOCIATIONS AND DISSOCIATIONS WITH COGNITIVE FUNCTIONING IN CHILDHOOD AND ADULTHOOD

BackgroundChildhood trauma and cognitive impairment are important risk factors for psychotic disorders. However, the relationship between trauma and psychosis throughout the lifespan, as well as between lifetime trauma and cognitive functioning, remain unclear.MethodsUsing data from a case-control study of African-American adults with psychotic disorders, we examined childhood and adult trauma, as well as their interaction with cognitive functioning, in adults with affective psychotic disorders (n=101), nonaffective psychotic disorders (n=109), non-psychotic psychiatric disorders (n=105), compared to controls (n=211). Childhood trauma was measured using the Childhood Trauma Questionnaire (CTQ), which produces dimensional measures of physical neglect, emotional neglect, physical abuse, emotional abuse, and sexual abuse. Adult trauma was measured using the Trauma History Questionnaire (THQ), which ascertains the presence of death-, and personal-related traumas throughout adulthood. Cognitive functioning was measured using a comprehensive computerized battery (‘Charlie’, https://github.com/sammosummo/Charlie).ResultsAll three psychiatric groups showed greater childhood trauma compared to controls, but the affective psychosis group showed the most trauma (Cohen d=0.97–1.29, p<0.001), followed by the nonaffective psychosis group (d=0.54–0.72, p<0.001), and then the non-psychotic group (d=0.05–0.16, p<0.04). Despite the fact that childhood trauma was significantly associated with adult trauma (OR=0.67–2.08,p<0.002), only the affective psychosis group showed a significantly increased likelihood of experiencing both death- and personal-related traumas in adulthood (OR=0.86–2.14, p<0.01), while the nonaffective psychosis group showed an increased likelihood of experiencing personal-related traumas (OR=1.00, p=0.003). Significant childhood-trauma-by-group interactions on cognitive functioning showed that greater childhood neglect was associated with better performance in the affective psychosis group on measures of processing speed (d=0.52, p=0.011), social processing (d=0.57, p=0.020), and executive functioning (d=0.50–0.71,p<0.020). A similar pattern emerged in the affective psychosis group with both death- and personal-related adult traumas on measures of processing speed (d=0.67–0.74, p<0.010), memory (d=0.67–0.68, p<0.014), and emotional processing (d=0.79, p=0.008). In the domain of complex reasoning, on the other hand, increased childhood sexual abuse in the affective psychosis group, and personal-related adult traumas in the psychosis group, showed a deleterious effect (d=–0.44, p=0.025; d=–0.65, p=0.010).DiscussionIndividuals with psychotic disorders, especially affective psychoses, experienced more childhood and adult trauma than controls, and also individuals with non-psychotic psychiatric disorders. However, both childhood neglect and adult trauma were associated with better cognitive functioning in the affective psychosis group. One explanation for this seemingly paradoxical finding may be that traumatic experiences in childhood and adulthood lead to increased cognitive vulnerability, as typically seen in psychotic disorders. Thus, individuals who experience more lifetime trauma may follow a different pathway to psychosis, involving less neurodevelopmental impairment, but greater environmental stress, leading to more affective, rather than nonaffective, manifestations of psychosis.

Childhood Trauma is Associated With Redox Ratio in Healthy Controls but Not in Patients With Psychotic Disorders

Studies have implicated childhood trauma (CT) as a risk factor for psychotic disorders, and recent reports have linked CT to elevations in markers of oxidative stress in patient and healthy samples. Moreover, redox ratio imbalance has been implicated in psychotic disorders. This study examined the relationship between CT and redox ratio measured by 31P magnetic resonance spectroscopy in patients with psychotic disorders and healthy controls.

Evidence for an interrelated cluster of Hallucinatory experiences in the general population: an incidence study.

Although hallucinations have been studied in terms of prevalence and its associations with psychopathology and functional impairment, very little is known about sensory modalities other than auditory (i.e. haptic, visual and olfactory), as well the incidence of hallucinations, factors predicting incidence and subsequent course. We examined the incidence, course and risk factors of hallucinatory experiences across different modalities in two unique prospective general population cohorts in the same country using similar methodology and with three interview waves, one over the period 1996-1999 (NEMESIS) and one over the period 2007-2015 (NEMESIS-2). In NEMESIS-2, the yearly incidence of self-reported visual hallucinations was highest (0.33%), followed by haptic hallucinations (0.31%), auditory hallucinations (0.26%) and olfactory hallucinations (0.23%). Rates in NEMESIS-1 were similar (respectively: 0.35%, 0.26%, 0.23%, 0.22%). The incidence of clinician-confirmed hallucinations was approximately 60% of the self-reported rate. The persistence rate of incident hallucinations was around 20-30%, increasing to 40-50% for prevalent hallucinations. Incident hallucinations in one modality were very strongly associated with occurrence in another modality (median OR = 59) and all modalities were strongly associated with delusional ideation (median OR = 21). Modalities were approximately equally strongly associated with the presence of any mental disorder (median OR = 4), functioning, indicators of help-seeking and established environmental risk factors for psychotic disorder. Hallucinations across different modalities are a clinically relevant feature of non-psychotic disorders and need to be studied in relation to each other and in relation to delusional ideation, as all appear to have a common underlying mechanism.

Age at migration and the risk of psychotic disorders: a systematic review and meta-analysis.

To conduct a systematic review and meta-analysis of the existing evidence on the association between age at migration and the risk of psychotic disorders. Observational studies were eligible for inclusion if they presented data on the association between age at migration and the risk of psychotic disorders among first-generation migrant groups. We used two random effects meta-analyses to pool effect estimates for each stratum of age at migration relative to (i) a native-born reference category and (ii) the youngest age stratum (0 to 2years). Ten studies met inclusion criteria, and five were included in the meta-analysis. The risk of psychotic disorder among people who migrate prior to age 18 is nearly twice as high as the native-born population, with no evidence of effect modification by age strata. People who migrate during early adulthood (19 to 29years) have a similar risk of psychotic disorder as the native-born population (IRR=0.93, 95% CI=0.60, 1.44) and a lower risk relative to those who migrate during infancy (0 to 2years) (IRR=0.58, 95% CI=0.33, 1.04). Migrant status is one of few well-established risk factors for psychotic disorder, yet we have limited understanding of the underlying etiology. The findings of this review advance our understanding of this association and identify high-risk groups to target for intervention.

Social capital and psychosis: a scoping review.

Social capital has been studied as a risk factor for psychotic disorders. The purpose of this scoping review was to scope the literature and synthesize findings on the association between social capital and psychosis. Three electronic databases were searched to identify relevant studies. Studies were included if they examined the association between social capital and either diagnosed psychotic disorders or symptoms of psychosis. Of 191 studies reviewed, 12 met the inclusion criteria. Ten studies measured social capital at the ecological level. Seven studies focused on risk of psychotic disorders or symptoms of psychosis, three studies focused on course of psychotic illness, and two studies focused on both risk and course of illness. A variety of social capital measures were used including scales, surveys, and census-based measures. The association between social capital and both the incidence of psychosis and patterns of service use varied based on measures used and study population. There was no association between social capital and recovery or duration of untreated illness. Prior literature has examined the impact of social capital on the incidence of psychotic disorders, as well as symptoms and course of illness. Based on the scant literature to date, it is difficult to make firm conclusions regarding the role of social capital in psychotic disorders. Heterogeneous measures of social capital make comparisons between studies challenging. Further specificity in measuring and defining dimensions of social capital is required for meaningful study of social capital and its association with psychotic disorders.

Subclinical psychosis in adult migrants and ethnic minorities: systematic review and meta-analysis.

It is well established that migration and ethnic minority status are risk factors for psychotic disorders. Recent studies have aimed to determine if they are also associated with subclinical psychosis (psychotic-like experiences and schizotypal traits). We aimed to determine to what extent migrant and ethnic minority groups are associated with higher risk of subclinical psychosis. We conducted a systematic review, using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement, and examined findings by ethnicity, migrant status, outcomes of subclinical psychosis and host country. A meta-analysis was carried out with robust variance estimation where possible, to handle statistically dependent effect size estimates. We included 28 studies (19 studies on psychotic-like experiences and 9 studies on schizotypal traits) and found that ethnicity, but not migrant status, was associated with current and lifetime psychotic-like experiences. In the narrative analysis, we observed the effect of psychosocial risk factors on this association: Black ethnicity groups showed consistent increased prevalence of current and lifetime psychotic-like experiences compared with the reference population across countries. More generalisable and standardised cohort studies of psychotic-like experiences and schizotypal traits in relation to migration/ethnicity are necessary to examine the effects of exposures and outcomes in different contexts, and to understand the underlying mechanisms of the association between subclinical psychosis and migrant and ethnic minority status. None.

Association of Urbanicity With Psychosis in Low- and Middle-Income Countries

Urban residence is one of the most well-established risk factors for psychotic disorder, but most evidence comes from a small group of high-income countries. To determine whether urban living is associated with greater odds for psychosis in low- and middle-income countries (LMICs). This international population-based study used cross-sectional survey data collected as part of the World Health Organization (WHO) World Health Survey from May 2, 2002, through December 31, 2004. Participants included nationally representative general population probability samples of adults (≥18 years) residing in 42 LMICs (N = 215 682). Data were analyzed from November 20 through December 5, 2017. Urban vs nonurban residence, determined by the WHO based on national data. Psychotic experiences, assessed using the WHO Composite International Diagnostic Interview psychosis screen, and self-reported lifetime history of a diagnosis of a psychotic disorder. Among the 215 682 participants (50.8% women and 49.2% men; mean [SD] age, 37.9 [15.7] years), urban residence was not associated with psychotic experiences (odds ratio [OR], 0.99; 95% CI, 0.89-1.11) or psychotic disorder (OR, 0.89; 95% CI, 0.76-1.06). Results of all pooled analyses and meta-analyses of within-country effects approached a null effect, with an overall OR of 0.97 (95% CI, 0.87-1.07), OR for low-income countries of 0.98 (95% CI, 0.82-1.15), and OR for middle-income countries of 0.96 (95% CI, 0.84-1.09) for psychotic experiences and an overall OR of 0.92 (95% CI, 0.73-1.16), OR for low-income countries of 0.92 (95% CI, 0.66-1.27), and OR for middle-income countries of 0.92 (95% CI, 0.67-1.27) for psychotic disorder. Our results provide evidence that urbanicity, a well-established risk factor for psychosis, may not be associated with elevated odds for psychosis in developing countries. This finding may provide better understanding of the mechanisms by which urban living may contribute to psychosis risk in high-income countries, because urban-rural patterns of cannabis use, racial discrimination, and socioeconomic disparities may vary between developing and developed nations.

S182. CHANGE IN CORTICAL MORPHOMETRY IN INDIVIDUALS WITH PERSISTING PSYCHOTIC EXPERIENCES: A LONGITUDINAL PILOT STUDY

BackgroundThere is an increasing interest in the presence of psychotic symptoms in the general population that do not meet the threshold for psychotic disorder. Such psychotic experiences (PEs) are more prevalent than conditions such as schizophrenia and often manifest during childhood and adolescence. PEs are a risk factor for psychotic disorders and a range of adverse psychosocial outcomes. PEs can become abnormally persistent with a corresponding increase in psychiatric morbidity. Previous research has highlighted subtle deviations in brain structure associated with the presence and persistence of PEs, but longitudinal assessments are needed to gauge if these deviations continue, perhaps as part of an atypical neurodevelopmental trajectory.MethodsLongitudinal imaging data, taken at ages 20 and 25, were available for 25 young adults who were part an MRI nested case control study within the Avon Longitudinal Study of Parents and Children. They were selected originally on the basis of presence or absence of PEs. Cortical surface data were analysed using Freesurfer. Presence of PEs was assessed at ages 18, 20, and 25 and we defined persistence as endorsing PEs at multiple time-points. Average cortical volume and thickness were extracted from each brain parcellation. We additionally calculated fractal dimensionality (FD) of each parcellation using a box-count algorithm to capture shape complexity. We compared the rate of change between healthy controls (HC) and those with persistent PEs in each parcellation and used permutation testing to control for multiple comparisons.ResultsBoth HC and PEs showed the expected age-related net loss in brain volume; an increase in white matter volume offset by a greater reduction in grey matter. We identified greater volume loss in PEs in the left parietal lobe and further examination of local volume highlighted additional changes. PEs were associated with a greater rate of volume loss in the anterior cingulate, postcentral, and lingual gyrus in the left hemisphere and in the right inferior parietal lobule and pars orbitalis. Thinning of the left inferior parietal lobule was greater in those with PEs. There was further converging evidence of focal abnormalities in the left postcentral gyrus in terms of reductions in cortical thickness and FD in PEs. Similarly, we found reduced FD relative to HC in the left rostral anterior cingulate. There was additional evidence for reductions in FD in the left hemisphere in the cuneus, isthmus cingulate, and middle frontal gyrus.DiscussionOur findings highlight a deviation from typical age-related changes in brain volume in individuals with persisting manifestations of PEs. Though these changes could reflect an acceleration of the typical volume loss that is seen with aging, there are several points of evidence against this. We found no differences in global volume changes and only the left parietal lobule was found to show a greater volume loss in PEs. On a local scale, findings seemed to mostly converge on parietal and cingulate regions in the left hemisphere with some evidence of aberrations in frontal regions. These pilot data are, uniquely, unconfounded by illness and treatment related factors and highlight the continued need for longitudinal assessments of brain structure in relation to PEs; there is an increasing risk of transitioning to a psychotic disorder with persistence of PEs and our findings may reflect the neuroanatomical basis for an anomalous developmental trajectory related to psychotic disorders.

Introducing the White Noise task in childhood: associations between speech illusions and psychosis vulnerability.

Auditory verbal hallucinations (AVH) are common during development and may arise due to dysregulation in top-down processing of sensory input. This study was designed to examine the frequency and correlates of speech illusions measured using the White Noise (WN) task in children from the general population. Associations between speech illusions and putative risk factors for psychotic disorder and negative affect were examined. A total of 1486 children aged 11-12 years of the Copenhagen Child Cohort 2000 were examined with the WN task. Psychotic experiences and negative affect were determined using the Kiddie-SADS-PL. Register data described family history of mental disorders. Exaggerated Theory of Mind functioning (hyper-ToM) was measured by the ToM Storybook Frederik. A total of 145 (10%) children experienced speech illusions (hearing speech in the absence of speech stimuli), of which 102 (70%) experienced illusions perceived by the child as positive or negative (affectively salient). Experiencing hallucinations during the last month was associated with affectively salient speech illusions in the WN task [general cognitive ability: adjusted odds ratio (aOR) 2.01, 95% confidence interval (CI) 1.03-3.93]. Negative affect, both last month and lifetime, was also associated with affectively salient speech illusions (aOR 2.01, 95% CI 1.05-3.83 and aOR 1.79, 95% CI 1.11-2.89, respectively). Speech illusions were not associated with delusions, hyper-ToM or family history of mental disorders. Speech illusions were elicited in typically developing children in a WN-test paradigm, and point to an affective pathway to AVH mediated by dysregulation in top-down processing of sensory input.

Psychotic experiences and their significance.

Psychotic experiences and their significance.