Anthropometry in antipsychotic-naïve first-episode psychosis patients: An exploratory approach to the role of environmental early life events in two independent samples.

BACKGROUND: Patients with schizophrenia exhibit a reduced life expectancy mainly due to medical-related pathologies which might have been initiated due to stressful events during fetal development. Indeed, intra-uterus growth patterns predict anthropometric measures in adulthood, describing risk factors for schizophrenia and metabolic disorders. We aim to evaluate anthropometric values in two cohorts of antipsychotic-naïve first-episode episode psychosis (FEP) and correlated them with surrogate markers of the fetal environment such as birth weight (BW) and season of birth. METHODS: BW, season of birth, and anthropometric values from 2 cohorts of FEP patients (Barcelona and Santander) were evaluated. In cohort B, 91 patients, and 110 controls while in cohort S, 644 and 235 were included respectively. RESULTS: Patients were shorter, slimmer, and with lower BMI compared with controls. In both cohorts, patients, and female patients born in winter displayed the shortest height. Regarding BW, height was significantly associated with the interaction of diagnosis and BW in the whole sample and the male subsample. CONCLUSIONS: Our results confirm reduced anthropometric features in FEP at onset while suggesting the influence of winter birth and BW, highlighting the role of early life events in the later outcome of FEP with sex differences.

Variation of subclinical psychosis across 16 sites in Europe and Brazil: findings from the multi-national EU-GEI study.

BACKGROUND: Incidence of first-episode psychosis (FEP) varies substantially across geographic regions. Phenotypes of subclinical psychosis (SP), such as psychotic-like experiences (PLEs) and schizotypy, present several similarities with psychosis. We aimed to examine whether SP measures varied across different sites and whether this variation was comparable with FEP incidence within the same areas. We further examined contribution of environmental and genetic factors to SP. METHODS: We used data from 1497 controls recruited in 16 different sites across 6 countries. Factor scores for several psychopathological dimensions of schizotypy and PLEs were obtained using multidimensional item response theory models. Variation of these scores was assessed using multi-level regression analysis to estimate individual and between-sites variance adjusting for age, sex, education, migrant, employment and relational status, childhood adversity, and cannabis use. In the final model we added local FEP incidence as a second-level variable. Association with genetic liability was examined separately. RESULTS: Schizotypy showed a large between-sites variation with up to 15% of variance attributable to site-level characteristics. Adding local FEP incidence to the model considerably reduced the between-sites unexplained schizotypy variance. PLEs did not show as much variation. Overall, SP was associated with younger age, migrant, unmarried, unemployed and less educated individuals, cannabis use, and childhood adversity. Both phenotypes were associated with genetic liability to schizophrenia. CONCLUSIONS: Schizotypy showed substantial between-sites variation, being more represented in areas where FEP incidence is higher. This supports the hypothesis that shared contextual factors shape the between-sites variation of psychosis across the spectrum.

Influence of time to clozapine prescription on the clinical outcome.

BACKGROUND: This study investigates whether early clozapine use is associated with improved responses in different clinical domains, including positive and negative symptoms, functioning, and well-being. METHODS: Data from 254 clozapine-treated patients at Cambridgeshire and Peterborough NHS Foundation Trust (CPFT) were analysed. Among them, 231 (90.9 %) had a diagnosis of schizophrenia, 21 (8.3 %) schizoaffective disorder, and 2 (0.8 %) had other diagnoses. The International Classification of Diseases-Mortality and Morbidity Statistics criteria (ICD-10) were employed (World Health Organization, 1992). The cohort was assessed using the positive and negative syndrome scale (PANSS), the Brief Negative Symptom Scale (BNSS), Global Assessment of Functioning Scale (GAF), and the short version of Warwick-Edinburgh Mental Well-being Scale (SWEMWBS). Logistic regression models (for positive and negative symptom remission) and linear regression (for functioning and well-being) were utilized to assess the influence of time to clozapine initiation (TCI), age at the first episode of psychosis (AFE), duration of clozapine treatment (DCT), and gender. RESULTS: Early clozapine treatment (within the first three years after the first episode of psychosis) was associated with increased negative symptom remission (exp (B) = 0.38; p = 0.02) and higher functioning scores (ß = -0.12, p = 0.046). However, no effect of time to clozapine initiation was found on positive symptom remission rates or well-being scores. CONCLUSIONS: Initiating clozapine treatment within the first 3 years of the first episode of psychosis may lead to reduced severity of negative symptoms and improved functioning in clozapine-treated patients. The time to clozapine initiation did not influence its effect on positive symptom remission rates.

Nurse-led lifestyle intervention in a cohort of schizophrenia patients treated with clozapine.

Patients diagnosed with schizophrenia are characterized by early mortality compared to the general population. The main cause of this premature death reflects medical complications linked to metabolic syndrome (MetS). The use of antipsychotics such as clozapine is associated with weight gain and metabolic disturbances in certain predisposed individuals. Non-pharmacological interventions for weight control have become a key element for secondary prevention in the health of patients diagnosed with schizophrenia. Here, we aim to evaluate the physical health effects of a nurse-led non-pharmacological intervention program in patients with a diagnosis of schizophrenia treated with clozapine. Thirty-one outpatients from the outpatient clinical facility of Hospital Clinic in Barcelona, Spain diagnosed with schizophrenia and other psychotic disorders receiving clozapine treatment were enrolled in a prospective interventional study, comprising an 8-week group program of therapeutic education in a healthy lifestyle. MetS factors, physical activity, diet, and lifestyle were evaluated at baseline, post-intervention (8 weeks), and 3 months after the program. Weight, body mass index, high-density lipoprotein cholesterol, and diet patterns displayed significant differences post-intervention and after 3 months, while only waist, hip perimeter, and lifestyle improved post-intervention. Our results suggest the effectiveness of the lifestyle intervention in patients under clozapine treatment despite its long-time differential effect. Strategies to prevent weight gain and metabolic decline will help prevent premature cardiometabolic disease in this vulnerable population.

Identifying risk factors for predominant negative symptoms from early stages in schizophrenia: A longitudinal and sex-specific study in first-episode schizophrenia patients.

BACKGROUND: People with schizophrenia and predominant negative symptoms (PNS) present a different clinical and functional profile from those without such symptomatology. Few studies have examined the risk factors and the incidence of PNS in first-episode schizophrenia patients (FES) and differentiating by sex. This study aims to assess prevalence, demographic and clinical characteristics related to PNS from early stages and to study if there are sex-specific features in terms of developing PNS. METHODS: In a sample of 121 FES patients derived from a multicentre and naturalistic study, those who developed PNS at 12-months were identified. Environmental, clinical, functional, and cognitive ratings were examined longitudinally. Binary logistic regressions were applied to detect baseline risk factors for developing PNS at one-year follow-up. RESULTS: In the present FES cohort, 24.8% of the patients (n=30) developed PNS (20% of the women, 27.6% of the men). Compared to non-PNS (75.2%, n=91), at baseline, PNS group had more negative (t=-6.347; p<0.001) and depressive symptoms (t=-5.026; p<0.001), poorer premorbid adjustment (t=-2.791; p=0.006) and functional outcome (t=-2.649; p<0.001), more amotivation (t=-7.333; p<0.001), more expressivity alterations (t=-4.417; p<0.001), worse cognitive reserve (t=2.581; p<0.011), a lower estimated intelligent quotient (t=2.417; p=0.017), worse verbal memory (t=2.608; p=0.011), and worse fluency (t=2.614; p=0.010). Regressions showed that the premorbid adjustment was the main predictor of PNS in females (p=0.007; Exp(B)=1.106) while in males were a worse verbal memory performance (p=0.031; Exp(B)=0.989) and more alterations in the motivation domain (p=0.001; Exp(B)=1.607). CONCLUSIONS: A different baseline clinical profile and notable risk factors differences in the development of PNS between males and females were found. Results suggest that sex may be an important confounder in studies comparing schizophrenia patients with predominant and non-predominant negative symptomatology.

Differences in Patterns of Stimulant Use and Their Impact on First-Episode Psychosis Incidence: An Analysis of the EUGEI Study.

BACKGROUND: Use of illegal stimulants is associated with an increased risk of psychotic disorder. However, the impact of stimulant use on odds of first-episode psychosis (FEP) remains unclear. Here, we aimed to describe the patterns of stimulant use and examine their impact on odds of FEP. METHODS: We included patients with FEP aged 18-64 years who attended psychiatric services at 17 sites across 5 European countries and Brazil, and recruited controls representative of each local population (FEP = 1130; controls = 1497). Patterns of stimulant use were described. We computed fully adjusted logistic regression models (controlling for age, sex, ethnicity, cannabis use, and education level) to estimate their association with odds of FEP. Assuming causality, we calculated the population-attributable fractions for stimulant use associated with the odds for FEP. FINDINGS: Prevalence of lifetime and recent stimulant use in the FEP sample were 14.50% and 7.88% and in controls 10.80% and 3.8%, respectively. Recent and lifetime stimulant use was associated with increased odds of FEP compared with abstainers [fully adjusted odds ratio 1.74,95% confidence interval (CI) 1.20-2.54, P = .004 and 1.62, 95% CI 1.25-2.09, P < .001, respectively]. According to PAFs, a substantial number of FEP cases (3.35% [95% CI 1.31-4.78] for recent use and 7.61% [95% CI 3.68-10.54] for lifetime use) could have been prevented if stimulants were no longer available and the odds of FEP and PAFs for lifetime and recent stimulant use varied across countries. INTERPRETATION: Illegal stimulant use has a significant and clinically relevant influence on FEP incidence, with varying impacts across countries.

Synergistic effects of childhood adversity and polygenic risk in first-episode psychosis: the EU-GEI study.

BACKGROUND: A history of childhood adversity is associated with psychotic disorder, with an increase in risk according to the number of exposures. However, it is not known why only some exposed individuals go on to develop psychosis. One possibility is pre-existing polygenic vulnerability. Here, we investigated, in the largest sample of first-episode psychosis (FEP) cases to date, whether childhood adversity and high polygenic risk scores for schizophrenia (SZ-PRS) combine synergistically to increase the risk of psychosis, over and above the effect of each alone. METHODS: We assigned a schizophrenia-polygenic risk score (SZ-PRS), calculated from the Psychiatric Genomics Consortium (PGC2), to all participants in a sample of 384 FEP patients and 690 controls from the case-control component of the EU-GEI study. Only participants of European ancestry were included in the study. A history of childhood adversity was collected using the Childhood Trauma Questionnaire (CTQ). Synergistic effects were estimated using the interaction contrast ratio (ICR) [odds ratio (OR)exposure and PRS - ORexposure - ORPRS + 1] with adjustment for potential confounders. RESULTS: There was some evidence that the combined effect of childhood adversities and polygenic risk was greater than the sum of each alone, as indicated by an ICR greater than zero [i.e. ICR 1.28, 95% confidence interval (CI) -1.29 to 3.85]. Examining subtypes of childhood adversities, the strongest synergetic effect was observed for physical abuse (ICR 6.25, 95% CI -6.25 to 20.88). CONCLUSIONS: Our findings suggest possible synergistic effects of genetic liability and childhood adversity experiences in the onset of FEP, but larger samples are needed to increase precision of estimates.

The relationship between genetic liability, childhood maltreatment, and IQ: findings from the EU-GEI multicentric case-control study.

This study investigated if the association between childhood maltreatment and cognition among psychosis patients and community controls was partially accounted for by genetic liability for psychosis. Patients with first-episode psychosis (N = 755) and unaffected controls (N = 1219) from the EU-GEI study were assessed for childhood maltreatment, intelligence quotient (IQ), family history of psychosis (FH), and polygenic risk score for schizophrenia (SZ-PRS). Controlling for FH and SZ-PRS did not attenuate the association between childhood maltreatment and IQ in cases or controls. Findings suggest that these expressions of genetic liability cannot account for the lower levels of cognition found among adults maltreated in childhood.

Corrigendum: Influence of clinical and neurocognitive factors in psychosocial functioning after a first episode non-affective psychosis: differences between males and females.

[This corrects the article DOI: 10.3389/fpsyt.2022.982583.].

Exploration of cannabis use and polygenic risk scores on the psychotic symptom progression of a FEP cohort.

Cannabis use is highly prevalent in first-episode psychosis (FEP) and plays a critical role in its onset and prognosis, but the genetic underpinnings promoting both conditions are poorly understood. Current treatment strategies for cannabis cessation in FEP are clearly inefficacious. Here, we aimed to characterize the association between cannabis-related polygenic risk scores (PRS) on cannabis use and clinical course after a FEP. A cohort of 249 FEP individuals were evaluated during 12 months. Symptom severity was measured with the Positive and Negative Severity Scale and cannabis use with the EuropASI scale. Individual PRS for lifetime cannabis initiation (PRSCI) and cannabis use disorder (PRSCUD) were constructed. Current cannabis use was associated with increased positive symptoms. Cannabis initiation at younger ages conditioned the 12-month symptom progression. FEP patients with higher cannabis PRSCUD reported increased baseline cannabis use. PRSCI was associated with the course of negative and general symptomatology over follow-up. Cannabis use and symptom progression after a FEP were modulated by cannabis PRS, suggesting that lifetime initiation and use disorders may have partially independent genetic factors. These exploratory results may be the first step to identify those FEP patients more vulnerable to cannabis use and worse outcomes to ultimately develop tailored treatments.

The association between reasons for first using cannabis, later pattern of use, and risk of first-episode psychosis: the EU-GEI case-control study.

BACKGROUND: While cannabis use is a well-established risk factor for psychosis, little is known about any association between reasons for first using cannabis (RFUC) and later patterns of use and risk of psychosis. METHODS: We used data from 11 sites of the multicentre European Gene-Environment Interaction (EU-GEI) case-control study. 558 first-episode psychosis patients (FEPp) and 567 population controls who had used cannabis and reported their RFUC.We ran logistic regressions to examine whether RFUC were associated with first-episode psychosis (FEP) case-control status. Path analysis then examined the relationship between RFUC, subsequent patterns of cannabis use, and case-control status. RESULTS: Controls (86.1%) and FEPp (75.63%) were most likely to report 'because of friends' as their most common RFUC. However, 20.1% of FEPp compared to 5.8% of controls reported: 'to feel better' as their RFUC (χ2 = 50.97; p < 0.001). RFUC 'to feel better' was associated with being a FEPp (OR 1.74; 95% CI 1.03-2.95) while RFUC 'with friends' was associated with being a control (OR 0.56; 95% CI 0.37-0.83). The path model indicated an association between RFUC 'to feel better' with heavy cannabis use and with FEPp-control status. CONCLUSIONS: Both FEPp and controls usually started using cannabis with their friends, but more patients than controls had begun to use 'to feel better'. People who reported their reason for first using cannabis to 'feel better' were more likely to progress to heavy use and develop a psychotic disorder than those reporting 'because of friends'.

Exploring the mediation of DNA methylation across the epigenome between childhood adversity and First Episode of Psychosis-findings from the EU-GEI study.

ABTRACT: Studies conducted in psychotic disorders have shown that DNA-methylation (DNAm) is sensitive to the impact of Childhood Adversity (CA). However, whether it mediates the association between CA and psychosis is yet to be explored. Epigenome wide association studies (EWAS) using the Illumina Infinium-Methylation EPIC array in peripheral blood tissue from 366 First-episode of psychosis and 517 healthy controls was performed. Adversity scores were created for abuse, neglect and composite adversity with the Childhood Trauma Questionnaire (CTQ). Regressions examining (I) CTQ scores with psychosis; (II) with DNAm EWAS level and (III) between DNAm and caseness, adjusted for a variety of confounders were conducted. Divide-Aggregate Composite-null Test for the composite null-hypothesis of no mediation effect was conducted. Enrichment analyses were conducted with missMethyl package and the KEGG database. Our results show that CA was associated with psychosis (Composite: OR = 1.68; p = <0.001; abuse: OR = 2.16; p < 0.001; neglect: OR = 2.27; p = <0.001). None of the CpG sites significantly mediated the adversity-psychosis association after Bonferroni correction (p < 8.1 × 10-8). However, 28, 34 and 29 differentially methylated probes associated with 21, 27, 20 genes passed a less stringent discovery threshold (p < 5 × 10-5) for composite, abuse and neglect respectively, with a lack of overlap between abuse and neglect. These included genes previously associated to psychosis in EWAS studies, such as PANK1, SPEG TBKBP1, TSNARE1 or H2R. Downstream gene ontology analyses did not reveal any biological pathways that survived false discovery rate correction. Although at a non-significant level, DNAm changes in genes previously associated with schizophrenia in EWAS studies may mediate the CA-psychosis association. These results and associated involved processes such as mitochondrial or histaminergic disfunction, immunity or neural signalling requires replication in well powered samples. The lack of overlap between mediating genes associated with abuse and neglect suggests differential biological trajectories linking CA subtypes and psychosis.

Examining the association between exposome score for schizophrenia and cognition in schizophrenia, siblings, and healthy controls: Results from the EUGEI study.

BACKGROUND: People with schizophrenia spectrum disorders (SSD) frequently present cognitive impairments. Here, we investigated whether the exposome score for schizophrenia (ES-SCZ) - a cumulative environmental exposure score - was associated with impairments of neurocognition, social cognition, and perception in patients with SSD, their unaffected siblings, and healthy controls. METHODS: This cross-sectional sample consisted of 1200 patients, 1371 siblings, and 1564 healthy controls. Neurocognition, social cognition, and perception were assesed using a short version of the Wechsler Adult Intelligence Scale-Third Edition (WAIS-III), the Degraded Facial Affect Recognition Task (DFAR), and the Benton Facial Recognition Test (BFR), respectively. Regression models were used to analyze the association between ES-SCZ and cognitive domains in each group. RESULTS: There were no statistically significant associations between ES-SCZ and cognitive domains in SSD. ES-SCZ was negatively associated with T-score of cognition in siblings (B=-0.40, 95% CI -0.76 to -0.03) and healthy controls (B=-0.63, 95% CI -1.06 to -0.21). Additionally, ES-SCZ was positively associated with DFAR-total in siblings (B=0.83, 95% CI 0.26 to 1.40). Sensitivity analyses excluding cannabis use history from ES-SCZ largely confirmed the main findings. CONCLUSIONS: Longitudinal cohorts may elucidate how environmental exposures influence the onset and course of cognitive impairments in trans-syndromic psychosis spectrum.

Relapse, cognitive reserve, and their relationship with cognition in first episode schizophrenia: a 3-year follow-up study.

Schizophrenia is frequently characterized by the presence of multiple relapses. Cognitive impairments are core features of schizophrenia. Cognitive reserve (CR) is the ability of the brain to compensate for damage caused by pathologies such as psychotic illness. As cognition is related to CR, the study of the relationship between relapse, cognition and CR may broaden our understanding of the course of the disease. We aimed to determine whether relapse was associated with cognitive impairment, controlling for the effects of CR. Ninety-nine patients with a remitted first episode of schizophrenia or schizophreniform disorder were administered a set of neuropsychological tests to assess premorbid IQ, attention, processing speed, working memory, verbal and visual memory, executive functions and social cognition. They were followed up for 3 years (n=53) or until they relapsed (n=46). Personal and familial CR was estimated from a principal component analysis of the premorbid information gathered. Linear mixed-effects models were applied to analyse the effect of time and relapse on cognitive function, with CR as covariate. Patients who relapsed and had higher personal CR showed less deterioration in attention, whereas those with higher CR (personal and familial CR) who did not relapse showed better performance in processing speed and visual memory. Taken together, CR seems to ameliorate the negative effects of relapse on attention performance and shows a positive effect on processing speed and visual memory in those patients who did not relapse. Our results add evidence for the protective effect of CR over the course of the illness.

Structural covariance predictors of clinical improvement at 2-year follow-up in first-episode psychosis.

The relationship between structural brain alterations and prediction of clinical improvement in first-episode psychosis (FEP) has been scarcely studied. We investigated whether structural covariance, a well-established approach to identify abnormal patterns of volumetric correlation across distant brain regions, which allows incorporating network-level information to structural assessments, is associated with longitudinal clinical course. We assessed a sample of 74 individuals from a multicenter study. Magnetic resonance imaging scans were acquired at baseline, and clinical assessments at baseline and at a 2-year follow-up. Participants were split in two groups as a function of their clinical improvement after 2 years (i.e., ≥ < 40% reduction in psychotic symptom severity, (n = 29, n = 45)). We performed a seed-based approach and focused our analyses on 3 cortical and 4 subcortical regions of interest to identify alterations in cortical and cortico-subcortical networks. Improvers presented an increased correlation between the volumes of the right posterior cingulate cortex (PCC) and the left precentral gyrus, and between the left PCC and the left middle occipital gyrus. They also showed an increased correlation between right posterior hippocampus and left angular gyrus volumes. Our study provides a novel mean to identify structural correlates of clinical improvement in FEP, describing clinically-relevant anatomical differences in terms of large-scale brain networks, which is better aligned with prevailing neurobiological models of psychosis. The results involve brain regions considered to participate in the multisensory processing of bodily signals and the construction of bodily self-consciousness, which resonates with recent theoretical accounts in psychosis research.

Child maltreatment, migration and risk of first-episode psychosis: results from the multinational EU-GEI study.

BACKGROUND: Child maltreatment (CM) and migrant status are independently associated with psychosis. We examined prevalence of CM by migrant status and tested whether migrant status moderated the association between CM and first-episode psychosis (FEP). We further explored whether differences in CM exposure contributed to variations in the incidence rates of FEP by migrant status. METHODS: We included FEP patients aged 18-64 years in 14 European sites and recruited controls representative of the local populations. Migrant status was operationalized according to generation (first/further) and region of origin (Western/non-Western countries). The reference population was composed by individuals of host country's ethnicity. CM was assessed with Childhood Trauma Questionnaire. Prevalence ratios of CM were estimated using Poisson regression. We examined the moderation effect of migrant status on the odds of FEP by CM fitting adjusted logistic regressions with interaction terms. Finally, we calculated the population attributable fractions (PAFs) for CM by migrant status. RESULTS: We examined 849 FEP cases and 1142 controls. CM prevalence was higher among migrants, their descendants and migrants of non-Western heritage. Migrant status, classified by generation (likelihood test ratio:χ2 = 11.3, p = 0.004) or by region of origin (likelihood test ratio:χ2 = 11.4, p = 0.003), attenuated the association between CM and FEP. PAFs for CM were higher among all migrant groups compared with the reference populations. CONCLUSIONS: The higher exposure to CM, despite a smaller effect on the odds of FEP, accounted for a greater proportion of incident FEP cases among migrants. Policies aimed at reducing CM should consider the increased vulnerability of specific subpopulations.

Impact of traumatic life events on clinical variables of individuals with first-episode psychosis and healthy controls.

BACKGROUND: Traumatic life events (TLEs) are one of the most robust environmental risk factors for the onset of first-episode psychosis (FEP). AIMS: To explore TLEs in FEP patients and healthy controls (HC), to analyze gender differences and to examine whether TLEs were associated with sociodemographic, clinical and psychofunctional variables in all FEP sample and split by age. METHODS: Descriptive and cross-sectional study. Three hundred and thirty-five FEP and 253 HC were recruited at 16 Spanish mental health research centers. The Traumatic Experiences in Psychiatric Outpatients Questionnaire was administered. RESULTS: We found a higher number of TLEs in FEP than in HC, and the proportion of individuals with three or more TLEs was significantly higher in the FEP group. No differences were found in terms of gender and age. There was no relationship between total number of TLEs and psychotic symptomatology and functional outcomes. CONCLUSIONS: The number and cumulative TLEs should be taken into account in the detection, epidemiology and process of recovery in FEP.

Use of multiple polygenic risk scores for distinguishing schizophrenia-spectrum disorder and affective psychosis categories in a first-episode sample; the EU-GEI study.

BACKGROUND: Schizophrenia (SZ), bipolar disorder (BD) and depression (D) run in families. This susceptibility is partly due to hundreds or thousands of common genetic variants, each conferring a fractional risk. The cumulative effects of the associated variants can be summarised as a polygenic risk score (PRS). Using data from the EUropean Network of national schizophrenia networks studying Gene-Environment Interactions (EU-GEI) first episode case-control study, we aimed to test whether PRSs for three major psychiatric disorders (SZ, BD, D) and for intelligent quotient (IQ) as a neurodevelopmental proxy, can discriminate affective psychosis (AP) from schizophrenia-spectrum disorder (SSD). METHODS: Participants (842 cases, 1284 controls) from 16 European EU-GEI sites were successfully genotyped following standard quality control procedures. The sample was stratified based on genomic ancestry and analyses were done only on the subsample representing the European population (573 cases, 1005 controls). Using PRS for SZ, BD, D, and IQ built from the latest available summary statistics, we performed simple or multinomial logistic regression models adjusted for 10 principal components for the different clinical comparisons. RESULTS: In case-control comparisons PRS-SZ, PRS-BD and PRS-D distributed differentially across psychotic subcategories. In case-case comparisons, both PRS-SZ [odds ratio (OR) = 0.7, 95% confidence interval (CI) 0.54-0.92] and PRS-D (OR = 1.31, 95% CI 1.06-1.61) differentiated AP from SSD; and within AP categories, only PRS-SZ differentiated BD from psychotic depression (OR = 2.14, 95% CI 1.23-3.74). CONCLUSIONS: Combining PRS for severe psychiatric disorders in prediction models for psychosis phenotypes can increase discriminative ability and improve our understanding of these phenotypes. Our results point towards the potential usefulness of PRSs in specific populations such as high-risk or early psychosis phases.