Centre for Youth Mental Health - Research Publications

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    Non-psychotic Outcomes in Young People at Ultra-High Risk of Developing a Psychotic Disorder: A Long-Term Follow-up Study
    Spiteri-Staines, AE ; Yung, AR ; Lin, A ; Hartmann, JA ; Amminger, P ; Mcgorry, PD ; Thompson, A ; Wood, SJ ; Nelson, B (OXFORD UNIV PRESS, 2024-02-16)
    BACKGROUND: The majority of individuals at ultra-high risk (UHR) for psychosis do not transition to a full threshold psychotic disorder. It is therefore important to understand their longer-term clinical and functional outcomes, particularly given the high prevalence of comorbid mental disorders in this population at baseline. AIMS: This study investigated the prevalence of non-psychotic disorders in the UHR population at entry and long-term follow-up and their association with functional outcomes. Persistence of UHR status was also investigated. STUDY DESIGN: The sample comprised 102 UHR young people from the Personal Assessment and Crisis Evaluation (PACE) Clinic who had not transitioned to psychosis by long-term follow-up (mean = 8.8 years, range = 6.8-12.1 years since baseline). RESULTS: Eighty-eight percent of participants at baseline were diagnosed with at least one mental disorder, the majority of which were mood disorders (78%), anxiety disorders (35%), and substance use disorders (SUDs) (18%). This pattern of disorder prevalence continued at follow-up, though prevalence was reduced, with 52% not meeting criteria for current non-psychotic mental disorder. However, 35% of participants developed a new non-psychotic mental disorder by follow-up. Presence of a continuous non-psychotic mental disorder was associated with poorer functional outcomes at follow-up. 28% of participants still met UHR criteria at follow-up. CONCLUSIONS: The study adds to the evidence base that a substantial proportion of UHR individuals who do not transition to psychosis experience persistent attenuated psychotic symptoms and persistent and incident non-psychotic disorders over the long term. Long-term treatment and re-entry into services is indicated.
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    Combining Clinical With Cognitive or Magnetic Resonance Imaging Data for Predicting Transition to Psychosis in Ultra High-Risk Patients: Data From the PACE 400 Cohort
    Hartmann, S ; Cearns, M ; Pantelis, C ; Dwyer, D ; Cavve, B ; Byrne, E ; Scott, I ; Yuen, HP ; Gao, C ; Allott, K ; Lin, A ; Wood, SJ ; Wigman, JTW ; Amminger, GP ; McGorry, PD ; Yung, AR ; Nelson, B ; Clark, SR (Elsevier, 2024-04)
    BACKGROUND: Multimodal modeling that combines biological and clinical data shows promise in predicting transition to psychosis in individuals who are at ultra-high risk. Individuals who transition to psychosis are known to have deficits at baseline in cognitive function and reductions in gray matter volume in multiple brain regions identified by magnetic resonance imaging. METHODS: In this study, we used Cox proportional hazards regression models to assess the additive predictive value of each modality-cognition, cortical structure information, and the neuroanatomical measure of brain age gap-to a previously developed clinical model using functioning and duration of symptoms prior to service entry as predictors in the Personal Assessment and Crisis Evaluation (PACE) 400 cohort. The PACE 400 study is a well-characterized cohort of Australian youths who were identified as ultra-high risk of transitioning to psychosis using the Comprehensive Assessment of At Risk Mental States (CAARMS) and followed for up to 18 years; it contains clinical data (from N = 416 participants), cognitive data (n = 213), and magnetic resonance imaging cortical parameters extracted using FreeSurfer (n = 231). RESULTS: The results showed that neuroimaging, brain age gap, and cognition added marginal predictive information to the previously developed clinical model (fraction of new information: neuroimaging 0%-12%, brain age gap 7%, cognition 0%-16%). CONCLUSIONS: In summary, adding a second modality to a clinical risk model predicting the onset of a psychotic disorder in the PACE 400 cohort showed little improvement in the fit of the model for long-term prediction of transition to psychosis.
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    Childhood trauma is prevalent and associated with co-occurring depression, anxiety, mania and psychosis in young people attending Australian youth mental health services
    Bendall, S ; Eastwood, O ; Spelman, T ; McGorry, P ; Hickie, I ; Yung, AR ; Amminger, P ; Wood, SJ ; Pantelis, C ; Purcell, R ; Phillips, L (SAGE PUBLICATIONS LTD, 2023-12)
    OBJECTIVES: Childhood trauma is common and associated with mental ill health. While high rates of trauma are observed across individual disorders, there is evidence that trauma is associated with an admixture of affective, anxiety and psychotic symptoms in adults. Given that early onset of mental disorder and trauma exposure herald poor outcomes, it is important to examine trauma prevalence rates in youth mental health services and to determine whether this trauma-related clustering is present in help-seeking young people. METHODS: We used data from the Transitions Study, a longitudinal investigation of young people attending headspace youth mental health services in Australia between January 2011 and August 2012. Participants were 775 young people aged 12-25. Childhood trauma was assessed using the Childhood Trauma Questionnaire. Multinomial regression was used to assess whether reported childhood trauma was more strongly associated with the co-occurrence of depression, anxiety, mania and psychosis symptoms than with any one in isolation. RESULTS: Approximately 84% of participants reported some form of abuse (emotional: 68%; physical: 32%; sexual: 22%) or neglect (emotional: 65%; physical: 46%). Exposure to multiple trauma types was common. Childhood trauma was significantly associated with each symptom domain. More severe childhood trauma was more strongly associated with the co-occurrence of symptoms than with any one symptom domain in isolation, such that more severely trauma-exposed young people were more likely to experience increased symptom clustering. CONCLUSIONS: Childhood trauma is pervasive in youth mental health services and associated with a symptom profile that cuts across traditional diagnostic boundaries.
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    Has improved treatment contributed to the declining rate of transition to psychosis in ultra-high-risk cohorts?
    Formica, MJC ; Phillips, LJ ; Hartmann, JA ; Yung, AR ; Wood, SJ ; Lin, A ; Amminger, GP ; McGorry, PD ; Nelson, B (ELSEVIER, 2022-05)
    BACKGROUND: The factors contributing to declining psychotic disorder transition rates in ultra-high-risk populations remain unclear. We examined the contribution of longitudinal changes in standard clinical treatment ('treatment as usual') to this decline. METHOD: An audit was conducted on 105 clinical files of patients who received standard care at a specialised ultra-high-risk service. The session notes of these files were quantified, allowing examination of treatment quantity, targets, psychotherapy, and medication. Differences in these aspects across patients' year of clinic entry were assessed. Variables with significant differences across years were examined using cox regression to assess their contribution to psychosis transition rates. RESULTS: Findings were that, as a function of patients' year of clinic entry, there were increases in: patients' number of sessions, cognitive behavioural therapy (CBT), problem and solving therapy. There was a relationship between baseline year cohort and psychosis transition rate, with lower rates observed in more recent cohorts. When changes in treatment between cohorts were adjusted for, the relationship between baseline year cohort and transition rate disappeared. The relationship between baseline year and transition rate was attenuated most by increases in CBT. CONCLUSION: Changes in standard treatment, particularly increases in CBT, may have contributed to the decline in psychosis risk observed in recent ultra-high-risk cohorts, although these variables do not fully explain this trend. Implications for clinical practice, prediction and intervention research are discussed. Future ultra-high-risk research should investigate the impact of other treatment factors, such as therapeutic alliance.
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    Neuroanatomical heterogeneity and homogeneity in individuals at clinical high risk for psychosis
    Baldwin, H ; Radua, J ; Antoniades, M ; Haas, SS ; Frangou, S ; Agartz, I ; Allen, P ; Andreassen, OA ; Atkinson, K ; Bachman, P ; Baeza, I ; Bartholomeusz, CF ; Chee, MWL ; Colibazzi, T ; Cooper, RE ; Corcoran, CM ; Cropley, VL ; Ebdrup, BH ; Fortea, A ; Glenthoj, LB ; Hamilton, HK ; Haut, KM ; Hayes, RA ; He, Y ; Heekeren, K ; Kaess, M ; Kasai, K ; Katagiri, N ; Kim, M ; Kindler, J ; Klaunig, MJ ; Koike, S ; Koppel, A ; Kristensen, TD ; Bin Kwak, Y ; Kwon, JS ; Lawrie, SM ; Lebedeva, I ; Lee, J ; Lin, A ; Loewy, RL ; Mathalon, DH ; Michel, C ; Mizrahi, R ; Moller, P ; Nelson, B ; Nemoto, T ; Nordholm, D ; Omelchenko, MA ; Pantelis, C ; Raghava, JM ; Rossberg, J ; Roessler, W ; Salisbury, DF ; Sasabayashi, D ; Schall, U ; Smigielski, L ; Sugranyes, G ; Suzuki, M ; Takahashi, T ; Tamnes, CK ; Tang, J ; Theodoridou, A ; Thomopoulos, S ; Tomyshev, AS ; Uhlhaas, PJ ; Vaernes, TG ; van Amelsvoort, TAMJ ; Van Erp, TGM ; Waltz, JA ; Westlye, LT ; Wood, SJ ; Zhou, JH ; McGuire, P ; Thompson, PM ; Jalbrzikowski, M ; Hernaus, D ; Fusar-Poli, P (SPRINGERNATURE, 2022-07-26)
    Individuals at Clinical High Risk for Psychosis (CHR-P) demonstrate heterogeneity in clinical profiles and outcome features. However, the extent of neuroanatomical heterogeneity in the CHR-P state is largely undetermined. We aimed to quantify the neuroanatomical heterogeneity in structural magnetic resonance imaging measures of cortical surface area (SA), cortical thickness (CT), subcortical volume (SV), and intracranial volume (ICV) in CHR-P individuals compared with healthy controls (HC), and in relation to subsequent transition to a first episode of psychosis. The ENIGMA CHR-P consortium applied a harmonised analysis to neuroimaging data across 29 international sites, including 1579 CHR-P individuals and 1243 HC, offering the largest pooled CHR-P neuroimaging dataset to date. Regional heterogeneity was indexed with the Variability Ratio (VR) and Coefficient of Variation (CV) ratio applied at the group level. Personalised estimates of heterogeneity of SA, CT and SV brain profiles were indexed with the novel Person-Based Similarity Index (PBSI), with two complementary applications. First, to assess the extent of within-diagnosis similarity or divergence of neuroanatomical profiles between individuals. Second, using a normative modelling approach, to assess the 'normativeness' of neuroanatomical profiles in individuals at CHR-P. CHR-P individuals demonstrated no greater regional heterogeneity after applying FDR corrections. However, PBSI scores indicated significantly greater neuroanatomical divergence in global SA, CT and SV profiles in CHR-P individuals compared with HC. Normative PBSI analysis identified 11 CHR-P individuals (0.70%) with marked deviation (>1.5 SD) in SA, 118 (7.47%) in CT and 161 (10.20%) in SV. Psychosis transition was not significantly associated with any measure of heterogeneity. Overall, our examination of neuroanatomical heterogeneity within the CHR-P state indicated greater divergence in neuroanatomical profiles at an individual level, irrespective of psychosis conversion. Further large-scale investigations are required of those who demonstrate marked deviation.
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    Association of Structural Magnetic Resonance Imaging Measures With Psychosis Onset in Individuals at Clinical High Risk for Developing Psychosis An ENIGMA Working Group Mega-analysis
    Jalbrzikowski, M ; Hayes, RA ; Wood, SJ ; Nordholm, D ; Zhou, JH ; Fusar-Poli, P ; Uhlhaas, PJ ; Takahashi, T ; Sugranyes, G ; Kwak, YB ; Mathalon, DH ; Katagiri, N ; Hooker, CI ; Smigielski, L ; Colibazzi, T ; Via, E ; Tang, J ; Koike, S ; Rasser, PE ; Michel, C ; Lebedeva, I ; Hegelstad, WTV ; de la Fuente-Sandoval, C ; Waltz, JA ; Mizrahi, R ; Corcoran, CM ; Resch, F ; Tamnes, CK ; Haas, SS ; Lemmers-Jansen, ILJ ; Agartz, I ; Allen, P ; Amminger, GP ; Andreassen, OA ; Atkinson, K ; Bachman, P ; Baeza, I ; Baldwin, H ; Bartholomeusz, CF ; Borgwardt, S ; Catalano, S ; Chee, MWL ; Chen, X ; Cho, KIK ; Cooper, RE ; Cropley, VL ; Dolz, M ; Ebdrup, BH ; Fortea, A ; Glenthoj, LB ; Glenthoj, BY ; de Haan, L ; Hamilton, HK ; Harris, MA ; Haut, KM ; He, Y ; Heekeren, K ; Heinz, A ; Hubl, D ; Hwang, WJ ; Kaess, M ; Kasai, K ; Kim, M ; Kindler, J ; Klaunig, MJ ; Koppel, A ; Kristensen, TD ; Kwon, JS ; Lawrie, SM ; Lee, J ; Leon-Ortiz, P ; Lin, A ; Loewy, RL ; Ma, X ; McGorry, P ; McGuire, P ; Mizuno, M ; Moller, P ; Moncada-Habib, T ; Munoz-Samons, D ; Nelson, B ; Nemoto, T ; Nordentoft, M ; Omelchenko, MA ; Oppedal, K ; Ouyang, L ; Pantelis, C ; Pariente, JC ; Raghava, JM ; Reyes-Madrigal, F ; Roach, BJ ; Rossberg, JI ; Rossler, W ; Salisbury, DF ; Sasabayashi, D ; Schall, U ; Schiffman, J ; Schlagenhauf, F ; Schmidt, A ; Sorensen, ME ; Suzuki, M ; Theodoridou, A ; Tomyshev, AS ; Tor, J ; Vaernes, TG ; Velakoulis, D ; Venegoni, GD ; Vinogradov, S ; Wenneberg, C ; Westlye, LT ; Yamasue, H ; Yuan, L ; Yung, AR ; van Amelsvoort, TAMJ ; Turner, JA ; van Erp, TGM ; Thompson, PM ; Hernaus, D (AMER MEDICAL ASSOC, 2021-07)
    IMPORTANCE: The ENIGMA clinical high risk (CHR) for psychosis initiative, the largest pooled neuroimaging sample of individuals at CHR to date, aims to discover robust neurobiological markers of psychosis risk. OBJECTIVE: To investigate baseline structural neuroimaging differences between individuals at CHR and healthy controls as well as between participants at CHR who later developed a psychotic disorder (CHR-PS+) and those who did not (CHR-PS-). DESIGN, SETTING, AND PARTICIPANTS: In this case-control study, baseline T1-weighted magnetic resonance imaging (MRI) data were pooled from 31 international sites participating in the ENIGMA Clinical High Risk for Psychosis Working Group. CHR status was assessed using the Comprehensive Assessment of At-Risk Mental States or Structured Interview for Prodromal Syndromes. MRI scans were processed using harmonized protocols and analyzed within a mega-analysis and meta-analysis framework from January to October 2020. MAIN OUTCOMES AND MEASURES: Measures of regional cortical thickness (CT), surface area, and subcortical volumes were extracted from T1-weighted MRI scans. Independent variables were group (CHR group vs control group) and conversion status (CHR-PS+ group vs CHR-PS- group vs control group). RESULTS: Of the 3169 included participants, 1428 (45.1%) were female, and the mean (SD; range) age was 21.1 (4.9; 9.5-39.9) years. This study included 1792 individuals at CHR and 1377 healthy controls. Using longitudinal clinical information, 253 in the CHR-PS+ group, 1234 in the CHR-PS- group, and 305 at CHR without follow-up data were identified. Compared with healthy controls, individuals at CHR exhibited widespread lower CT measures (mean [range] Cohen d = -0.13 [-0.17 to -0.09]), but not surface area or subcortical volume. Lower CT measures in the fusiform, superior temporal, and paracentral regions were associated with psychosis conversion (mean Cohen d = -0.22; 95% CI, -0.35 to 0.10). Among healthy controls, compared with those in the CHR-PS+ group, age showed a stronger negative association with left fusiform CT measures (F = 9.8; P < .001; q < .001) and left paracentral CT measures (F = 5.9; P = .005; q = .02). Effect sizes representing lower CT associated with psychosis conversion resembled patterns of CT differences observed in ENIGMA studies of schizophrenia (ρ = 0.35; 95% CI, 0.12 to 0.55; P = .004) and individuals with 22q11.2 microdeletion syndrome and a psychotic disorder diagnosis (ρ = 0.43; 95% CI, 0.20 to 0.61; P = .001). CONCLUSIONS AND RELEVANCE: This study provides evidence for widespread subtle, lower CT measures in individuals at CHR. The pattern of CT measure differences in those in the CHR-PS+ group was similar to those reported in other large-scale investigations of psychosis. Additionally, a subset of these regions displayed abnormal age associations. Widespread disruptions in CT coupled with abnormal age associations in those at CHR may point to disruptions in postnatal brain developmental processes.
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    The association between migrant status and transition in an ultra-high risk for psychosis population
    O'Donoghue, B ; Geros, H ; Sizer, H ; Addington, J ; Amminger, GP ; Beaden, CE ; Cadenhead, KS ; Cannon, TD ; Cornblatt, BA ; Berger, GE ; Chen, EYH ; de Haan, L ; Hartmann, JA ; Hickie, IB ; Ising, HK ; Lavoie, S ; Lin, A ; Markulev, C ; Mathalon, DH ; McGlashan, TH ; Mifsud, NG ; Mossaheb, N ; Nieman, DH ; Nordentoft, M ; Perkins, DO ; Riecher-Roessler, A ; Schaefer, MR ; Schloegelhofer, M ; Seidman, LJ ; Smesny, S ; Thompson, A ; Tsuang, MT ; van der Gaag, M ; Verma, S ; Walker, EF ; Wood, SJ ; Woods, SW ; Yuen, HP ; Yung, AR ; McGorry, PD ; Nelson, B (SPRINGER HEIDELBERG, 2021-06)
    PURPOSE: Migrant status is one of the most replicated and robust risk factors for developing a psychotic disorder. This study aimed to determine whether migrant status in people identified as Ultra-High Risk for Psychosis (UHR) was associated with risk of transitioning to a full-threshold psychotic disorder. METHODS: Hazard ratios for the risk of transition were calculated from five large UHR cohorts (n = 2166) and were used to conduct a meta-analysis using the generic inverse-variance method using a random-effects model. RESULTS: 2166 UHR young people, with a mean age of 19.1 years (SD ± 4.5) were included, of whom 221 (10.7%) were first-generation migrants. A total of 357 young people transitioned to psychosis over a median follow-up time of 417 days (I.Q.R.147-756 days), representing 17.0% of the cohort. The risk of transition to a full-threshold disorder was not increased for first-generation migrants, (HR = 1.08, 95% CI 0.62-1.89); however, there was a high level of heterogeneity between studies The hazard ratio for second-generation migrants to transition to a full-threshold psychotic disorder compared to the remainder of the native-born population was 1.03 (95% CI 0.70-1.51). CONCLUSIONS: This meta-analysis did not find a statistically significant association between migrant status and an increased risk for transition to a full-threshold psychotic disorder; however, several methodological issues could explain this finding. Further research should focus on examining the risk of specific migrant groups and also ensuring that migrant populations are adequately represented within UHR clinics.
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    Twelve-Month Cognitive Trajectories in Individuals at Ultra-High Risk for Psychosis: A Latent Class Analysis
    Allott, K ; Schmidt, SJ ; Yuen, HP ; Wood, SJ ; Nelson, B ; Markulev, C ; Lavoie, S ; Brewer, WJ ; Schäfer, MR ; Mossaheb, N ; Schlögelhofer, M ; Smesny, S ; Hickie, IB ; Berger, GE ; Chen, EYH ; De Haan, L ; Nieman, DH ; Nordentoft, M ; Riecher-Rössler, A ; Verma, S ; Thompson, A ; Yung, AR ; Amminger, P ; McGorry, PD ; Hartmann, J (Oxford University Press (OUP), 2022-01-01)
    Abstract Understanding longitudinal cognitive performance in individuals at ultra-high risk for psychosis (UHR) is important for informing theoretical models and treatment. A vital step in this endeavor is to determine whether there are UHR subgroups that have similar patterns of cognitive change over time. The aims were to: i) identify latent class trajectories of cognitive performance over 12-months in UHR individuals, ii) identify baseline demographic and clinical predictors of the resulting classes, and iii) determine whether trajectory classes were associated with transition to psychosis or functional outcomes. Cognition was assessed using the Brief Assessment of Cognition in Schizophrenia (BACS) at baseline, 6- and 12-months (N = 288). Using Growth Mixture Modeling, a single unimpaired improving trajectory class was observed for motor function, speed of processing, verbal fluency, and BACS composite. A two-class solution was observed for executive function and working memory, showing one unimpaired and a second impaired class. A three-class solution was found for verbal learning and memory: unimpaired, mildly impaired, and initially extremely impaired, but improved (“caught up”) to the level of the mildly impaired. IQ, omega-3 index, and premorbid adjustment were associated with class membership, whereas clinical variables (symptoms, substance use), including transition to psychosis, were not. Working memory and verbal learning and memory trajectory class membership was associated with functioning outcomes. These findings suggest there is no short-term progressive cognitive decline in help-seeking UHR individuals, including those who transition to psychosis. Screening of cognitive performance may be useful for identifying UHR individuals who may benefit from targeted cognitive interventions.
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    Global research priorities for youth mental health
    Mei, C ; Fitzsimons, J ; Allen, N ; Alvarez-Jimenez, M ; Amminger, GP ; Browne, V ; Cannon, M ; Davis, M ; Dooley, B ; Hickie, IB ; Iyer, S ; Killackey, E ; Malla, A ; Manion, I ; Mathias, S ; Pennell, K ; Purcell, R ; Rickwood, D ; Singh, SP ; Wood, SJ ; Yung, A ; McGorry, PD (WILEY, 2020-02)
    AIM: Over the past two decades, the youth mental health field has expanded and advanced considerably. Yet, mental disorders continue to disproportionately affect adolescents and young adults. Their prevalence and associated morbidity and mortality in young people have not substantially reduced, with high levels of unmet need and poor access to evidence-based treatments even in high-income countries. Despite the potential return on investment, youth mental disorders receive insufficient funding. Motivated by these continual disparities, we propose a strategic agenda for youth mental health research. METHOD: Youth mental health experts and funders convened to develop youth mental health research priorities, via thematic roundtable discussions, that address critical evidence-based gaps. RESULTS: Twenty-one global youth mental health research priorities were developed, including population health, neuroscience, clinical staging, novel interventions, technology, socio-cultural factors, service delivery, translation and implementation. CONCLUSIONS: These priorities will focus attention on, and provide a basis for, a systematic and collaborative strategy to globally improve youth mental health outcomes.
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    M22. IGG ANTIBODIES TO TOXOPLASMA GONDII ARE ASSOCIATED WITH INCREASED LONG-TERM RISK FOR PSYCHOSIS IN INDIVIDUALS AT ULTRA-HIGH RISK FOR PSYCHOSIS
    Berger, M ; Burkhardt, E ; Yung, A ; Nelson, B ; Francey, S ; Lin, A ; Wood, S ; Thompson, A ; Berger, G ; Philipps, L ; Harrington, S ; McGorry, P ; Yolken, R ; Amminger, GP (Oxford University Press (OUP), 2020-05-18)
    Abstract Background The prevalence of antibodies to Toxoplasma gondii, a ubiquitous parasitic protozoan causing the infectious disease toxoplasmosis, is increased in patients with psychotic disorders compared to the general population. We have previously shown that antibody titers for T.gondii correlate with the severity of positive symptoms in young people at ultra-high risk (UHR) for psychosis, suggesting that infection with T. gondii may be relevant to the manifestation of psychosis. However, it is unclear if T. gondii antibodies represent a risk factor for psychosis onset or non-psychotic outcome in UHR individuals. The aim of the present study was to examine whether seropositivity for T.gondii is associated with transition to psychosis and other outcomes in young people at UHR for psychosis. Methods The study sample consisted of 96 individuals at UHR for psychosis who were referred to the Personal Assistance and Crisis Evaluation (PACE) clinic in Melbourne, Australia, between 2001 and 2004, consented to optional blood tests for infectious agents and were followed up for up to 10 years after baseline (median (interquartile range) duration of follow-up: 7.15 (3.14 – 7.72) years). Serum IgG antibodies to six viral and parasitic pathogens (Toxoplasma gondii, Herpes Simplex Virus Type 1 and 2, Cytomegalovirus, Epstein Barr Virus, Varicella-Zoster Virus) were measured at baseline. Outcome measures included transition to psychosis, general psychiatric symptomatology and positive psychotic symptoms (BPRS), negative symptoms (SANS), depressive symptoms (HAM-D), anxiety symptoms (HAM-A) and functioning (SOFAS and GAF). Cox proportional hazards regression and linear regression models were used to examine the associations of seropositivity and antibody titers at baseline and transition to psychosis and other outcomes at follow-up. Results A total of 17 individuals (17.7%) were seropositive for Toxoplasma gondii at baseline. The rate of transition to psychosis was higher among seropositive (35.7%) compared to seronegative participants (14.6%), although this was not statistically significant (p=0.101). Antibody titers (IgG) for Toxoplasma gondii were significantly higher at baseline in participants who later transitioned to psychosis (1.34 ± 1.36 vs. 0.79 ± 0.73, p=0.027). Seropositivity for T.gondii IgG at baseline significantly predicted transition to psychosis within the follow-up duration (hazard ratio [HR]=3.61, 95%CI 1.08 – 12.00, p=0.036). Toxoplasma IgG at baseline were significantly associated with higher BPRS scores at follow-up in participants who were seropositive at baseline (Beta=6.38, 95%CI 0.43 – 12.34, p=0.038). No significant associations were found between antibodies to other pathogens and outcome, or between antibodies to Toxoplasma gondii and any other outcomes. Discussion Our findings suggest that the presence of IgG class antibodies for Toxoplasma gondii is associated with a higher risk for psychosis transition in individuals at UHR for psychosis, but not with risk for other long-term outcomes. These observations provide support for the hypothesis that infection with Toxoplasma gondii may be an environmental risk factor for psychosis and suggest that IgG antibodies for Toxoplasma gondii in individuals at UHR for psychosis have prognostic relevance.