Members of the (OASIS) team and the service users of OASIS. Formal Thought Disorder in people at Ultra High Risk of Psychosis   Demjaha A, Weinstein S, Stahl D, Day F, Valmaggia L, Rutigliano G, Micheli A, Fusar-Poli P, McGuire P Institute of Psychiatry, Psychology and Neuroscience, King’s College London United Kingdom   INTRODUCTION Formal Thought Disorder (FTD) is a cardinal feature of psychosis. However, the extent to which FTD is evident in ultra-high-risk (UHR) individuals and whether is linked to the progression to psychosis remains unclear.   The main instruments that are used to assess psychopathology in UHR subjects, the Comprehensive Assessment of the At Risk Mental State (CAARMS),1 the Scale of Prodromal Symptoms (SOPS), and the Schizophrenia Prediction Instrument (SPIA) include items that correspond to features of FTD with evidence that UHR individuals score positively on these items,2, 3 however, they do not provide specific assessment of FTD.   No studies have examined FTD in UHR subjects using instruments that have been specifically designed to evaluate FTD. The Thought and Language Index (TLI) is one such instrument, sensitive to subtle language anomalies and has previously been successfully applied in patients with schizophrenia, non-clinical individuals with psychotic symptoms and healthy volunteers. 4,5 AIMS Use the TLI to determine whether FTD is a feature of the UHR state, and to compare it with thought disorder in patients with a psychotic disorder. Investigate whether the severity of FTD in UHR participants at presentation is related to transition to psychosis. Assess the effect of combining TLI scores with baseline measures of Attenuated Psychotic Symptoms and six Basic Symptoms incorporated within CAARMS. SAMPLE  Measurements The presence of the UHR was determined using the Comprehensive Assessment of the At-Risk Mental State (CAARMS) Six of the Huber’s BS are incorporated within the CAARMS: subjective experience of cognitive change, subjective emotional disturbance, avolition, subjective complaints of impaired motor functioning, subjective complaints of impaired bodily sensations, and subjective complaints of impaired autonomic functioning.6 These were used to create an aggregate score for subsequent analyses. FTD was assessed using the Thought and Language Index (TLI). The TLI rates 8 types of speech abnormality: looseness, peculiar word usage, peculiar sentence usage, peculiar logic (Positive or Disorganization FTD subscale), poverty of speech, weakening of goal (Negative FTD subscale), and perseveration and distractibility (Non-specific FTD subscale). Statistical analysis:  The analysis of variance (ANOVA) was conducted to test group differences for total TLI scores and TLI subscale scores. t tests were conducted for independent samples. To examine the combined effect of TLI, APS And BS measures, the data were aggregated by summing their standardized scores in a composite variable. RESULTS CONCLUSION FTD is evident in people at UHR for psychosis and is qualitatively similar to that seen in patients with psychotic disorders, but less severe. Specialised instruments developed for the assessment of FTD in patients with psychosis, such as the TLI, provide a means of evaluating FTD in UHR participants, and complement existing instruments for the evaluation of psychopathology in this group. Prospective studies in large samples are required to confirm whether assessing the severity of FTD may be useful in helping to predict whether an individual at high risk will go on to develop psychosis. REFERRENCES Phillips LJ, Yung AR, McGorry PD. Identification of young people at risk of psychosis: validation of Personal Assessment and Crisis Evaluation Clinic intake criteria. Australian and New Zealand Journal of Psychiatry 2000;34(sup2):S164-S169. Addington J, Liu L, Buchy L, et al. North American prodrome longitudinal study (NAPLS 2): the prodromal symptoms. The Journal of nervous and mental disease 2015;203(5):328-335. Cornblatt BA, Carrión RE, Auther A, McLaughlin D, Olsen RH, John M, Correll CU. Psychosis prevention: A modified clinical high risk perspective from the recognition and prevention (RAP) program. American Journal of Psychiatry 2015. Liddle PF, Ngan ET, Caissie SL, Anderson CM, Bates AT, Quested DJ, White R, Weg R. Thought and Language Index: an instrument for assessing thought and language in schizophrenia. The British Journal of Psychiatry 2002;181(4):326-330. Sommer IE, Derwort AM, Daalman K, de Weijer AD, Liddle PF, Boks MP. Formal thought disorder in non-clinical individuals withauditory verbal hallucinations. Schizophrenia research 2010;118(1):140-145 Huber G, Gross G, Schüttler R, Linz M. Longitudinal studies of schizophrenic patients. Schizophrenia bulletin 1980;6(4):592-605. Figure 1. Mean severity of total TLI and its Positive, Negative and Nonspecific subscales in the UHR , FEP and HC groups Figure 2. Mean severity of TLI items in the UHR , FEP and HC groups Table 2. Mean TLI total and subscale scores of the three groups Table 1. Sociodemographic and Clinical Characteristics of ARMS, FEP and HC groups Figure 3. Mean severity of TLI Scores for Patients With and Without Transition to Psychosis ACKNOWLEDGEMENTS Members of the (OASIS) team and the service users of OASIS.   Guy’s and St Thomas’ Charitable Foundation; South London and Maudsley Trust.