Date of download: 7/2/2016 Copyright © 2016 American Medical Association. All rights reserved. From: Stress-Induced Increase in Kynurenic Acid as a Potential Biomarker for Patients With Schizophrenia and Distress Intolerance JAMA Psychiatry. 2014;71(7): doi: /jamapsychiatry Schematic Illustration of the Experimental ProcedureThe stress challenge consisted of the Paced Auditory Serial Addition Task (PASAT) and the Mirror-Tracing Persistence Task (MTPT). The order of the tasks was randomized across participants. Subjective feeling of negative affect was measured using the Positive and Negative Affect Schedule at 3 points during the study session (arrowheads). Saliva was collected at baseline and then again at 20 and 40 minutes after the end of the stress challenge. The duration of the stress challenge varied between participants depending on whether a participant quit 2, 1, or 0 tasks. Figure Legend:

Date of download: 7/2/2016 Copyright © 2016 American Medical Association. All rights reserved. From: Stress-Induced Increase in Kynurenic Acid as a Potential Biomarker for Patients With Schizophrenia and Distress Intolerance JAMA Psychiatry. 2014;71(7): doi: /jamapsychiatry Distress Tolerance and Intolerance of Patients With Schizophrenia and Healthy ControlsIn performing 2 psychological stress challenge tasks, patients with schizophrenia were significantly more likely to be distress intolerant than healthy controls. A χ 2 test was used to examine the frequency of distress-tolerant vs distress-intolerant participants across patients with schizophrenia and healthy controls (P =.003). Figure Legend:

Date of download: 7/2/2016 Copyright © 2016 American Medical Association. All rights reserved. From: Stress-Induced Increase in Kynurenic Acid as a Potential Biomarker for Patients With Schizophrenia and Distress Intolerance JAMA Psychiatry. 2014;71(7): doi: /jamapsychiatry Salivary Kynurenic Acid (KYNA) Levels in Distress-Tolerant and Distress-Intolerant Participants and Negative AffectA, All subgroups showed increased salivary KYNA levels 20 minutes after the stressor. However, in participants who tolerated 1 or both tasks, the KYNA response was similar in patients with schizophrenia and healthy controls. “Stress duration” bar indicates the timing of the stress task relative to sample collection. B, In participants showing distress intolerance, the KYNA response significantly separated patients with schizophrenia from healthy controls (P =.04 for interaction effect) such that only patients with distress intolerance had higher baseline KYNA levels and KYNA response to stress. “Stress duration” bar indicates the timing of the stress task relative to sample collection. C, Subjectively experienced maximum negative affect during the psychological stress challenge (stress) was substantially higher compared with baseline (P <.001). Patients with schizophrenia generally had higher negative affect at baseline than healthy controls. Error bars indicate standard error of the mean. D, However, there was no difference in the magnitude of negative affect change between patients with schizophrenia and healthy controls (P =.36). Error bars indicate standard error of the mean. Figure Legend: