A Study Exploring Changes in a Variety of Biomarkers Following Dosing With MT1988 in Participants at Clinical High Risk for Psychosis

Inclusion Criteria: * Aged 17 to 30 years at time of consent. * Capacity to provide informed consent. (For patients under 17 years, participants must assent and informed consent provided by one parent or legal guardian). * Meet diagnostic criteria for Clinical High Risk of Psychosis (CHR). * For females of reproductive potential - not pregnant or nursing and willing to comply with contraceptive requirements. Exclusion Criteria: * Clinically significant medical disorder or laboratory test abnormality at Day 1. * History of or current condition which may prevent participant from complying with study procedures. * Past or current schizophrenia, other disorder with symptoms of psychosis, major cognitive disorder resulting from traumatic brain injury. * Received antipsychotic medication equivalent to a total lifetime haloperidol dose \>50 mg. * Current use of medications which could interfere with the study endpoints - to be assessed by the Investigator at screening. * Unable to abstain from nicotine (e.g. cigarettes, vape) for two hours before cognitive testing. * Unable to abstain from marijuana use on test day prior to test completion. * History of suicide attempt or behavior in previous 12 months, or risk of suicidal behavior during the study.