Karolinska Schizophrenia Project

Inclusion Criteria:

For FEP:

• Diagnosis as assessed using DSM-IV of one of the following: schizophrenia,schizophreniform psychosis, psychosis not otherwise specified (NOS), briefpsychosis, schizoaffective syndrome, delusional disorder

• First exposure to anti-psychotic medication less than 4 weeks prior to inclusion

Exclusion Criteria:

For FEP:

• Other dominant psychiatric illness deemed to be related to current psychoticsymptoms

For HC:

• A history of diagnosis of a major psychiatric disorder, including substance usedisorders.

• Family history of psychotic disorders in first degree relatives.

For all:

• Evidence based on medical history, clinical signs, MRI or laboratory tests ofclinically significant somatic disorder, or previous disorder with brain engagement (e.g. tumour, neuroinflammatory disease, epilepsy) or significant brain trauma.

• Exposure to an effective radiation dose of 25 mSv during the past year.

• Pregnancy, lactating or breastfeeding (women).

• Meets diagnostic criteria of substance use disorder (excluding nicotine dependence)as assessed using DSM-IV or as determined using repeated positive urine screensduring the course of the study.

• Metallic object in the eye, or ferro/electromagnetic implants. History ofclaustrophobic anxiety during MRI.

• Symptoms of severe bacterial, fungal, or viral infection (including upperrespiratory tract infection), with systemic effects as detected by e.g. fever,within 7 days prior to inclusion.

• Treatment with any antihemostatic medication within 2 weeks of lumbar puncture andarterial line placement of either the baseline or 1 year follow-up.

• Blood donation (1 unit or more) within 90 days prior to Screening, plasma donationfrom 1 week prior to Screening, and platelet donation from 6 weeks prior toinclusion.

• Other unspecified reasons that, in the opinion of the Investigator or the Sponsor,make the participant unsuitable for enrollment. This may include very high symptomseverity or signs of aggressiveness and hostility.