KaSP is a multimodal observational study with the goal of clarifying underlying mechanisms that cause psychotic disorders, such as schizophrenia. Participants with psychotic symptoms are recruited early after first contact with health care, within 4 weeks of starting anti-psychotic medication, and are compared to controls without psychiatric diagnoses on several measures.

KaSP aims to recruit 120 patients sparsely medicated or drug-naive first episode psychosis (FEP) individuals, along with 80 healthy controls.

Participants undergo the following assessments and measurements:

• Clinical assessment
• Cognitive testing
• Lab results from cerebrospinal fluid, blood, urine, saliva and skin biopsy
• Brain imaging using Magnetic Resonance Imaging (MRI) and Positron Emission Tomography (PET)
• Pre-Pulse Inhibition (PPI) (a test to evaluate the startle response)
• Measures of arterial stiffness and amount of vascular narrowing

Participants with psychosis are invited back for repeat measurements at 1,5 and 5 years after study enrollment. Controls may be invited back at 1,5 years for repeat of some of the assessments.

Inclusion Criteria:

For FEP:

• Diagnosis as assessed using DSM-IV of one of the following: schizophrenia, schizophreniform psychosis, psychosis not otherwise specified (NOS), brief psychosis, 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 psychotic symptoms

For HC:

• A history of diagnosis of a major psychiatric disorder, including substance use disorders.
• Family history of psychotic disorders in first degree relatives.

For all:

• Evidence based on medical history, clinical signs, MRI or laboratory tests of clinically 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 screens during the course of the study.
• Metallic object in the eye, or ferro/electromagnetic implants. History of claustrophobic anxiety during MRI.
• Symptoms of severe bacterial, fungal, or viral infection (including upper respiratory 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 and arterial line placement of either the baseline or 1 year follow-up.
• Blood donation (1 unit or more) within 90 days prior to Screening, plasma donation from 1 week prior to Screening, and platelet donation from 6 weeks prior to inclusion.
• Other unspecified reasons that, in the opinion of the Investigator or the Sponsor, make the participant unsuitable for enrollment. This may include very high symptom severity or signs of aggressiveness and hostility.

FEP are recruited from psychiatry clinics in the greater Stockholm area. HC are recruited by advertisement.