Prevalence of Pathogenic Antibodies in Psychosis (PPiP)2 study


The PPiP2 study aims to investigate the prevalence of autoimmune antibodies in patients with psychosis symptoms.



The immune system normally controls our ability to fight infection. If the immune system goes wrong it may attack our own body, causing diseases called ‘autoimmune’ diseases. It has been discovered that some of these autoimmune diseases can affect the brain, and in the early stages of the disease they can manifest through symptoms of psychosis.


We can diagnose some of these autoimmune diseases using blood tests to detect specific antibodies.  We are specifically interested in antibodies that may be the cause of symptoms of psychosis and possibly in some cases of schizophrenia.




PPiP2 is a cross-sectional study recruiting study participants from over 40 NHS mental health trusts (full list here),  across England and will continue to recruit patients until the end of August 2020.

The PPiP2 study includes adult (16-70 yrs) participants from NHS mental health services who are experiencing their first episode of psychosis or relapse of psychosis symptoms. For participants who relapsed there needs to be a period of at least six months of remission prior to the current episode. Patients with any other neurological disorder would not be included in the study.


Local researchers, based in each participating NHS Trust are approaching potential participants from both inpatient and community services. If the potential participant is eligible for the study, the researcher will take informed consent to participate in PPiP2 and will collect a small sample of blood. This sample will be tested for at least four anti-neuronal antibodies, namely NMDAR, LGI1, CASPR2 and GABA-A. Apart from basic demographic and clinical data no further assessments are required.


Test results will be communicated to the local research team and the participant's psychiatrist.  If results are negative no action is required. However, it is advised to refer patients with identified anti-neuronal membrane antibody in their serum to a neurologist. This can be a neurologist with special interest in neuroimmunology based in one of the SINAPPS2 trial site located in multiple hospitals across England or a local neurologist.


If you, or someone you care for, is interested in taking part in the PPiP2 study, you can find more information clicking here.

Clinicians who would like to refer patients to PPiP2 could contact either the local PPiP2 research team  or the PPIP2 management team.


The PPiP2 study is funded by Medical Research Council, Developmental Pathway Funding Scheme: MR/N019067/1 and it is approved by the East of England (Norfolk) Local Research Ethics Committee (Reference 12/EE/0307).

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PPiP2 sites distribution - for the full list click here or visit the "Get Involved" page on the top menu

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This study is funded by the MRC.