Prevalence of pathogenic antibodies in psychosis (PPiP1) study


The PPiP1 study aimed to investigate the prevalence of antibodies against neuronal cell surface targets in patients experiencing their first episode of psychosis in comparison with healthy participants in the control group.



The immune system normally controls our ability to fight infection. If the immune system goes wrong it may cause diseases known as ‘autoimmune’ diseases. These diseases involve autoimmune ‘antibodies’ that target healthy parts of the body, instead of infections. We can detect these antibodies using blood tests. We are specifically interested in antibodies that may be the cause of symptoms of psychosis or schizophrenia. During PPiP1 study we worked with NHS Mental Health services across England to investigate the prevalence of these antibodies in people with first episode of psychosis.



The PPiP1 study included 228 patients from Early Intervention in Psychosis services across 37 NHS Mental Health Trusts in England. Participants were aged between 14-35 years of age, were experiencing their first episode of acute psychosis and had been receiving antipsychotic medication for less than 6 weeks.


The study also included a control group of 105 healthy participants, in order to compare prevalence of these antibodies between psychiatric and non-psychiatric populations.

We tested serum samples for antibodies against NMDAR, LGI1, CASPR2, the GABA-A receptor and the AMPA receptor using live cell-based assays. We assessed clinical outcomes such as severity of symptoms, and catatonia and social and cognitive functioning at baseline and 6 months.


PPiP1 ceased recruitment in 2014.


Full results are published in Lennox, B.R., Palmer-Cooper, E.C., Pollak, T., Hainsworth, J., Marks, J., Jacobson, L., Lang, B., Fox, H., Ferry, B., Scoriels, L. and Crowley, H., 2017. Prevalence and clinical characteristics of serum neuronal cell surface antibodies in first-episode psychosis: a case-control study. The Lancet Psychiatry, 4(1), pp.42-48. For access click here.



The PPiP1 study was funded by Medical Research Council: MR/J012939/1 and it was approved by The East of England (Norfolk) Local Research Ethics Committee (Reference 12/EE/0207)