BBB dysfunction has been indicated in some groups of schizophrenia patients by measuring increased albumin and immunoglobulin (IgG) cerebrospinal fluid (CSF) levels. Most of the authors described a raised protein level in 5-20% of the schizophrenic patients (Muller & Ackenheil, 1995). Increased S100B levels were demonstrated in the serum of patients suffering from schizophrenia as well as depression, and this may reflect increased BBB permeability. Furthermore, this increase remains in those patients who develop a residual state with relevant negative symptoms, whereas S100B levels normalize in recovering patients (Shalev, Serlin & Friedman, 2009). CSF albumin and CSF IgG values correlate significantly with some of the SANS (Scale for the Assessment of Negative Symptoms) subscales and the SANS total score, this shows the correlation between BBB permeability and behavioral changes. It is important to say that although negative symptoms are often signs of chronicity of the disease, the abnormal CSF findings in Muller's experiment (1995) are not related to the duration of the disease, because the patients were quite young and the duration of the disease was less than 3 years.
The investigators hypothesize that a primary vascular pathology, which leads to BBB breakdown, will result a leakage of serum-derived vascular components in to the brain tissue and may cause brain dysfunction such as disturbed thinking processes, mood and behavior, as we can see in psychiatric patients.