Microglia Activation in Recent-Onset Schizophrenia: A Quantitative (R)-[11C]PK11195 Positron Emission Tomography Study

Background Schizophrenia is a brain disease involving progressive loss of gray matter of unknown cause. Most likely, this loss reflects neuronal damage, which should, in turn, be accompanied by microglia activation. Microglia activation can be quantified in vivo using (R)-[11C]PK11195 and positron emission tomography (PET). The purpose of this study was to investigate whether microglia activation occurs in patients with recent-onset schizophrenia. Methods Ten patients with recent-onset schizophrenia and 10 age-matched healthy control subjects were included. A fully quantitative (R)-[11C]PK11195 PET scan was performed on all subjects, including arterial sampling to generate a metabolite-corrected input curve. Results Compared with control subjects, binding potential of (R)-[11C]PK11195 in total gray matter was increased in patients with schizophrenia. There were no differences in other PET parameters. Conclusions Activated microglia are present in schizophrenia patients within the first 5 years of disease onset. This suggests that, in this period, neuronal injury is present and that neuronal damage may be involved in the loss of gray matter associated with this disease. Microglia may form a novel target for neuroprotective therapies in schizophrenia.