This meta-analysis found that across multiple disorders, including neurodegenerative disorders (e.g., Alzheimer’s disease [AD], PD), neuropsychiatric disorders (e.g., MDD, schizophrenia), traumatic brain injury, autoimmune, and other disorders, TSPO PET signal was significantly higher in cases vs. controls in cortical gray matter (SMD = 0.36) and that, by disorder, AD and neurodegenerative conditions show particular patterns of elevation in certain regions. Here, TSPO is linked to Parkinson disease.