TSPO expression and brain structure in the psychosis spectrum

Brain Behav Immun. 2018 Nov;74:79-85. doi: 10.1016/j.bbi.2018.06.009. Epub 2018 Jun 12.


Psychosis is associated with abnormal structural changes in the brain including decreased regional brain volumes and abnormal brain morphology. However, the underlying causes of these structural abnormalities are less understood. The immune system, including microglial activation, has been implicated in the pathophysiology of psychosis. Although previous studies have suggested a connection between peripheral proinflammatory cytokines and structural brain abnormalities in schizophrenia, no in-vivo studies have investigated whether microglial activation is also linked to brain structure alterations previously observed in schizophrenia and its putative prodrome. In this study, we investigated the link between mitochondrial 18 kDa translocator protein (TSPO) and structural brain characteristics (i.e. regional brain volume, cortical thickness, and hippocampal shape) in key brain regions such as dorsolateral prefrontal cortex and hippocampus of a large group of participants (N = 90) including individuals at clinical high risk (CHR) for psychosis, first-episode psychosis (mostly antipsychotic-naïve) patients, and healthy volunteers. The participants underwent structural brain MRI scan and [18F]FEPPA positron emission tomography (PET) targeting TSPO. A significant [18F]FEPPA binding-by-group interaction was observed in morphological measures across the left hippocampus. In first-episode psychosis, we observed associations between [18F]FEPPA VT (total volume of distribution) and outward and inward morphological alterations, respectively, in the dorsal and ventro-medial portions of the left hippocampus. These associations were not significant in CHR or healthy volunteers. There was no association between [18F]FEPPA VT and other structural brain characteristics. Our findings suggest a link between TSPO expression and alterations in hippocampal morphology in first-episode psychosis.

Keywords: Clinical high risk; MRI; PET; Psychosis; TSPO.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Brain / diagnostic imaging
  • Brain / metabolism*
  • Brain / pathology*
  • Case-Control Studies
  • Female
  • Hippocampus / diagnostic imaging
  • Hippocampus / metabolism
  • Hippocampus / pathology
  • Humans
  • Magnetic Resonance Imaging / methods
  • Male
  • Positron-Emission Tomography / methods
  • Prefrontal Cortex / diagnostic imaging
  • Prefrontal Cortex / pathology
  • Psychotic Disorders / diagnostic imaging
  • Psychotic Disorders / genetics
  • Psychotic Disorders / metabolism*
  • Psychotic Disorders / pathology*
  • Receptors, GABA / biosynthesis*
  • Receptors, GABA / genetics
  • Receptors, GABA / metabolism
  • Transcriptome
  • Young Adult


  • Receptors, GABA
  • TSPO protein, human