TSPO expression and brain structure in the psychosis spectrum

Area of Science:

• Neuroscience
• Psychiatry
• Radiology

Background:

• Psychosis involves brain structural abnormalities, but causes are unclear.
• Microglial activation, part of the immune system, is implicated in psychosis.
• Previous studies linked peripheral inflammation to brain changes, but in-vivo microglial activation links are less explored.

Purpose of the Study:

• To investigate the relationship between mitochondrial 18 kDa translocator protein (TSPO) expression and structural brain characteristics in individuals at clinical high risk (CHR) for psychosis, first-episode psychosis (FEP) patients, and healthy volunteers.
• To explore if in-vivo microglial activation is associated with brain structure alterations in schizophrenia and its prodrome.

Main Methods:

• Utilized structural brain MRI and [18F]FEPPA positron emission tomography (PET) to target TSPO.
• Assessed regional brain volume, cortical thickness, and hippocampal shape in dorsolateral prefrontal cortex and hippocampus.
• Included 90 participants: CHR individuals, antipsychotic-naïve FEP patients, and healthy controls.

Main Results:

• A significant interaction between [18F]FEPPA binding and group was found in left hippocampal morphology.
• In first-episode psychosis, TSPO total volume of distribution (VT) correlated with specific hippocampal shape alterations.
• No significant associations were found in CHR individuals or healthy volunteers, nor with other brain structures.

Conclusions:

• Findings suggest a link between TSPO expression and hippocampal morphology alterations in first-episode psychosis.
• This indicates a potential role for microglial activation in the structural brain changes observed in early psychosis.
• Further research is needed to elucidate the precise mechanisms linking neuroinflammation and psychosis-related brain alterations.