Quantitative Susceptibility Mapping MRI in Deep-Brain Nuclei in First-Episode Psychosis

Area of Science:

• Neuroimaging
• Neurochemistry
• Psychiatry

Background:

• Psychosis is linked to neurochemical alterations in deep-brain nuclei, particularly dopamine system dysfunction.
• Quantitative susceptibility mapping (QSM), an MRI technique, measures brain magnetic susceptibility, correlating with iron concentration.
• Iron is a crucial cofactor in dopamine pathways and co-localizes with inhibitory neurons, making QSM a potential tool to study these processes in psychosis.

Purpose of the Study:

• To investigate neurochemical changes in deep-brain nuclei of patients with first-episode psychosis using QSM.
• To explore the relationship between iron concentration, measured by QSM, and psychosis.

Main Methods:

• Magnetic resonance imaging (MRI) using quantitative susceptibility mapping (QSM) was performed on 83 first-episode psychosis patients and 64 healthy controls.
• Mean susceptibility was measured in six deep-brain nuclei, with a subset of participants reassessed after three months.
• Linear mixed models analyzed the influence of group, region, age, gender, and other factors on QSM.

Main Results:

• Patients with psychosis exhibited significantly reduced susceptibility in the putamen and globus pallidus externa (GPe).
• A significant reduction in R2* was also observed in the GPe of patients.
• Age, gender, framewise displacement, session, group, and region were significant predictors of QSM, while dose, treatment duration, and volume were not.

Conclusions:

• Reduced QSM and R2* in the GPe suggest decreased iron concentration in this region among psychosis patients.
• The susceptibility reduction in the putamen was not clearly linked to iron changes.
• Observed changes were independent of symptoms, dose, and treatment duration, hinting at QSM as a potential trait marker for psychosis, warranting further longitudinal validation.