Neuroinflammation as measured by positron emission tomography in patients with recent onset and established schizophrenia: implications for immune pathogenesis

Author(s)

Conen, Silke ^[1] ; Gregory, Catherine J. ^[1] ; Hinz, Rainer ^[2] ; Smallman, Richard ^[1] ; Corsi-Zuelli, Fabiana ^[3] ; Deakin, Bill ^[1] ; Talbot, Peter S. ^[1]

Affiliation

^[1] Univ Manchester, Manchester Acad Hlth Sci Ctr, Div Neurosci & Expt Psychol, Manchester M13 9PT, Lancs - England

^[2] Univ Manchester, Manchester Acad Hlth Sci Ctr, Div Informat Imaging & Data Sci, Manchester M13 9PL, Lancs - England

^[3] Univ Sao Paulo FMRP USP, Div Psychiat, BR-14048900 Sao Paulo - Brazil

• Document type: Journal article
• Source: MOLECULAR PSYCHIATRY; v. 26, n. 9, p. 5398-5406, SEP 2021.
• Web of Science Citations: 13

Abstract

Positron emission tomography (PET) imaging of the 18 kDa translocator protein (TSPO), which is upregulated in activated microglia, is a method for investigating whether immune activation is evident in the brain of adults with schizophrenia. This study aimed to measure TSPO availability in the largest patient group to date, and to compare it between patients with recent onset (ROS) and established (ES) schizophrenia. In total, 20 ROS patients (14 male), 21 ES (13 male), and 21 healthy controls completed the study. Patients were predominantly antipsychotic-medicated. Participants underwent a PET scan using the TSPO-specific radioligand {[}C-11](R)-PK11195. The primary outcome was binding potential (BPND) in the anterior cingulate cortex (ACC). Secondary outcomes were BP(ND)in six other regions. Correlations were investigated between TSPO availability and symptom severity. Data showed that mean BP(ND)was higher in older (ES and controls) compared with younger (ROS and controls) individuals, but did not significantly differ between ROS or ES and their respective age-matched controls (ACC; ANOVA main effect of diagnosis:F-1,F-58 = 0.407,p = 0.526). Compared with controls, BP(ND)was lower in antipsychotic-free (n = 6), but not in medicated, ROS patients. BP(ND)in the ES group was negatively correlated with positive symptoms, and positively correlated with negative symptom score. Our data suggest ageing is associated with higher TSPO but a diagnosis of schizophrenia is not. Rather, subnormal TSPO levels in drug-free recent-onset patients may imply impaired microglial development and/or function, which is counteracted by antipsychotic treatment. The development of novel radioligands for specific immune-mechanisms is needed for further clarification. (AU)

• FAPESP's process: 19/13229-2 - Inflammatory profile in the general population: transdiagnostic dimensions in the context of the psychosis continuum
• Grantee: Fabiana Maria das Graças Corsi Zuelli
• Support Opportunities: Scholarships in Brazil - Doctorate