Table 2

Summary of findings from neuroimaging studies exploring the effect of inflammation on glutamate/dopamine and/or reward circuitry

StudyNeuroimaging techniqueParticipantsFindings
Slavich et al (2010)fMRI31 healthy subjectsExposure to the laboratory-based social stressor: sTNFαRII ↑ ∝↑ dorsal anterior cingulate cortex and anterior insula activity
Muscatell et al (2015)fMRI31 healthy female subjectsExposure to the laboratory-based social stressor: IL-6 ↑∝↑ amygdala, subACC, middle temporal gyrus, and dmPFC activity
Haroon et al (2016)MRS,CSI50 medication-free MDDlog plasma CRP ↑ ∝log left basal ganglia glutamate↑; log left basal ganglia glutamate ∝ anhedonia and psychomotor slowing; plasma and CSF CRP ∝ CSI measures of basal ganglia glutamate and the glial marker myoinositol
Felger et al (2016)fMRI48 medication-free MDDCRP ↑∝↓ connectivity between ventral striatum and vmPFC, which in turn correlated with anhedonia↑; CRP ↑ ∝↓dorsal striatal to vmPFC and presupplementary motor area connectivity, which correlated with ↑ motor speed and ↓ psychomotor slowing
Lapidus et al (2014)1H MRS17 MDD vs 17 HCAnhedonia severity ∝↓ occipital GSH levels, which indirectly reflect oxidative stress in neuroinflammation
Harrison et al (2015)qMTI20 healthy subjectsAfter typhoid vaccination injection: inflammation-induced change in insular microstructure ∝ inflammation-induced motor activity (eg, fatigue) ↓
Harroon et al (2014)MRS31 patients with hepatitis CAfter IFN-α treatment: IFN-α ∝↑ glutamate in dACC and basal ganglia, which were correlated with motivation ↓
Dowell et al (2016)qMTI23 patients with hepatitis CAfter IFN-α injection: inflammation-induced acute change in striatal microstructure predicted development of fatigue but not mood symptoms
Capuron et al (2012)18F-dopa PET fMRI28 patients with hepatitis CCross-sectional studies: after IFN-α treatment, inflammation-induced activation of the ventral striatum↓∝ anhedonia and fatigue
Longitudinal studies: ↑ 18F-dopa uptake and ↓18F-dopa turnover in caudate, putamen and ventral striatum; baseline and percentage change in 18F-dopa uptake and turnover ∝depression, fatigue and neurotoxicity
Swarz et al (2017)fMRI448 healthy subjectsIL-18 risk haplotype ∝ anhedonia in women through ↑ threat-related amygdala reactivity
  • ∝: significant correlation; ↑: increased; ↓: decreased.

  • CRP, C reactive protein; CSF, cerebrospinal fluid; CSI, chemical shift imaging; HC, healthy controls; 1H MRS, proton MRS; IL-6, interleukin 6 ; IL-18, interleukin 18; MDD, major depressive disorder; MRS, magnetic resonance spectroscopy; PET, positron emission tomography; dmPFC, dorsomedial prefrontal cortex; fMRI, functional MRI; qMTI, quantitative magnetisation transfer imaging; qMTI, quantitative magnetisation transfer imaging; sTNFαRII, a soluble receptor for tumour necrosis factor-α; subACC, subgenera region of the anterior cingulate cortex.