Neuroinflammation in patients with chronic fatigue syndrome/myalgic encephalomyelitis: An11C-(R)-PK11195 PET study

Abstract

Chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME) is a disease characterized by chronic, profound, disabling, and unexplained fatigue. Although it is hypothesized that brain inflammation is involved in the pathophysiology of CFS/ME, there is no direct evidence of neuroinflammation in patients with CFS/ME. Activation of microglia or astrocytes is related to neuroinflammation. 11C-(R)-(2-chlorophenyl)-N-methyl-N-(1-methylpropyl) -3-isoquinoline-carboxamide (11C-(R)-PK11195) is a ligand of PET for a translocator protein that is expressedby activatedmicrogliaor astrocytes. We used 11C-(R)-PK11195 and PET to investigate the existence of neuroinflammation in CFS/ME patients. Methods: Nine CFS/ME patients and 10 healthy controls underwent 11C-(R)-PK11195 PET and completed questionnaires about fatigue, fatigue sensation, cognitive impairments, pain, and depression. To measure the density of translocator protein, nondisplaceable binding potential (BPND) values were determined using linear graphical analysis with the cerebellum as a reference region. Results: The BPND values of 11C-(R)-PK11195 in the cingulate cortex, hippocampus, amygdala, thalamus, midbrain, and pons were 45%-199% higher in CFS/ME patients than in healthy controls. In CFS/ME patients, the BP ND values of 11C-(R)-PK11195 in the amygdala, thalamus, and midbrain positively correlated with cognitive impairment score, the BP ND values in the cingulate cortex and thalamus positively correlated with pain score, and the BPND value in the hippocampus positively correlated with depression score. Conclusion: Neuroinflammation is present inwidespread brain areas in CFS/MEpatients and was associated with the severity of neuropsychologic symptoms. Evaluation of neuroinflammation in CFS/ME patients may be essential for understanding the core pathophysiology and for developing objective diagnostic criteria and effective medical treatments. Copyright © 2014 by the Society of Nuclear Medicine and Molecular Imaging, Inc.