Selection of true healthy individuals as a control group can be challenging as even in the absence of known disease, undiagnosed chronic systemic inflammatory states that can influence brain TSPO expression such as atherosclerosis, dyslipidemia, and diabetes can exist.21 Larger prospective studies with full age and gender-matched controls, which have been rigorously screened for other recognized causes of brain TSPO upregulation, are therefore required to robustly evaluate differences in [11C](R)PK11195 binding between VS and healthy control populations. This evidence concerns the gene TSPO and metabolic syndrome.