Cortical activity during olfactory stimulation in multiple chemical sensitivity: a 18F-FDG PET/CT study

Purpose To investigate the differences in brain glucose consumption during olfactory stimulation between subjects affected by multiple chemical sensitivity (MCS) and a group of healthy individuals. Methods Two 18F-FDG PET/CT scans were performed in 26 subjects (6 men and 20 women; mean age 46.7±11 years) with a clinical diagnosis of MCS and in 11 healthy controls (6 women and 5 men; mean age 45.7±11 years), the first scan after a neutral olfactory stimulation (NS) and the second after a pure olfactory stimulation (OS). Differences in 18F-FDG uptake were analysed by statistical parametric mapping (SPM2). Results In controls OS led to an increase in glucose consumption in BA 18 and 19 and a reduction in glucosemetabolismin BA 10, 11, 32 and 47. In MCS subjects, OS led to an increase in glucose consumption in BA 20, 23, 18 and 37 and a reduction in glucose metabolism in BA 8, 9 and 10. Conclusion The results of our study suggest that cortical activity in subjects with MCS differs from that in healthy individuals during olfactory stimulation.