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

Area of Science:

• Neuroscience
• Medical Imaging
• Toxicology

Background:

• Multiple Chemical Sensitivity (MCS) is a condition characterized by adverse reactions to various chemicals.
• Olfactory system dysfunction is often reported in individuals with MCS.
• Understanding the neurological underpinnings of MCS is crucial for diagnosis and treatment.

Purpose of the Study:

• To compare brain glucose metabolism during olfactory stimulation in individuals with MCS versus healthy controls.
• To identify specific brain regions showing altered activity in MCS patients.
• To investigate the role of the olfactory system in the pathophysiology of MCS.

Main Methods:

• Utilized two (18)F-FDG PET/CT scans per subject under neutral and odorant stimulation.
• Included 26 subjects diagnosed with MCS and 11 healthy controls.
• Analyzed differences in glucose uptake using statistical parametric mapping (SPM2).

Main Results:

• Healthy controls showed increased glucose metabolism in visual cortex areas (BA 18, 19) and decreased metabolism in frontal areas (BA 10, 11, 32, 47) during olfactory stimulation.
• MCS subjects exhibited increased glucose metabolism in temporal and visual areas (BA 20, 23, 18, 37) and decreased metabolism in frontal areas (BA 8, 9, 10).
• Distinct patterns of cortical activation and deactivation were observed between the two groups.

Conclusions:

• Cortical activity during olfactory stimulation significantly differs between individuals with MCS and healthy controls.
• The study suggests altered brain responses to odors in MCS, potentially involving visual and frontal lobe regions.
• These findings contribute to understanding the neurobiological basis of olfactory processing in MCS.