Nikhil Prasad Fact checked by:Thailand Medical News Team Oct 23, 2025 3 hours, 45 minutes ago
Medical News: New Study Uncovers Shared Brain Network Imbalance Behind Long COVID and Sensitivity Disorders
A groundbreaking study from Aarhus University, Aarhus University Hospital, Gødstrup Hospital in Denmark, and the University of Oxford has revealed striking similarities in brain connectivity among patients with post-COVID-19 symptoms, functional somatic disorders (FSD), and multiple chemical sensitivity (MCS). The research sheds new light on the neurological basis of these puzzling and often misunderstood conditions, offering the first clear biological evidence of a shared neural disruption.
Brain Connectivity Changes Link Long COVID and Chemical Sensitivity
Researchers examined 57 female participants, including patients diagnosed with FSD, MCS, and post-COVID-19, along with healthy controls. Using advanced brain imaging techniques known as diffusion-weighted MRI and voxel-based probabilistic tractography, they explored how different brain regions communicate through neural networks. The analysis revealed a pronounced reduction in inter-hemispheric connectivity, meaning the brain’s two hemispheres communicated less effectively in affected patients compared with healthy individuals. This
Medical News report highlights that the disruption appeared consistently across all three conditions, suggesting a common underlying neurobiological signature.
Reduced Brain Communication Across Conditions
The study found that patients with FSD, MCS, and post-COVID exhibited a 70.9 percent decrease in inter-hemispheric connectivity, compared to only 29.1 percent in healthy participants. While the post-COVID group displayed slightly milder reductions than those with chronic FSD or MCS, the pattern was remarkably consistent. Interestingly, the research did not find significant differences within individual hemispheres, suggesting that the problem lies in how the two sides of the brain coordinate information.
This loss of cross-hemisphere balance may help explain the wide range of symptoms seen in these conditions—from fatigue and dizziness to sensory intolerance and brain fog. The scientists propose that such alterations might interfere with the “small-world” network organization of the brain, a system that maintains efficient communication between distant regions while minimizing energy costs. Disruption of this balance, they noted, is also seen in neurological conditions such as depression, Alzheimer’s, and Parkinson’s disease.
The Role of Smell and Sensory Dysfunction
Another key finding involved the olfactory (smell) system. Many patients with MCS and post-COVID suffer from smell-related problems, and the researchers found this may be a critical missing link. Those with post-COVID had significantly worse performance on smell and taste tests than other groups, reflecting impaired sensory processing. The study identified abnormal connections between brain regions involved in smell interpretation, such as the orbitofrontal cortex, thalamus, and parietal lobes. Interestingly, while some brain connections weakened, others st
rengthened—possibly as a compensatory mechanism to offset damage in affected areas.
Shared Pathways Point to Common Origins
The analysis revealed that 10 out of 12 specific neural pathways showed abnormalities in at least one patient group. Three of these connections were shared among all three disorders, underscoring the possibility of a shared biological foundation. For instance, enhanced connectivity was found between regions linked to smell processing in both post-COVID and MCS patients. The authors suggest that chronic sensory disruptions might cause the brain to reorganize its networks in maladaptive ways, reinforcing symptoms rather than relieving them.
Implications and Future Research
The study’s authors, led by Dr. Shirin Haghshenas Bilehsavar of Aarhus University and the University of Oxford, emphasized that this is the first structural neuroimaging study to investigate multiple chemical sensitivity and its overlap with post-COVID conditions. They propose that the reduced inter-hemispheric connectivity could serve as a new biomarker for identifying and tracking these disorders. Future research with larger and more diverse populations will be needed to confirm whether these changes are long-term consequences of illness or pre-existing vulnerabilities that increase risk.
The study findings were published on a preprint server and are currently being peer reviewed.
https://www.biorxiv.org/content/10.1101/2025.10.22.683928v1
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Read Also:
https://www.thailandmedical.news/articles/coronavirus
https://www.thailandmedical.news/articles/long-covid
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