Altered cortical myelination based on gray-to-white matter signal intensity contrast in shift workers.

Shift work has been associated with various adverse health outcomes, particularly those involving cognitive function and mental health. However, the neurobiological mechanisms linking shift work to these outcomes remain poorly understood. This pilot study aimed to examine the effects of shift work on cortical gray-to-white matter signal intensity contrast (GWC), an indirect marker of intracortical myelin content, through vertex-wise cortical analysis. Structural magnetic resonance imaging (MRI) data were obtained from 33 shift workers and 79 day workers. Vertex-wise cortical analysis was performed to identify regions with significant group differences in GWC, controlling for age and sex. Shift workers demonstrated significantly elevated GWC in several cortical regions implicated in cognitive function and emotional regulation, including the superior frontal gyrus, caudal middle frontal gyrus, inferior parietal lobule, lingual gyrus, and cuneus. Elevated GWC was also identified in regions strongly linked to certain psychiatric disorders. These findings offer preliminary evidence of structural brain alterations associated with shift work, suggesting potential neural pathways underlying the cognitive and mental health challenges experienced by shift workers. Further longitudinal research is warranted to validate these results and inform targeted interventions aimed at mitigating neurological and psychological risks related to shift work.