This study used ultra-high field MRI (7.0 Tesla) and quantitative imaging to investigate microstructural changes in the frontocortical regions of individuals with major depressive disorder (MDD). The researchers focused on intracortical myelin (measured by T1 relaxation time) and iron concentration (measured by T2* relaxation time) in the orbitofrontal and rostral anterior cingulate cortices of 48 MDD patients and 10 healthy controls. Results revealed that MDD diagnosis and symptom severity were significantly associated with decreased intracortical myelination (higher T1 values) in the lateral orbitofrontal cortex. No significant relationships were found with iron concentration. These findings suggest intracortical demyelination as a potential mechanism contributing to the cortical abnormalities observed in MDD.

Jurjen Heij, Wietske van der Zwaag, Tomas Knapen, Matthan W. A. Caan, Birte Forstmann, Dick J. Veltman, Guido van Wingen, Moji Aghajani