The Orbitofrontal Cortex Gray Matter Is Associated With the Interaction Between Insomnia and Depression

Area of Science:

• Neuroscience
• Psychiatry
• Medical Imaging

Background:

• Insomnia and depression frequently co-occur in primary insomnia (PI) and major depressive disorder (MDD).
• Understanding the shared and distinct brain alterations in these conditions is crucial.

Purpose of the Study:

• To investigate homogeneous and heterogeneous brain structure changes in patients with primary insomnia and major depressive disorder.
• To identify brain regions affected by depression, insomnia, and their interaction.

Main Methods:

• Structural MRI scans were acquired from 65 MDD patients and 67 PI patients.
• Subjects were categorized into four groups based on depression and insomnia severity.
• General linear models and partial correlation analyses were used to assess cortical thickness, volume, and clinical significance.

Main Results:

• Depression significantly impacted cortical thickness in the superior parietal lobe, middle cingulate cortex, and parahippocampal gyrus.
• Insomnia was associated with altered cortical thickness in the posterior cingulate cortex.
• A significant interaction between depression and insomnia revealed decreased gray matter volume in the right orbitofrontal cortex.

Conclusions:

• The right orbitofrontal cortex plays a key role in the neuropathology of comorbid insomnia and depression.
• These findings offer novel insights into the neural mechanisms underlying the comorbidity of insomnia and depression.