Cortical thickness reduction in combat exposed U.S. veterans with and without PTSD

Area of Science:

• Neuroscience
• Psychiatry
• Military Medicine

Background:

• Combat exposure is a significant risk factor for developing posttraumatic stress disorder (PTSD).
• Understanding the neurobiological underpinnings of PTSD and combat exposure is crucial for veterans' health.
• Cortical thickness changes may serve as a biomarker for neurobiological impact.

Purpose of the Study:

• To investigate cortical thinning in U.S. Veterans with varying PTSD symptom severity.
• To explore neural correlates of PTSD symptom dimensions and their relationship with combat exposure.
• To examine the interactive effects of combat exposure and PTSD on cortical thickness.

Main Methods:

• Sixty-nine combat-exposed Veterans underwent high-resolution MRI scans for cortical thickness estimation.
• Assessed PTSD severity using the Clinician Administered PTSD Scale (CAPS) and combat exposure with the Combat Exposure Scale (CES).
• Conducted vertex-wise whole cerebrum analyses, examining PTSD symptom dimensions and interactions.

Main Results:

• Widespread negative correlations between CAPS severity and cortical thickness, especially in the prefrontal cortex, persisted after controlling for confounds.
• Most PTSD dimensions (except anxious arousal) negatively correlated with cortical thickness in distinct brain regions.
• Combat Exposure Scale (CES) negatively correlated with left lateral prefrontal cortical thickness, irrespective of PTSD diagnosis.
• A significant interaction revealed CES negatively correlated with cortical thickness in non-PTSD participants, but not in PTSD participants.

Conclusions:

• Severe PTSD symptoms in U.S. Veterans are associated with significant cortical thinning.
• Cortical thinning is also observed in Veterans with severe combat exposure but no PTSD diagnosis, suggesting potential concealed injury.
• These findings highlight the neurobiological impact of combat and the need for early detection and intervention.