Medial prefrontal-thalamic white matter microstructure is associated with harm avoidance in OCD: a discovery and...

Area of Science:

• Neuroscience
• Psychiatry

Background:

• Understanding the neural underpinnings of harm avoidance and incompleteness is crucial for diagnosing and treating psychiatric disorders like Obsessive-Compulsive Disorder (OCD).
• Existing research on neural pathways related to these symptom dimensions is limited, especially across diverse clinical populations.

Purpose of the Study:

• To investigate the neural pathways associated with harm avoidance and incompleteness using diffusion MRI.
• To replicate and extend previous findings in OCD to a transdiagnostic sample including healthy controls (HC), individuals with OCD, Obsessive-Compulsive Personality Disorder (OCPD), and other non-OCD disorders.

Main Methods:

• Whole brain tractography was used to reconstruct connections between prefrontal and subcortical regions (thalamus and striatum).
• Fractional anisotropy (FA) was calculated for each connection in 38 HC, 47 OCD, 21 OCPD, and 20 non-OCD participants.
• Harm avoidance and incompleteness symptom dimensions were assessed using the Obsessive-Compulsive Trait Core Dimensions Questionnaire.

Main Results:

• Higher left and right dorsomedial PFC-thalamus FA correlated with increased harm avoidance in a replication model (OCD and HC).
• The left dorsomedial PFC-thalamus connection was also associated with higher incompleteness in the initial model.
• These associations remained significant for harm avoidance when OCPD and non-OCD groups were included, but not for incompleteness or PFC-striatum connections.

Conclusions:

• Increased dorsomedial PFC-thalamus FA is associated with heightened harm avoidance across diagnostic groups, suggesting a transdiagnostic neural mechanism.
• This finding highlights the dorsomedial PFC-thalamus pathway as a potential therapeutic target for psychiatric conditions characterized by harm avoidance.
• The study did not find associations between PFC-striatum connections and the studied symptom dimensions.