Mindfulness has shown an inverse relationship with avoidant coping styles, PTSD symptoms, and substance use disorders.

Trait mindfulness and mindfulness training are associated with treatment efficacy in comorbid substance abuse and PTSD.

The current study suggests mindfulness mediates the relationship between PTSD symptoms and substance dependence.

A reverse mediation model suggests mindfulness mediates the relationship between substance dependence and PTSD symptoms.

Results may point to the role of mindfulness in the bidirectional and cyclical nature of this comorbidity.

Findings contribute to understanding underlying processes of comorbid PTSD and substance use, and may inform treatment.