Transdiagnostic emotion regulation processes explain how emotion-related factors affect co-occurring PTSD and MDD in relation to trauma

•PTSD and depressive symptoms are associated with expressive suppression, rumination.•PTSD + MDD have higher rates of expressive suppression, rumination than PTSD.•Emotion regulation is shared process between negative affect and PTSD, MDD.•Emotion regulation is shared process between regulation expectancies and PTSD, MDD.•Emotion regulation is how negative affect/regulation expectancies affect PTSD, MDD.