Neural Mechanisms of Mindfulness-based Cognitive Therapy (MBCT) for Posttraumatic Stress Disorder (PTSD)

Inclusion Criteria: * Meets current Diagnostic and Statistical Manual of Mental Disorders, fifth edition (DSM-5) criteria for PTSD (with or without Major Depressive Disorder) or subsyndromal PTSD (has qualifying trauma, has intrusive and avoidant symptoms, and at least one negativity and one arousal symptom, and significant impairment); type of trauma shall be interpersonal violence, combat, and/or sexual assault, etc. Exclusion Criteria: * Dissociative PTSD * Delayed-onset PTSD * Magnetic Resonance Imaging (MRI) contraindications (e.g. metal in body, inability to be in the scanner - claustrophobia, severe back pain, etc.) * Serious medical or neurologic conditions (e.g. stroke, seizures) * Suicide risk * Psychosis * Life history of schizophrenia * Life history of bipolar disorder * Current substance dependence * Other factors that preclude safe and meaningful participation in the study, at discretion of the PI and study team