The purpose of this study is to investigate the effects of Mindfulness-Based Cognitive Therapy (MBCT) on brain mechanisms associated with interoceptive awareness and rumination in individuals suffering from major depressive disorder (MDD).

Inclusion Criteria:

• current mild-to-moderate depression symptoms (score 12-36 on IDS-C30)
• history of at least 3 depressive episodes or history of 2 years of depression symptoms
• on either no pharmacological treatment or on maintenance antidepressant treatment for at least 8 weeks before the start of the intervention
• English literacy
• normal or near-normal vision

Exclusion Criteria:

i. A score of 37 of higher on the Inventory of Depressive Symptomatology - Clinician version (IDS-C30).

ii. Significant risk for suicide, defined by a score of 3 on Item 18 in the IDS-C30, or as assessed by evaluating clinician.

iii. Severe and unstable medical illness including cardiovascular, hepatic, renal, respiratory, endocrine, neurological, or hematological disease.

iv. The following DSM disorders: any bipolar disorder (current or past), a primary psychotic disorder (current or past), or current psychotic symptoms. However, entry of patients with anxiety disorder(s) will be permitted if the depressive disorder is judged to be the predominant disorder.

v. Active diagnosis of substance abuse or dependence disorders within the last 3 months.

vi. General conditions that would impede participation in a group intervention, as assessed by the evaluating clinician or the therapist delivering the MBCT intervention (such as severe characterological disorders, cognitive impairment, tendencies toward physical aggression).

vii. Past or current training in mindfulness (MBCT, Mindfulness-Based Stress Reduction) or in the Relaxation Response.

viii. Significant training in meditation (or related practices), i.e., more than 10 meditation classes in the past 3 months, or more than 10 classes in yoga, Tai Chi, or Qi Gong in the past 3 months.

ix. Currently taking any psychoactive drugs (whether prescription, over-the-counter, or recreational) other than prescribed antidepressants. This restriction includes the following supplements: Hypericum perforatum (St. John's wort), Valeriana officinalis (valerian), and 5-Hydroxytryptophan (5-HTP).

x. Any change in type or dosage of treatment (whether with antidepressant medication or with psychotherapy or psychosocial intervention) in the 8 weeks preceding the start of the intervention.

xi. Standard exclusion criteria for undergoing magnetic resonance imaging (MRI) procedures for research purposes, i.e., Meniere's disease, epilepsy, claustrophobia, currently pregnant or breastfeeding or planning to conceive or breastfeed during the study, cardiac pacemaker, prosthetic heart valve, neurostimulator, implanted pumps, cochlear implants, non-MR-compatible implants or devices.

xii. A history of neurological disease or injury, including a history of seizures or significant head trauma (i.e., extended loss of consciousness, neurological sequelae, or known structural brain lesion).

xiii. Unable or unwilling to fill in online questionnaires or to be contacted over the phone by study staff for periodic assessments.