NAC and MBCT for Mild Depression in Young People

Inclusion Criteria: 1. age between 15 years, 0 months to 24 years, 11 months old; 2. presenting with mild depression, defined by meeting DSM-5 criteria for a current major depressive episode, mild severity, or persistent depressive disorder, or other specified depressive disorder (depressive episode with insufficient symptoms to meet criteria for a major depressive episode); 3. medication-naïve or medication free for at least 5 half-lives since the last use of a psychoactive medication, with the exception of stimulants for ADHD; 4. if on ADHD stimulant medication over 2 months prior to screening, willing to maintain stimulant dose constant during the study participation; 5. Tanner stage greater than or equal to III; Exclusion Criteria: 1. significant suicidal risk, defined by suicidal ideation of type 3, 4 or 5 on the Columbia Suicide Severity Rating Scale (C-SSRS) in the past 3 months, or any lifetime suicidal attempts; 2. current major depressive episode, moderate or severe 3. current or lifetime history of manic or hypomanic episodes, and/or diagnosis of bipolar disorder; 4. current or lifetime history of psychotic disorders, and/or prior diagnosis of schizophrenia spectrum disorders; 5. active or current substance use disorders in the last 3 months, except cannabis or alcohol use disorder, mild; 6. diagnosis of autism spectrum disorder, pervasive developmental disorder, obsessive-compulsive disorder, post-traumatic stress disorders, Tourette's syndrome 7. any contraindication to MRI scanning; 8. pregnancy; 9. history of major neurological disorder (e.g, epilepsy), or head trauma with \> 10 minutes loss of consciousness; 10. intellectual disability (IQ less than or equal to 70), as determined by the Weschler Abbreviated Scale of Intelligence (WASI); 11. previous participation in any mindfulness-based treatment; 12. initiating psychotherapy within 2 months prior to screening, or planning to initiate psychotherapy during study participation; if on therapy, frequency and type should remain stable for 2 months prior to enrollment and during study participation; 13. no current diagnosis of asthma 14. history of allergic reaction to N-acetylcysteine