Anxiety & Depression Association of America

Cannabis users 1) the study team will require majority of adolescents with cannabis use to have a significant cannabis use (self-reported use on ≥15 of the prior 30 days and positive tetrahydrocannabinol (THC) urine toxicology). Depression Positive 1) participants with subthreshold depression, defined as a raw severity score of ≥30 on the Children's Depression Rating Scale-Revised (CDRS-R, for ages 14-17) and as a raw severity score of ≥12 on the Montgomery Asberg Depression Rating Scale (MADRS, for ages 18-20)

1. MRI contraindications such as claustrophobia, metallic ink tattoos, orthodontic braces, or pacemakers 2. positive pregnancy tests 3. neurological illnesses and medical conditions such as unique pain syndromes (e.g. multiple sclerosis, rheumatoid arthritis) 4. estimated full-scale Intelligence Quotient (IQ) ≤80 to ensure that participants have the ability to understand the study112 5. current Substance Use Disorder (SUD) other than cannabis or nicotine. 6. certified for or self-reported medical cannabis use, or intent to become certified 7. current stimulant use (methamphetamine or cocaine) by self-report or urine toxicology 8. oral contraceptives will be allowed and controlled for in order to maximize recruitment of older adolescents. Depressed THC non-users: 1. psychotropic medication-free for >1 month (or >3 months for medications with a long half- life such as fluoxetine) prior to study enrollment. 2. Diagnostic and Statistical Manual 5 (DSM-5) diagnoses of bipolar disorder, psychotic disorders, autism spectrum all non-cannabis substance-related disorders will be exclusionary. 3. Self-injurious acts (e.g. cutting) and suicidal ideations (SI) without a specific as passive SI) are common in adolescent depression and will be allowed. constitutes an imminent risk to self or others (defined as active SI), the withdrawn from the study and emergency procedures will be initiated immediately,