This study is about helping teenagers with depression using a treatment called Behavioral Activation (BA). It involves using a special brain scan called functional magnetic resonance imaging (fMRI) to see how the brain changes during therapy.

Researchers want to know if BA helps with low motivation and avoiding things that make you scared. They will compare depressed teens to healthy ones to see differences. The study needs 136 participants, aged 15-17. Some will get BA therapy, while others will just be observed as healthy controls.

Participants will have five fMRI scans and therapy sessions over a period. Teens must not take certain medications before joining and need access to a smartphone or computer for some activities. It's important not to have conditions like bipolar disorder, schizophrenia, or recent substance abuse.

• Duration: Multiple sessions over several weeks.
• Eligibility: Teens aged 15-17 with Major Depressive Disorder (MDD).
• Risks: Includes discomfort during MRI scans, but no medication involved.