Abnormalities in the Positive Valence System (PVS) are associated with depressive symptoms and reduced behavioral activation in mid- and late-life. This study will investigate the engagement of the PVS during exposure to social rewards, part of a novel streamlined psychotherapy for mid- and late-life depression. Use of computational modeling will enable identification of neuroimaging and behavioral profiles associated with greater treatment response, and may guide future personalization of psychotherapy.

Inclusion Criteria:

1. Ages aged 50-85 [stratified so that 50% are older than 65]
2. Diagnosis of unipolar major depressive disorder without psychotic features, determined by the SCID
3. Montgomery-Åsberg Depression Rating Scale (MADRS) score ≥ 20.
4. Mini Mental Status Exam (MMSE) ≤ 1 SD below the mean score for patient's age and education
5. Off antidepressants or on a stable dose of an antidepressant for 8 weeks and do not intend to change the dose in the next 10 weeks.
6. Capacity to provide written consent for research assessment and treatment.

Exclusion Criteria:

1. Intent or plan to attempt suicide in the near future.
2. History or presence of psychiatric diagnoses other than major depressive disorder without psychotic features, generalized anxiety disorder, or specific phobia.
3. Use of psychotropic drugs or cholinesterase inhibitors other than use of ≤ 0.5 mg of lorazepam daily up to seven times per week.
4. Neurological disorders (dementias, history of stroke, multiple sclerosis, Parkinson's disease, epilepsy, etc.); cardiac, renal, or respiratory failure; severe chronic obstructive pulmonary disease; metastatic cancer; or debilitated states or less common medical illnesses that may either influence brain systems of interest or ability to participate in the study. Dr. Alexopoulos or another research psychiatrist will review any medical illnesses that does not appear in the list above and determine whether it interferes with the study of positive valence system functions in depression.
5. Contraindications to MRI scanning including cardiac pacemaker, heart valve replacement, vascular stent, insulin pump, cochlear implant, any other metallic biomedical implant contraindicating to MRI, and claustrophobia.

Individual participant data that underlie the results reported in publications, after de-identification, as well as study protocol, treatment manuals, statistical analysis plan and informed consent. We will also share our fMRI tasks and analytic code by request with all interested researchers.

After we publish the main results, we will make de-identified data available to other researchers, under a data-sharing agreement overseen by the Weill Cornell ALACRITY Center's Executive Committee.

Investigators whose proposed use of the data has been approved by an independent review committee identified for this purpose. All researchers requesting data will commit to using the data solely for research purpose; secure the data; return or destroy it once analyses are completed; do not share it with other researchers.

9 weeks