PROJECT SUMMARY The aims and goals are similar to those proposed in the parent application. Briefly, we plan to measure 1) CNS glutamate using single voxel and chemical-shift, multivoxel, MRS, 2) microstructural white matter integrity using diffusion tensor imaging/tract-based spatial statistics and myelin mapping, 3) peripheral and central biomarkers of inflammation and 4) depressive symptoms and cognition in 65 medication-free depressed and 35 controls aged 35-65. A sample of 80 subjects (55 depressed, 25 controls) have already been studied. We propose support to recruit 10 more depressed and 10 more controlled subjects. Issues specific to this request: Our study has faced closure between the months of March-September 2020 due to COVID-19-related shutdown. However, all staff salaries have been paid in full due to understandable and compassionate reasons. We request recouping the salary paid for the past 7 months and restart up costs. The full impact of the study could be fully realized by augmenting the sample with 20 more patients – resulting in a completion sample of 100. We have provided power analysis in support of this conclusion.