Longitudinal Observational Biomarker Study

The purpose of this study is to test whether treatment-resistant late life depression is associated with declines in memory and attention and brain structure and function. The study will also test if changes in brain structure and function are associated with decreases in memory. In this study, investigators will conduct a series of assessments/tests, mainly brain imaging and assessments of participant's memory and attention, to better understand how depression is linked to memory and thinking in older persons. Investigators hope that their study will help the scientific community to understand why some people with depressive symptoms that are resistant to treatment in late-life experience declines in their memory and attention and whether effective treatment of such depression reduces that risk. Finally, investigators hope that this study will eventually lead to the development of better treatment options.