Vortioxetine has been shown to improve core depressive symptoms and improve cognitive function in adult outpatients with MDD and subjective complaints of cognitive function. This pilot study is intended to evaluate the extent to which BNA technology can provide clinically valuable information and provide information toward designing a subsequent confirmatory study that will further elucidate the effect of vortioxetine on MDD and cognitive function in this population. This exploratory study will ascertain the acute changes in core depression symptoms, cognitive function, tolerability, and safety using flexible-dose vortioxetine in adult outpatients with MDD with subjective complaints of cognitive functioning, as measured by BNA changes and standard outcome measures for depression and cognition.