Identifying which depression patients will respond to antidepressants remains one of psychiatry's most pressing challenges, with treatment failures costing months of suffering and trial-and-error prescribing. Brain imaging may finally offer a path toward personalized antidepressant selection based on neuroanatomy rather than guesswork. Analysis of 107 adults with moderate to severe depression revealed that baseline hippocampal structure strongly predicted treatment outcomes with escitalopram, a widely prescribed SSRI. Patients who ultimately responded to the medication possessed significantly larger left hippocampal volumes and greater left-brain lateralization in this memory-critical region before starting treatment. The volumetric advantage was substantial—responders showed a 189-cubic-millimeter difference in left hippocampal size compared to non-responders. Following six weeks of escitalopram treatment, successful responders demonstrated specific structural adaptations in their right hippocampus, including volume increases of approximately 80 cubic millimeters in the overall structure and 50 cubic millimeters in the hippocampal head region. These findings suggest the brain's memory center undergoes asymmetric remodeling during effective antidepressant therapy. From a clinical perspective, this research edges closer to precision psychiatry where brain scans could guide medication selection. However, the relatively modest effect sizes and the study's focus on a single antidepressant limit immediate applications. The hippocampal lateralization findings align with broader neuroscience showing left-brain dominance in positive emotional processing, though replication across diverse populations and multiple antidepressant classes will be essential before clinical implementation. Still, this represents meaningful progress toward ending the current era of psychiatric trial-and-error prescribing.