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Large-scale lesion symptom mapping of depression identifies brain regions for risk and resilience.

Understanding neural circuits that support mood is a central goal of affective neuroscience, and improved understanding of the anatomy could inform more targeted interventions in mood disorders. Lesion studies provide a method of inferring the anatomical sites causally related to specific functions, including mood. Here, we perform a large-scale study evaluating the location of acquired, focal brain lesions in relation to symptoms of depression. 526 individuals participated in the study across 2 sites (356 male, average age 52.4 +/- 14.5 years). Each subject had a focal brain lesion identified on structural imaging and an assessment of depression using the Beck Depression Inventory-II, both obtained in the chronic period post-lesion (>3 months). Multivariate lesion-symptom mapping was performed to identify lesion sites associated with higher or lower depression symptom burden, which we refer to as "risk" versus "resilience" regions. The brain networks and white matter tracts associated with peak regional findings were identified using functional and structural lesion network mapping, respectively. Lesion-symptom mapping identified brain regions significantly associated with both higher and lower depression severity (r = 0.11; p = 0.01). Peak "risk" regions include the bilateral anterior insula, bilateral dorsolateral prefrontal cortex, and left dorsomedial prefrontal cortex. Functional lesion network mapping demonstrated that these "risk" regions localized to nodes of the salience network. Peak "resilience" regions include the right orbitofrontal cortex, right medial prefrontal cortex, and right inferolateral temporal cortex, nodes of the default mode network. Structural lesion network mapping implicated dorsal prefrontal white matter tracts as "risk" tracts and ventral prefrontal white matter tracts as "resilience" tracts, although the structural lesion network mapping findings did not survive correction for multiple comparisons. Taken together, these results demonstrate that lesions to specific nodes of the salience network and default mode network are associated with greater risk versus resiliency for depression symptoms in the setting of focal brain lesions.