Structural and functional influences of urban and rural childhoods on the medial prefrontal cortex

Urbanization has been implicated as having an important influence on brain development and risk for psychiatric disorders but the mechanisms in brain and the role of genetic background have been unresolved. Here we explored major urbanization changes in recent history in China, and its correlates with brain structure and function in a genetically controlled sample with similar current education and socioeconomic status. Principal component analyses showed no global genomic differences across urban and rural groups. Subjects with rural childhoods had relatively increased medial prefrontal cortex (mPFC) gray matter volumes. The engagement of medial prefrontal cortex during working memory was relatively reduced under increased interpersonal stress. Further, increased trait anxiety and depression was associated with reduced stress-related mPFC engagement but only in subjects with urban childhoods. This is the first study to examine the impact of childhood urbanicity on brain development and function controlling for genetic and socioeconomic variation. We find that urbanicity during childhood is associated with changes in mPFC structure and function that are consistent with conceptualizations of how urbanicity might increase the influence by which interpersonal stressors are neurally processed.