Childhoods in urban or rural environments may differentially affect risk for neuropsychiatric disorders. Here, we leveraged on dramatic urbanization and rural-urban migration since the 1980s in China to explore the hypothesis that rural or urban childhoods may differentially influence memory processing and neural responses to neutral and aversive stimuli.

Explore the underlying mechanisms of childhood environment effect on brain function and neuropsychiatric risk.

We examined 420 adult subjects with similar current socioeconomic status and living in Beijing, China, but with differing rural (n=227) or urban (n=193) childhoods. In an episodic memory paradigm scanned in a 3T GE MRI, subjects viewed blocks of neutral or aversive pictures in the encoding and retrieval sessions.

Episodic memory accuracy for neutral stimuli was less than for aversive stimuli (P<0.001). However, subjects with rural childhoods apparently performed less accurately for memory of aversive but not neutral stimuli (P<0.01). In subjects with rural childhoods, there was relatively increased engagement of bilateral striatum at encoding, increased engagement of bilateral hippocampus at retrieval of neutral and aversive stimuli, and increased engagement of amygdala at aversive retrieval (P<0.05 FDR corrected, cluster size>50).

Rural or urban childhoods appear associated with physiological and behavioural differences, particularly in the neural processing of aversive episodic memory at medial temporal and striatal brain regions. It remains to be explored the extent to which these effects relate to individual risk for neuropsychiatric or stress-related disorders.