Effect of ZNF804A gene polymorphism (rs1344706) on the plasticity of the functional coupling between the right dorsolateral prefrontal cortex and the contralateral hippocampal formation.

ZNF804A has now been recognized as a schizophrenia risk gene by multiple genome-wide association studies with its intronic polymorphism rs1344706 being reported as the first genome-wide significant risk variant for schizophrenia. Although the functional impact of this gene is still unknown, rs1344706's contribution to the functional coupling between the right dorsolateral prefrontal cortex (DLPFC) and the contralateral hippocampal formation (HF) has been reported by several studies. The current study tested whether the right DLPFC-left HF functional coupling showed plasticity during cognitive training (Study I) and whether rs1344706 affected the plasticity (Study II). In Study I, we conducted a randomized controlled trial with 30 subjects receiving 20 sessions of adaptive training on a memory span task (the training group) and 30 subjects practicing on a non-adaptive easy version of the same memory span task for 20 sessions (the control group). All subjects were scanned using fMRI before and after the training. Analyses of resting-state and task-state fMRI data consistently showed that the adaptive memory span training significantly strengthened the right DLPFC-left HF functional coupling. In Study II, we conducted a genetic association study with 101 subjects (combining the data from the training group in Study I with those from an additional subsequent sample of 71 subjects who received the same training and fMRI scans). Results showed that rs1344706 was significantly associated with training-induced changes in functional coupling. Subjects carrying the non-risk allele (C) of rs1344706 showed greater training-induced plasticity than the risk allele (A) homozygotes. These findings expanded our current understanding of the functional impact of the schizophrenia risk variant of ZNF804A gene and suggested that the ZNF804A gene could be used as a prospective target for future antipsychotic drugs and clinical research.