Interaction of Catechol-O-methyltransferase Val Met Polymorphism and Sex Influences Association of Parietal Intrinsic Functional Connectivity and Immediate Verbal Memory

Introduction: Sex differences modulate catechol-O-methyltransferase (COMT) genotype effect at a synaptic dopamine level, which influences brain function as well as cognitive performance. In this study, we investigated how COMT Val Met polymorphism and sex affect intrinsic functional connectivity and memory.

Methods: Intrinsic functional networks were extracted using independent component analysis of resting-state functional magnetic resonance imaging data from 186 healthy young COMT-genotyped participants. The association of these functional networks and memory function was tested to investigate whether the effect of COMT × sex interaction influences the association of intrinsic functional connectivity and memory performance. Quadratic curve fit estimation was used to examine the relationship between functional connectivity and speculative dopamine level among groups.

Results: COMT MM/MV carriers, relative to VV carriers, showed increased functional connectivity in left superior parietal lobule and right inferior frontal gyrus. Further, male MM/MV carriers showed significant higher mean functional connectivity in left inferior parietal lobule relative to male VV carriers and female MM/MV carriers, which was associated with worse immediate verbal recall performance. Additionally, the relationship between inferior parietal lobule functional connectivity and speculative dopamine level among groups fits the quadratic curve.

Conclusions: These findings suggest that the interaction of COMT genotype and sex might regulate synaptic dopaminergic concentrations and influence the association of intrinsic functional connectivity and immediate verbal memory in left inferior parietal lobule.