The oxytocinergic system in functional neurological disorder: Preliminary testing of associations with interoception...

The oxytocinergic system has been proposed as a vulnerability factor in the pathophysiology of Functional Neurological Disorder (FND), a condition associated with stressful life-events and disturbed bodily awareness. Recent work from our group demonstrated reduced interoceptive function alongside elevated salivary oxytocin (OXT) levels in patients with mixed-FND. Here, we tested the same patients with FND (N = 41) and matched healthy controls (N = 48) of that study, addressing two additional aims: (I) exploratively testing the genetic associations of the oxytocin receptor gene (OXTR) (i.e. investigating both genetic and epigenetic variables between groups and in interaction with interoceptive measures), and (II) evaluating whether integrating (epi)genetic and OXT measures improves overall model fit to explain interoceptive dysfunction and self-reported childhood trauma scores. No group difference was observed regarding the allelic distribution of the rs53576 SNP or in OXTR methylation levels. For salivary OXT, an interaction effect between OXTR genotype and intron methylation (p = 0.036), as well as an interaction between group and genotype (p = 0.026) was identified. With respect to aim II, including oxytocinergic variables in the model did not explain additional interoceptive variance. However, including OXTR promoter methylation rates and salivary OXT levels alongside the group variable appeared to improve model fit and to account for more variance in self-reported childhood trauma. While our preliminary genetic findings need to be interpreted with caution due to limited sample size and exploratory analyses, we suggest future research to profit from the inclusion of oxytocinergic markers when investigating risk-factors associated with FND.