Does the oxytocin receptor polymorphism (rs2254298) confer 'vulnerability' for psychopathology or 'differential susceptibility'? insights from evolution

The diathesis-stress model of psychiatric conditions has recently been challenged by the view that it might be more accurate to speak of 'differential susceptibility' or 'plasticity' genes, rather than one-sidedly focusing on individual vulnerability. That is, the same allelic variation that predisposes to a psychiatric disorder if associated with (developmentally early) environmental adversity may lead to a better-than-average functional outcome in the same domain under thriving (or favourable) environmental conditions. Studies of polymorphic variations of the serotonin transporter gene, the monoamino-oxidase-inhibitor A coding gene or the dopamine D4 receptor gene indicate that the early environment plays a crucial role in the development of favourable versus unfavourable outcomes. Current evidence is limited, however, to establishing a link between genetic variation and behavioural phenotypes. In contrast, little is known about how plasticity may be expressed at the neuroanatomical level as a 'hard-wired' correlate of observable behaviour. The present review article seeks to further strengthen the argument in favour of the differential susceptibility theory by incorporating findings from behavioural and neuroanatomical studies in relation to genetic variation of the oxytocin receptor gene. It is suggested that polymorphic variation at the oxytocin receptor gene (rs2254298) is associated with sociability, amygdala volume and differential risk for psychiatric conditions including autism, depression and anxiety disorder, depending on the quality of early environmental experiences. Seeing genetic variation at the core of developmental plasticity can explain, in contrast to the diathesis-stress perspective, why evolution by natural selection has maintained such 'risk' alleles in the gene pool of a population

The associations between endogenous oxytocin levels and emotion recognition in bipolar disorder

Objective: Recent studies in patients with Bipolar Disorder (BD) have revealed problems in emotion recognition, specifically for negative emotions, which have been subsequently related to amygdala activity. Previously, the prosocial neuropeptide oxytocin has been shown to be one hormone that alters emotion perception capacities and modulates amygdala response. Accordingly, the aim of this study was to see if plasma oxytocin levels have specific effects on predicting emotion recognition patterns in BD. Methods: Twenty-eight remitted BD patients were recruited for this study and the Vienna Emotion Recognition Task was given. In addition, blood samples were collected for plasma oxytocin analysis. Results: Strong associations were found between fearful emotions and basal oxytocin levels, which were supported by a stepwise regression analysis. Patients with higher levels of basal oxytocin also exhibited greater recognition of fearful emotions. Conclusions: The relationship between recognition of fearful faces and individual endogenous oxytocin levels may contribute to explaining individual differences in social functioning and amygdala dysfunction in BD