Disentangling the link between depressive symptoms and plasma oxytocin in men: The role of brooding rumination.

The links between plasma oxytocin and depression are controversial, ranging from negative to positive associations. The present study was conducted to reconcile those conflicting findings; amongst the features of depression, we considered rumination and hypothesised that rumination would function as moderator between depressive symptoms and oxytocin. Seventy five clinically normal adult male volunteers were assessed for depressive characteristics by means of the Ruminative Responses Scale and Beck's Depression Inventory-II; plasma oxytocin was measured by means of competitive enzyme immunoassay. The results demonstrate that high depressive symptoms were negatively associated with oxytocin concentrations at high rumination levels while such an association did not exist at low levels of rumination. The present findings suggest there are complex associations between oxytocin and brooding rumination, the latter being an important feature among depressive symptoms observed in clinically normal individuals. This complexity can underlie the current lack of consensus on the role of oxytocin in depression.