Reduced cooperativeness and reward-dependence in depression with above-normal plasma vasopressin concentration

The neuropeptide vasopressin is centrally involved in the regulation of social behaviour and response to stress. We previously found support for a subcategory of depression defined by above-normal plasma vasopressin (AVP) concentration. This subcategory is validated by a positive family history of depression and correlating plasma AVP and cortisol concentrations. The data support the validity of above-normal plasma AVP concentration as a genetically determined biological marker for a subcategory of depression. The aim of the present study was to test whether above-normal plasma AVP concentration in depression is related to personality characteristics reflecting a specific social behaviour style. The data of 78 patients from a previously investigated sample were reanalysed. Fifty-eight patients were available after 2 years, 15 of whom with initially above-normal plasma AVP. The dimensions of the Temperament and Character Inventory (TCI) were scored, with particular focus on the dimensions of Cooperativeness (CO) and Reward-dependence (RD). Normative subjects and other depressed subjects were used as controls. After full remission, patients with initially above-normal AVP had low CO compared with normal and patient controls. During depression, these patients had both low CO and low RD compared with normal controls and low RD compared with patient controls. Low CO is a presumably premorbid trait and reduced RD a state-dependent characteristic in depression with above-normal plasma AVP. The low CO further supports the validity of above-normal plasma AVP concentration as a genetically determined biological marker for a subcategory of depression.