Background: Cranial diabetes insipidus (CDI) is characterised by arginine vasopressin (AVP) deficiency. Oxytocin (OT) is structurally related to AVP and is synthesised in the same hypothalamic nuclei, but a clinical syndrome of OT deficiency is not currently recognised. Psychological research has demonstrated that OT influences social and emotional behaviours, particularly empathic behaviour.
Aim: We hypothesised that patients with acquired CDI and anterior hypopituitarism would display OT deficiency, and consequently perform worse on empathy-related tasks, compared to age-matched clinical control (CC isolated anterior hypopituitarism) and healthy control (HC) groups.
Method: Fifty-six participants (Age 46.54±16.30 years; CDI: n=20, 8 males; CC: n=15, 6 males; HC: n=20, 7 males) provided two saliva samples (pre- and post-empathy tasks) which were analysed for OT using an ELISA method, and undertook two empathy tasks: the Reading the Mind in the Eyes Task (RMET) and the Facial Expression Recognition (FER) task.
Results: CDI patients (mean OT =86.1 pg/ml, S.E.=15.9) and CC patients (mean OT =86.6 pg/ml, S.E.=18.4) had lower OT concentrations compared to HC participants (mean OT =131.5 pg/ml, S.E.=15.9), but this did not quite reach significance (P=0.084). CDI and CC patients performed significantly worse on the RMET compared to HC participants (P=0.007). Regression analyses revealed that patients OT response during the study significantly predicted their RMET performance (P=0.025). CDI and CC patients also performed significantly worse compared to HC participants at identifying high intensity facial expressions (P=0.004).
Conclusions: Hypopituitarism may be associated with reduced OT concentrations and impaired empathic ability. Whilst further studies are needed to replicate these findings, our data suggest that OT replacement may offer a therapeutic approach to improve psychological well-being in patients with hypopituitarism.