EPA-0767 – Plasma Oxytocin and Testosterone Levels in Patients with Psychotic Disorder, Their Unaffected Siblings and Healthy Controls: Results from the EU-GEI Project

Abstract

Introduction:

The incidence of psychotic disorders is increased among men and culminates in adolescence. After menopause, there is a second peak in the incidence among women. It has therefore been suggested that sex steroids, such as oxytocin and testosterone, may confer decreased or increased risks for psychotic disorders.

Objectives:

To investigate differences in peripheral oxytocin and testosterone plasma levels in patients with a first psychotic episode, their unaffected siblings and healthy controls.

Methods:

Plasma hormone assays of oxytocin and testosterone were obtained from 85 patients with a psychotic disorder, 27 of their unaffected siblings and 59 healthy controls. Sex-hormone binding globulin (SHBG) was collected to calculate the free androgen index (FAI; testosterone/SHBG), a broad indicator of androgen status. We analyzed group differences in hormone levels, as well as associations with demographic and illness parameters.

Results:

There were no significant differences in plasma oxytocin levels or FAI across groups. Adjusted for age, smoking, time of blood draw and BMI, we found a significant group difference in plasma testosterone levels in males (F(6,72)= 2.8; p<0.05), not in females. This effect was primarily caused by significantly higher mean plasma testosterone levels in antipsychotic-naive men (n=15) compared to their unaffected brothers (p<0.01) and healthy controls (p<0.05).

Conclusions:

This study contradicts previous findings of decreased testosterone and oxytocin levels in patients with a psychotic disorder. Increased plasma testosterone in antipsychotic-naive male patients may reflect social distrust and paranoid thinking. It further underlines a potential mechanism of antipsychotic medication of normalizing androgen activity.