Background: Hypersexual disorder (HD) integrating pathophysiological aspects such as sexual desire deregulation, sexual addiction, impulsivity and compulsivity was suggested as a diagnosis for the DSM-5. "Compulsive Sexual Behavior Disorder" is now presented as an impulse-control disorder in ICD-11. Recent studies showed dysregulated HPA axis in men with HD. Oxytocin (OXT) affects the function of the HPA axis; no studies have assessed OXT levels in patients with HD. Whether a CBT treatment for HD symptoms has an effect on OXT levels has not been investigated.

Methods: We examined plasma OXT levels in 64 male patients with HD and 38 male age-matched healthy volunteers. Further, we examined correlations between plasma OXT levels and dimensional symptoms of HD using the rating scales measuring hypersexual behaviour: Hypersexual disorder screening inventory (HDSI) and the Sexual Compulsive scale (SCS). A part of the patients (N = 30) completed the manual-based group-administered CBT program for HD and had a secondary measurement of OXT at post-treatment. OXT was measured with Radioimmunoassay (RIA).

Results: Patients with HD had significantly higher OXT (Mean 31.0 ± SD 9.9 pM) levels compared to healthy volunteers (Mean 16.9 ± SD 3.9 pM) (p < 0.001). There were significant positive correlations between OXT levels and the rating scales measuring hypersexual behaviour (Spearman rhos between HDSI r = 0.649, p < 0.001 and SCS r = 0.629, p < 0.001) in the study participants combined. Patients who completed CBT treatment had significant reduction of OXT levels from pre-treatment (30.5 ± 10.1pM) to post-treatment (20.2 ± 8.0pM) (p < 0.001). Patients with HD had a significant positive correlation of their changes in HD:CAS with plasma oxytocin level before and after CBT(r = 0.388, p value= 0.0344).

Conclusions: The results suggest hyperactive oxytonergic system in male patients with hypersexual disorder which may be a compensatory mechanism to attenuate hyperactive stress system. A successful CBT group therapy may have effect on hyperactive oxytonergic system.