Background The role of Oxytocin (OT) as social hormone is supported by the improvement of recognition of the expression of the faces after administration of intranasal OT. Impaired social behaviour, partly related to altered perception of emotions, is commonly reported in Huntington’s disease (HD).

Aims To evaluate OT plasma level as possible predictor of social cognition performances in a population of symptomatic HD patients.

Methods 12 patients with symptomatic HD (stage II S&F) without cognitive impairment were evaluated at the baseline and after 2 years follow up (8 pt) for social cognition through an extensive battery of neuropsychological tests (Faux Pas test, Bush vignettes test, emotion recognition from both faces expression and verbal stimuli, Strange stories test).

Plasma OT levels at the baseline were analysed in the whole cohort of subjects and the relationship between the levels of OT and social cognition at the baseline and at the follow up was analysed. OT plasma levels were also compared to that of a population of healthy controls matched for age.

Results OT levels did not differ in the two populations, however with a trend for lower values in HD group (average 9.9 ± 7.2 controls, 6.5 ± 2.4 HD).

At the baseline OT blood levels did show any significative correlation with social cognition and cognitive tests.

The follow up analysis showed that higher OT levels correlated with better performances at the Neutral\Faux Pas score (p < 0.05) and with higher ability of recognising happiness from verbal stimuli (p < 0.05).

Conclusions Even though not statistically significant patients showed lower OT circulating levels compared to controls; moreover the follow-up analysis pointed out a possible role of OT in predicting the progression of social cognition in HD. The present data, limited by the sample size and by the biological tissue studied, need to be confirmed in a larger population analysis even by correlating with cerebrospinal fluid measurement.