[Therapeutic effects of oxytocin in autism: Current status of the research]

The neuropeptide oxytocin (OT) is an evolutionary highly conserved molecule that plays a part in the regulation of complex social cognition and behaviours. From a pathophysiological point of view, several studies have evidenced dysfunctions of the oxytocinergic system in autism spectrum disorders (ASD): a lowering of plasma OT and genetic or epigenetic anomalies of the OT receptor. Therefore, some authors have hypothesized that an abnormality in the OT neurotransmission may account for several features of autism and that a treatment restoring a normal OT pathway functioning could improve social abilities. OT administration has thus been used in clinical trials, especially in groups of subjects suffering from autism. Some studies found that OT decreased repetitive behaviours, enhanced emotional understanding of speech intonation, improved performance of the Reading the Mind in the Eyes Test and reinforced cooperation. Nevertheless, the findings of the OT administration studies on clinical samples show great diversity. The context, the personality and childhood experiences of the subject could be moderators influencing the effect of exogenous OT. Besides, three mechanisms could play a part in the action of OT on ASD social symptoms: anxiety reduction (with a lowering in the hypothalamic-pituitary-adrenal axis responsiveness and in the amygdale reactivity to social stimuli), increased affiliative motivation (involving the dopaminergic pathway and several regions of the social brain) and enhanced perceptual selectivity and social stimuli salience. To conclude, OT could be a promising molecule used as a treatment to promote social behaviours, helping individuals with ASD to develop new relationships. OT could be administered during a cognitive-behavioural therapy to reinforce the efficacy of such procedures. More studies are needed, on larger samples, to investigate the safety and efficacy of OT administration and to specify optimal dosages and characteristics of patients who may benefit from this treatment.