To test the possible association between oxytocin and melatonin levels with the severity of social and cognitive dysfunctions, and to study the correlation between these parameters in children with autism.
A case-control study was carried out in the Department of Chemistry and Biochemistry, College of Medicine, Al-Nahrain University, Baghdad, Iraq. The study was performed on 60 male autistic patients recruited from the Pediatric Department of Al-Sader General Hospital, Baghdad, Iraq between November 2014 and April 2015. The levels of oxytocin and melatonin were measured in the serum of these autistic male patients, and categorized as mild, moderate, and severe (20 patients each), and was compared with 26 age- and gender-matched control subjects.
The data indicated that the levels of oxytocin (44.72 ± 36.1 µIU/mL) and melatonin in patients (23.08 ± 10.41 pg/mL) were significantly lower ( p<0.05) than that of age-matched (102.1 ± 34.31 µIU/mL) and gender-matched controls (53.05 ± 38.38 pg/mL). These parameters were remarkably associated with the severity of the disease that was indicated by the significant decrease in the levels of oxytocin (47 ± 25.47 µIU/mL) and melatonin in moderate (20 ± 6.14 pg/mL), and patients with severe oxytocin (27.92 ± 10.23 µIU/mL) and patients with severe melatonin (21.69 ± 7.02 pg/mL) when compared with mild autistic patients with oxytocin (59.22 ± 27.32 µIU/mL) and melatonin (27.55 ± 14.71 pg/mL). These 2 parameters showed a significant positive correlation with each other in moderate (r=0.513; p=0.021), and severe patients (r=0.598; p=0.005).
Receiver operating characteristic analysis revealed that oxytocin can be considered as a good diagnostic marker in severe autistic patients while melatonin can be considered as a good diagnostic marker in all autistic subgroups. This study proves the possibility of using oxytocin and melatonin in the diagnosis, and as markers of autism severity.