The neurological basis for autism is still not fully understood, and the role of the interaction between neuro-inflammation and neurotransmission impairment needs to be clearer. This study aims to test the possible association between impaired levels of gamma aminobutyric acid (GABA), serotonin, dopamine, oxytocin, and interferon-γ-induced protein-16 (IFI16) and the severity of social and cognitive dysfunctions in individuals with autism spectrum disorders. GABA, serotonin, dopamine, oxytocin, and IFI16 as biochemical parameters related to neurochemistry and inflammation were determined in the plasma of 52 Saudi autistic male patients, categorized as mild-moderate and severe as indicated by their Childhood Autism Rating Scale (CARS) or social responsiveness scale (SRS), and compared to 30 age- and gender-matched control samples. The data indicated that Saudi patients with autism have remarkably impaired plasma levels of the measured parameters compared to age and gender-matched controls. While serotonin in platelet-free plasma and dopamine did not correlated with the severity in social and cognitive dysfunction, GABA, oxytocin, and IFI16 were remarkably associated with the severity of both tested scores (SRS and CARS). The relationship between the selected parameters confirms the role of impaired neurochemistry and neuro-inflammation in the etiology of autism spectrum disorders and the possibility of using GABA, oxytocin, and IFI16 as markers of autism severity. Receiver operating characteristic analysis together with predictiveness diagrams proved that the measured parameters could be used as predictive biomarkers of clinical symptoms and provide significant guidance for future therapeutic strategy to re-establish physiological homeostasis.

Background: Autism spectrum disorders (ASDs) comprise a neurodevelopmental disease marked by impaired social communication and repetitive activities. An imbalance between excitatory and inhibitory neurotransmitters, such as glutamate and GABA, may play a significant function in ASDs. The neurophysiological process behind epilepsy is abnormal neuronal excitatory firing in particular brain regions brought on by a lack of GABAergic inhibition. The study of GABAergic dysfunction could explain the substantial comorbidity with epilepsy or increased susceptibility to seizures observed in people with autism. Objective: This study analyzes molecular indicators directly and indirectly related to GABAergic inhibitory signaling in individuals with autism and healthy controls, with the purpose of uncovering probable diagnoses. Methods: The study included 46 male autistic participants and 26 age- and gender-matched healthy controls. Plasma levels of two chloride co-transporters (KCC2, NKCC1), and vitamin D3 were evaluated using ELISA. Results: Autistic individuals showed a significant drop in all three examined variables when compared to healthy controls. Statistical methods such as correlation, combined receiver operating characteristic (ROC) curve analysis, and multiple regression modeling were used to assess the diagnostic value and interrelationships of these biomarkers. A significant increase in the area under the curve was seen using the combined ROC curve analysis. The combined variables also exhibited significantly higher sensitivity and specificity as an index of high predictiveness values. Measurement of plasma levels of vitamin D status and chloride co-transporters (KCC2, NKCC1) in children with ASD may help to better understand how sleep disturbances and epilepsy as comorbidities of ASD linked to vitamin D deficiency and peculiar inhibitory/excitatory effects of GABA.