Analysis of research on the effectiveness of using probiotics for children with autism spectrum disorders, in order to reduce the core and accompanying autism symptoms. Review of randomized clinical trials

Purpose
The prevalence of autism spectrum disorder (ASD) has increased tenfold over the last 40 years and the World Health Organization (WHO) has placed it alongside other globally occurring common illnesses, such as cancer, cardiovascular disorders and diabetes. As there are yet no effective methods for treating ASD, the most frequently used therapeutic interventions are psychological, psychosocial, rehabilitation and developmental support, which in combination aim to support patients and their families. Early intervention improves the prognosis, but usually a cure is impossible. Patient’s lives are often burdened with social difficulties in contact with their families, peers and in education, particularly when other disorders, diseases or intellectual impairment are present, leading to undesirable behaviours, including aggression or self-aggression. Aim of the study was to review the literature available, so as to determine the effectiveness of probiotics used for treating axial and accompanying symptoms of autism in patients diagnosed with ASD, with a particular focus on children and adolescents.

Views
The randomised clinical trials available on the clinicaltrials.gov register (accessed on June 27th, 2021) and the PubMed database (search: probiotic + autism, probiotic + ASD, probiotic + Asperger syndrome, probiotic + pervasive developmental disorder, randomised controlled trial filter) have been analysed in the present study. All studies were included, without any operational time limit. The same PubMed search was also re-run for open-label trials. Out of the 140 papers found, five were open-trials. We also supplemented our study by additionally analysing the studies cited by the latest papers on probiotics in autism.

Conclusions
There are still no consistent outcomes in studies on the use of probiotics in children and adolescents with ASD, and the scope of existing studies is limited. Nevertheless, the authors considered it worthwhile to explore whether probiotic interventions can indeed reduce the severity of ASD-related symptoms and behaviours. Further studies are required on specific indications, duration of treatment and the effectiveness of interventions in the defined problem areas.