Effect of Limosilactobacillus Reuteri on Social Deficits in Children With Autistic Spectrum Disorder

• Probiotics (Dietary supplement): Combination of L. reuteri strains.
• Placebo (Dietary supplement): Placebo identical to the active product, except the addition of probiotics.

Primary outcomes

• Changes in Social Responsiveness Scale-2 (SRS-2) score [From baseline to end of study (6 months)]: Changes in the SRS-2 score in the L. reuteri group compared to the placebo group. The SRS-2 is a 65-item questionnaire, with higher scores indicating greater social impairment and severity of autism-related traits.

Secondary outcomes

• Change in Autism Diagnostic Observation Schedule, 2nd Ed (ADOS-2) Calibrated Severity Score (CSS) for Social Affect [From baseline to end of study (6 months)]: Change in ADOS-2 CSS for Social Affect in the L. reuteri group compared to the placebo group. ADOS-2 is a semi-structured, standardized assessment that observes social interaction, communication, play, and restricted or repetitive behaviors across five modules tailored to age and language level. Higher scores indicate a higher level of autism-related behaviors.
• Change in total Autism Diagnostic Observation Schedule, 2nd Ed (ADOS-2) score [From baseline to end of study (6 months)]: Change in total ADOS-2 score in the L. reuteri group compared to the placebo group. ADOS-2 is a semi-structured, standardized assessment that observes social interaction, communication, play, and restricted or repetitive behaviors across five modules tailored to age and language level. Higher scores indicate a higher level of autism-related behaviors.
• Change in GI symptoms [From baseline to end fo study (6 months)]: Change in GI symptoms, assessed by the 6 item Gastrointestinal Severity Index (6-GSI) in the L. reuteri group compared to the placebo group. 6-GSI is a six item questionnaire with total score 0-12 with higher scores indicating worse outcome.
• Change in ABAS-2 score [From baseline to end fo study (6 months)]: Change in adaptive behaviour, assessed by the Adaptive Behavior Assessment System, Second Edition (ABAS-2) in the L. reuteri group compared to the placebo group. ABAS-2 is a 4-point rating scale with the scoring system divided into skill area scores (range 1 to 19), domain scores (range 40 to 160) and general adaptive composite (40 to 150). A higher score indicates a better outcome.
• Proportion of responders [At 6 months]: Proportion of responders at 6 months, evaluating all assessments and questionnaires, in the L. reuteri group compared to the placebo group.

Other outcomes

• Change in Family Quality of Life [From baseline to end fo study (6 months)]: Change in family Quality of Life (QoL), assessed by the Pediatric Quality of Life Inventory™ Family Impact Module (PedsQL™ Family Impact Module), in the L. reuteri group compared to the placebo group. The range of the total score is 0-100 with a higher score indicating a better outcome.
• Change in quality of sleep [From baseline to end of study (6 months)]: Change in sleep quality, assessed by the Children's Sleep Habits Questionnaire, in the L. reuteri group compared to placebo. The CSHQ is scored on 33 of 52 items, using a 1-3 scale, with total score range 33-99. A higher score indicates worse outcome and the cut-off of a total score of 41 or higher indicating potential sleep problems.
• Impact of dietary habits [At baseline and end of study (6 months)]: Impact of dietary habits, assessed by a Food Frequency Questionnaire (FFQ), on the gut microbiota profile and effect of the L. reuteri intervention.
• Changes in gut microbiota structure and composition [Baseline, 3 and 6 months]: Changes in the gut microbiota structure and composition and the effect of the L. reuteri intervention, assessed by metagenomic analysis of fecal samples

Sex: All, ages: 4 Years to 12 Years

Inclusion Criteria:

* Boys or girls aged between 4 to 12 years at screening.
* ASD diagnosis confirmed by a qualified clinician according to DMS-5 criteria, M-CHAT used as a screening tool.
* Parents/caregivers/legal guardians are ≥18 years.
* Readiness and the opportunity for parents/caregivers/legal guardians to fill out a study diary, questionnaires, and report regularly during the intervention period.
* Parents/caregivers/legal guardians with ability to understand and comply with the requirements of the study, as judged by the Investigator.
* Parents/caregivers/legal guardians willing and able to give informed consent for their and their child's participation in the study.

Exclusion Criteria:

* Neurological syndromes that could explain autism disorders.
* Organic gastrointestinal disorders (e.g. IBD, peptic ulcers and cancer). Celiac disease is accepted
* Any other severe clinically relevant disease or disorder which may affect the participation in the study, based on the investigator's judgement.
* Allergy or intolerance to one of the excipients of the probiotic product.
* Children with reported exposure to probiotic supplements in the 15 days prior to Screening Visit (V1).
* Children with reported exposure to oral and/or systemic antibiotics in the 7 days prior to Screening Visit (V1).
* Children with reported exposure to proton pump inhibitors in the 7 days prior to Screening Visit (V1).
* Participation in other interventional clinical study.

• Romina L Squartini, MD, Principal investigator, Sanatorio Maipú