Folinic Acid as a Treatment for Autism Spectrum Disorder in Children

The Pervasive Developmental Disorder-Behavior Inventory (PDDBI) is a validated caregiver-completed instrument used to assess adaptive and maladaptive behaviors in individuals with autism spectrum disorder (ASD). The Autism Composite T-score is a standardized score (mean = 50, standard deviation = 10) that summarizes overall autism symptom severity, with higher scores indicating greater symptom severity. This outcome measure evaluates the change from baseline to Week 12 in PDDBI Autism Composite T-score. Lower T-scores indicate improvement in autism-related symptoms. Changes in scores will be compared between participants receiving folinic acid and those receiving placebo.

Change from baseline to Week 12 in standardized language function scores as assessed using the Clinical Evaluation of Language Fundamentals (CELF), a standardized individually administered assessment of receptive and expressive language skills in children. CELF standardized scores have a mean of 100 and a standard deviation of 15, with higher scores indicating better language performance. Changes in scores will be compared between participants receiving folinic acid and those receiving placebo.

Change from baseline to Week 12 in standardized receptive vocabulary scores as assessed using the Receptive One-Word Picture Vocabulary Test (ROWPVT), a standardized individually administered assessment of a child's ability to understand spoken words. Scores are standardized with a mean of 100 and a standard deviation of 15, where higher scores indicate better receptive vocabulary ability. Changes in scores will be compared between participants receiving folinic acid and those receiving placebo.

Change from baseline to Week 12 in standardized expressive vocabulary scores as assessed using the Expressive One-Word Picture Vocabulary Test (EOWPVT), a standardized individually administered assessment of a child's ability to produce spoken words. Scores are standardized with a mean of 100 and a standard deviation of 15, where higher scores indicate better expressive vocabulary ability. Changes in scores will be compared between participants receiving folinic acid and those receiving placebo.

Change from baseline to Week 12 in Clinical Global Impression-Severity (CGI-S) and Clinical Global Impression-Improvement (CGI-I) scores, assessed using the Clinical Global Impression Scale, a standardized assessor-rated measure of illness severity and overall clinical improvement. CGI-S scores range from 1 (normal, not at all ill) to 7 (among the most extremely ill), where lower scores indicate better outcomes, and CGI-I scores range from 1 (very much improved) to 7 (very much worse), where lower scores indicate greater improvement. Changes in scores will be compared between participants receiving folinic acid and those receiving placebo.

Change from baseline to Week 12 in total scores on the Aberrant Behavior Checklist (ABC), a standardized caregiver-completed questionnaire that assesses behavioural symptoms in children across domains such as irritability, lethargy, stereotypy, hyperactivity, and inappropriate speech. Total scores range from 0 to 174, with higher scores indicating greater severity of behavioural problems (worse outcomes). Changes in scores will be compared between participants receiving folinic acid and those receiving placebo.

Change from baseline to Week 12 in total problem scores on the Child Behavior Checklist (CBCL), a standardized caregiver-reported questionnaire that assesses a broad range of emotional and behavioural problems in children. Total scores are standardised T-scores (typically ranging from approximately 30 to 100, with a mean of 50 and standard deviation of 10), where higher scores indicate greater behavioural and emotional problems (worse outcomes). Changes in scores will be compared between participants receiving folinic acid and those receiving placebo.

Change from baseline to Week 12 in standardised adaptive behavior scores as assessed using the Vineland Adaptive Behavior Scales (VABS), a standardized caregiver-reported assessment of a child's adaptive functioning across domains such as communication, daily living skills, socialization, and motor skills. Adaptive behavior composite scores are standardised (typically ranging from approximately 20 to 160, with a mean of 100 and standard deviation of 15), where higher scores indicate better adaptive functioning (better outcomes). Changes in scores will be compared between participants receiving folinic acid and those receiving placebo.

Change from baseline to Week 12 in eye-tracking measures of visual attention, specifically the proportion of total gaze duration directed toward social stimuli (e.g., faces or biological motion) compared with non-social stimuli, assessed using a standardized eye-tracking paradigm. Higher proportions indicate greater relative attention to social stimuli. Changes in proportions will be compared between participants receiving folinic acid and those receiving placebo.

Change from baseline to Week 24 in the incidence of adverse events (AEs) and serious adverse events (SAEs), monitored throughout the study period to assess the safety and tolerability of folinic acid treatment.

Change from baseline to Week 12 in plasma glutathione redox ratio (reduced glutathione:oxidized glutathione; GSH:GSSG), a biomarker of oxidative stress balance. Higher ratios indicate a more reduced (favorable) redox state. Plasma reduced glutathione (GSH, µM) and oxidized glutathione (GSSG, µM) will be measured at baseline (T1) and Week 12 (T2).

Change from baseline to Week 12 in plasma methylation ratio (S-adenosylmethionine:S-adenosylhomocysteine; SAM:SAH), a biomarker of methylation capacity. Higher ratios indicate greater methylation potential (better outcomes). Additional biomarkers related to one-carbon metabolism, including plasma homocysteine (µmol/L), will measured where available.

Change from baseline to Week 12 in plasma ergothioneine concentration (ET, nM). Plasma ergothioneine (ET, nM), hercynine (nM), and ophthalmic acid will be measured at baseline (T1) and Week 12 (T2).

Change from baseline in serum and plasma folate status biomarkers. Folate status biomarkers include measures related to one-carbon metabolism and amino acid pathways. Plasma amino acid concentrations (µmol/L) will be interpreted with reference to established age-specific clinical ranges.

Association between folate receptor autoantibody (FRAA) status and change in autism outcome measures. FRAA status will be classified as positive or negative based on the assay-specific cutoff defined by the testing laboratory: Blocking FRAA (pmol blocked per mL) and binding FRAA (optical density [OD] units per µL).

Change from baseline in autism outcome measures following 24 weeks of folinic acid treatment.