The investigator planned to study the efficiency of folinic acid treatment on autistic symptoms in children suffering from autism spectrum disorder.

The aim of this study is to realise a pilot study in France in order to evaluate the efficiency of folinic acid in treatment of autism spectrum disorder and get first estimations about prevalence of auto antibodies anti-FRα in France.

The study is a randomized controlled trial monocentric,evaluating folinic acid 10mg per day versus placebo, in single-blind during 12 weeks.

Primary objective : The primary objective is to evaluate the efficiency of folinic acid (calcium folinate) 5mg twice a day during 12 weeks on reduction of autistic troubles, particularly on communication and social interaction

Secondary objective :

• Evaluate the efficiency of folinic acid on reduction of autistic symptoms perceived by parents
• Evaluate the constancy of auto antibodies anti-FRα rates

Inclusion Criteria:

1. Children with autism spectrum disorders defined by : Autism Diagnostic Observation Schedule (ADOS), Autism Diagnostic Interview (ADI), Childhood Autism Rating Scale (CARS) or diagnosed by a physician (pediatrician, child psychiatrist)
2. Children aged 3 to 10 years
3. Weight> 10 kg
4. Language impairment (based on the medical assessment)
5. Ability to maintain other therapies started before the study
6. No changes of therapeutic treatments within the 8 weeks before the start of the study

Exclusion Criteria:

1. Treatment may impair folate metabolism (methotrexate, anticonvulsivants : phenobarbital sodium valproate, phenytoin, primidone, carbamazepine, valproic acid, divalproex, antibiotics : tetracycline, trimethoprim, pyrimethamine, inhibitors of proton pump inhibitors of histamine-2)
2. Antipsychotic treatment (including treatment with Risperidone)
3. Vitamin or mineral supplementation exceeding guidelines
4. Children with severe irritability (Aberrant Behavior Checklist> 17)
5. Gastroesophageal reflux disease
6. Any known renal or liver disease
7. Child born premature (<37SA)
8. Known intolerance to lactose
9. Hypersensitivity / allergic reaction to calcium folinate
10. The sibling children with autism spectrum disorders

To be completed after discussions with the different research teams participating in the study