This group consists of twenty autistic children received forty sessions of HBOT, the time of the session is one hour. The sessions were done at pressure 1.5 ATA (atmosphere absolute) and with 100% oxygen concentration, either in multiplace or monoplace chamber. The number of sessions per week allowed is five sessions per week, all participants were required to complete forty sessions within two months. After six months from the last session, another forty sessions would be taken in the same manner

This group consists of twenty autistic children received Risperidone (dose: 0.25 mg per day in children weighing less than (20 kg); 0.5 mg per day in persons weighing more) for eight months.

The medication schedule in the initial 2 months was based on the child's weight and clinical response. Adjusting the total daily dose according to response and/or adverse effects, at the end of these eight months of treatment we began the discontinuation phase. In this phase, gradual placebo substitution occurs. The discontinuation reduced the maintenance dose by 25% per week. Thus, the dose was 75% of the last week in the eight months for the first week, followed by 50% of the last week for the second week, 25% of the last week for the third week, and placebo only by the fourth week.

This group consists of twenty autistic children received HBOT as the HBOT group in addition to Risperidone as the Risperidone group in the same manner and duration

It is antipsychotic drug used by dose: 0.25 mg per day in children weighing less than (20 kg); 0.5 mg per day in persons weighing more for 8 months.

The CARS is a 15 items behavioral rating scale developed to identify autism as well as to quantitatively describe the severity of the disorder. The items are as follows: I. Relating to People; II. Imitation; III. Emotional Response; IV. Body Use; V. Object Use; VI. Adaptation to Change; VII. Visual Response; VIII. Listening Response; IX. Taste; Smell, and Touch Response and Use; X. Fear or Nervousness; XI. Verbal Communication; XII. Nonverbal Communication; XIII. Activity Level; XIV. Level and Consistency of Intellectual Response; and XV. General Impressions. Each item is scored from 1 (no pathology) to 4 (severe pathology) in 0.5 intervals. A total score of 15-29.5 is considered non-autistic to minimal; a score of 30-36.5 is considered mild to moderate autism; a score of 37-60 is considered severe autism (these are based on raw scores)