Kern 2001a.

Methods	Parallel trial N, N‐dimethylglycine versus placebo
Participants	Inclusion criteria: diagnosis of autism and/or PDD according to DSM‐IV criteria Exclusion criteria: not reported Location/Setting: USA Sample size: placebo 19, dimethylglycine 18 Number of withdrawals/dropouts: 1 discontinued due to negative behavioural effects in dimethylglycine group; 1 child discontinued due to damage to the tablets in the placebo group Gender: not reported Mean age: 3‐11 years IQ: not reported Baseline ABC‐I or other BoC: not reported Concomitant medications: 7 children were on psychoactive medication (clonidine, thioridazine, paroxetine, imipramine, methylphenidate and fluoxetine) History of previous medications: not reported
Interventions	Intervention (dimethylglycine) for 4 weeks: started at 1 x 125 mg tablet/day for children weighing < 40 lbs (approx 18 kg) for 4 weeks. The dosage was 2 tablets (250 mg/day) for children weighing 41‐70 lbs (approx 18‐32 kg), 3 tablets (375 mg/day) for 71‐100 lbs (approx 32‐45 kg), 4 tablets (500 mg/day) for 101‐130 lbs (approx 45‐59 kg), and 5 tablets (725 mg/day) for > 131 lbs (approx 59 kg). Comparator (placebo) for 4 weeks: 1 x 125 mg tablet each morning for 4 weeks for children weighing < 40 lbs (approx 18 kg), 2 tablets for 41‐70 lbs (approx 18‐32 kg), 3 tablets for 71‐100 lbs (approx 32‐45 kg), 4 tablets for 101‐130 lbs (approx 45‐59 kg), and five tablets for > 131 lbs (approx 59 kg)
Outcomes	Primary outcomes: irritability, measured using the ABC‐I subscale (Aman 1985); however, it was not reported fully (only t‐scores) Secondary outcomes: none reported Timing of outcome assessments: before treatment and 4 weeks after treatment
Notes	Study start date: 1998 Study end date: 1999 Source of funding: supported by FoodScience Corporation Conflicts of interest: none declared