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. 2016 Feb 4;2016(2):CD009996. doi: 10.1002/14651858.CD009996.pub2

Nemzer 1986.

Methods Single‐center, randomized, double‐blind, placebo‐controlled, cross‐over trial
 Country: United States
Number of study sites: 1
 Statistical methods: NR
Participants Sample size: 14 children/adolescents with an ADHD diagnosis according to DSM‐III criteria
Dropouts: NR
 Psychiatric comorbid conditions: NR
 Age range: 7 years to 12 years
 Mean age (SD): 9.36 (NR) years
 Sex: 11 (79%) males
 ADHD subtype: NR
Interventions Four interventions (all 14 children/adolescents participated in each of the four interventions):

  1. Dextroamphetamine (short acting), weight‐based dosing (children < 32 kg (70.5 lbs) received 5 mg/day, twice a day; children/adolescents > 32 kg (70.5 lbs) received 10 mg/day), twice a day, (n = 14)

  2. Tyrosine supplement, 140 mg/kg/day, (n = 14)

  3. Tryptophan supplement, 100 mg/kg/day, (n = 14)

  4. Placebo (n = 14)


Duration: 28 days (4 x 7‐day treatment periods)
Outcomes Relevant outcomes:

  1. ADHD core symptom severity, assessed with Conners' Parent Rating Scale and Conners' Teacher Rating Scale

  2. Academic performance, assessed with Wechsler Intelligence Scale for Children ‐ Revised

  3. Adverse events


Other outcomes:

  1. Tyrosine serum levels

  2. Tryptophan serum levels
Notes ClinicalTrials.gov identifier: not available
Authors' affiliation: university
 Study funding: NR
Risk of bias
Bias Authors' judgement Support for judgement
Random sequence generation (selection bias) Unclear risk Method of sequence generation not described
Allocation concealment (selection bias) Unclear risk Method of allocation concealment not described
Incomplete outcome data (attrition bias) 
 All outcomes Unclear risk Dropouts not discussed
Selective reporting (reporting bias) Unclear risk Study protocol not available and the possibility of reporting bias could not be assessed
Other bias Low risk Study appears to be free of other biases
Blinding of participants and personnel (performance bias) 
 All outcomes Low risk Intervention and placebo are described as identical
Blinding of outcome assessment (detection bias) 
 All outcomes Unclear risk Blinding of outcome assessment not described