Effect of D-amphetamine on inhibition and motor planning as a function of baseline performance.
Level 2 - randomized trial
Individual randomized double-blind crossover trial
PubMed 20602089 · doi:10.1007/s00213-010-1912-x
What was done
Participants with no prior stimulant exposure completed a double-blind crossover trial comparing a single oral dose of D-amphetamine (0.3 mg/kg) to placebo. Participants were stratified into high and low performance groups based on their baseline scores on antisaccade (inhibition) and predictive saccade (motor planning) tasks. Executive functions, mood states, heart rate, and blood pressure were measured prior to drug intake (T0) and at 1.5, 2.5, and 3.5 hours post-dose.
What was found
Antisaccade errors decreased significantly with D-amphetamine irrespective of baseline performance (p = 0.025). Antisaccade latency showed a significant drug-by-group interaction (p = 0.04): participants with short baseline latencies exhibited longer latencies on D-amphetamine compared to placebo, whereas those with long baseline latencies exhibited shorter latencies on D-amphetamine. Motor planning was not affected. Mood ratings significantly improved on D-amphetamine (p < 0.001), with the magnitude of elation relating to baseline reaction time variability. No exact numerical means or effect sizes were reported in the abstract.
Why it matters
This study provides human experimental evidence supporting an inverted-U model of dopaminergic effects on executive function, demonstrating that dopamine augmentation affects response speed conditionally based on baseline performance while improving inhibitory error rates broadly.
Limits
The abstract omits the sample size (n), participant demographics, and exact effect sizes or point estimates. As a single-dose study in healthy, stimulant-naive volunteers, findings cannot be directly generalized to chronic administration, clinical populations such as individuals with ADHD, or other executive domains.
Cited by
- supports Cognitive enhancement from stimulants follows an inverted U-shaped curve where individuals with low baseline performance may experience slight gains, while high-performing individuals risk cognitive impairment.