Amphetamine prevented the usual decline in attention across a continuous-performance task in healthy adults. The same experiment did not establish improvements in gambling decisions, card sorting or all measures of inhibition.
MacQueen and colleagues tested 69 healthy adults after placebo or 10 or 20 mg d-amphetamine. The Conners’ Continuous Performance Test assessed attention over time, while the Iowa Gambling Task and Wisconsin Card Sorting Test sampled other cognitive demands. The study concerned known experimental doses in humans, not an observational comparison of people with methamphetamine dependence.
Placebo participants showed declining signal-detection performance across the attention task. That vigilance decrement was not observed after either amphetamine dose. The 20-mg dose also reduced reaction-time variability and the task’s ADHD confidence index. However, there were no observed drug effects on gambling, card sorting or the CPT inhibition and perseveration measures. A lower task-derived ADHD index in healthy volunteers is not a clinical diagnosis or proof that a disorder was treated.
The relevant benefit was maintaining performance during a particular repetitive task. It should not be expanded into better judgment, improved learning in every context or safer driving. Dose, baseline ability and the task’s response requirements remain part of the finding. A laboratory experiment can isolate an acute drug comparison more directly than a use-history study, but its selected population and limited outcomes constrain generalization. The results provide evidence for selective vigilance effects rather than universal cognitive enhancement, and no concentration-based rule for an individual forensic assessment.
See a clinical trial with no demonstrated treatment-specific executive benefit.