How does ADHD medication affect those without adhd?

Like +++ coffee. If you don't have adhd, the stimulant will cause irritability, tremors, headache, stomach ache, muscle cramps, insomnia, agitation, & in higher doses hallucinations or hypertension, arrhythmia, or rapid heart rate. In spite of all those, adhd medications are extremely safe.
Depends on age. Stimulants affect nearly all prepubertal children the same: decreased physical activity, better attention/focus, overall more subdued, no "high"; also decreased appetite & onset insomnia. In adults without adhd, se are the same, as is improved concentration, but most feel energized with mood elevation. Adults with adhd respond like prepubertal children. When/why change occurs not known.