Now in adulthood, would a person need a new alternative for aderral for adhd?

Maybe. Stimulants are still the drug of choice for adult add. But there may be need to switch meds depending on outcomes or adverse effects. This is part of the close follow up that is absolutely necessary for add patients. Your doctor should check your progress (neurodevelopmental signs) and ill effects at every visit.
Not necessarily. Stimulants typically continue to work in adults with adhd pretty much like the do in younger individuals. The main difference is that adults may be better indeciding how long they needed treatment benefits to last, depending on their job and other activities. Different stimulant (and nonstimulant) adhd meds have different lengths of effectiveness that may be worth exploring with your doctor.
Adderall (dextroamphetamine and racemic amphetamine) Same medications for youngsters with adhd work for adult adhd.