By fixing the underlying conditions that lead to the behaviour classified as ADHD rather than depending on stimulants as a(n admittedly very effective) crutch to power through them.
How would MDMA (or any drug) alter this? Stimulants used to treat ADHD typically work by either getting you to produce more of those neurotransmitters or getting them to stick around for longer by inhibiting reuptake. I'm not sure of any drug or treatment that could permanently change these things in the brain.