Answer:
ADHD or Attention Deficit Hyperactive Disorder is result of a deficiency of norepinephrine. Along with dopamine, norepinephrine is a neurotransmitter that is involved in alertness, reaction, and focus.
Amphetamine is a stimulant that increases the release of dopamine and norepinephrine making it more available. Amphetamines can also slow down the reabsorption of the neurotransmitters by the neuron.
Although, it should be noted that amphetamines do not TREAT ADHD per se. They are used to control the symptoms of ADHD.