Final answer:
Dopamine and norepinephrine are the primary neurotransmitters affected in ADHD. Treatments like methylphenidate increase dopamine levels to help alleviate symptoms.
Step-by-step explanation:
Neurotransmitters like dopamine and norepinephrine are thought to be the most affected by the diagnosis and treatment of Attention-Deficit/Hyperactivity Disorder (ADHD). Medications such as methylphenidate work by blocking the dopamine transporter, which increases the amount of dopamine in the synaptic cleft, enhancing neurotransmission. This helps alleviate symptoms of ADHD by improving attention and reducing impulsivity and hyperactivity.
Additionally, other neurotransmitter systems such as the serotonergic system may be implicated in ADHD. Antidepressants that modulate serotonin levels can sometimes be used as treatments for ADHD and may point towards the involvement of this neurotransmitter too.