Norepinephrine

Norepinephrine (also called noradrenaline) is a neurotransmitter that works alongside dopamine to regulate attention, alertness, concentration, and the stress response. In ADHD, the availability of norepinephrine in the brain's prefrontal regions is also compromised.

Norepinephrine is especially important for executive control: sustaining attention on tasks that aren't immediately stimulating, filtering out irrelevant distractions, and maintaining an appropriate level of alertness. When the noradrenergic system isn't working efficiently, a person struggles to 'switch on' for work even when they genuinely want to.

Some ADHD medications, such as atomoxetine (marketed as Strattera), work specifically by increasing norepinephrine availability and offer a non-stimulant alternative for people who don't tolerate classic stimulants well.