(electronic tones) - [Narrator] It can make you happy, suppress your appetite, reduce fatigue, increase your attention span, and it's used to treat narcolepsy, depression, and ADHD.

What magical substance does all this?

Adderall.

(electronic tones) Over 25 million people worldwide use amphetamine, which is the active ingredient in Adderall.

Amphetamine has been around since the 1800s, and has a pretty neat history.

First synthesized in 1887 by Romanian chemist, Lazar Edeleanu, amphetamine appeared on the market in 1933, under the name Benzedrine, or bennies, for short.

In 1943, the US Army began issuing pep pills to fight battle fatigue and boost morale.

These pep pills were pure amphetamine, which is a stimulant.

By the end of World War II, American and British troops had shipped an estimated 150 million of these pills.

Japanese and German troops also used these pep pills, and Hitler would get daily injections of amphetamine.

American troops continued using amphetamine well to the Korean and Vietnam wars, but stopped once the drug was no longer sold over the counter in 1956.

'Cause, you know, unrestricted access to pure amphetamine is probably not a good idea.

Today, amphetamine is used in low doses, primarily to treat what?

(typing) Oh, right, used to treat ADHD.

The majority of ADHD drugs stimulate the central nervous system.

You'd think it wouldn't make sense to treat hyperactivity and lack of focus by adding stimulation, but we'll let neuroscience expert Dr. Ryan Davison explain.

- People with ADHD tend to have lower levels of dopamine, a key chemical in the brain's reward center.

This lack of dopamine means people with ADHD are constantly seeking stimulation.

Amphetamines stimulate the release of dopamine and other neurotransmitters in their brain, so those minor distractions don't cause you to lose focus.

- [Narrator] Nerve cells and neurotransmitters act like they're at a middle school dance.

Neurotransmitters like dopamine are on one side of the gym, and receptor cells sit at the other.

Amphetamine starts at the party by pushing dopamine out into the dance floor, where they then partner up with the receptors.

Amphetamine also keeps dopamine on the dance floor, leaving more for the receptors to catch.

So before we go, here's Dr. Davison with another fun fact that shows why little tweaks in structure can make for big changes.

- Here's what a molecule of amphetamine looks like.

This little guy is a group of a carbon and three hydrogen atoms, also called a methyl group.

If you add one more methyl group onto the end of an amphetamine molecule, it turns into its much more dangerous cousin, methamphetamine.

These four little atoms can turn you from a studious citizen into a total tweaker.