How Stimulants Work to Reduce ADHD Symptoms

Stimulants are the most common type of medicine used to treat ADHD. They work by increasing the availability of certain chemicals in the brain, thus making the pathways in the brain work more effectively. Stimulants lessen ADHD symptoms in 70% to 80% of people who take them.

How the Brain Works

Our brains are made up of nerve cells called neurons, which are separated by tiny gaps called synapses. All brain and nervous system functions are based on how these neurons communicate across synapses. The neurons relay information to each other by sending chemical messengers or neurotransmitters across the synapses throughout the neural network.

Neurotransmitters are produced within a neuron. The neuron releases the neurotransmitter and it travels into the synapse. The neurotransmitter may then be accepted by the next neuron attaching at a site called a receptor, thereby transmitting information from one nerve cell to another throughout the brain.

In order for these pathways to work effectively so that the message gets through, the neuron must produce and release enough of the neurotransmitter. The neurotransmitter must also stay in the synapse long enough for it to bind to the receptor site.

After the neurotransmitter is released, the excess portion is then reabsorbed by the neuron that produced it. What sometimes seems to happen in individuals with ADHD is the neurotransmitter is prematurely reabsorbed back into the neuron. When this occurs, that portion of the neural network can't relay messages in an adequate and timely way.

How Stimulants Work

Dopamine and norepinephrine play a key role in the areas of the brain responsible for regulating attention and executive function. Stimulant medication reduces ADHD symptoms by increasing the dopamine levels in your brain. It does this by slowing down how much dopamine is reabsorbed back into the neural network.

As a result, more neurotransmitter is held in the synapse between neurons long enough for it to properly bind to the receptor, helping messages within the brain be more effectively transmitted and received. This improves activity and communication in those parts of the brain which operate on dopamine and norepinephrine and signal for specific tasks.

Brain imaging studies have demonstrated that when you're on stimulant medication, there's increased metabolic activity in the prefrontal cortex, specific subcortical regions, and the cerebellum—all important centers for executive function. These areas of the brain appear more active when neurotransmitter levels are elevated.

The differences in the way stimulants work may explain why some people with ADHD respond to one type of stimulant medication better than another.

Methylphenidate

Research suggests that methylphenidate increases levels of dopamine by blocking the reuptake of dopamine and norepinephrine in your brain. That is, it reduces how much of the neurotransmitter is reabsorbed into the neuron so that more is left in the synapse. It also promotes dopamine release from within the neuron, which sends more out into the synapse.

Common methylphenidate-based stimulants include:

• Concerta (methylphenidate extended-release tablets)
• Focalin (dexmethylphenidate)
• Metadate (methylphenidate hydrochloride)
• Ritalin (methylphenidate)

Amphetamines

Amphetamines (another type of stimulant medication) mostly increase the release of dopamine and norepinephrine from their storage sites into the synapse. A less significant mechanism of amphetamines is slowing the reuptake of the neurotransmitters.

Some amphetamine-based stimulants include:

• Adderall (amphetamine dextroamphetamine)
• Dyanavel XR (amphetamine)
• Vyvanse (lisdexamfetamine dimesylate)