ADHD Neurotransmitters And How They Work Inside The Brain

Reviewed by Heather Cashell, LCSW

Published 06/27/2022

The brain is the body's most complex organ. It works in mysterious and amazing ways to control just about everything your body does. While we've learned so much about how the brain functions and develops, there's still so much to discover in this field.

Inside your brain, over 86 billion neurons communicate with each other consistently. Without these neurons, also called nerve cells, your brain would have difficulty dealing with and adapting to the various functions inside the human body.

For neurons to do their job effectively, they need to communicate with each other non-stop using neurotransmitters. When sodium ions rush into the nerve cell, and potassium ions rush into the nerve cell, it creates an electrical impulse that transfers the neurotransmitter from one nerve cell (or muscle cell) to the next.

With that being said, you might be asking yourself what neurotransmitters are and what they have to do with ADHD. Don't worry; we're going to discuss everything you need to know about neurotransmitters inside the brain, the different neurotransmitters that affect ADHD, and how else neurotransmitters can affect the body.

What Are Neurotransmitters?

As we mentioned above, neurotransmitters act as chemical messengers inside the brain and body. They're tiny little molecules that get sent from one neuron to the next, or from a neuron to a muscle, by way of electrical impulse.

The electrical signal travels down the neuron's axon before being converted into a chemical signal with the help of neurotransmitters. Once it reaches the end of the neuron, the neurotransmitter travels through the synaptic gap between neurons and binds with receptors on the other neuron or muscle.

When the neurotransmitters bind to the receptors, it creates a reaction or response inside the body. These responses help regulate the various processes and functions inside the body, including mood, heart rate, appetite, focus, sleep, and much more.

While there are over 100 different neurotransmitters and neuropeptides inside the brain, they are categorized into one of the three categories -- modulatory, excitatory, or inhibitory neurotransmitters. Let's take a closer look at the differences between the three:

  1. Excitatory Neurotransmitter - these neurotransmitters increase the excitability of the response and trigger the neuron's depolarization, which increases the chance of a response.
  2. Inhibitory Neurotransmitter - these neurotransmitters decrease the excitability of the response and trigger hyperpolarization, which decreases the chance of a response.
  3. Modulatory Neurotransmitter - also known as neuromodulators, these neurotransmitters can affect multiple neurons at once, opposed to just one at a time.

Of the over 100 neurotransmitters found throughout the brain and body, three play a major role in ADHD symptoms -- dopamine, norepinephrine, and serotonin. These three neurotransmitters fall under the modulatory neurotransmitter.

To ensure that you understand what each neurotransmitter does and how it affects ADHD patients, we're going to look at each neurotransmitter individually.

Dopamine And ADHD

Dopamine is one of the most common and popular neurotransmitters in the brain, but it also acts as a hormone in the blood. It plays a major role in our ability to feel pleasure, helps regulate our mood, allows us to think or plan, and even increases our amount of interest in certain activities.

The body makes dopamine by itself through a two-step process that involves converting the amino acid tyrosine (which we get through the food we eat) into dopa, converted into dopamine. All in all, it plays a role in pain processing, mood, sleep, attention, motivation, learning, heart rate, and movement.

When it comes to ADHD, scientists and researchers have found that most patients have a shortage of dopamine in their system. Studies show that an increase of dopamine in the system helps relieve the symptoms of ADHD, suggesting it plays a role in the disorder.

As we learn more about ADHD and dopamine, we learn that ADHD patients generally have an over-efficient way of removing dopamine from their system. The excessive removal of dopamine doesn't give the body enough time to process the dopamine, which means those with ADHD don't benefit from it.

Ritalin, a popular drug to help combat ADHD, helps block dopamine transporters and slow down the removal process after being released. This gives the body the necessary time to receive the response, which wasn't happening before.

Norepinephrine And ADHD

Norepinephrine, commonly referred to as noradrenaline, is another type of neurotransmitter that also acts as a hormone. This neurotransmitter is synthesized by dopamine thanks to an enzyme called dopamine beta-hydroxylase.

In the brain, norepinephrine-producing neurons are generally found in the medulla and pons, both in the brainstem. Most of the norepinephrine for the central nervous system is produced inside the locus coeruleus.

This neurotransmitter can also be found in sympathetic neurons located near the spinal cord and the adrenal glands, where it's released as a hormone.

The effects and response from the release of norepinephrine depend on where the receptor is located and the type of receptor it activates. It plays a role in heart rate, blood pressure, blood sugar, mood, attention, sleep, and memory.

Norepinephrine also plays a role in the body's fight-or-flight response and is released in times of stress. Its function is similar to adrenaline for the body, but the brain. While an increase of norepinephrine can cause you to be more alert, it can also cause panic attacks and hyperactivity.

Since norepinephrine is supposed to wake our brain up and help us stay alert in stressful situations, you can start to see the connection to ADHD. As you can likely imagine, it's hard to stay focused and give your attention to something when the chemical that triggers attention and focus isn't working properly inside the brain.

Serotonin And ADHD

Next up, we have serotonin -- which is just as popular and well-known as dopamine. Where dopamine is converted from the amino acid tyrosine, serotonin is converted from the amino acid tryptophan -- which is found in turkey and a big reason why we love Thanksgiving meals so much.

While it's manufactured in the brain, nearly 90% of the serotonin found in the body is located in the digestive tract and blood platelets. In the brainstem, it's produced in the Raphe nuclei.

Like dopamine, serotonin plays a major role in mood, appetite, sleep, and even your motor skills. It helps control your bowel movements, regulates the feelings of anxiety and happiness, is part of the reason you feel nausea, helps control when you sleep and when you wake, improves wound-healing, and regulates libido.

When it comes to ADHD, most of the research surrounding the neurotransmitter serotonin is linked to 5-HTTLPR, a serotonin transporter gene. Researchers have found two variants of this gene, one with short alleles and one with long alleles that either lead to an excess or deficiency of serotonin.

Since high or low serotonin levels lead to a wide range of health concerns, including symptoms experienced with ADHD patients, the use of SSRIs (also known as Selective Serotonin Reuptake Inhibitors) helps to increase the amount of serotonin in the body. As a result, the symptoms are reduced, and quality of life is regained.

Are There Any Other ADHD Neurotransmitters?

Neurotransmitters are diverse and versatile, so it's no wonder that when one neurotransmitter is out of whack, your entire body feels the effect.

Since many neurotransmitters work together and some are even derived from each other, your body must keep a healthy balance across the board. With that being said, several other neurotransmitters play a role (no matter how small) in ADHD.

Here are five of those lesser-known neurotransmitters when talking about ADHD:

  1. GABA - also known as gamma-Aminobutyric acid, GABA acts as an inhibitory neurotransmitter. It plays a large role in attention, with low levels leading to a lack of it.
  2. Glutamate - an excitatory neurotransmitter that plays a major role in overall cognition, mood, senses, and motor skills. With ADHD, high levels of glutamate can lead to aggression and impulsive actions...
  3. Adrenaline - also called epinephrine, is an excitatory neurotransmitter that stimulates the body's fight-or-flight response. It works with noradrenaline (norepinephrine) to control alertness and attention.
  4. Histamine - an excitatory neurotransmitter that also acts as a neuromodulator. Some studies suggest that high levels of histamine cause ADHD symptoms become more intense.
  5. Acetylcholine - an excitatory neurotransmitter that also acts as a neuromodulator. Choline, an essential nutrient, is the precursor to acetylcholine, which plays a major role in learning, memory, motor control, and attention.

The brain and body are full of ADHD neurotransmitters and hormones that affect how you think, feel, act, speak, move, and anything else you do daily. An increase or decrease in these neurotransmitters leads to a wide range of health concerns, including ADHD.

Researchers and doctors often look at these neurotransmitters first and foremost when studying a patient, knowing that they'll point them in the right direction -- especially when determining the cause of ADHD in a patient.

Finding The Help, You Need

Of course, there's still so much to learn about neurotransmitters, and scientists are hard at work every day trying to understand all of it. As for us, it's our job to know how to detect ADHD symptoms, as well as signs that you might have a deficiency in the production, synthesis, or release of neurotransmitters.

Don't worry, Mind Diagnostics has you covered with a comprehensive ADHD online test. It's a test designed to determine whether or not you might have ADHD and what you should do to find help. It won't take up too much of your time, but the results could change your life for the better.

Feel free to contact us if you have any questions or need assistance finding a therapist that's ready to serve you well.