Chemicals And The Brain

The brain is a complex network of neurons that communicate through the use of chemicals. These chemical compounds are referred to as “neurotransmitters” because they carry information between braincells. Each unique neurotransmitter carries different information and is responsible for different tasks within the brain.

How Neurotransmitters Allow The Brain To Communicate

When discussing the brain, it can often be complicated or difficult to imagine when using scientific jargon. Each neuron is one nerve cell whose purpose is to pass information along through the Central Nervous System (CNS). Between each of these cells is a layer of keyholes which fit different kinds of keys. Depending on the kind of message that needs to be sent, a neuron may choose one key and match it to the appropriate hole on the other neuron.

These keyholes are what are known as receptors and the keys are the chemical communicators (neurotransmitters). Each neurotransmitter is shaped uniquely and can only fit into certain kinds of receptors. While this seems simplistic, it’s an effective illustration of how these microscopic cells can decide which information to send and how it travels. While science has discovered 60 unique neurotransmitters used throughout the brain, we’ll focus on a handful of important and well-studied chemicals here.

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A well-known chemical communicator created in the body, serotonin comes primarily from the digestive system, though the brain does create a portion itself. With its relationship to the GI tract, serotonin is associated with regulating levels of hunger, bowel function, and even signaling nauseous feelings after eating something undesirable. Within the brain, serotonin is an important mood regulator. Serotonin can moderate the levels of emotions like anxiety and happiness when someone has a healthy brain chemistry. This back and forth between the brain and the complex nerves in the gut is something science is still studying.

When serotonin levels are abnormal, issues tend to arise. Research has established a relationship between depression and an imbalance of neurotransmitters. It’s not cut and dry whether depression reduces serotonin levels or low serotonin levels lead to depression, but the two are linked. Common depression medications like SSRIs raise the amount of serotonin available in the body to try and restore balance to a serotonin deficient brain. Too much serotonin can lead to an issue known as serotonin syndrome. This predominantly occurs in people taking medication that increases their serotonin levels, and it can be deadly.


Dopamine, popularly referred to as the “feel good” chemical, originates from specialized neurons in the brain called dopaminergic neurons. The brain releases dopamine when it’s expecting something it likes. Dopamine is released for food, sex, and any enjoyable or gratifying activity. In this way, dopamine acts as a tool to form habits and condition you to certain behaviors. If every Friday is pizza day, dopamine will help build expectation before dinner, reward you as you eat the pizza, and reinforce the habit afterward.

In communicating with the central nervous system, dopamine also regulates things like:

  • Blood flow
  • Motor control
  • Memory function
  • Mood
  • Pain processing
  • Sleep, and more

Seeing as dopamine influences so many different processes in the body, an imbalance can cause several serious issues. Too little dopamine can hinder regulation of motor function which can lead to Parkinson’s disease. Like serotonin, low levels of dopamine are linked to depressive symptoms like low energy and sleep problems.

Whereas low levels of dopamine cause depressive symptoms, too much dopamine frequently pulls the opposite direction. Hallucinations, delusions, and mania can all appear as a result of too much dopamine. Past manic symptoms, someone with severe enough dopamine imbalances can develop schizophrenia.

As one of the neurotransmitters governing rewards and habits, too much dopamine can cause issues for people in controlling detrimental habits. Obesity and overeating are commonly linked to overactive dopamine release related to food. Different drugs can stimulate the brain to release dopamine, which starts the cycle of chemical dependency and substance use disorder. The flood of dopamine from drugs can overwhelm the brain and desensitize it to normal amounts of dopamine created within the body, creating the intense desire to keep using drugs.


Glutamate is an excitatory neurotransmitter, which is a scientific way of saying it encourages communication between braincells. This job is incredibly important because without it, the central nervous system wouldn’t be able to send messages properly. Glutamate is a common chemical communicator, it’s involved in over 90% of the connections in the brain.

It’s role in allowing different parts of the brain to communicate means that processes like memory and learning rely on glutamate. The efficiency and success of these processes depend on a healthy amount of glutamate circulating normally. If there’s too much glutamate floating around between cells, the neurons can become desensitized to the chemical and the brain won’t be able to communicate as well. In extreme cases, too much glutamate for too long can cause nerves in the brain to die. These types of damage can result in diseases like ALS, GAD, and ataxia.

If the brain starts running low on glutamate, disruptive and depressive symptoms may appear. Trouble focusing, low energy, and mental exhaustion are all common symptoms of low glutamate levels. Without enough of this necessary chemical, the brain can’t send messages efficiently and that results in these mental health issues.


This chemical, along with a related hormone epinephrine (adrenaline) is responsible for changing heart-rate and blood flow around the body. This is helpful in fight or flight situations where the heart needs to pump more blood to fuel muscles and survive whatever challenge someone is facing.

This chemical also plays a role in moderating wakefulness, concentration, and sleep schedule timing. Along with its partner hormone adrenaline, norepinephrine is a key chemical in adapting to changing external factors.

Deficiencies in norepinephrine levels causes a host of issues related to concentration and mood. Not enough norepinephrine can leave someone feeling lethargic, depressed, and contributes to diseases like PTSD and anxiety. A lack of norepinephrine can sometimes manifest as ADHD because the brain needs it to help regulate concentration.

Without norepinephrine, the body can’t properly energize and mobilize certain systems, but with too much, it can be hard to shut down those same sensations. Heightened levels of this neurotransmitter are associated with increased alertness, but too high and you may experience a panic attack, increased blood pressure, and hyperactivity.


As a chemical communicator cortisol is well known for the role it plays in the body’s reaction to stress. As the brain detects a situation as threatening, cortisol is released by the adrenal glands near the kidneys and floods the body helping shut down systems that aren’t important for immediate survival like digestion. Cortisol also helps moderate functions like blood pressure, blood sugar, and inflammation.

The most common issues related to cortisol occur when the body produces too much. If the brain can no longer reliably differentiate stressful situations, it will release cortisol frequently just in case. The release of cortisol is essentially intended to help respond to immediate danger, but in the modern world dangers are less clear cut for most people. Chronic stress in forms like job dissatisfaction, getting stuck in traffic, or being in a bad relationship can all continuously signal the body to release cortisol.

Putting the body on high alert constantly does no favors to mental health or physical health. Anxiety and depression are both commonly linked to cortisol imbalances in the body. Serious cases can lead to dangerous issues like heart disease, obesity, and chronic sleep issues. Extreme instances of cortisol overproduction may lead to a disease call Cushing Syndrome, which is associated with rapid weight gain, diabetes, muscle weakness, and more unfavorable symptoms.

Mental Health

It’s clear that as chemical communicators, each of these neurotransmitters have profound impacts on people’s quality of life and mental health. Imbalances in each chemical are linked to mood disorders like depression, anxiety, or schizophrenia. The frequent overlap in symptoms related to imbalances in different neurotransmitters can make diagnosing and prescribing treatment difficult.

While difficult, advances in medicine are helping people live normal lives by regulating their levels of dopamine, serotonin, or cortisol. This kind of manipulation can lead to serious side effects if done incorrectly or if someone decides to self-medicate with illicit substances.

How Drugs Impact Chemical Balances

Drugs directly change the brain chemistry as you take them which is what leads to the feeling of being high. Different drugs signal the brain to release certain hormones and neurotransmitters that it otherwise wouldn’t release, especially in large amounts. This relationship is especially noticeable with dopamine.

Substances, both legal and illegal, can drastically change the amount of dopamine available in the brain. Alcohol, nicotine, cocaine, opioids, and amphetamines all flood the brain with dopamine. The quick rise in the “feel good” chemical can begin a cycle of chemical dependency if someone continues to take the drug regularly.

If the brain usually creates a neurotransmitter itself, it has a hand on balance and appropriate distribution. Drugs that indiscriminately raise dopamine levels can hinder the brain’s capability to produce normal amounts of dopamine on its own. The brain is very pragmatic in this way. If you’ve found an external source for large amounts of dopamine, the brain will not spend the energy to make its own to avoid redundancy. If you ever stop taking the drug of choice, the brain won’t respond and pick up production immediately. Without normal levels of dopamine, you’ll quickly feel the effects of chemical imbalance in the form of withdrawal. Some withdrawals are more dangerous than others, but none should be taken lightly.

Substance use disorders can form quickly as habitual use of drugs escalates. Dopamine rewards force the body into anticipating and desiring more drugs to varying degrees in different people depending on genetic and environmental factors. Regardless, the dynamics present in neurotransmitter health and balance highlight the need to treat addiction as a disease and not a moral failing. After using drugs, people’s brains are trained to work against them and prioritize more drugs until they stop to get help and go through withdrawal.

For more information, contact a treatment provider today.

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Dr. Ashish Bhatt

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  • Dr. Ashish Bhatt, MD, MRO is an accomplished physician, addiction medicine specialist, and psychiatrist with over 20 years of medical and administrative leadership.

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