Are Schizophrenia Dopamine Levels High Or Low?

Reviewed by Heather Cashell, LCSW

Published 12/28/2020

Schizophrenia is a serious and chronic brain disorder that is believed to affect over 20 million people all over the world. The symptoms are generally characterized by hallucinations and delusions, but people living with schizophrenia experience a wide variety of symptoms each day.

For example, individuals with schizophrenia could experience abnormal thinking, unwanted behaviors, a distorted view of what’s real, changes in the five senses (touch, sight, smell, hearing, and vision), confusion, loss of motivation, and even difficulty speaking.

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Genetics and the way someone is raised are certainly believed to play a role in individuals developing schizophrenia. With that being said, it’s the impact dopamine, and other neurotransmitters have on the brain’s function that is at the heart of most research today. That’s where the connection between dopamine and schizophrenia begins.

So, what is dopamine?

Dopamine is a neurotransmitter found in the brain. Many people refer to it as the ‘pleasure neurotransmitter’ because it plays a large role in feeling pleasure. In fact, dopamine is the chemical our brain releases when we do something we enjoy -- it makes us feel happy.

When we consume L-Tyrosine, an amino acid found in cheese, soybeans, beef, lamb, pork, fish, chicken, nuts, eggs, dairy, beans, and whole-grain, the body converts it into L-DOPA, the precursor to dopamine. L-Phenylalanine is also considered a precursor to dopamine since the body can convert it into L-Tyrosine.

Once produced, dopamine won’t enter the bloodstream because it can’t cross the blood-brain barrier. Instead, it travels through the neural pathways that make up the brain. These little ‘roadways’ throughout the brain are what help different regions of the brain communicate with each other.

The neurotransmitter travels through the neuron until it reaches the axon, which is the end of the neuron. Following the end of the neuron is a tiny little space that separates one nerve cell from another nerve cell. The tiny space is called the synapse.

After dopamine reaches the axon, it’s released into the synapse via the presynaptic nerve. Once inside the synapse, it either binds to a receptor on the end of the other nerve cell, is transported back through the presynaptic nerve, or is broken down and never utilized.

If the dopamine binds to a dopamine receptor on the other end of the nerve cell, it causes a response in the brain and body. This is the pleasurable feeling we get from dopamine.

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Unfortunately, many people have an imbalance of neurotransmitters in the brain, and dopamine is one of the most-studied ones. Some people produce too much dopamine, while others don’t produce enough. Some people might even have issues with the synthesis, release, transportation, or breakdown of dopamine.

How Does Dopamine Affect Schizophrenia?

You might be wondering, “What is the role of dopamine in schizophrenia?” and where do schizophrenia and dopamine start to overlap.

Researchers have identified dopamine as one of the major neurotransmitters involved in schizophrenia symptoms. Over time, they’ve discovered that the symptoms are largely caused by high levels of dopamine in the brain.

In fact, there are four major dopamine pathways in the brain that play a role in schizophrenia, and they’re often the main pathways targeted by antipsychotics prescribed by your doctor. Let’s take a closer look at these four dopamine pathways and where they’re located in the brain:

  1. Mesolimbic Pathway - a dopamine pathway that originates in the ventral tegmental area (VTA) and travels to the nucleus accumbens (NAc). This pathway is where dopamine exerts the feeling of pleasure and reward. When dopamine levels are too high, it leads to many of the positive symptoms of schizophrenia (hallucinations, delusions, disorganization).
  2. Mesocortical Pathway - a dopamine pathway that originates in the ventral tegmental area (VTA) and travels throughout the prefrontal cortex. It plays a large role in working memory, cognition, and decision making. When dopamine levels are too high, it leads to many of the negative symptoms of schizophrenia (apathy, lack of emotion, lack of motivation, poor social function, and poor cognition).
  3. Nigrostriatal Pathway - a dopamine pathway that originates in the substantia nigra and travels to different parts of the basal ganglia, including the putamen and caudate. It’s believed that nearly 80% of all dopamine in the brain is found in this pathway. It plays a major role in motor planning and purposeful movements. Dopamine metabolism in the presynapse is altered with schizophrenia.
  4. Tuberoinfundibular Pathway - a dopamine pathway that originates in parts of the hypothalamus, including the arcuate and paraventricular nuclei, and travels to the median eminence, which is located in the infundibular region of the hypothalamus. This pathway is largely responsible for inhibiting prolactin release. Prolactin is produced in the pituitary gland and plays a major role in milk production and the development of mammary glands.

These four dopamine pathways play a major role in understanding where positive (mesolimbic pathway) and negative (mesocortical pathway) originate from. Medication prescribed by your doctor is designed to bind to dopamine receptors in these pathways.

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Since there’s no response or reaction when it binds to the dopamine receptor (where we would normally feel pleasure and reward), the medication allows the brain to avoid hyperactivity in these pathways. Unfortunately, the medication can also cause side effects.

For example, binding to dopamine receptors in the nigrostriatal pathway is known to cause extrapyramidal symptoms, which include jerky movements, spasms, muscle contractions, motor restlessness, rigidity, slowness of movement, tremors, and more.

In addition to that, binding to dopamine receptors in the tuberoinfundibular pathway is known to increase prolactin levels in the blood. This can cause irregular menstrual cycles in females, breast milk production in males, osteoporosis, and menopausal symptoms.

Are There Other Neurotransmitters Involved?

While dopamine receives a large amount of attention when looking at schizophrenia symptoms, it’s not the only neurotransmitter researchers are eyeing with this disorder.

Of the over 40 different neurotransmitters studied by researchers today, there are four others that are believed to play a role in schizophrenia -- glutamate, GABA, serotonin, and acetylcholine.

Let’s take a closer look at these neurotransmitters and what they’re responsible for:

  1. Glutamate - the major excitatory neurotransmitter that’s found in nearly 60% of neurons in the brain. It plays a major role in learning and memory as we mature, more specifically long-term potentiation in the brain. Researchers believe schizophrenia symptoms can be triggered by high or low levels of glutamate.
  2. GABA - also known as gamma-aminobutyric acid, GABA is an inhibitory neurotransmitter that’s found throughout the brain. It plays an important role in motor control, vision, regulating anxiety, minimizing fear, and producing a calming effect in the body. Researchers believe low levels of GABA in the brain can lead to schizophrenia symptoms.
  3. Serotonin - also known as 5-hydroxytryptamine, serotonin is one of the most popular and well-known neurotransmitters. It’s an inhibitory neurotransmitter that plays a large role in regulating our emotions and mood. Many people call it the ‘happy chemical’ in the brain. It also plays a role in eating, sleeping, digestion, and communication between nerve cells. Researchers believe high levels and low levels of serotonin can lead to schizophrenia symptoms.
  4. Acetylcholine - an excitatory neurotransmitter that was the first neurotransmitter ever identified by researchers. It has a variety of roles in the brain and body, including the activation and movement of muscles, motivation, arousal, attention, learning, and memory. Researchers believe changes in the muscarinic acetylcholine system play a role in schizophrenia symptoms.

Dopamine might receive a majority of the attention, but it’s not the only neurotransmitter researchers are eyeing in the development of schizophrenia. It’s believed that most patients experience a combination of imbalances in the brain that ultimately lead to their symptoms.

Understanding The Symptoms Of Schizophrenia

Early detection is often the best medicine when experiencing schizophrenia symptoms. It gives mental health professionals a prime opportunity to evaluate you mentally, emotionally, physically, and socially to give you the best treatment plan moving forward.

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Of course, early detection is only possible when the individual and individual’s loved ones are aware of the common symptoms and warning signs of schizophrenia. With that being said, let’s take a look at some of the most prominent symptoms experienced with schizophrenia:

  • Bizarre beliefs that might seem real to the individual but aren’t real and are more a result of paranoia. Also known as delusions.
  • Hallucinations include hearing things, seeing things, smelling things, and feeling things that aren’t real.
  • Disorganized speech often makes it difficult to understand the individual on a regular basis.
  • Disorganized behavior makes it seem as if the person is confused or unaware of what to do.
  • Social withdrawal, lack of expression, lack of emotion, reduced motivation, and the absence of other normal behaviors.
  • Catatonic behavior leads to a lack of movement or lack of communication in the individual.

Since everyone experiences schizophrenia differently, it’s very important that the individual receives a professional evaluation by a mental health professional experienced with schizophrenia symptoms. This is a crucial part of the healing process.

When To Receive Help For Your Symptoms

Schizophrenia is a major and serious condition that needs professional evaluation immediately. Not only are the professionals the only ones experienced with diagnosing schizophrenia, but they’re the ones that are capable of putting together an effective treatment plan for the individual designed to bring out the best in them.

That’s why it’s important to seek help immediately after detecting or noticing the symptoms. The individual’s loved ones often play a major role in the detection stage. Siblings, teachers, coaches, friends, and other family members also play a crucial role in providing a support group.

At Mind Diagnostics, we understand there is a wide range of people out there unaware that their symptoms are harmful or wrong. Many people have grown too familiar with their symptoms and believe what they’re experiencing is normal. That’s where we come in.

We’ve created a series of mental health tests designed to understand your symptoms and calculate your risk level of developing certain disorders, addictions, and conditions. Our comprehensive schizophrenia test is one of our most popular, and it’s free for anyone to take.

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