Schizophrenia is a mental health condition that can affect your thoughts, feelings, and behaviors. Symptoms mainly fall into three categories and include:

Schizophrenia is usually diagnosed by a healthcare professional when someone is between their late teens and early 30s. Treatment focuses on managing symptoms and improving day-to-day functioning.

The exact causes of schizophrenia are unknown, but it likely has both genetic and environmental causes.

Scientists think that changes in brain structure and function can contribute to the development of schizophrenia. This includes differences in the volume of certain brain regions in people with schizophrenia compared to people without it.

Different types of brain imaging allow doctors and researchers to look at the differences between the brains of people with and without schizophrenia. These images can help researchers learn more about the causes of schizophrenia and develop new treatments.

MRIs are the most common type of brain scan. They create a detailed picture of the whole brain.

Researchers may also use functional MRIs, which measure brain activity through changes in blood flow, or diffusion tensor imaging (DTI), a type of MRI that looks at the brain’s white matter.

PET scans may also be used to look at how neurotransmitters work in the brain. Neurotransmitters are chemicals in your body that transfer messages between neurons. They can also transfer messages from neurons to muscles.

Research done with these different types of brain imaging reveals differences in both structure and function between the brains of people with and without schizophrenia.

PET scan shows differences in brain activity between people with schizophrenia and people without.Share on Pinterest
PET scan displaying differences in brain activity in people with and without schizophrenia. Science History Images / Alamy Stock Photo

Brain scans of people with schizophrenia show several structural differences throughout the brain, including white and gray matter.

White matter

White matter is made up of several different kinds of cells, including:

  • myelin, cells that wrap around nerves
  • glia, which protect neurons (nervous system cells)
  • perivascular cells, which help form a barrier that protects brain cells from blood
  • projection fibers that connect to different areas of the brain, allowing for communication between brain regions

Despite all these different types of cells, white matter still has much fewer neurons than gray matter.

Brain scans of people with schizophrenia show the following changes to white matter:

  • reductions in white matter in the frontal lobe before and after diagnosis and treatment
  • an increase in another type of white matter, called interstitial white matter neurons, below the cortex

There are also some inconsistent findings in brain scans on white matter.

According to a 2019 review of schizophrenia research, some studies have observed decreased density (thickness) of a type of white matter, called oligodendrocytes. This type of white matter is located below the cortex, very close to gray matter. Some studies have also observed changes in the density of white matter under the anterior cingulate cortex, near the front of your head.

However, other studies have not observed these changes in density and ultimately, more research is needed.

Changes in white matter are related to psychotic symptoms and a lower ability to think in people with schizophrenia. According to the same review, there’s also evidence that natural changes to white matter during puberty may be an underlying cause of schizophrenia.

Gray matter

Gray matter is the outermost layer of the brain. It’s mostly made up of the cell bodies of neurons. Gray matter makes up the ridges and grooves you may associate with pictures of the brain.

Changes that can be seen in the gray matter of people with schizophrenia include:

  • thinning throughout different parts of the brain’s cortex
  • reduced gray matter surface area and volume

Specifically, 2020 research has found that people early in their condition have less gray matter in the prefrontal and temporal lobes.

On the other hand, people with chronic schizophrenia are more likely to have reduced gray matter in the frontal, temporal, superior parietal, and occipital lobes.

Changes in gray matter are linked to changes in cognitive (thinking) and motor (movement) functions. These functions include storing and retrieving verbal information.

These changes are progressive, which means they worsen over time. They are more severe in people who:

  • are not receiving treatment for their schizophrenia
  • have more severe symptoms of schizophrenia
  • began having signs of schizophrenia at a young age

Neurotransmitters are chemicals that your body uses to transmit messages between neurons or from neurons to muscles. They start as electrical signals that move along the axon of a neuron.

At the end of the axon, this electrical signal is converted into a neurotransmitter. The axon releases the neurotransmitter to interact with another neuron or a muscle. This triggers a response from the recipient neuron or muscle.

MRIs can’t be used to look at neurotransmitters, but PET scans can show how these chemicals are working in the brain. A type of imaging called proton magnetic resonance spectroscopy may also be used.

Dopamine

Dopamine is a type of neurotransmitter involved in many brain functions, including:

  • motor control
  • reward system
  • motivation

Studies show that people with schizophrenia have increased dopamine, especially in the brain’s subcortex. Researchers have found that both baseline levels of dopamine and the amount of dopamine released are elevated.

Increased dopamine is associated with psychotic and cognitive symptoms of schizophrenia. Because of this, many antipsychotic medications work by balancing levels of dopamine.

Serotonin

Serotonin is involved in many basic functions, including:

  • sleep
  • memory
  • appetite
  • mood

Currently, there is not much research on serotonin’s role in schizophrenia. However, one piece of 2018 research suggests that the release of too much serotonin can lead to psychosis.

An excess release of serotonin leads to the release of glutamate, which causes the release of dopamine.

Glutamate

Glutamate is an excitatory neurotransmitter, which means it activates the neuron receiving it. It works throughout the brain and the rest of the nervous system.

The 2018 research mentioned earlier found that the type of neuron receptor that attracts glutamate may not work correctly in people with schizophrenia. This increases the level of glutamate between neurons in the brain’s synapses.

Since glutamate works across all areas of the brain, these changes can have many effects. Specifically, glutamate changes in schizophrenia may lead to cognitive symptoms, like problems with working memory.

A healthcare professional can’t use a single test, such as a brain scan, to diagnose schizophrenia. Instead, many factors go into a schizophrenia diagnosis.

This diagnosis is based largely on your symptoms but may also be influenced by:

  • family history
  • personal health history
  • brain scans

Part of why doctors can’t use brain imaging on its own to diagnose schizophrenia is because the meaning of these images still isn’t well understood. It’s not fully clear, for example, if observed brain changes cause schizophrenia or if schizophrenia itself causes these changes.

However, scans like an MRI can help rule out other conditions that can cause similar symptoms, like brain tumors or neurodegenerative diseases.

Researchers are looking into ways of using brain imaging to help diagnose schizophrenia.

According to a 2020 study, a trained machine with a learning algorithm classified brain scans as belonging to a person with schizophrenia better than psychologists and radiologists did. These findings hint at the future of brain imaging technology.

Scientists think that brain differences in people with schizophrenia may begin to develop before birth. All brains also change during puberty. This combination of two distinct periods of brain changes may trigger schizophrenia, according to 2015 research.

Imaging has shown that the brain continues to change over time, even after schizophrenia treatment. Earlier brain changes related to schizophrenia happen in the prefrontal and temporal lobes, while later changes take place in the frontal, temporal, superior parietal, and occipital lobes.

However, we don’t yet know if these changes cause schizophrenia or if schizophrenia causes these changes.

Brain imaging shows clear differences between the brains of people with schizophrenia and those of people without. However, more research is needed to learn exactly what these differences are and mean.

Still, brain imaging has great potential to help us learn what causes schizophrenia, how it progresses, and how to treat it.