Can problems in the brain contribute to developing schizophrenia? Unfortunately, there is a strong stigma surrounding schizophrenia. There are many possible biological causes, and problems in the brain are one of these.
- What are brain abnormalities in schizophrenia?
- What are some biochemical brain abnormalities in schizophrenia?
- What are structural and functional brain abnormalities in schizophrenia?
- What causes the brain abnormalities that contribute to schizophrenia?
Meaning of Brain Abnormalities in Schizophrenia
What does it mean to have a brain abnormality that is connected to a diagnosis of schizophrenia? Studies show that individuals with schizophrenia demonstrate changes in the brain's functioning (biochemical) and structure (brain volume).
Schizophrenia is a psychotic disorder involving perceptual (hallucinations or delusions) and behavioral abnormalities (speech or motor movements), with positive and negative symptoms.
The brain areas most affected are usually the prefrontal and medial temporal lobes which play a part in working memory and declarative memory.1 The biochemical abnormalities most associated with schizophrenia are problems with the neurotransmitters serotonin, dopamine, and glutamate. So how do these abnormalities lead to or contribute to schizophrenia?
Our frontal lobes are very important in working memory. What does this mean? Our working memory is necessary for daily decision-making and problem-solving. An example of this is adding up the cost of our groceries as we shop.
Our medial temporal lobes help us with our declarative memory. These are conscious memory processes that help us focus on facts or events stored in our long-term memory. An example is the ability to recall an address of a cafe you like in your hometown. This information is stored in your long-term memory.
Biochemical Brain Abnormalities in Schizophrenia
There are a few biochemicals within our brains called neurotransmitters that are connected to schizophrenia. There is still a lot of research to be done, but here is what researchers have found out about these chemicals. Schizophrenia seems to be a neurodevelopmental and progressive disorder with multiple biochemical problems or abnormalities. The main biochemicals involved are dopamine, serotonin, and glutamate.
Dopamine
Research studies show a strong connection between dopamine and schizophrenia. There are too many receptors accepting dopamine in the brains of those with schizophrenia. Hyper-responsive dopamine receptors can cause hallucinations and feelings of paranoia. Researchers call this connection the Dopamine Hypothesis.
Having high dopamine levels can lead to positive symptoms of schizophrenia, which means something unusual is present that should not be present (like hallucinations, delusions, and disorganized behavior or speech). Too much dopamine action in the brain is connected to these symptoms.
The Dopamine Hypothesis states that schizophrenia may be caused by higher than normal levels of dopamine in the brain.
Dopamine-blocking medications help lessen positive symptoms of schizophrenia. In contrast, recreational drugs that trigger dopamine pathways tend to produce symptoms similar to the positive symptoms of schizophrenia.
Glutamate
Research studies also show a connection between too little of the neurotransmitter glutamate and negative symptoms of schizophrenia. The glutamate hypothesis is an explanation for schizophrenia that says individuals diagnosed with schizophrenia possess a lack of the neurotransmitter glutamate in certain brain areas (mostly the prefrontal cortex).
Glutamate is a free amino acid within the brain and a major excitatory neurotransmitter, involved in information processing throughout the cortex and the creation of memories in the hippocampus.
Negative symptoms of schizophrenia mean something is missing that SHOULD be present, like movement, emotional expression, or speech.
Serotonin
The neurotransmitter serotonin plays a role in many different mental disorders. Individuals with unbalanced or unregulated serotonin levels in the brain tend to also display cortical shrinkage: the outer layer of the brain shrinks in size. They also tend to have high rates of depression and decreased phospholipids. Even though they are unregulated, the levels of serotonin in those with schizophrenia are typically too high rather than too low.
Brain Volume Abnormalities in Schizophrenia
Cerebral tissue of the brain is also impacted by a diagnosis of schizophrenia. Significant shrinkage or enlarged fluid-filled areas (ventricles) in the cerebral cortex are common in the brains of those with schizophrenia.
Studies involving brain images of those diagnosed with schizophrenia show decreased gray matter brain volume and enlarged lateral and third ventricles. These brain abnormalities can cause issues with judgment and decision-making since they involve the areas of the brain that control these tasks.
Gray matter is the neural tissue of the brain that contains nerve-cell bodies and nerve fibers.
Lateral and third ventricles, Wikimedia Commons
Increased fluid in the brain is part of the reason for these changes in brain volume and size in those with schizophrenia. Excess fluid in the brain can cause issues that range from headaches to more severe issues such as alterations to the immune system.
Brain scans, Wikimedia Commons
Brain Structure and Function Abnormalities in Schizophrenia
The anatomy of the brain plays a large part in understanding schizophrenia and its symptoms. Multiple brain scans of those with schizophrenia show problems in several areas of the brain. The areas most impacted seem to be the prefrontal cortex and medial temporal lobe.
Medial Temporal and Prefrontal Lobes, Wikimedia Commons
The prefrontal cortex is in charge of our planning, problem-solving, and critical thinking skills. When researchers scan the frontal lobes of those with schizophrenia, they discover that there is a large decrease in neural waves in this brain area, which means there is less synchronized neural firing or communication. The disruption of neural network communication is a contributor to symptoms of schizophrenia.
What about other areas of the brain? The thalamus (in the medial temporal lobe) also seems to be involved in schizophrenia. Recently, researchers discovered that when someone experiences hallucinations, the thalamus is overactivated. The amygdala, another important brain area, is overactivated when someone experiences extreme paranoia.
Deep within the brain, the thalamus is in charge of taking in sensory information, filtering the information, and sending it to the cortex area of the brain. The amygdala is like a processing center for fear signals and responses.
The delicate connections and functions of each part of the brain are so intricate that even the mildest changes can have severe consequences. What causes all of these problems in the brain? Why do each of these brain areas stop functioning properly?
Causes of Brain Abnormalities in Schizophrenia
Research has found two main possible causes of brain abnormalities in those with schizophrenia: prenatal maternal viruses and genetics.
Prenatal Maternal Viruses
Researchers wondered if illnesses that happen during pregnancy can cause problems for the fetus. Researchers wanted to know if the children of pregnant women who had the flu during pregnancy were more likely to develop schizophrenia later on in life. After several studies, they found a connection between these two dynamics. This is an example of an environmental factor associated with the risk of developing schizophrenia.
Are people who are born in highly populated areas (like big cities) at greater risk for developing schizophrenia due to higher rates of viral infections like the flu? Researchers found that both viral transmission and living in a big city increase the risk of developing schizophrenia. These findings provide support for the idea that the environmental factor of viral infections could be a cause of schizophrenia.
Genetic Factors
Can you inherit schizophrenia from your parents? Those with family members who have or had schizophrenia are at much greater risk of developing the disorder. This is called a genetic predisposition. The odds are pretty high: 1 in 10 children born into a genetic line of someone with schizophrenia are likely to develop the disorder.2
Scientists want to know why this is the case. Are there specific genes that increase the risk of developing schizophrenia? While no one factor seems to determine if someone will develop schizophrenia, genetics is a big piece of the puzzle. There are other factors to take into consideration, though. Often there are things like poor nutrition, prenatal viral infections, and maternal stress that interact with a person's genes and activate the genetic factors linked to schizophrenia. This is called epigenetics or gene-environment interaction.
Epigenetics or gene-environment interaction is the study of how behaviors and the environment interact with each other to cause changes in the way a person's genes are expressed.
Brain Abnormalities - Key takeaways
- Schizophrenia is a psychotic disorder involving perceptual (hallucinations or delusions) and behavioral abnormalities (speech or motor movements), with positive and negative symptoms.
- The Dopamine Hypothesis: an explanation for schizophrenia based on the fact that antipsychotic medications are antidopaminergic, and recreational drugs that trigger dopamine pathways produce symptoms similar to the positive symptoms of schizophrenia.
- The glutamate hypothesis is an explanation for schizophrenia based on the fact that individuals diagnosed with schizophrenia possess a lack of the neurotransmitter glutamate in certain brain areas (mostly the prefrontal cortex).
- Positive symptoms mean the presence of something unusual that should not be present, like hallucinations, delusions, and disorganized behavior or speech.
- Negative symptoms of schizophrenia mean something is missing that should be present, like movement, emotional expression, or speech.
References
- Karlsgodt, K. H., Sun, D., & Cannon, T. D. (2010). Structural and Functional Brain Abnormalities in Schizophrenia. Current directions in psychological science, 19(4), 226–231. https://doi.org/10.1177/0963721410377601
- Miyamoto S, LaMantia AS, Duncan GE, Sullivan P, Gilmore JH, Lieberman JA. Recent advances in the neurobiology of schizophrenia. Mol Interv. 2003 Feb;3(1):27-39. doi: 10.1124/mi.3.1.27. PMID: 14993436.
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