An electroencephalogram (EEG) is a non-invasive method that records the brain’s electrical activity using small electrodes placed on the scalp. Schizophrenia is a mental disorder that influences how a person thinks, feels, and behaves. Researchers use EEG to investigate the brain function connected to schizophrenia.
Characteristic EEG Patterns in Schizophrenia
Researchers have identified several characteristic electrical activity patterns in the brains of individuals with schizophrenia. One pattern involves event-related potentials (ERPs), which are the brain’s electrical responses to specific thoughts or perceptions. A specific ERP component, the P300 wave, is often reduced, a finding thought to reflect difficulties in attention and information processing.
Another finding is a reduction in mismatch negativity (MMN). MMN is an automatic brain response that occurs when a person hears a sound that deviates from a sequence of repetitive sounds. A diminished MMN amplitude points to foundational issues in how the brain processes auditory information and may contribute to perceptual disturbances.
Disruptions are also seen in the brain’s high-frequency gamma band oscillations (30-100 Hz). These oscillations are involved in binding sensory information together to form coherent perceptions. In schizophrenia, disorganized or reduced gamma activity is associated with cognitive deficits and difficulties in integrating sensory inputs.
Even when an individual is at rest, their EEG patterns can show differences, often including an increase in low-frequency delta and theta wave activity. These findings suggest baseline differences in brain connectivity and arousal levels in schizophrenia. This indicates that the brain’s functional organization is altered even without external stimulation.
The Role of EEG in Diagnosis and Risk Assessment
While EEG provides insights into brain function, it is not used as a standalone tool to diagnose schizophrenia. No single electrical pattern can definitively confirm the disorder. Instead, EEG serves as a supportive instrument that provides objective data on brain dysfunction that can align with a person’s symptoms.
EEG can also help differentiate schizophrenia from other conditions with similar symptoms. For instance, certain types of epilepsy can cause psychosis, and an EEG can help rule out such underlying neurological disorders by detecting seizure-related activity. This helps clinicians achieve a more accurate diagnosis and treatment plan.
The technology is also used in research for assessing the genetic risk of developing the disorder. Certain EEG abnormalities are considered endophenotypes—biological markers found more commonly in the unaffected family members of individuals with schizophrenia than in the general population. A reduced P300 or diminished MMN can indicate a genetic vulnerability, allowing researchers to identify high-risk individuals for potential early intervention.
Monitoring Treatment and Predicting Outcomes
Beyond diagnosis, EEG is a tool for monitoring the brain’s response to treatment. Some of the electrical abnormalities observed in the disorder can change with the use of antipsychotic medications. For example, certain treatments may lead to a normalization of specific EEG patterns, providing objective evidence that the medication is having a physiological effect.
Researchers are also exploring how baseline EEG readings might predict a patient’s response to different treatments. Pre-treatment patterns, such as the power of theta or beta waves, have been identified as potential predictors of how well a person might respond to antipsychotics. This research aims to move toward personalized medicine by helping guide the selection of the most effective medication.
By tracking changes in brainwave activity over time, clinicians can gain a deeper understanding of how an intervention is working. Changes in delta and beta waves in the brain’s frontal and temporal regions are associated with improvements in symptoms. This offers a way to objectively monitor progress and make more informed decisions about ongoing care.
EEG in Conjunction with Other Brain Imaging
To gain a more complete understanding of schizophrenia, researchers often combine EEG with other neuroimaging methods, such as magnetic resonance imaging (MRI) and functional MRI (fMRI). EEG’s strength is its high temporal resolution, allowing it to measure brain activity in real-time, down to the millisecond. This is useful for studying the rapid cognitive and perceptual processes disrupted in schizophrenia.
However, EEG has poor spatial resolution, meaning it is not precise in pinpointing where in the brain the electrical activity originates. This is where other techniques become complementary. Structural MRI provides detailed images of the brain’s anatomy, while fMRI shows where brain activity is occurring by measuring changes in blood flow, offering high spatial resolution.
The trade-off is that fMRI has a much slower temporal resolution compared to EEG. By combining these methods, a practice known as multimodal imaging, researchers can leverage the strengths of each. This integrated approach allows them to observe both the precise timing from EEG and the specific location from fMRI, providing a comprehensive picture of brain function in schizophrenia.