Psychosis describes a mental health condition where an individual experiences a disconnection from reality, often involving hallucinations or delusions. Brain scans are investigative tools used by researchers to explore the brain’s structure and function. Scientists examine how these imaging techniques contribute to understanding the biological underpinnings of psychosis. This aims to uncover brain patterns and changes associated with the condition.
Types of Brain Imaging
Brain imaging techniques visualize the brain and its activity. Magnetic Resonance Imaging (MRI) provides detailed pictures of brain structures by using strong magnetic fields and radio waves. MRI helps observe brain region size and shape. Functional Magnetic Resonance Imaging (fMRI) builds upon MRI by detecting changes in blood flow and oxygen levels, which indicate brain activity. fMRI shows which brain parts are active during specific tasks or at rest, and how different regions communicate.
Positron Emission Tomography (PET) scans involve injecting a radioactive tracer into the bloodstream. The tracer travels to the brain and accumulates in areas of higher metabolic activity, such as those using more glucose. PET scans can also measure neurochemical processes, like the distribution and density of neurotransmitter receptors, providing insights into the brain’s chemistry. While Computed Tomography (CT) scans use X-rays to create cross-sectional images of the brain, they offer less detailed structural information compared to MRI and have a more limited role in psychosis research.
Brain Changes Associated With Psychosis
Brain imaging studies identify various structural changes in individuals with psychosis, though these findings often represent associations within groups rather than universal individual characteristics. A common observation is a reduction in gray matter volume, particularly in regions like the prefrontal cortex and hippocampus. This gray matter loss can also affect areas such as the temporal and occipital lobes. White matter can also show altered integrity in psychosis. Studies have noted decreased density of oligodendrocytes and changes in white matter below the cortex.
Functional imaging reveals abnormal brain activity patterns in individuals with psychosis. This includes altered functional connectivity. For instance, there can be increased connectivity between the default mode network and the salience network, as well as between somatomotor and thalamic regions. Conversely, decreased connectivity has been observed within the prefrontal cortex and between the thalamus and the prefrontal cortex. These functional changes can disrupt the brain’s hierarchical organization, impacting how sensory information is integrated with internal signals.
Neurochemical changes, particularly involving the neurotransmitter dopamine, are frequently observed using PET scans. Psychosis is associated with dysregulated presynaptic striatal dopaminergic function, meaning there can be heightened dopamine transmission. This dysregulation is linked to the positive symptoms of psychosis, such as hallucinations and delusions. Studies using tracers like 18F-FDOPA have shown elevated dopamine synthesis capacity in the striatum of individuals with schizophrenia and those at high risk for psychosis. This suggests an imbalance in the brain’s dopamine system.
How Brain Scans Inform Research
Brain scans are research tools that help understand biological processes contributing to psychosis. They aid in identifying the underlying mechanisms of psychosis, such as how brain regions interact or how neurotransmitter systems are affected. This approach moves beyond describing symptoms to exploring the neural basis of the disorder.
Researchers also use brain imaging to search for biomarkers. For psychosis, the goal is to find brain-based markers that could indicate an individual’s risk for developing the condition, predict its progression, or forecast how they might respond to different treatments. For example, some studies are exploring connectivity patterns in sensory regions as potential biomarkers for early psychosis. Insights from these scans can guide the development of new therapies, both pharmacological and non-pharmacological. Understanding specific brain alterations can lead to more targeted interventions.
Why Brain Scans Don’t Diagnose Psychosis
Despite their value in research, brain scans are not used to definitively diagnose psychosis. Brain changes observed in individuals with psychosis are highly variable. These variations can also overlap with brain characteristics seen in healthy individuals or those with other neurological conditions.
There is no single brain scan finding specific enough to reliably identify psychosis. Abnormalities found through imaging, such as decreased activity in certain brain regions, can be present across various psychiatric conditions, including depression, anxiety, and bipolar disorder. Therefore, a diagnosis of psychosis relies on a thorough clinical evaluation conducted by a mental health professional. This assessment considers reported symptoms, personal and family health history, and direct observation of behavior over time.