Neuroimaging in Psychosis

Neuroimaging in Psychosis Research

• Neuroimaging techniques, like MRI, PET, SPECT, EEG, and MEG, are used to study brain structure and function in psychosis research.
• Specific types of MRI include structural (sMRI), diffusion tensor imaging (DTI), functional (fMRI), and magnetic resonance spectroscopy (MRS).
• Positron emission tomography (PET) requires radioactive tracers to visualize receptor activity in the brain.
• Electroencephalography (EEG) and magnetoencephalography (MEG) measure electrical and magnetic brain activity, respectively.

Aetiology/Cause of Psychosis

• Schizophrenia is understood as a dimensional, rather than categorical, illness, with varying degrees of severity.
• Clinical high-risk (CHR) states for psychosis involve emerging symptoms, and some individuals will transition to psychosis.
• Early-life factors such as obstetric complications, childhood trauma, marginalized group status, substance use, and socioeconomic factors influence brain development, possibly contributing to psychosis risk.
• Neuroimaging studies are crucial to understand brain structure and function in psychosis and to identify potential causal factors involved.

Brain Structure in Schizophrenia

• Neuroimaging studies show alterations in brain structure in schizophrenia, such as reduced grey matter volume in specific areas, like the frontal and temporal lobes, and differences in cortical thickness and subcortical volumes (e.g. hippocampus, amygdala, thalamus, striatum).
• These changes might be developmental or neurodegenerative, potentially influenced by early-life experiences.
• Antipsychotic medication can also affect brain structure over time.
• The right anterior cingulate, insula, thalamus, and temporal gryus are among the areas affected.

Neurodevelopmental Trajectories in Schizophrenia

• Early-life factors interact with genetic predispositions to affect brain development which can lead to schizophrenia.
• Longitudinal studies are needed to pinpoint the timing of neurodevelopmental changes in psychosis onset to further understand the pathogenesis of the disorder.
• Schizophrenia is better characterized as a spectrum disorder that may be associated with different neurodevelopmental trajectories versus a purely neurodegenerative process.

Biological Models and Psychosis

• Neuroimaging can be used to evaluate the dopamine hypothesis of psychosis.
• PET imaging assesses dopamine receptor binding, synaptic dopamine uptake, and dopamine synthesis capacity.
• Elevated dopamine activity is observed in certain brain regions (e.g., striatum) in schizophrenia compared to healthy controls. More research remains necessary.
• The dopamine hypothesis struggles to explain all aspects of psychosis, implying a multi-system etiologic process.
• Other neurotransmitters besides dopamine may be involved in the development of schizophrenia.

Diagnosis and Measurement

• Diagnosis of psychosis often relies on clinical evaluations and subjective assessments, with ongoing efforts to use objective biological measures, like neuroimaging, to inform or aid these diagnoses.
• Challenges remain with standardization, variability in data across patient groups and settings, and with identifying biomarkers and methods that offer useful diagnostic assistance to improve the accuracy and objectivity of diagnoses.

Current Research Directions

• Longitudinal studies, including neuroimaging, are crucial to observe brain changes before and during the development of psychosis.
• Further exploration is required to understand the trajectory of the disease and the impact of various risk factors and potentially treatments.
• Advanced methods, such as machine learning, can potentially enhance predictions of psychosis, offering better-guided treatment decisions in early stages and improving prognosis prediction.

Explore the role of neuroimaging techniques in understanding psychosis, including structural and functional MRI, PET, EEG, and MEG. This quiz also covers the aetiology of psychosis, emphasizing schizophrenia as a dimensional illness and the various early-life factors influencing its development.