Functional Magnetic Resonance Imaging – Implications for Detection of Schizophrenia

Functional Magnetic Resonance Imaging – Implications for Detection of Schizophrenia

Calhoun Vince D, Demirci Oguz

European Neurological Review, 2009;4(2):103-6

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Abstract
Functional magnetic resonance imaging (fMRI) is an invaluable non-invasive instrument that has been used to investigate physiological disturbances that lead to manifest psychiatric illnesses. It is hoped that efficient application of fMRI can be utilised to characterise and diagnose mental illnesses such as schizophrenia. Although there are various fMRI research studies presenting very promising diagnosis results for schizophrenia, we believe that there is much to be done to develop effective diagnostic tools for clinical purposes. We present specific examples based mostly on our past and recent work together with various examples from the recent literature. We discuss where we currently stand in the efforts of fMRI being used for diagnosis of schizophrenia, examine common possible biases and offer some solutions with the hope that fMRI can be more efficiently used in diagnostic research.

Keywords
Functional magnetic resonance imaging (fMRI), schizophrenia, bias, classification, detection

Disclosure: Data collection was funded by the Department of Energy, grant DE-FG02-99ER62764.
Acknowledgements: The authors would like to thank the Mind Research Network staff for their efforts during the data collection process. This work was funded by the US National Institutes of Health (NIH), under grants 1R01 EB 000840, 1R01 EB 005846 and 2R01 EB000840.
Received: 25 March 2009 Accepted: 23 July 2009
Correspondence: Oguz Demirci, The Mind Research Network, 1101 Yale Boulevard, Albuquerque, NM 87131, US. E: oguzdemirci@gmail.com

Functional magnetic resonance imaging (fMRI) is a fairly new tool that has been used to measure brain activation utilising the dependency of the magnetic properties of haemoglobin on the amount of oxygen it carries. Blood-oxygen-level-dependent (BOLD) signals measure the alterations in cerebral blood flow that mark functional brain activity.1 The intrinsic BOLD contrast makes fMRI an invaluable non-invasive instrument for the investigation of the underlying physiological disturbances that lead to manifest psychiatric disorders. The brain is imaged at discrete time intervals while a subject is required to carryout a task or presented with a stimulus.

The success of the operation depends on three aspects: the scanning sequence used, the design of the stimulus paradigm and the methodsused for data analysis.2 Possible failures during any of these three steps can cause unfavourable evaluation of the measured functional activity and affect the reliability of the conclusions drawn. The fact that these three steps are often carried out by different scientists requires strong collaboration among groups.

It is hoped that successful application and analysis of fMRI in neurological disorders can be used to characterise and diagnose mental illnesses such as Alzheimer’s disease, schizophrenia,bipolar disorder, mild traumatic brain injury and addiction. Both healthy controls and patients can be scanned during various tasks, and responses to these stimuli can be measured and compared to discover the differences between the two groups and investigate how the brain function of patients differs from that of healthy controls.

Among these mental illnesses, schizophrenia is a neurodevelopmental disorder that might result from several factors such as genetic inheritance, disturbance of the in utero environment and exposure to biological and psychosocial factors in infancy and early childhood.3 It is extremely important to be able to determine people with a high risk of schizophrenia to prevent the onset of schizophrenia in persons with prodromal symptoms and to reduce the severity of the illness in those who already have schizophrenia via early diagnosis and intervention.3

There is no gold standard in the diagnosis of schizophrenia and thereare complications in the objective evaluation of the examinations. Interviews and symptom history are the main factors that determine the diagnosis, but conclusions may change because different combinationsof symptoms may be observed in various patients, and these symptoms may change over time for a particular patient.4 This makes schizophrenia a complex disorder to diagnose even for an expert. Biological markers – defined as objective, measurable phenomena that may identify subjects at increased risk of development of disease – should be sought in orderto intervene as soon as possible so as to improve prognosis.3 Objective clinical diagnosis methods are better obtained using biologically measured quantities such as fMRI. Therefore, fMRI has been used in schizophrenia research studies to evaluate prognostic and diagnostic methods. We would like to provide an overview of schizophrenia research using fMRI data and give specific examples based mostly onour past and recent work.

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Keywords:
Functional magnetic resonance imaging (fMRI), schizophrenia, bias, classification, detection

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