[Functional MRI for schizophrenia: importance of the type of task being scanned].

BACKGROUND:Functional magnetic resonance imaging (fMRI) is an important technique for detecting neural network problems in patients with schizophrenia. Very often, however, the professionals involved are insufficiently aware of the fact that when fMRI scans are used for patients with schizophrenia, it is the type of task that patients are performing or failing to perform which is of vital importance for the correct interpretation of the results. AIM:To demonstrate that in scans of patients with schizophrenia the choice of task can influence neuroimaging results, particularly when the neural problems under study are performance-related. METHOD:We begin by presenting a brief history of functional neuroimaging techniques. This provides a context for the study of the potential role of fMRI in detecting dysfunctional brain networks in schizophrenia. In this way we demonstrate more clearly why the rapidly developing scanning techniques and analysis methods are becoming more and more important for measuring specific differences between psychiatric disorders. Then, we discuss the complex relationship between cognitive deficits in patients with schizophrenia, problems in task performance, and disease-related effects on brain activation measured by fMRI. RESULTS:This is illustrated by our own recent work, in which we demonstrate the complex relationship between cognitive deficits in the task performance of patients with schizophrenia and differences in brain activity measured with fMRI. We stress the importance of task-independent neural networks for the interpretation of results. These networks may play a role similar to that of the potentially confounding effects of task choice. Finally, we consider challenges for the future and comment on how fMRI needs to be developed so that it can be used successfully in clinical practice in order to assist with the diagnosis, prognosis and treatment of schizophrenia. CONCLUSION:It is crucial for neuroimaging research into schizophrenia, and for potential clinical applications, that new types of tasks are developed that avoid the confounding effects on neural activity which are caused by performance differences stemming from aspecific factors such as demotivation or task-disengagement.