The role of neuroimaging for the diagnosis and treatment of anxiety disorders

Abstract

Neuroimaging comprises a set of tools, which include different types of magnetic resonance imaging such as fMRI, MRS, ASL, and radiotracer imaging such as PET and SPECT. The focus of this review is to address the question whether functional magnetic resonance imaging (fMRI) can contribute to the diagnosis and treatment of anxiety disorders. Key anxiety processes and neural substrates are reviewed. The main findings and shortcomings of fMRI in the context of anxiety are briefly summarized. Finally, the next stages of developing fMRI for diagnosis and treatment are highlighted. The main conclusion of this review is that fMRI could become a clinical tool for the diagnosis and treatment of anxiety disorders but neuroimaging groups will need to better develop its specificity and sensitivity so that fMRI results can be meaningful for an individual patient not just for groups of individuals. fMRI -what is it and what does it measure?Functional magnetic resonance imaging (fMRI) is a technique that enables one to map cognitive, affective, and experiential processes onto brain substrates. However, fMRI is not about increased or decreased activation in a certain part of the brain; rather it is a proxy measure about how complex cognitive, emotional, social and other experiential processes are implemented in different neural systems. For example, it is important to realize that it makes little sense to talk about hyperactivity in the amygdala in individuals with anxiety disorder without referencing the process, which is being measured during the amygdala hyperactivity, i.e. the task that individuals are engaged in while the functional images are obtained. Although the human brain comprises only about 2% of the body mass, it accounts for approximately 20% of its total oxygen consumption [1]. Deoxyhemoglobin has paramagnetic effects in the blood upon the nuclear magnetic resonance transverse relaxation times of nearby water protons in the tissue [2]. The fact that changes in the oxygen level in the blood can affect the fraction of hemoglobin in the deoxygenated state can be utilized as an image contrast and was termed as blood oxygenation level dependent (BOLD) functional magnetic resonance imaging (fMRI) [3]. Recent BOLD fMRI experiments in the awake Correspondence should be sent to: Martin P Paulus, Professor in Residence,

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