Evidence-Based Medicine Evaluation of Electrophysiological Studies of the Anxiety Disorders

Abstract

We provide a systematic, evidence-based medicine (EBM) review of the field of electrophysiology in the anxiety disorders. Presently, electrophysiological studies of anxiety focus primarily on etiological aspects of brain dysfunction. The review highlights many functional similarities across studies, but also identifies patterns that clearly differentiate disorder classifications. Such measures offer clinical utility as reliable and objective indicators of brain dysfunction in individuals and indicate potential as biomarkers for the improvement of diagnostic specificity and for informing treatment decisions and prognostic assessments. Common to most of the anxiety disorders is basal instability in cortical arousal, as reflected in measures of quantitative electroencephalography (qEEG). Resting electroencephalographic (EEG) measures tend to correlate with symptom sub-patterns and be exacerbated by condition-specific stimulation. Also common to most of the anxiety disorders are condition-specific difficulties with sensory gating and the allocation and deployment of attention. These are clearly evident from evoked potential (EP) and event-related potential (ERP) electrical measures of information processing in obsessive compulsive disorder (OCD), post-traumatic stress disorder (PTSD), panic disorder (PD), generalized anxiety disorder (GAD) and the phobias. Other'ERP measures clearly differentiate the disorders. However, there is considerable variation across studies, with inclusion and exclusion criteria, medication status and control group selection not standardized within condition or across studies. Study numbers generally preclude analysis for confound removal or for the derivation of diagnostic biomarker patterns at this time. The current trend towards development of databases of brain and cognitive function is likely to obviate these difficulties. In particular, electrophysiological measures of function are likely to play a significant role in the development and subsequent adaptations of DSM-V and assist critically in securing improvements in nosological and treatment specificity.

Application of Neurofeedback in General Neurology Practice

“…QEEG analysis of patients with chronic headache (Table 1) is consistent with a prior report indicating an increase of beta power in frontal and=or occipital locations (Walker, 2011). These patients frequently suffer from coexisting anxiety contributing also to elevated beta band expression (Budzynski, Budzynski, Evans, & Abarbanel, 2009;Clark et al, 2009). Pretreatment QEEG findings of patients with memory and cognitive problems (Table 1) revealed a marked increase of theta and sometimes even delta power, likely confirming an organic etiology of their underling condition.…”

The Quantitative Electroencephalogram and the Low-Resolution Electrical Tomographic Analysis in Posttraumatic Stress Disorder

“…[18][19][20][21] The affected frontal structures were linked previously to the experience and regulation of emotion, 22 while the right temporal lobe dysfunction can elicit the re-enactment and re-living of past experiences that may cause the flashback symptoms. 23 One of the current neural models for PTSD is associated with deficits in information processing as well as with hypervigilance to salient and threat-related stimuli.…”

EEG source activity during processing of neutral stimuli in subjects with anxiety disorders

“…Disturbed bioelectric activity in the critical period of stimulus assessment and selection of the appropriate reaction proves the instability of the neural systems responsible for information selection, engagement, focusing attention and use of working memory (Clark et al 2009). …”