The eyes have it: Eye movements and anorexia nervosa

Abstract

Anorexia nervosa (AN) is a significant mental health issue, yet little is known regarding the underlying factors that contribute to illness onset and maintenance. AN has the highest death rate of any mental illness and a recovery rate of less than 50% in surviving patients. Thus gaining an understanding of the neurobiological underpinnings of this condition is of great importance for tailoring appropriate treatments for this illness. To date, the scientific study of AN is considerably variable with few empirical findings being consistently reported. This has been particularly true in relation to the illness' underlying neurobiology. Unlike many other psychiatric conditions, the brain regions and neurotransmitter systems involved in the illness are unknown. A key review published by our group in ANZJP (Phillipou et al., 2014a) highlighted the lack of consistency of the neurobiological literature in AN, and emphasised the need to utilise tasks known to employ specific brain networks to uncover the neurobiological underpinnings of this illness. This was the specific aim of our recent research programme in which we compared patients with AN to healthy individuals on a range of saccadic eye movement tasks. Saccadic eye movement tasks are well-characterised research tools frequently utilised in psychiatric populations to understand cognitive deficits while drawing inferences about compromised neural pathways. Our recent research programme was the first detailed analysis of saccadic eye movements in AN.Eye movements have been thoroughly assessed in aetiological investigations of other psychiatric and neurological conditions, providing valuable information on brain regions and neurotransmitter involvement in these illnesses. The neural circuitry of saccadic eye movements is well understood, and deficits in different saccadic parameters (e.g. error rate, latency, gain and peak velocity) are indicative of specific neurobiological abnormalities. Collectively, our recent research has identified four saccadic eye movement abnormalities in AN, all of which are consistent with saccadic disinhibition and dysfunction of gamma-aminobutyric acid (GABA) in the superior colliculus (SC). These are as follows: (1) hyperscanning (i.e. increased fixations of shorter duration) during two different tasks of face and body viewing, respectively (Phillipou et al., 2015a(Phillipou et al., , 2015b; (2) shorter prosaccade latencies (Phillipou et al., 2016); (3) increased inhibitory errors on a memory-guided saccade (oculomotor delayed response) task (Phillipou et al., 2016); and (4) increased rate of saccadic intrusions, called square wave jerks, during a fixation task, which in combination with anxiety levels were identified as a potential biomarker of AN (Phillipou et al., 2014b).These findings have encouraged the development of a hypothesis for a novel neurobiological underpinning to AN, and have implicated a brain region and neurotransmitter system in the aetiology of the illness that have been previously overlooked. Although further researc...

An Overlooked Brain Region in the Aetiology of Anorexia Nervosa: The Importance of Behaviourally Driven Neuroimaging Analysis

“…Widespread microstructural differences were identified in the AN group encompassing a range of different cortical and subcortical brain regions. The white matter microstructure of a small, deep brain structure called the superior colliculus, which we have hypothesised to be involved in AN from our other works, 10–14 was not found to differ in this set of analyses. A region-of-interest (ROI) approach applied to this small brain region, however, showed that individuals with AN did indeed show deficits in the white matter microstructure of this brain region.…”

Body dysmorphic disorder: a treatment synthesis and consensus on behalf of the International College of Obsessive-Compulsive Spectrum Disorders and the Obsessive Compulsive and Related Disorders Network of the European College of Neuropsychopharmacology

“…Since the publication of the review by Phillipou et al (2016b), an additional study compared the efficacy of continuation pharmacotherapy in people with BDD who initially responded to medication. Phillips et al (2016) treated 100 BDD adult patients with open-label escitalopram* [mean dose at the end of 14 weeks was 26.2 mg/ day (SD 7.2)], whereafter responders (n = 58) were randomized to continuation pharmacotherapy or placebo, and followed for a further 6 months.…”

High‐definition transcranial direct current stimulation in anorexia nervosa: A pilot study

“…The secondary objectives of the trials are exploratory and will assess clinical outcomes from baseline to end point, including Eating Disorder Examination Questionnaire (EDE‐Q; short form) total scores, AN symptom scale scores (adapted from McClelland et al ; Likert scale ratings including urge to eat, urge to exercise, urge to restrict, feeling of fatness, feeling of fullness, mood, and anxiety), and SWJ rate during a fixation task. Additional exploratory outcome measures will include physical measurements (including BMI) and resting state functional connectivity of the left IPL from baseline to treatment end point, as well as assessments that have previously been reported in the literature as characteristics of AN including a battery of eye movement tasks (Phillipou et al, ; Phillipou, Rossell, Gurvich, Castle, & Abel, ; Phillipou, Rossell, Gurvich, Castle, Troje, et al, ; Phillipou, Rossell, Gurvich, Hughes, et al, ) and set‐shifting (i.e., the Wisconsin Card Sorting Test) (Steinglass, Walsh, & Stern, ). Follow‐up assessments will also be completed at 4‐ and 12‐weeks post‐intervention.…”