Psychiatry - Research Publications
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ItemA biomarker and endophenotype for anorexia nervosa?(SAGE PUBLICATIONS LTD, 2022-08-01)OBJECTIVE: Recent research has suggested that a type of atypical eye movement, called square wave jerks, together with anxiety, may distinguish individuals with anorexia nervosa from those without anorexia nervosa and may represent a biomarker and endophenotype for the illness. The aim of this study was to identify the presence of this proposed marker in individuals currently with anorexia nervosa relative to healthy controls, and to identify the state independence and heritability of this putative marker by exploring whether it also exists in individuals who are weight-restored from anorexia nervosa and first-degree relatives (i.e. sisters of people with anorexia nervosa). METHODS: Data from 80 female participants (20/group: current anorexia nervosa, weight-restored from anorexia nervosa, sisters of people with anorexia nervosa and healthy controls) were analysed. Square wave jerk rate was acquired during a fixation task, and anxiety was measured with the State Trait Anxiety Inventory. RESULTS: Current anorexia nervosa, weight-restored from anorexia nervosa and sisters of people with anorexia nervosa groups made significantly more square wave jerks than healthy controls, but did not differ from one another. Square wave jerk rate and anxiety were found to discriminate groups with exceptionally high accuracy (current anorexia nervosa vs healthy control = 92.5%; weight-restored from anorexia nervosa vs healthy control = 77.5%; sisters of people with anorexia nervosa vs healthy control = 77.5%; p < .001). CONCLUSION: The combination of square wave jerk rate and anxiety was found to be a promising two-element marker for anorexia nervosa, and has the potential to be used as a biomarker or endophenotype to identify people at risk of anorexia nervosa and inform future treatments.
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ItemHigh-definition transcranial direct current stimulation in anorexia nervosa: A pilot study(WILEY, 2019-11)OBJECTIVE: Anorexia nervosa (AN) is a serious psychiatric condition often associated with poor outcomes. Biologically informed treatments for AN, such as brain stimulation, are lacking, in part due to the unclear nature of the neurobiological contributions to the illness. However, recent research has suggested a specific neurobiological target for the treatment of AN, namely stimulation of the inferior parietal lobe (IPL). The aim of this study was to stimulate-noninvasively-the left IPL in individuals with AN using high-definition transcranial direct current stimulation (HD-tDCS). METHOD: Twenty participants will be randomized to receive 10 daily sessions of HD-tDCS or sham HD-tDCS (placebo). Assessments will be carried out at baseline and end point, as well as 4- and 12-week follow-ups. DISCUSSION: This pilot investigation will primarily determine the feasibility and acceptability of this intervention.
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ItemDifferences in regional grey matter volumes in currently ill patients with anorexia nervosa(WILEY, 2018-01)Neurobiological findings in anorexia nervosa (AN) are inconsistent, including differences in regional grey matter volumes. Methodological limitations often contribute to the inconsistencies reported. The aim of this study was to improve on these methodologies by utilising voxel-based morphometry (VBM) analysis with the use of diffeomorphic anatomic registration through an exponentiated lie algebra algorithm (DARTEL), in a relatively large group of individuals with AN. Twenty-six individuals with AN and 27 healthy controls underwent a T1-weighted magnetic resonance imaging (MRI) scan. AN participants were found to have reduced grey matter volumes in a number of areas including regions of the basal ganglia (including the ventral striatum), and parietal and temporal cortices. Body mass index (BMI) and global scores on the Eating Disorder Examination Questionnaire (EDE-Q) were also found to correlate with grey matter volumes in a region of the brainstem (including the substantia nigra and ventral tegmental area) in AN, and predicted 56% of the variance in grey matter volumes in this area. The brain regions associated with grey matter reductions in AN are consistent with regions responsible for cognitive deficits associated with the illness including anhedonia, deficits in affect perception and saccadic eye movement abnormalities. Overall, the findings suggest reduced grey matter volumes in AN that are associated with eating disorder symptomatology.
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ItemEye movements in anorexia nervosa: State or trait markers?(WILEY, 2020-10)OBJECTIVE: Differences in saccadic eye movements are widely reported in mental illnesses, and can indirectly inform our understanding of neurobiological and cognitive underpinnings of psychiatric conditions, including anorexia nervosa (AN). Preliminary research has suggested that individuals with AN may show specific eye movement abnormalities; whether these deficits are representative of state or trait effects is, however, unclear. The aim of this study was to identify whether there are demonstrable differences in performance on saccadic eye movement tasks in individuals with current AN (c-AN), those who are weight-restored from AN (wr-AN), biological sisters of individuals with AN (AN-sis), and healthy controls (HC). METHODS: Eighty participants took part in the study (n = 20/group). A set of saccadic eye movement tasks was administered, including prosaccade, antisaccade, memory-guided saccade, and visual scanpath tasks. RESULTS: The c-AN group showed an increased rate of inhibitory errors to 10° targets on the memory-guided saccade task. DISCUSSION: The results are discussed in terms of the potential role of the superior colliculus in AN, and that the findings may reflect a state measure of AN.
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ItemAn Overlooked Brain Region in the Aetiology of Anorexia Nervosa: The Importance of Behaviourally Driven Neuroimaging Analysis(SAGE PUBLICATIONS LTD, 2018-12-20)The neurobiological contributions to anorexia nervosa (AN) remain poorly understood, hindering the development of effective neurobiological treatments such as medications and brain stimulation. A large number of studies have been undertaken utilising neuroimaging techniques, such as magnetic resonance imaging (MRI), to gain a better understanding of the brain mechanisms involved in the illness. However, the analyses undertaken by many studies have utilised a whole-brain analytical approach as much of this research has been exploratory in nature. This is, however, problematic as small brain regions that differ between groups may not have the statistical power to produce statistically significant results. This is highlighted in a recent study undertaken by our group utilising diffusion-weighted imaging. In this research, we identified widespread white matter microstructural differences in individuals with AN, but only showed differences in a small brain region (the superior colliculus) when a region-of-interest approach that was driven by behavioural findings was utilised. The importance of hypothesis-driven neuroimaging analyses is discussed in this article.
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ItemSelf perception and facial emotion perception of others in anorexia nervosa(FRONTIERS MEDIA SA, 2015-08-10)BACKGROUND: Whether individuals with anorexia nervosa (AN) are able to accurately perceive emotions from faces of others is unclear. Furthermore, whether individuals with AN process images of their own face differently to healthy individuals has thus far not been investigated. Therefore, the aim of this study was to investigate facial affect processing and the processing of one's own face through measures of emotion identification, functional magnetic resonance imaging (fMRI) and eyetracking. METHODS: Twenty-four females with AN and 25 matched healthy control participants were presented with an implicit emotion processing task during fMRI and eyetracking, followed by an explicit emotion identification task. RESULTS: The AN group were found to 'hyperscan' stimuli and avoided visually attending to salient features of their own face images. RESULTS of the fMRI revealed increased activity to own face stimuli in AN in the right inferior and middle temporal gyri, and right lingual gyrus. AN participants were not found to display emotion identification deficits to the standard emotional face stimuli. DISCUSSION: The findings are discussed in terms of increased anxiety to disorder-relevant stimuli in AN. Potential clinical implications are discussed in relation to the use of eyetracking techniques to improve the perception of self in AN.
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ItemSelf-reported and behavioural impulsivity in anorexia nervosa(BAISHIDENG PUBLISHING GROUP INC, 2016-09-22)AIM: To examine how self-reported and behavioural impulsivity are related in anorexia nervosa (AN). METHODS: Twenty-four females with AN and 25 healthy controls (HC) participant in the study. Self-reported impulsivity was assessed with the Barratt Impulsiveness Scale (BIS-11). The scale yields three second-order factors: Attentional, motor and non-planning. Behavioural impulsivity was investigated with the continuous performance test (CPT), a computer-based task of sustained attention in which numbers are flashed briefly on screen and participants are required to click the mouse when the same number appears consecutively. The rate of commission and omission errors can be used a measure of behavioural imulsivity. RESULTS: AN participants self-reported increased attentional [AN: 20.67 (3.64), HC: 13.88 (2.91), P = 0.001] and reduced motor impulsivity [AN: 11.55 (2.28), HC: 14.08 (2.78), P = 0.002]. The rate of omission or commission errors on the CPT did not differ between groups (P > 0.05). BIS-11 and CPT measures did not significantly correlate, but attentional impulsivity was related to negative mood states in AN (depression: r = 0.52, P = 0.010, anxiety: r = 0.55, P = 0.006, stress: r = 0.57, P = 0.004). CONCLUSION: The discrepancy between self-reported and behavioural impulsivity are discussed in terms of perfectionism in AN. Furthermore, it is suggested that improving negative mood states may resolve this inconsistency in AN.
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ItemSaccadic Eye Movements in Anorexia Nervosa(PUBLIC LIBRARY SCIENCE, 2016-03-24)BACKGROUND: Anorexia Nervosa (AN) has a mortality rate among the highest of any mental illness, though the factors involved in the condition remain unclear. Recently, the potential neurobiological underpinnings of the condition have become of increasing interest. Saccadic eye movement tasks have proven useful in our understanding of the neurobiology of some other psychiatric illnesses as they utilise known brain regions, but to date have not been examined in AN. The aim of this study was to investigate whether individuals with AN differ from healthy individuals in performance on a range of saccadic eye movements tasks. METHODS: 24 females with AN and 25 healthy individuals matched for age, gender and premorbid intelligence participated in the study. Participants were required to undergo memory-guided and self-paced saccade tasks, and an interleaved prosaccade/antisaccade/no-go saccade task while undergoing functional magnetic resonance imaging (fMRI). RESULTS: AN participants were found to make prosaccades of significantly shorter latency than healthy controls. AN participants also made an increased number of inhibitory errors on the memory-guided saccade task. Groups did not significantly differ in antisaccade, no-go saccade or self-paced saccade performance, or fMRI findings. DISCUSSION: The results suggest a potential role of GABA in the superior colliculus in the psychopathology of AN.