A Study to Characterize Event Related Potential Markers of Attentional Bias Towards Words and Images of Food
GSK is planning to undertake two anti-obesity drug studies in the area of obesity. In addition to assessment by questionnaires, it would be of significant value to incorporate an objective non-interventional measure of cognitive or motivational processing associated with evaluating and responding to food stimuli. Obesity is associated with increased attentional bias to palatable foods. The aims of this protocol are two-fold, first to characterize Event Related Potentials (ERPs) of two common aspects of food stimuli relevant to eating disorders -presence of food and its palatability, and secondly, to assess the modulation of these ERPs by appetite. Following a successful completion of this study, it is the intention to use the paradigm developed in future studies in the area of obesity.
|Study Design:||Observational Model: Case-Only
Time Perspective: Retrospective
|Official Title:||An Experimental Medicine Study to Characterize Event Related Potential Markers of Attentional Bias Towards Words and Images of Food in Healthy Volunteers|
- Event Related Potential Amplitude, Latency and Area Under the Curve, Reaction [ Time Frame: 1 hour ] [ Designated as safety issue: No ]
- Hip-to-waist ratio and BMI [ Time Frame: 6 hours ] [ Designated as safety issue: No ]
|Study Start Date:||October 2009|
|Study Completion Date:||October 2010|
|Primary Completion Date:||December 2009 (Final data collection date for primary outcome measure)|
At approximately 09:00 the subject will be given breakfast. After this, no food will be served until study procedures for the day are over. However, a 330 ml bottle of still water at room temperature will be given at ~11:00 and at ~13:00. During this period the subject will be required to remain in the unit.
At approximately 13:00 the subject will be given a standard high calorie lunch that the subject is required to finish
GlaxoSmithKline is currently developing a number of drugs for the treatment of overheating including 'binge eating' in obesity. Historically, the behavioural effectiveness of anti-obesity drugs in clinical drug trials have utilised subjective rating scales to assess a person's drive or motivation to eat. Findings from these studies have good construct validity, but suffer from the shortcomings of self-reporting, e.g. the subject bias, dishonesty, misinterpretation. It follows that in addition to self-reporting, it would strengthen the interpretation of any future studies on anti-obesity drugs, if there were to be an objective measure of brain activity in relation to cognitive/motivational processes associated with evaluation and responding to food related cues.
Measuring event related potentials (ERPs) during cognitive processes of food related cues, using the electroencephalography technique (EEG) offers a an alternative objective approach to examining the effectives of anti-obesity drugs.
This protocol proposes to develop and use two cognitive tasks examining response to food related cues (pictorial and words) with concurrent recording of ERPs, in order to characterize neurophysiological events associated with attentional bias towards food related stimuli.
The first task is an image processing task. This task uses food images similar to those in the International Affective Picture System (IAPS) used in ERP studies of perceptual processing of emotional stimuli [Olofsson, 2008; Schupp, 2006]. In this task a subject views different categories of images; palatable high-calorie food images, non-palatable low-calorie food images and non-edible plant images. The latter is the neutral category against which the ERPs of the two food categories will be compared. Affective pictures have been used to assess emotional valence by measuring differences in anterior ERP measurements between images from differing groups.
The protocol also proposes to measure late positive potential in order to assess higher level cognitive processing possibly with early memory formation. Again, the proposal is to assess AUCs, in this case in the 400-600 ms region and then look at difference curves between the late potential potentials to different valency stimuli. For the late positive potentials, anterior laterality will also be assessed. The second task is a cued-target task of visuospatial attention to motivationally salient words. The task is a version of the Posner paradigm. The appearance of a food or nonfood word inside a top or bottom frame (the cue) distracts the attention of the subject towards that spatial location. Following the word either one of the two frames changes appearance (the target).
In addition to these emotion and attention measures, the protocol proposes to assess the more standard N1, P1 and P3 [Luck, 2005]. After completing the ERP recordings the subject will be asked to rate each picture for salience and valence in order to provide a comparison between objective neurophysiological and subjective attention and emotional ratings.