Effects of LDX on Cognitive Processes and Appetite

This study will investigate the effect of lisdexamfetamine dimesylate (LDX) on the mediating factors of reward and cognition on appetite.

This study will investigate the specific reward and cognitive mechanisms that mediate the effects of LDX on eating in participants with sub-clinical binge-eating disorder symptoms. A sub-clinical sample will be recruited in line with the Research Domain Criteria Initiative established by the US National Institute of Mental Health which encourages research on dimensions of observable behaviour rather than a categorical, symptom-based approach to the study of mental health. The tendency towards binge-like eating will be modelled using an eating in the absence of hunger paradigm in which participants consume a pasta meal and are then offered the opportunity to consume as many palatable cookies as they like. Reward processes will be assessed by measuring neural and behavioural responses to palatable food pictures using functional Magnetic Resonance Imaging (fMRI). Responses to emotional stimuli will be assessed using the P1vital® Oxford Emotional Test Battery. Impulsive responding will be assessed using the delay discounting task and the stop signal task. Attentional processing will be assessed using the sustained performance task and working memory will be assessed with the n-back task.

Eligibility Criteria:
Inclusion Criteria:

* Fluent English speakers
* Be willing to be informed of chance pathological findings from the fMRI scan
* Must have binge-eating symptoms that is measured by a minimum score of 18 on the Binge Eating Scale
* Must have a minimum BMI of 18.5
* Must be below 152.4kg
* Must have clearance from a qualified physician before participating

Exclusion Criteria:

* Symptoms or diagnosis of other eating disorders.

  * Psychotherapy and/or pharmacotherapy for binge-eating disorder (BED) 3 months before the study, as this will suggest a diagnosis of BED and may influence eating behaviour.
  * Metabolic (e.g. metabolic disorder, diabetes), psychological (e.g. depression), substance, or neurological (e.g. epilepsy, headache disorder, multiple sclerosis, traumatic brain injuries) diseases or medication in relation to these diseases
  * Intake of any medication that can interfere with the drug or measurements, determined through questionnaires in the screening session
  * Current smoking, as it can interfere with appetite
  * Current pregnancy or breastfeeding
  * Not passing a breathalyser test on the morning of testing.
  * Food allergies (e.g. peanut allergy, lactose and gluten intolerance) or vegetarian/vegan diet
  * Disliking the study lunch to ensure that participants will consume the provided food
  * Women will be asked to participate only in weeks when they are not menstruating or in their pre-menstrual week, to avoid hormonal disruption to appetite.

The following are exclusion criteria are specific to the MRI scanner:

* Non-removable metal object in or on their body, such as: heart pace-maker, artificial heart valve, metal prosthesis, implants or splinters, non-removable dental braces
* Left-handed
* Tattoos that are older than 10 years
* Claustrophobia
* Limited temperature perception and/or increased sensitivity to warming of the body
* Pathological hearing ability or an increased sensitivity to loud noises
* Operation less than three months ago
* Simultaneous participation in other studies that involve drug intake or blood sampling
* Acute illness or infection during the last 4 weeks
* Cardiovascular disorders (e.g., hypertrophic cardiomyopathy, long QT syndrome) to ensure medical fitness to participate
* Moderate or severe head injury