The Effect of a Single Dose of Lamotrigine on Brain Function in Healthy Volunteers

Glutamate has been implicated in the aetiology of mood disorders and there is current interest in developing novel agents targeting this system. However, the role of glutamate in human emotional function is relatively unknown. Lamotrigine's pharmacological profile involves a blockade of voltage-gated sodium channels, leading to an inhibition in the release of glutamate and resulting in a general inhibitory effect on cortical neuronal function.

The current study plans to investigate the effects of modifying glutamate on emotional processing, cognitive function and neural activity. For this, 36 healthy volunteers will be recruited to the study and randomised to receive a single dose of lamotrigine (300 mg) or placebo. Two hours after drug administration, the effects of emotional processing via the use of cognitive tasks will be assessed using fMRI. This will be followed by an emotional test battery that will measure aspects of cognitive function as well.

Inclusion criteria

• Male or female
• Aged 18-40 years
• Willing and able to give informed consent for participation in the study
• Sufficiently fluent English to understand and complete the task

Exclusion criteria

• Current usage of psychoactive medication
• Current usage of the contraceptive pill
• Any past or current Axis 1 DSM-IV psychiatric disorder
• Significant medical condition
• Current pregnancy or breastfeeding
• Current or past history of drug or alcohol dependency
• Participation in a psychological or medical study involving the use of medication within the last 3 months
• Previous participation in a study using the same, or similar, emotional processing tasks
• Smoker > 5 cigarettes per day
• Typically drinks > 6 caffeinated drinks per day
• Takes folic acid supplements
• History of recurrent allergies and rashes
• Contraindication to MRI (e.g. claustrophobia and metallic implants)