Predicting the wide-ranging effects of enhancing dopamine on cognition

It is known that adequate dopaminergic stimulation is important for many psychological functions including, memory, learning and social cognition. It is also known that dopamine levels can be increased by a number of pharmaceutical agents such as methylphenidate, and that such agents are associated with significant individual differences. At present our ability to predict individual differences in the effect of enhancing dopamine across a wide-range of tasks is limited. The current study aims to further our understanding of the relationship between baseline measures - such as impulsivity, working memory and social support - and the effects of enhancing dopamine (via methylphenidate administration) across a wide range of tasks. The results of this study will help make progress towards the development of a model which enables the effects of enhancing dopamine on various domains of cognition to be predicted from an individual's scores on a selection of baseline measures. On study day one participants will first undergo a medical screening interview to ensure that they do not meet any of the exclusion criteria. Subjects will then complete a baseline measure of working memory, receive one oral capsule of either 20mg MPH or placebo, rest for approximately 1.5 hours, and then complete the battery of cognitive tests. On study day two, subjects will complete the same procedure, but without the medical screening interview; in this session subjects will receive the capsule (methylphenidate or placebo) that they did not receive on study day one.