NCT02453698

Stimulant Effects on Brain Activity

Stimulant Effects on Brain Activity During the Stop Signal Task

• Status: Completed
• Phase: Phase 1
• Study type: Interventional
• Enrollment: 19 (actual)
• Sponsor: The Hospital for Sick Children · Academic / Other
• Sex: Male
• Age: 18 Years – 35 Years
• Healthy volunteers: Accepted

Summary

The aim of this study is to investigate the effects of Methylphenidate on neural activity underlying inhibitory control and error monitoring in healthy adults. More specifically, the investigators aim to establish the baseline modulatory effect of Mehtlylphenidate on bottom-up and top-down aspects of these cognitive processes. This work will further our understanding of Attention Deficit Hyperactivity Disorder, Methylphenidate, and executive functioning.

Detailed description

Methylphenidate (MPH) is the stimulant medication most commonly used in the treatment of attention deficit hyperactivity disorder (ADHD). MPH suppresses the reuptake of dopamine by blocking dopamine transporter, which is elevated in ADHD. However, the precise mechanism by which suppressed dopamine transporter activity relieves ADHD symptoms is not fully understood, partly because dopamine pathways are implicated in various processes that could play a role in the deficits of ADHD and other disorders. MPH-induced dopamine variation has extensive effects in the brain and influences various executive functions in unknown ways. Hypotheses: Inhibitory Control: The investigators predict that MPH should increase the top-down activity in right dorsolateral prefrontal cortex associated with response restraint during go-phases and bottom-up activity in caudate and right inferior frontal cortex associated with response cancellation during successful stop trials. A greater modulation of top-down or bottom-up activity would imply a selective effect of MPH on one pathway over the other. Error Processing: The investigators predict that MPH should increase the intensity of deactivation in the bottom-up dopamine pathway on error detection (substantia nigra, dorsal striatum and ACC), and increase the intensity of deactivation in the top-down pathway on post-error slowing (caudal OFC, ventral striatum, ventral substantia nigra). A greater modulation of top-down or bottom-up activity would imply a selective effect of MPH on one pathway over the other.

Conditions

• Healthy Volunteers

Interventions

Type	Name	Description
DRUG	Methylphenidate	oral dose of methylphenidate. The MPH dose was selected based on previous studies in healthy adults (Mehta et al., 2000; Volkow, Fowler, Wang, Ding, \& Gatley, 2002) and adults with ADHD (Aron et al., 2003). MPH reaches its peak plasma concentration 1-3 hours after an oral dose, and has a plasma half-life of 1.5-2.5 hours.
OTHER	Placebo	Lactose Placebo

Timeline

• Start date: 2011-01-01
• Primary completion: 2012-01-01
• Completion: 2012-03-01
• First posted: 2015-05-25
• Last updated: 2015-05-25

Locations

1 site across 1 country: Canada