Stimulant Effects on Brain Activity

Phase 1

Completed

• Conditions: Healthy Volunteers
• Interventions: Other: Placebo; Drug: Methylphenidate

• Registration Number: NCT02453698
• Lead Sponsor: The Hospital for Sick Children

Brief 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.

Study Timeline

• Study Start: 2011-01
• Primary Completion: 2012-01
• Study Completion: 2012-03
• Status Verified: 2015-05
• Study First Submitted: 2015-05-21
• Study First Submitted QC: 2015-05-22
• Last Update Submitted: 2015-05-22
• Study First Posted: 2015-05-25
• Last Update Posted: 2015-05-25

Recruitment & Eligibility

• Status: COMPLETED
• Sex: Male
• Target Recruitment: 19

Inclusion Criteria

Not provided

Exclusion Criteria

Not provided

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: CROSSOVER

Arm && Interventions

Group	Intervention	Description
Control Group	Placebo	-
Methylphenidate	Methylphenidate	-

Primary Outcome Measures

Name	Time	Method
Neural activity assessed using fMRI	7 days	Assessed using fMRI

Trial Locations

Locations (1)

The Hospital for Sick Children; 🇨🇦 Toronto, Ontario, Canada