Pilot Study Using an NMDA Antagonist to Modulate Transcranial Direct Current Stimulation (tDCS) Effects on Sensory Discrimination

Study Results

Results pending

The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.

Basic Information

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Recruitment Status

UNKNOWN

Clinical Phase

PHASE1/PHASE2

Total Enrollment

12 participants

Study Classification

INTERVENTIONAL

Study Start Date

2015-04-30

Study Completion Date

2016-04-30

Brief Summary

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Transcranial direct current stimulation (tDCS) is a non-invasive form of brain stimulation which uses a very weak constant current to temporarily excite the brain area of interest via small electrodes placed on the scalp. Currently, tDCS is being used as a tool to investigate mental processes (cognition) and motor function (movement) in healthy controls and to treat neurological (i.e. stroke) and psychiatric (i.e. depression and dementia) patients. tDCS has been found to improve motor processes and cognitive performance, including attention and memory functions. This study will attempt to examine the effects of tDCS on a specific aspect of short term memory to sounds measured from electrical activity (EEG) from the top of the scalp. This study will also assess the effect of a drug, dextromethorphan (DMO), commonly found in cough syrup, which is thought to regulate tDCS treatment through brain receptors. The study involves four laboratory test sessions. EEG assessments will be done in two sessions involving 'anodal' tDCS stimulation (to temporarily excite cortical activity locally), one session with DMO treatment and one with placebo treatment, and two sessions involving 'sham' tDCS stimulation (device is turned off), with the same DMO and placebo treatments. These findings will contribute to our understanding of the brain chemistry involved in tDCS treatment and its effects on cognitive abilities.

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Detailed Description

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Conditions

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Schizophrenia

Study Design

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Allocation Method

RANDOMIZED

Intervention Model

CROSSOVER

Blinding Strategy

DOUBLE

Participants Investigators

Study Groups

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Direct Current Stimulation active

Electrodes will be placed on the scalp overlying the left auditory cortex (anodal electrode) and on the contralateral forehead above the orbit (reference/cathode). Stimulation will be applied using a battery-driven constant-current regulator (Oasis Pro, Edmonton). In active tDCS sessions, the DC current will be initially increased in a ramp-like fashion over 10 s until reaching 2 mA and will be similarly decreased at the end of stimulation. In active tDCS, stimulation will be maintained for a total of 20 minutes. This will occur in two separate sessions, occurring within weeks.

Group Type ACTIVE_COMPARATOR

Direct Current Stimulation

Intervention Type DEVICE

Comparison between active Direct Current Stimulation (2 mA, 20 minutes) and Sham stimulation (the device is set up, but only turned on for 30 seconds).

Conductive saline-soaked rubber electrodes super-imposed on sponge plates will be placed on the scalp overlying the left auditory cortex (anodal electrode) and on the contralateral forehead above the orbit (reference/cathode). Stimulation will be applied using a battery-driven constant-current regulator (Oasis Pro, Edmonton). In active tDCS sessions, the DC current will be initially increased in a ramp-like fashion over 10 s until reaching 2 mA and will be similarly decreased at the end of stimulation. In active tDCS, stimulation will be maintained for a total of 20 minutes. This will occur in two separate sessions, occurring within weeks. For 'sham' stimulation, the device will only be turned on for 30 seconds. This will occur in two separate sessions, occurring within weeks.

Direct Current Stimulation sham

In sham sessions, the device will have the same placement and intensity, but will only be turned on for 30 seconds. The DC current will be initially increased in a ramp-like fashion over 10 s until reaching 2 mA and will be similarly decreased at the end of stimulation. This will occur in two separate sessions, occurring within weeks.

Group Type SHAM_COMPARATOR

Direct Current Stimulation

Intervention Type DEVICE

Comparison between active Direct Current Stimulation (2 mA, 20 minutes) and Sham stimulation (the device is set up, but only turned on for 30 seconds).

Conductive saline-soaked rubber electrodes super-imposed on sponge plates will be placed on the scalp overlying the left auditory cortex (anodal electrode) and on the contralateral forehead above the orbit (reference/cathode). Stimulation will be applied using a battery-driven constant-current regulator (Oasis Pro, Edmonton). In active tDCS sessions, the DC current will be initially increased in a ramp-like fashion over 10 s until reaching 2 mA and will be similarly decreased at the end of stimulation. In active tDCS, stimulation will be maintained for a total of 20 minutes. This will occur in two separate sessions, occurring within weeks. For 'sham' stimulation, the device will only be turned on for 30 seconds. This will occur in two separate sessions, occurring within weeks.

NMDA antagonist active

Dextromethorphan (DMO), a non-competitive NMDA antagonist, will be delivered in the form of generic Life Brand Clear Cough Syrup DM (Trillium Healthcare Products Inc, Brockville, ON). Each subject will receive a dose of 50 ml DM with no-sugar cranberry juice (100 ml) to drink. This same dose will be delivered in two separate sessions, occurring within weeks.

Group Type ACTIVE_COMPARATOR

Dextromethorphan

Intervention Type DRUG

Comparison between Dextromethorphan and a no-sugar placebo. Dextromethorphan (DMO), a non-competitive NMDA antagonist, will be delivered in the form of generic Life Brand Clear Cough Syrup DM (Trillium Healthcare Products Inc, Brockville, ON), which has high dose of DMO (15 mg/5 ml) with no other major additives. Each subject will receive a dose of 50 ml DM with no-sugar cranberry juice (100 ml) to drink from a mug, while wearing a nose plug. This same dose will be delivered in two separate sessions, occurring within weeks. Each subject will receive a dose of a placebo (150 ml of no-sugar cranberry juice) to drink from a mug, while wearing a nose plug. This same dose will be delivered in two separate sessions, occurring within weeks.

NMDA antagonist placebo

Each subject will receive a dose of a placebo (150 ml of no-sugar cranberry juice) to drink. This same dose will be delivered in two separate sessions, occurring within weeks.

Group Type PLACEBO_COMPARATOR

Dextromethorphan

Intervention Type DRUG

Comparison between Dextromethorphan and a no-sugar placebo. Dextromethorphan (DMO), a non-competitive NMDA antagonist, will be delivered in the form of generic Life Brand Clear Cough Syrup DM (Trillium Healthcare Products Inc, Brockville, ON), which has high dose of DMO (15 mg/5 ml) with no other major additives. Each subject will receive a dose of 50 ml DM with no-sugar cranberry juice (100 ml) to drink from a mug, while wearing a nose plug. This same dose will be delivered in two separate sessions, occurring within weeks. Each subject will receive a dose of a placebo (150 ml of no-sugar cranberry juice) to drink from a mug, while wearing a nose plug. This same dose will be delivered in two separate sessions, occurring within weeks.

Interventions

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Direct Current Stimulation

Comparison between active Direct Current Stimulation (2 mA, 20 minutes) and Sham stimulation (the device is set up, but only turned on for 30 seconds).

Conductive saline-soaked rubber electrodes super-imposed on sponge plates will be placed on the scalp overlying the left auditory cortex (anodal electrode) and on the contralateral forehead above the orbit (reference/cathode). Stimulation will be applied using a battery-driven constant-current regulator (Oasis Pro, Edmonton). In active tDCS sessions, the DC current will be initially increased in a ramp-like fashion over 10 s until reaching 2 mA and will be similarly decreased at the end of stimulation. In active tDCS, stimulation will be maintained for a total of 20 minutes. This will occur in two separate sessions, occurring within weeks. For 'sham' stimulation, the device will only be turned on for 30 seconds. This will occur in two separate sessions, occurring within weeks.

Intervention Type DEVICE

Dextromethorphan

Comparison between Dextromethorphan and a no-sugar placebo. Dextromethorphan (DMO), a non-competitive NMDA antagonist, will be delivered in the form of generic Life Brand Clear Cough Syrup DM (Trillium Healthcare Products Inc, Brockville, ON), which has high dose of DMO (15 mg/5 ml) with no other major additives. Each subject will receive a dose of 50 ml DM with no-sugar cranberry juice (100 ml) to drink from a mug, while wearing a nose plug. This same dose will be delivered in two separate sessions, occurring within weeks. Each subject will receive a dose of a placebo (150 ml of no-sugar cranberry juice) to drink from a mug, while wearing a nose plug. This same dose will be delivered in two separate sessions, occurring within weeks.

Intervention Type DRUG

Other Intervention Names

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Life Brand Clear Cough Syrup DM

Eligibility Criteria

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Inclusion Criteria

* Healthy, medication free
* Non-smoker
* Right-handed

Exclusion Criteria

* Any current or past Axis I or Axis II disorder including a current or recent history of alcohol/substance abuse
* A clinically significant medical illness or organic brain disorder known to cause psychosis or cognitive impairment
* Any neurological diagnosis (including epilepsy)
* Recent head trauma (\<6 months)
* Metallic implants or any electrical device (e.g., pacemaker) in the body
* Major learning disability
* Body mass index \>38kg/m¬2
* Use of illicit drugs
* Abnormal hearing

Minimum Eligible Age

18 Years

Maximum Eligible Age

35 Years

Eligible Sex

ALL

Accepts Healthy Volunteers

Yes