TMS Measures of Plasticity and Excitatory/Inhibitory Ratio as Biomarkers: R-baclofen Effects in Normal Volunteers

Summary

Our overall objective is to apply Transcranial Magnetic Stimulation (TMS) to develop measures of human synaptic plasticity and of brain excitatory:inhibitory ratio (E:I ratio), which we propose as novel biomarkers and outcome measures that will expedite clinical trials of treatments for Autism Spectrum Disorder (ASD). One potential therapeutic agent, R-baclofen will be investigated under this protocol.

TMS is a safe, inexpensive and noninvasive means to focally stimulate the human brain. Presently, TMS is in extensive use as a means to measure regional brain excitability, which is dependent on local synaptic strength. TMS can be used to temporarily alter synaptic strength as well as to acutely measure levels of cortical excitability and short and long interval inhibition. Since altered synaptic plasticity and an imbalanced inhibitory:excitatory ratio are cited as fundamental abnormalities in ASD, we hypothesize that both severity of ASD-related learning deficits and their improvement after therapy will correlate with TMS measures of synaptic plasticity and E:I ratio. We propose to embed TMS measures of synaptic plasticity and E:I ratio in a 'Proof of Principal' trial of R-baclofen and to examine:

Aim 1: Whether R-baclofen (a potential therapeutic agent for ASD) predictably alters TMS measures of synaptic plasticity and E:I ratio as a function of plasma concentration in adult volunteers. We will test the following hypotheses:

1. R-baclofen produces a significant change in TMS measures of LTD and E:I ratio; and
2. R-baclofen plasma levels and TMS measures of LTD and E:I ratio show a predictable exposure-response relationship.

Exploratory Aim 1: Whether the presence of genetic polymorphisms of the BDNF and GABA-B receptor genes has a moderating effect on TMS measures and on R-baclofen effects. We will test the following hypotheses:

1. Presence of the BDNF val66met allele will be associated with decreased long-term depression (LTD) of cortical excitability
2. Polymorphisms of GABA-B receptor genes will be associated with altered magnitude of response to R-baclofen as measured by TMS

Conditions

• Autism

Interventions

DRUG

R-baclofen

oral R-baclofen at 0x2, 3, 10, and 25 mg

Sponsors & Collaborators

• Boston Children's Hospital

  collaborator OTHER

• Seaside Therapeutics, Inc.

  collaborator INDUSTRY

• Gonzalez-Heydrich, Joseph, M.D.

  lead INDIV

Principal Investigators

• Joseph Gonzalez-Heydrich, MD · Boston Children's Hospital

• Alvaro Pascual-Leone, M.D. Ph. D. · Berenson-Allen Center for Noninvansive Brain Stimulation BIDMC

• Lindsay M Oberman, Ph. D · Berenson-Allen Center for Noninvansive Brain Stimulation BIDMC

Study Design

Allocation

RANDOMIZED

Purpose

BASIC_SCIENCE

Masking

QUADRUPLE

Model

CROSSOVER

Eligibility

Min Age

18 Years

Max Age

30 Years

Sex

ALL

Healthy Volunteers

Yes

Timeline & Regulatory

Start

2010-10-31

Primary Completion

2012-07-31

Completion

2012-07-31

Countries

• United States

Study Locations