Neural Systems of Stuttering: Anatomical, Functional, and Treatment Studies

Hypothesis

Hypothesis

Hypothesis:
1. If developmental stuttering is associated with atypical cerebral anatomy, then structural anomalies on volumetric MRI will be more common in adults who stutter in comparison to healthy matched controls.

2. If developmental stuttering is associated with atypical function activation, then adults who stutter will have atypical activation during a fMRI language test in comparison to healthy fluent adults.

3. If adults who stutter have increased dopamine activity, then treatment with a dopamine blocking agent should improve fluency, and may reverse the atypical fMRI activations observed with dysfluency. Specific subject variables and anatomic anomalies may be associated with treatment response.

Goals:
1. To determine whether anatomy of speech, language, and motor areas differs when adults who stutter are compared to fluent matched controls.

2. To determine whether activation-deactivation of speech, language, and motor areas differs when adults who stutter are compared to controls, and to determine whether there is a relationship between anatomic and functional asymmetries.

3. To determine whether adults who stutter respond to a dopamine blocking agent, and to learn whether there is a relationship between activation-deactivation patterns and response.

Methods:
Forty right-handed adults between the ages of 18 and 45 will be enrolled. Twenty will have a history of persistent developmental stuttering, and twenty will be healthy fluent controls matched for age, education, and handedness.

For Goal 1, three anatomical regions will be measured on volumetric MRI: Pars Triangularis, Planum Temporale, and Motor Knob. Total Brain Area will be measured in order to compare absolute and proportional volumes. Size and asymmetry of the regions will be compared between groups.

For Goal 2, the Fox et al PET paradigm will be modified for fMRI administration. Choral reading will be contrasted with solo paragraph reading in adults with PDS and in healthy matched controls. Subjects will subvocalize in the scanner, and will be evaluated in the same two conditions outside of the scanner in order to evaluate induced fluency in the stuttering group.

For Goal 3, A double-blind placebo controlled crossover design will be used to evaluate whether the administration of risperidone will decrease the severity of stuttering. Half of the sample will be randomly selected to receive 6 weeks of risperidone treatment first. The other half will be randomly assigned to receive the placebo treatment first, followed by a two-week washout period. The fMRI paradigm described in Goal 2 will be used, and each study subject will have MRI studies and fluency measures conducted three times.