The purpose of this research study is to examine the effects of transcranial Direct Current Stimulation (tDCS) on verbal retrieval and cognition and sensorimotor control and to determine if tDCS can be used as a way to improve retrieval, sensory, and motor abilities in individuals with Parkinson's disease (PD).
Diagnosed with PD having a verbal fluency deficit based on neuropsychological test (T-score < 40 or a T-score <-1.0 SD below the average T-score): Semantic Object Retrieval Test (SORT), COWAT (both letter and category fluency), Boston Naming Test (BNT), Rey Auditory Verbal Learning Test (RAVLT)
50 - 90 years old
Capable of understanding and signing an informed consent (able to answer consent comprehension questions)
Fluent in speaking and reading English
Montreal Cognitve Assessment (MOCA) score <23, unless an accompanying study partner/caregiver is with them and we can obtain the written consent of both the participant and the participant's accompanying study partner/caregiver (i.e., the participant's spouse, adult child, parent, or adult sibling);
history of seizures;
unexplained episodes of loss of consciousness (as these may be related to brain alterations or epilepsy);
suffering from severe or frequent headaches;
Parallel
transcranial direct current stimulation
DeviceTranscranial direct current stimulation will be delivered via a Neuroelectrics Starstim tES. Stimulation will consist of 1 milliamp stimulation, with anodal stimulation delivered at electrode Fz (International 10/10 System for electroencephalography electrode placement) and electrodes F7, FP1, FP2, and F8 as returns. All electrodes are 1 cm diameter Ag/AgCl electrodes and make contact with the scalp via connective gel. Stimulation will linearly ramp up from 0 milliamps to 1 milliamp over 60 seconds, then remain at 1 milliamp of stimulation over 20 minutes, and finally ramping down at to 0 milliamps over 60 seconds.
Sham transcranial direct current stimulation
DeviceSham transcranial direct current stimulation will be delivered via a Neuroelectrics Starstim tES. The sham setup will consist of anodal electrode Fz (International 10/10 System for electroencephalography electrode placement) and electrodes F7, FP1, FP2, and F8 as returns. All electrodes are 1 cm diameter Ag/AgCl electrodes and make contact with the scalp via connective gel. Stimulation will linearly ramp up from 0 milliamps to 1 milliamp over 60 seconds, ramp down to 0 milliamps over 60 seconds and then be left off for 20 minutes.
Treatment group differences in change from Baseline to 1-week Post-Treatment on Category Fluency
valuation of treatment group differences in change on Category Fluency from baseline to 1-week post-treatment. Metric: Number of Correct Items Generated (minimum=0 words; no maximum)
Treatment group differences in change from Baseline to 2-months Post-Treatment on Category Fluency
Evaluation of treatment group differences in change on Category Fluency from baseline to 2-months post-treatment. Metric: Number of Correct Items Generated (minimum=0 words; no maximum)
Treatment group differences in change from Baseline to 1-week Post-Treatment on Phonemic Fluency
Evaluation of treatment group differences in change on Phonemic Fluency from baseline to 1-week post-treatment. Metric: Number of Correct Items Generated (minimum=0 words; no maximum)
Treatment group differences in change from Baseline to 2-months Post-Treatment on Phonemic Fluency
Evaluation of treatment group differences in change on Phonemic Fluency from baseline to 2-months post-treatment. Metric: Number of Correct Items Generated (minimum=0 words; no maximum)
Treatment group differences in change from Baseline to 1-week Post-treatment on Speaking Rate during overt reading
Evaluation of treatment group differences in change in speaking rate from baseline to 1-week post-treatment. Metric: syllables per second on a passage reading task (minimum=0; no maximum).
Treatment group differences in change from Baseline to 2-months Post-Treatment on Speaking Rate during overt reading
Evaluation of treatment group differences in change on speaking rate from baseline to 2-months post-treatment. Metric: Syllables per second during a reading passage (minimum=0; no maximum).
Treatment group differences in change from Baseline to 1-week Post-treatment on Speaking Rate during self-generated speech
Evaluation of treatment group differences in change in speaking rate from baseline to 1-week post-treatment. Metric: Syllables per second during self-generated speech (minimum=0; no maximum).
Treatment group differences in change from Baseline to 2-months Post-Treatment on Speaking Rate during self-generated speech
Evaluation of treatment group differences in change on speaking rate from baseline to 2-months post-treatment. Metric: Syllables per second during self-generated speech (minimum=0; no maximum).
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The University of Texas at Dallas
Lead sponsor
University of Texas Southwestern Medical Center
Collaborator
