Transcranial Direct Current Stimulation for Primary Progressive Aphasia

Baseline Performance Predicts tDCS-mediated Improvements in Language Symptoms in Primary Progressive Aphasia

In the present sham-controlled study, the investigators examine whether tDCS could be used to enhance language abilities (e.g., picture naming) in individuals with primary progressive aphasia (PPA) primarily characterized by difficulties with speech production.

Primary Progressive Aphasia (PPA) is a neurodegenerative condition characterized by insidious irreversible loss of language abilities. Prior studies suggest that transcranial direct current stimulation (tDCS) directed toward language areas of the brain may help to ameliorate symptoms of PPA. In the current study, the investigators are examining whether tDCS could be used to enhance language abilities (e.g., picture naming) in individuals with PPA variants primarily characterized by difficulties with speech production (non-fluent and logopenic). Participants are being recruited from the Penn Frontotemporal Dementia Center to receive 10 days of both real and sham tDCS (counter-balanced, full-crossover design; participants are naïve to stimulation condition). A battery of language tests are being administered at baseline, immediately post-tDCS (real and sham), and six weeks and twelve weeks following stimulation. Real tDCS may improve language performance in some individuals with PPA. Specifically, the investigators expect that tDCS will be more effective in people whose baseline performance is worse based on previous research. Severity of deficits at baseline may be an important factor in predicting which patients will respond positively to language-targeted tDCS therapies.

Transcranial direct current stimulation (tDCS) is a type of noninvasive brain stimulation that modulates the resting excitability of neuronal populations, thereby altering patterns of brain activity in potentially behaviorally relevant ways. The stimulation involves 20 minutes of constant stimulation at 1.5 mA.

Sham tDCS uses identical stimulation parameters as the active condition, however terminates after 30 seconds in order to mimic the sensation of real tDCS.

Transcranial direct current stimulation (tDCS) is a type of noninvasive brain stimulation that modulates the resting excitability of neuronal populations, thereby altering patterns of brain activity in potentially behaviorally relevant ways. The stimulation involves 20 minutes of constant stimulation at 1.5 mA.

Aphasia Severity (WAB-AQ): Effects of Active tDCS (Baseline vs. 0 Weeks Immediately Following Stimulation)

The Western Aphasia Battery (WAB) was administered at baseline and immediately post-tDCS (real; sham) following the termination of the tDCS session on the same day (0 week). We computed WAB-Aphasia Quotient (WAB-AQ), a measure of overall aphasia severity with higher scores indicating better language performance. The WAB assesses the following language domains in subtests: fluency, comprehension, repetition, and naming. We examined change in WAB-AQ and each of the sub-tests from baseline. Difference scores were computed by subtracting the post-intervention score (0 weeks) from baseline for each study arm to assess the impact of real/active vs sham tDCS on severity and each sub-test. Scale title: WAB-AQ; scale values: 0-100; higher scores=better outcome.

Naming Ability (WAB Naming Subtest): Effects of Active tDCS Baseline vs. 0 Weeks Immediately Following Stimulation

WAB-naming subtest used common objects as stimuli. Participants were required to name the objects. Three-point maximum score could be earned for each stimulus and a total of 60-points could be earned on this task; points were deducted if the response was incorrect and required a cue or if the response included a paraphasia.

Inclusion Criteria: Between the ages of 45-80 Native English speaker Diagnosed with Primary Progressive Aphasia Subject understands nature of study and able to give informed consent Exclusion Criteria: Cognitive impairment of sufficient severity to preclude giving informed consent History of seizures or unexplained loss of consciousness Previous craniotomy or any breach of the skull Metallic objects in the head or face other than dental braces, fillings or implants Pacemaker or implantable cardioverter-defibrillator Pregnant

McConathey EM, White NC, Gervits F, Ash S, Coslett HB, Grossman M, Hamilton RH. Baseline Performance Predicts tDCS-Mediated Improvements in Language Symptoms in Primary Progressive Aphasia. Front Hum Neurosci. 2017 Jun 30;11:347. doi: 10.3389/fnhum.2017.00347. eCollection 2017.