Abstract Details

Title Differential Response to Transcranial Direct Current Stimulation Across Primary Progressive Aphasia Subtypes: A Case Study Analysis

Topic Aging, Dementia, and Behavioral Neurology

Presentation(s) P6 - Poster Session 6 (5:00 PM-6:00 PM)

Poster/Presentation
Number 13-008

Objective To examine whether frontal high-definition tDCS (HD-tDCS) paired with modified constraint-induced language therapy (mCILT) differentially benefits participants with the nonfluent/agrammatic variant (naPPA) versus logopenic variant (lvPPA).

Background Primary Progressive Aphasia (PPA) comprises neurodegenerative syndromes with variant-specific language network damage. naPPA affects frontal regions, while lvPPA involves posterior temporoparietal areas. While behavioral therapies are standard care, transcranial direct current stimulation (tDCS) has emerged as a promising potential intervention. Two frameworks exist for optimizing tDCS stimulation location: the restitution hypothesis proposes stimulating damaged regions to rescue function, while the compensation hypothesis suggests stimulating preserved regions to enhance compensatory mechanisms.

Design/Methods We analyzed two participants from an ongoing NIH-funded R01 crossover study. Participants received 10 sessions of active or sham HD-tDCS over the left frontotemporal region paired with mCILT across two separate 12-week treatment arms. We examined noun and verb accuracy during a 96-item picture naming task using within-subject paired t-tests comparing baseline to 6-week performance.

Results The naPPA participant demonstrated significant noun improvement during active stimulation (change score = +0.219, p = 0.017) and trending verb improvement (CS = +0.219, p = 0.07), with minimal sham response for nouns (CS = +0.031, p = 0.745) and verbs (CS = +0.063, p = 0.423). The lvPPA participant showed significant improvement in nouns during sham stimulation (CS = +0.313, p = 0.005) but not verbs (CS = +0.063, p = 0.325) and no significant improvement during active stimulation for nouns (CS = -0.063, p = 0.325) and verbs (CS = +0.063, p = 0.325).

Conclusions Findings support the restitution hypothesis: naPPA showed selective improvement with active stimulation while lvPPA showed no significant benefit. However, individual-level factors like low baselines and testing fatigue could introduce confounds, while near-significant statistics demonstrate insufficient power. Group-level analyses of the full R01 cohort are essential to address limitations and establish evidence-based treatment protocols.

Authors/Disclosures
Oluwasijibomi Osunkoya PRESENTER	Mr. Osunkoya has nothing to disclose.
Catherine Norise, MD (Penn Memory Center)	Dr. Norise has nothing to disclose.
Roy H. Hamilton, MD, MS, FANA, FAAN	Dr. Hamilton has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Highland Instruments. Dr. Hamilton has received personal compensation in the range of $0-$499 for serving on a Scientific Advisory or Data Safety Monitoring board for Cognito Therapeutics. Dr. Hamilton has received personal compensation in the range of $10,000-$49,999 for serving as an officer or member of the Board of Directors for McKnight Brain Research Foundation. The institution of Dr. Hamilton has received research support from NIH. The institution of Dr. Hamilton has received research support from Department of Defense. The institution of Dr. Hamilton has received research support from Chan Zuckerberg Initiative.

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