Reductions in GABA following a tDCS-language intervention for primary progressive aphasia

Ashley D. Harris, Zeyi Wang, Bronte Ficek, Kim Webster, Richard AE Edden, Kyrana Tsapkini

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


Transcranial direct current stimulation (tDCS) has shown efficacy in augmenting the effects of language therapy in primary progressive aphasia (PPA). The mechanism of action of tDCS is not understood, but preliminary work in healthy adults suggests it modulates γ-aminobutyric acid (GABA) levels to create an environment optimal for learning. It is unknown if this proposed mechanism translates to aging or neurodegenerative conditions. This study tested the hypothesis that tDCS reduces GABA at the stimulated tissue in PPA. We applied GABA-edited magnetic resonance spectroscopy to quantify GABA levels before and after a sham-controlled tDCS intervention with language therapy in PPA. All participants showed improvements but those receiving active tDCS showed significantly greater language improvements compared to sham both immediately after the intervention and at 2-month follow-up. GABA levels in the targeted tissue decreased from baseline after the intervention and remained decreased 2 months after the intervention. This work supports the hypothesis that tDCS modulates GABAergic inhibition to augment learning and is clinically useful for PPA combined with language therapy.

Original languageEnglish (US)
Pages (from-to)75-82
Number of pages8
JournalNeurobiology of aging
StatePublished - Jul 2019


  • Anodal tDCS
  • GABA-edited MRS
  • Language therapy
  • Learning
  • Neural plasticity
  • Neurodegenerative disorder

ASJC Scopus subject areas

  • General Neuroscience
  • Aging
  • Clinical Neurology
  • Developmental Biology
  • Geriatrics and Gerontology


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